Incidence / Prevalence / Risk Factors

The most common procedure performed by veterinary orthopedic surgeons is cranial cruciate ligament (CCL) repair.  In the United States, owners spent an estimated 1.3 billion dollars in 2003 for treatment of ruptured cruciate ligaments in dogs.  CCL rupture is the most common stifle injury in dogs.

Predisposing factors are identified as age-related ligament degeneration, pre-existing inflammation, anatomical abnormalities, excessive tibial slope, hormone imbalance and repetitive trauma.  The effected joint is commonly somewhat arthritic by the time the rupture occurs.

Thirty to forty percent of dogs who have one cruciate ligament surgically repaired will tear the contralateral ligament at some point.  This estimate may be conservative, as other sources quote this number as being nearly fifty percent.

Nearly one-third of dogs with ruptured CCL show degenerative joint disease in the hip joint, and over forty percent of dogs with bilateral ruptures have osteoarthritis in the hip.

Normal Stifle Anatomy of the Dog

Normal healthy range of motion in the canine stifle joint is reported to be 40 to 45 degrees flexion and 160 – 165 degrees extension.  Arthritic animals may exhibit reduced ranges, especially in extension where the joint is more compressed.

The canine stifle joint consists of the femur proximally, the tibia distally, the patella anteriorly, and the fabellae posteriorly.  In between the femoral and tibial condyles, medial and lateral menisci are found.  Sixty-five percent of the compressive load in the stifle is distributed by the menisci.  All of these surfaces are contained in a single synovial capsule.  A medial collateral ligament runs between the medial femoral epicondyle and the proximal tibia, posterior on the joint.  The lateral collateral ligament runs between the lateral femoral epicondyle and the fibular head, again, posterior on the joint.  Sesamoid bones exist in the gastrocnemius and popliteal tendons.

The patellar ligament attaches to the tibial tuberosity distally.  This attachment is also the insertion of the quadriceps femoris.  Attachments to the femur include the proximal attachment of the patellar ligament and the paired collateral femoropatellar ligaments which wrap around to the sesmoids in the gastrocnemius tendons.

The cruciate ligments are named for their relative tibial attachments.  The caudal (or medial) cruciate ligament runs from the posterior tibial plateau (behind the caudal attachment of the medial meniscus) to the medial intercondylar fossa of the femur.  It prevents caudal translation of the tibia.  It is at greatest risk when the stifle is in a flexed position.

The cranial (lateral) cruciate ligament crosses through the intercondylar fossa at right angles to the caudal cruciate ligament.  Its attachments are the anterior tibial plateau and the lateral femoral condyle.  This ligament prevents cranial translation of the tibia, limits internal rotation of the tibia, and prevents hyperextension of the stifle.  It is at greatest risk when the stifle joint is in extension.

Extensors of the stifle include:  rectus femoris, vastus lateralis, vastus intermedius and vastus medialis (collectively known as quadriceps femoris), and cranial part of sartorius – innervated by the femoral nerve (L4-6); popliteus – innervated by the tibial nerve (L7 – S1); biceps femoris – cranial portion and semimembranosus femoral and tibial attachment – innervated by sciatic nerve (L6-S2); tensor fasciae latae – innervated by cranial gluteal nerve (L6-S1).

Flexors of the stifle include:  gastrocnemius and superficial digital flexor – innervated by tibial nerve (L7-S1 ); biceps femoris – caudal portion, semitendinosus, semimembranosus tibial attachment – innervation sciatic nerve (L6 – S2 ); caudal part of sartorius – innervated by femoral nerve (L4-6); gracilis – innervated by obturator nerve (L4-6).

Peroneus longus crosses the stifle joint by connection to the lateral collateral ligament – innervated by the peroneal nerve (L6-7).

The cranial cruciate ligament is the only passive restraint resisting cranial translation of the tibia.  But, the muscles crossing the stifle joint anteriorly also provide active restraint against anterior tibial translation.

What happens when a CCL is torn?  Signs, symptoms, testing, and radiography

The rupture is often a gradual process, starting out with a partial tear that worsens over time.  Early signs include stifle stiffness and progressive lameness.

Complete ruptures generally present as three-legged lameness for a short time.  In larger breed dogs, the lameness is expected to be chronic unless surgery is performed.  Some believe that scar tissue formation can sufficiently re-stabilize the joint in smaller dogs and cats after 8 weeks of cage rest.  In all of the non-surgical cases studied, 4 months were required to show maximum improvement.

Swelling at the stifle joint will most likely be present with a ruptured CCL for a short time following the injury.  Cranial translation under the weight of the femoral condyle may cause crush injuries of remaining meniscal tissue, the medial meniscus is particularly susceptible to this.

The “drawer sign” is the definitive sign for a ruptured CCL.  This type of cranial translation of the tibia is not possible with an intact CCL.  The drawer sign is tested for by stablizing the femur with one hand and pushing the tibia in a cranial direction with the other.  This is generally done with the dog lying on its side.  Any amount of cranial translation of the tibia is abnormal.  The drawer sign can also be elicited by stabilizing the femur and flexing the hock.  Sometimes sedation is required to elicit the drawer sign because tight muscles can mask it in a strong, splinting or otherwise anxious dog.

Resistance to full stifle extension can indicate partial ligamentous or meniscal tears.  MRI or arthroscopy may be required to confirm partial tears.

Subtle lameness of a partial tear may present as short striding in the rear, or a “stiff” rear limb that does not flex equally to the contralateral limb – it is held in a fixed, partly flexed position and perhaps even circumducted with gait.  A dog may sit on the hip opposite the injury, with the effected leg extended out to the side – known as the “positive sit test.”

On palpation, indistinct medial and lateral edges of the patellar ligament can indicate joint effusion.  They should be sharply palpable in a healthy stifle joint.

Medial buttress (periarticular fibrosis) is a sign of chronic stifle instability and stifle arthritis.

Reports state that osteophytes can develop as quickly as 1-3 weeks after CCL rupture.

When the CCL tears, it frequently tears part of the medial meniscus with it.  Meniscal damage may or may not exhibit audible clicking on flexion  extension.  Crepitus on flexion / extension is often present with osteoarthritis.

Treatment Options

Prevention of cranial drawer motion of the tibia is thought to be the most significant function of the CCL.  This is because the tibia is under pressure to translate cranially  even in stationary weight-bearing due to the downward caudal slope of the tibial plateau meeting the downward pressure of the femur.  Therefore, surgical interventions are aimed at neutralizing cranial tibial thrust.  The ultimate goals of surgery are the minimization of degenerative joint disease (DJD) progression and management of meniscal injury.

Radiographs aid in making the post-surgical prognosis.  If advanced DJD is present already, potential pain reduction may be considerably limited.  Radiographs obviously will not visualize the torn ligament, but will help reveal indicators like joint effusion and osteophytes.

The most common surgical treatments for a ruptured CCL are extracapsular repair, tibial tuberosity advancement, and tibial plateau leveling osteotomy.

Extracapsular Repair

The joint is opened and inspected.  The damaged ligament and or meniscal material is removed.  Significant bone spurs are removed.  A thick suture material is used to form a loop around the lateral side of the stifle. It loops around the fabella through a hole drilled in the front of the tibia.  The suture material effectively replaces the lost ligament and restabilizes the knee.  The suture stabilizes the joint only temporarily.  It will likely break within months of insertion, or may have to be removed due to rejection by the animal’s body.  The body will produce fibrous material in response to the implant.  This fibrous material becomes the new stabilizing apparatus.  The extracapsular repair is the least expensive of the three common surgical repair techniques, costing approximately $900 to $1500.

Tibial Tuberosity Advancement (TTA)

TTA is the mid-priced option – costing around $1800 – $2000.  This procedure neutralizes the contribution of the quadriceps muscle to cranial tibial thrust and also results in caudal tibial thrust at certain points of the stance phase of gait.  The attempt is to reduce the shear force created between the femur and tibia when the dog walks by repositioning the tibial plateau and the patellar ligament at 90 degrees to one another. The change in the relative angle is created by separating the tibial tuberosity from the tibia, tipping the proximal portion anteriorly, reattaching it to the tibia using titanium or steel cage, fork, and plate.  Bone grafts are used to aid healing.  Recovery time may be longer than the other procedures.

Tibial Plateau Leveling Osteotomy (TPLO)

The tibial plateau normally slopes downward from anterior to posterior.  The TPLO levels the tibial slope so that weight / gravity will not cause the femur to slide backward down the tibial slope in the absence of the tethering effect of the CCL.  The torn ends of the ligament are removed, and the meniscus is examined for damage.  If tears are found in the meniscus, the damaged portions are removed.  The leveling of the tibial slope is done by making a curved cut in the bone, rotating the fragment approximately ¼ turn anteriorly to leave a flat surface on the proximal end of the tibia.  A plate (or plates) with screws, holds the rotated fragment in place while the bone pieces knit together.  This procedure is currently the most expensive of the three, costing approximately $2,500 or more.

Intracapsular Repair

No longer popular in theU.S., but reportedly used frequently in theU.K.It takes more time surgically than the extracapsular repair, likely making it more expensive.  However, it has not been proven to give superior results.  The stifle joint is opened and damaged material is removed.  A new ligament is created by a strip of fascia dissected from an adjacent area and threaded through the intercondylar fossa.  It is attached at the caudal point by an implant or sewn into place.

It has been noted that even dogs with old injuries and advanced arthritis in the damaged joint might still benefit from TPLO or TTA.  But, these benefits will be limited by the extent of their arthritis.

Normal range of motion can be restored after surgeries like these with proper rehabilitation. If dogs don’t get rehabilitation after stifle surgery they tend to lose 5 to 10 degrees range of motion.

Rehabilitation Protocols

Depending on where the dog has its surgical procedure performed, the owners may or may not receive a recommendation for professionally-provided physical therapy and rehabilitation including hydrotherapy and proprioceptive training.  Some typical components of basic post-surgical care are outlined in the following paragraphs.

Stairs are to be avoided for the first 8 weeks.  Also, during this time period a physical support harness is suggested to help the animal navigate slippery surfaces.  This physical support should also be employed when stairs are unavoidable.

For the first two months, leash walking is recommended.  Running or jumping are to be avoided.

Toe-touch weight bearing is expected to begin within the first 2 weeks, followed by steady improvement.  If this is not happening, a veterinary recheck is advised to see if infection or implant failure may be present.

Restrictions on activity should continue for two full months, even though the animal will probably seem fully capable prior to the end of that time.  The bone must be given sufficient time to heal completely.

These animals should be kept on the lean side of optimal their entire lives.  Ribs should be palpable but not visible.  The dog should have a waist when viewed from above and from the side.

Glucosamine / chondroitin supplements are an excellent consideration.

Sutures are removed 10-14 days post treatment.  Follow-up radiographs are generally recommended two months post-treatment for TPLOs and TTAs.

Typical Components of Home-Care Rehabilitation Regimen

1^st week

Reduction of Inflammation and Initiation of Motion 

Focus of first 1-2 days is to minimize swelling with ice packs.  After redness and swelling have resolved, approximately 3^rd day, rehabilitation can begin, generally with a warm compress followed by gentle passive range of motion (PROM) within comfort limits.  After approximately 3 days of PROM, 3-5 minute leash walks can begin.  Pace should encourage weight-bearing on all four limbs (four-beat gait, walking pace.)

2^nd and 3^rd weeks

First Stretching of Joint Tissues

PROM procedure continues.  When full flexion is achieved, the position is held.  Full extension should is held similarly.  Time for leash walking is doubled.

4^th and 5^th weeks

StrengthBuildingand Reduction of Adhesions

Sit to stand exercises are introduced.  Massage of skin over stifle joint and muscular tissues of the leg is performed.  Time for leash walking is doubled again.

6^th and 7^th week

Endurance

Continual walking on a short leash for 30 minutes, 1 – 2 x per day.

8^th thru 10^th week

Re-examination by veterinarian should occur.  Increase strength, begin to challenge joint.

Walks increase by 10 minutes.  Stair climbing is re-introduced, at a walking pace.  Jogging begins, and swimming can be added to regimen as long as entry and exit from the water involve walking in, without jumping or climbing.

11^th week

Light play exercise with toys, i.e. tugging.

12^th – 16^th week

Healing should be complete and activity restrictions are removed.

“Special thanks to Rachel Huseby for her contribution in creating these online courses.”

Take the test to complete this course.

References

Brooks, Wendy C. “Ruptured Anterior (Cranial) Cruciate Ligament.” VeterinaryPartner.com. Veterinary Information Network, Inc.,10 Feb. 2009. Web.02 Oct. 2010. <http://www.veterinarypartner.com/Content.plx?P=A>.

“Cranial Cruciate Ligament Injury.” Advanced Veterinary Care Center. Web.15 Oct. 2010. <http://www.advancedveterinarycarecenter.com/veterinary-specialty.asp?spec=su&specID=53>.

Dyce, K. M., W. O. Sack, and C. J. G. Wensing. Textbook of Veterinary Anatomy.Philadelphia: Saunders, 2002. Print.

Evans, Howard E., Alexander DeLahunta, and Malcolm E. Miller. Guide to the Dissection of the Dog.Philadelphia: W.B. Saunders, 2000. Print.

Harasen, G. “Canine Cranial Cruciate Ligament Rupture in Profile: 2002-2007.” Canadian Veterinary Journal 49 (2008): 193-94. Print.

Jaegger, G. “Reliability of Goniometry in LabradorRetrievers.” American Journal of Veterinary Research 63.7 (2002): 979-86. Print.

“Joint Kinematics During Aquatic and Land Treadmill Activity in Dogs with Surgically Repaired Cranial Cruciate Ligament Injury.” Canine Rehabilitation and Biomechanics.University of Louisville. Web.02 Oct. 2010. <http://louisville.edu/speed/research/centers-and-labs/irap/canine-rehabilitation.html>.

Tomlinson, Julia. Personal Communication.9 Nov. 2010. Email. Twin Cities Animal Rehabilitation Clinic,Burnsville, MN.

Twin Cities Veterinary Surgery. Post-operative Information: Tibial Plateau Leveling Osteotomy (TPLO). Print.

Weh, Michael. “Canine CCL Injury: Diagnosis and Surgical Decision Making.” Proc. of CVC in Baltimore,Baltimore,MD.1 Apr. 2010. Web.1 Nov. 2010. <http://veterinarycalendar.dvm360.com/avhc/Medicine/Decision-making-in-cranial-cruciate-injuries-Proce/ArticleStandard/Article/detail/727339?contextCategoryId

Urinary Incontinence – Prevalence

A commonly used veterinary reference text reports that urinary incontinence will affect more than 20% of spayed female dogs. It is most common in the larger breeds. Early tail docking, obesity and concurrent vaginal abnormalities are recognized as factors that may increase risk.

Urinary incontinence is rare in cats. However, detrusor muscle instability has been associated with feline leukemia.

Urinary incontinence is a serious matter when it occurs in a companion animal. It can change the mood of a household and dramatically impact the animal’s quality of life. Even if logistics and sanitation are handled well, urine scald can cause discomfort for the animal. Urinary incontinence often compels owners to consider euthanasia of an animal that is otherwise reasonably functional and healthy.

Subluxations can contribute to an animal’s ability to store and void urine appropriately. Having a solid understanding of the neurological pathways behind these processes may increase your effectiveness as a practitioner; and potentially keep a family together, happier and longer.

Urinary System Review

The urinary system begins with the kidneys, paired retroperitoneal structures located slightly cranial to the mid-lumbar region. Their blood supply comes from the renal arteries, which are direct branches from the aorta. The kidneys receive neurological input from the autonomic nervous system. Sympathetic input stimulates renin secretion, decreases filtration rate, stimulates sodium reabsorption and contraction of the ureters. Parasympathetic input causes relaxation of smooth muscle in the kidney and upper ureter.

Urine leaves the kidney via the ureter, a tube made of smooth muscle. Urine is transferred from the kidneys to the bladder by peristalsis in the ureters. The ureter enters the bladder at an angle oblique enough to, under normal conditions prevent backflow from a full bladder into the ureter.

The bladder acts as a holding station for urine and a neurological relay station for the processes of storage and voiding. The smooth muscle portion of the bladder is called the detrusor muscle. It is located in the bladder wall. When the detrusor muscle contracts, it increases pressure within the bladder causing it to empty.

Urine leaves the bladder via the urethra. At the proximal end, the neck, of the urethra, smooth muscle creates the internal urethral sphincter. Generally, the internal urethral sphincter is less well developed in females than in males. The distal end of the urethra is encircled by striated muscle known as the external urethral sphincter.

How Does Micturition Occur?

Micturition Reflex

Expansion of the bladder as it fills initiates a spinal bladder-emptying reflex via the pelvic splanchnic nerve. The pelvic splanchnic nerve contains both sensory and preganglionic parasympathetic fibers. The sensory fibers sense stretch in the bladder wall. Parasympathetic fibers in the pelvic nerve innervate the detrusor muscle, causing its contraction. Contraction of the detrusor muscle causes the bladder to empty. The preganglionic parasympathetic nerve cell bodies reside in the intermediolateral cell column (IML) in the sacral spinal cord. The preganglionic fibers synapse with the postganglionic fibers at or near the bladder wall. Main segmental contributions reported for the pelvic splanchnic nerve in the dog are S1-S3.

Tonic Inhibition of the Micturition Reflex

via Sympathetics

Sympathetic stimulation at low levels directly inhibits the parasympathetic input to the detrusor muscle, allowing the detrusor muscle to relax and stretch. These sympathetic fibers originate in the IML around the thoracolumbar levels of the spinal cord. These preganglionic sympathetic fibers synapse at the inferior mesenteric ganglion and ganglia of the pelvic plexus. Fibers travel in the hypogastric and pelvic nerves.

This same sympathetic input also holds tone on the internal urethral sphincter muscle. Normal tone on the internal sphincter keeps the proximal urethra empty. The proximal urethra is especially stretch sensitive and strongly engages the micturition reflex when urine begins to enter.

Sympathetic innervation to the bladder also controls the blood vessels supplying the bladder. These fibers originate in the upper lumbar spine. It is believed that some sensory information travels through the sympathetic nerves, likely sensation of visceral pain.

via Striated Muscle

Tone is held on the external urethral sphincter by somatic (voluntary) motor fibers that travel via the pudendal nerve. Nerve cell bodies of the pudendal nerve are located in the ventral horn of the sacral spinal cord, S1-3, in “Onuf’s nucleus.” The external urethral sphincter itself is located in the urogenital diaphragm.

Voluntary Urination

Voluntary urination is usually initiated by contraction of the abdominal muscles which increases pressure on the bladder wall. Stretch receptors in the proximal urethra are excited, stimulating the micturition reflex. The reflex is self-regenerative, initial contraction of the bladder causes further excitation of stretch receptors, continuing until the bladder is nearly empty and the stretch receptors are silenced. Voluntary urination also involves inhibition of the tonic contraction of the striated muscle of the external urethral sphincter.

Suprasegmental Control

Bladder filling is primarily organized in the spinal cord, whereas coordinated and conscious voiding involves higher centers – coordination of storage and voiding occurs in the pontine micturition center (PMC, a.k.a. Barrington’s nucleus) and conscious decisions to void involve the cerebral cortex.

Suprasegmental control comes into play when the bladder becomes full. This suprasegmental control inhibits both sympathetic and somatic activities. (The relaxation of the bladder wall is shut down, tone on the internal and external urethral sphincters are decreased.) The parasympathetic activity becomes dominant and the bladder wall contracts to express the urine.

PMC cells send fibers to excite parasympathetic preganglionic motor neurons in the sacral IML, which in turn stimulate contraction of the detrusor muscle. The same PMC cells fire to interneurons at the thoracolumbar and sacral levels of the spinal cord. Interneurons at the thoracolumbar level inhibit the sympathetic fibers that provide inhibition of detrusor contraction and support tonic contraction of the internal urethral sphincter. Interneurons in the sacral cord inhibit fibers that support tonic contraction of the external urethral sphincter.

The frontal lobe appears to be involved in the inhibition of micturition until a socially appropriate situation presents itself. The hypothalamus and periaqueductal grey matter (PAG) in the mesencephalon are the only areas which seem to have monosynaptic contact with the PMC.

The PAG receives information from the bladder and relays it to the conscious control areas in the cerebral cortex. The PAG is the area that provides inhibitory input to the PMC, preventing voiding until an appropriate time as decided by the cortex. It is believed that voluntary voiding involves and interruption of the tonic suppression of the PMC by the PAG. Studies of the PMC show that the lateral region is charged with continence, while the medial region is responsible for activation of micturition.

The PMC is located in the dorsolateral pontine tegmentum and overlaps with the locus coeruleus. The PMC contains direct, inverse, and independent neurons. Direct neurons project to the spinal cord and appear to be directly associated with bladder contraction. Inverse may be involved with bladder relaxation phase, and independent neurons may associate micturition and attention via close relationship with locus coeruleus. (Locus coeruleus is most active in situations requiring attention and/or vigilance.)

Some evidence shows that the potential for evoking micturition increases with time from the last act of micturition, based on the behavior of certain direct neurons.

Innervation Review

by Individually Named Nerves

Hypogastric Nerve: Preganglionic fibers originate in the IML near the thoracolumbar junction and synapse in the caudal (inferior) mesenteric ganglion. The hypogastric nerve leaves the caudal mesenteric ganglion just caudal to the kidneys, and courses near the ureters. It enters the pelvis and connects to the pelvic plexus. It contains sympathetic fibers and (likely) visceral sensory fibers.

Pelvic Splanchnic Nerve: The pelvic splanchnic nerve contains preganglionic parasympathetic fibers originating from the ventral sacral rami and sympathetic fibers arriving via the hypogastric nerve. A retroperitoneal plexus is formed. The pelvic splanchnic nerve also contains sensory fibers relaying information from stretch receptors in the bladder wall.

Pudendal Nerve: The pudendal nerve originates from S1 – 3 nerve roots in the dog. The nucleus of origination is called “Onuf’s Nucleus.” The nerve courses just beneath the sacrosciatic ligament (one resources calls it “partly embedded” in the sacrosciatic ligament) dorsal to the internal pudendal artery. It carries sensory and somatic motor fibers – sensory from the urethra and external urethral sphincter, and motor to the striated muscle of the external urethral sphincter.

by Function

Afferent Systems: Sensations of bladder fullness and pain travel to the spinal cord via pelvic and hypogastric nerves, respectively. Sensory input from the bladder neck and urethra travels via the pudendal and hypogastric nerves. Stretch is conveyed via A-delta fibers, and nociception is carried via c-fibers. Nerve cell bodies for these sensory nerves are in the DRGs at sacral segments and the thoracolumbar junction.

Most afferent information from the bladder is transmitted to the PAG in the mesencephalon via the lateral funiculus. Additional sensory information from the bladder transmits via the spinothalamic tract, spinohypothalamic tract, and the dorsal columns.

Efferent Systems: Hypogastric and pelvic nerves provide sympathetic inhibition to the parasympathetic ganglia on the bladder wall and excitatory to the internal urethral sphincter. These sympathetic fibers originate in the IML of the spinal cord near the thoracolumbar junction.

Parasympathetic innervation to the bladder travels via the pelvic splanchnic nerves, providing motor input to the detrusor muscle. The preganglionic fibers originate in the IML of the sacral spinal cord.

Somatic motor neurons that innervate the external urethral and anal sphincters have their nerve cell bodies in Onuf’s nucleus within the sacral segments of the spinal cord. These nerve fibers travel in the pudendal nerve.

Urinary Incontinence – Causes

When an animal presents with urinary incontinence, testing for a urinary tract infection (UTI) should be performed. If no UTI is present, or if urinary incontinence persists after a UTI is resolved, a neurological cause should be investigated.

Neurological causes of incontinence can be categorized as follows:

Peripheral Nerve Lesions

Parasympathetic denervation will eliminate active contraction of the detrusor muscle leading to overflow incontinence. Overflow incontinence is characterized by the bladder filling to capacity and overflowing a few drops at a time. Small amounts of urine are leaked out, while larger amounts of urine are retained.

In humans, radical hysterectomy can cause damage to the parasympathetic innervation to the bladder. A radical hysterectomy removes the uterus, cervix, top part of the vagina, ovaries, fallopian tubes, lymph nodes, lymph channels, and tissue in the pelvic cavity that surrounds the cervix.

In animals, a spay removes the ovaries and the uterus. It is unlikely to cause parasympathetic denervation. However, surgical damage to the pelvic plexus should not be immediately ruled out when the animal’s history includes a surgery in the pelvic region.

Damage to the pelvic splanchnic nerve will not create complete sensory loss from the bladder due to sensation from the bladder neck and urethra traveling in pudendal nerve. However, the micturition reflex will not initiate without afferent information from stretch receptors in the bladder wall, which does travel solely in the pelvic splanchnic nerve.

Damage to sensory nerve fibers can be from a crush injury in the sacral region of the spinal cord or damage to the dorsal horn cells, as in ischemia or spinal stenosis.

Lesions of the cauda equina / conus medullaris

Cauda equina syndrome is caused compression of the sacral spinal nerves. This can result from a lumbar disc herniation that is central rather than dorsolateral. Because the sacral nerve roots lie closest to the midline in the cauda equina, they will be impacted most dramatically.

Cauda equina syndrome reflects lower motor neuron symptoms. Most often sensory and motor deficits are present. Sensory loss is in the pattern of “saddle anesthesia,” desensitization of the buttocks and perineum.

Urine will still be sent to the bladder via peristalsis in the ureters. But, the message from the brain to contract the detrusor muscle is interrupted. Continence is only via intrinsic elasticity in the urethra, as there is loss of voluntary control of the external sphincter. . The bladder fills to capacity, then overflow incontinence results. The postganglionic innervation to the detrusor will remain intact, but will be decentralized.

Spinal Lesions (Subpontine and Suprasacral)

When sympathetic input (originating in the thoracolumbar spinal cord) is compromised, the sensation of bladder fullness is still sent through the reflex arc and to the PAG. Parasympathetic contraction of the detrusor goes uninhibited. The internal urethral sphincter will be hypotonic. Urine can enter the proximal urethra freely. Voluntary control of external urethral sphincter is intact, and will be the only resistance to voiding when the reflex contraction of the detrusor muscle is initiated.

Afferent information is required for the PAG to take the brakes off the PMC. Absence of initiation of micturition by the PMC is very similar to the PMC being disconnected from the micturition machinery. Either way, the PMC can’t give the coordinated “go” signal to each system component.

Absence of initiation from the PMC results in dyssynergia of the sphincter and detrusor muscles. After a time, spinal reflexes will take over resulting in detrusor hyperreflexia, also known as “automatic bladder.” A hyperreflexic detrusor generally will not sustain a contraction long enough to completely empty the bladder. This leads to post-void residual urine left in the bladder, which can cause recurrent UTIs. This leads to increased reactivity of the bladder (a viscious cycle.) Anticholinergic medication will exacerbate this by suppressing the parasympathetic contraction of the detrusor muscle, creating an even less efficient voiding contraction.

The external urethral sphincter may not receive its inhibitory input, therefore the bladder must overcome the resistance of the external urethral sphincter via increasing pressure. This can cause urine back-up into the ureters and kidney damage.

Note: In any situation where the animal’s ability to urinate voluntarily is absent, owners should be trained in expressing the animal’s bladder by external means.

Brainstem Lesions (Pontine and Suprapontine)

Anisocoria is often found in cats having urinary incontinence associated with feline leukemia. False negatives can occur in feline leukemia screening tests. If anisocoria and urinary incontinence are present, retesting is advised even if previous tests for feline leukemia were negative.

Pontine lesions affecting storage and voiding of urine are often accompanied by internuclear opthalmoplegia (decreased or absent adduction in the affected eye) due to the proximity of the medial longitudinal fasciculus to the PMC.

Suprapontine lesions could cause overactive detrusor and decreased bladder capacity, due to potential elimination of the tonic suppression of the PMC by the PAG.

Lesions of the Cerebral Cortex

Lesions of the cerebral cortex may present as inappropriate decision making with regard to situation, or lack of awareness that urination has occurred. Disturbance in the conscious ability to switch between storage and voiding presents as failure of storage.

Common Veterinary Diagnosis – Urethral Incompetence

Dogs with urethral incompetence generally exhibit intermittent incontinence, often while sleeping. It is said to be common in spayed females. This condition is commonly treated by veterinarians with phenylpropanolamine hydrochloride, also known as Proin or PPA. PPA is a sympathomimetic which increases the sympathetic response of the body in general. In the case of micturition, it would increase tone on the internal urethral sphincter and reinforce the inhibition of the detrusor muscle.

Defecation

A study quoted in a common veterinary consult text indicated that 50% of pets with fecal incontinence are euthanized, making this an extremely important area of focus for animal chiropractors.

As in humans, animals have an enteric nervous system made up of Meissner’s and Auerbach’s plexuses. These systems have internal pacemakers and connections to the autonomic nervous system that can speed or slow activity in the enteric system. The details of this enteric nervous system are beyond the scope of this course. So, most of this exploration will discuss the digestive path of the animals we work with, and rely on the neurological review in the micturition section for the pathway / nucleus information. Addressing the peripheral systems, which we can do as chiropractors, can have a dramatic impact on bowel performance.

A dog’s intestine is approximately six times its body length, a cat’s – four times, and a horse’s – twelve times. Cat’s have no cecum, dogs have a minimal one, and a horse’s is approximately 1 meter in length or 4% of the full intestinal length. In dogs and cats the transition from small to large intestine is called the ileocolic junction.

Normal transit time through the gut in horses is 24-48 hours. In dogs, one study indicated that 50% of material reached the terminal ileum in 5.5 hours, and 95% in 12 hours. In cats, transit time in the small intestine was reported to be approximately 2 to 3 hours.

Much of the overall activity of the colon is directed to delay transit time, sending the bolus in a retrograde direction so additional processing can occur. Therefore, although it may seem counter-intuitive at first, decreased colonic activity is associated with diarrhea, while increased colonic activity is associated with constipation.

In general, defecation occurs 5-10 times per day in horses, and 2-3 times per day in carnivores. It is somewhat based upon how often the animal eats. Food entering the stomach stimulates evacuation of the colon, due to the gastrocolic reflex.

Conscious sensation of the need to defecate is originated by distension of the distal rectum. This information is carried toward the central nervous system by the pelvic splanchnic nerve. Incontinence without awareness is generally associated with dysfunction of the smooth muscle of the internal sphincter or impacted stool in the rectum. Neurologic sensory deficits may also be involved.

Contraction of the abdominal musculature initiates the process of defecation. Innervation involved in this part of the process is segmental, mid- to lower thoracic.

As in the bladder, there are two sphincter muscles associated with the anus, the internal anal sphincter (involuntary, smooth muscle, tone is held by the sympathetic nervous system) and the external anal sphincter (voluntary, striated muscle, innervated by the pudendal nerve.)

Parasympathetic Innervation: The vagus nerve supplies innervation to the gut, up to the splenic flexure. Sacral segments innervate the descending and sigmoid colon and the anorectum.

Sympathetic Innervation: Thoracolumbar sympathetic chain – through the celiac and mesenteric ganglia, terminating mostly in the enteric nervous system.

Conscious control seems to originate in the pre-frontal area and the anterior cingulate gyrus.

In a patient with fecal incontinence, examine the anal reflex, tone to tail, rear limb reflexes, placement and strength indicators to determine if the lesion is in the spinal cord and, if so, is pre- or post lumbar plexus.

Dysfunction in levator ani or coccygeus mm. may contribute to fecal incontinence due to its effect on the external anal sphincter tone.

Sometimes drugs are given to increase segmental (mixing) contraction of the bowel and slow overall gut transit time.

Incontinence involving diarrhea should cause investigation of fecal impaction causing overflow incontinence.

Fecal urgency is generally associated with dysfunction of the striated external anal sphincter or increased pressure in the bowel, i.e. diarrhea.

Common Veterinary Diagnosis – Megacolon

Constipation, obstipation and megacolon are all more common in cats than dogs. Some work is showing that megacolon in cats results from a disturbance in normal colonic smooth muscle function. Most severe dilation usually occurs in the transverse and descending colon, although the whole colon can be involved.

Information regarding the most common starting point for megacolon was unavailable – but my experience has shown that by the time a cat is being radiographed for this condition, both the transverse and the descending colon are generally involved.

Congenital abnormalities in the caudal spine, especially in Manx cats, are often concurrent with megacolon.

Other risk factors include previous pelvic fractures and conditions making defecation posture difficult or painful. Megacolon is also associated with low physical activity and obesity.

Sacral nerve trauma can result from a tail pulling injury. A practitioner should keep this in mind, especially when working with a cat that has unsupervised outdoor access or lives with small children.

Special thanks to Rachel Huseby for her contribution in creating these online courses.”

Take the test to complete this course.

References

Dyce, K. M., W. O. Sack, and C. J. G. Wensing. Textbook of Veterinary Anatomy.Philadelphia: Saunders, 2002. Print.

Felten, David L., Ralph F. Józefowicz, and Frank H. Netter. Netter’s Atlas of Human Neuroscience.Teterboro,NJ: Icon Learning Systems, 2003. Print.

Ferguson, M. “Localization of Sympathetic and Sensory Neurons Innervating the Rat Kidney.” Journal of the Autonomic Nervous System 16.4 (1986): 279-88. Print.

Fowler, C. J., D. Griffiths, and W. C. DeGroat. “The Neural Control of Micturiton.” Nature Reviews: Neuroscience 9 (2008): 453-66. Print.

Fowler, Clare. “Neurologic Bowel, Bladder and Sexual Dysfunction.” World Federation of Neurology. Elsevier Science B.V., 2001. Web.02 Oct. 2010. <http://www.wfneurology.org/seminarsClinicalNeurology.php>.

Guyton, Arthur C., and John E. Hall. Textbook of Medical Physiology.Philadelphia: Saunders, 2000. Print.

“Hysterectomy – Radical Hysterectomy.” Health-cares.net.18 July 2005. Web.05 Nov. 2010. <http://womens-health.health-cares.net/radical-hysterectomy.php>.

Kandel, Eric R., James H. Schwartz, and Thomas M. Jessell. Principles of Neural Science.New York: Elsevier, 1991. Print.

Kuipers, R., LJ Mouton, and G. Holstege. “Afferent Projections to the Pontine MicturitionCenterin the Cat.” Journal of Comparative Neurology 494 (2006): 36-53. Print.

Purves, Dale, and S. Mark Williams. Neuroscience.Sunderland,MA: Sinauer Associates, 2001. Print.

The cranial nerves provide access points the central nervous system (CNS,) via their nuclei in the brain stem.  With an intimate understanding of their function, a practitioner can identify weaknesses and asymmetries, mild to profound.  While profound weaknesses often point to more grave prognoses, mild asymmetries can indicate portions of the central nervous system that are simply functioning at a suboptimal level.

Stimulating weaker cranial nerve nuclei with appropriately targeted therapy can begin to “light up” specific areas of the CNS – strengthening these weakened areas by increasing  the frequency of local neuronal transmission.  From the brainstem nuclei, we increase input to the cerebellum and the cerebral cortex, and ultimately back to the body through the CNS’s efferent systems.

Using the information contained in this course, you should be able to accurately identify and support compromised components of the CNS, which in turn will help the body respond optimally to your chiropractic adjustments.  Metaphorically – If the car won’t start, doesn’t it make sense to get it rolling down a hill, picking up some momentum of its own before you pop the clutch?  Of course it does.

CN I – The Olfactory Nerve

ANATOMY AND FUNCTION 

CN I is a chemoreceptor that sends information directly to the cortex.  The uniqueness of this direct nature lies in the fact that it does not involve the thalamus.  Therefore, olfactory stimulus is unaffected by thalamic integration with other areas of the brain until after it hits the cortex.  CN I’s pathways to the cortex are entirely ipsilateral.  Contralateral connections do exist between the left and right tracts.  These are mainly inhibitory.  They function to allow an individual to better localize the source of a scent.

The epithelial cells of the olfactory system are continuously regenerated throughout life.  Regeneration takes about 60 days.

CN I terminates mainly in the piriform cortex, located where the cortex of the insula meets the cortex of the frontal lobe.  It also has direct connections to structures of the limbic system, which is why certain smells elicit memories or emotional responses.

In mammals the vomeronasal organ contains chemoreceptors that are sensitive to pheromones.  These signals are transmitted directly to the amygdala and hippocampus via the accessory olfactory bulb.

TESTING AND LESIONS 

CN I  is difficult to test for hemisphericity with animals, but testing can be attempted by holding one nostril shut.  See if the animal responds to smell of food in general first.  Then see if they respond to odors with one nostril held closed, i.e. attempting to target toward them, or are they just “sniffing to sniff.”

Problems with olfactory sense commonly stem from excessive mucous production, as in allergy or infection.  Excessive mucous can block the normal transport of stimulants to the chemoreceptors.  When olfactory desensitization is suspected, also search the animal’s history or physical presentation for possible trauma or neoplasm which may have damaged the nerve fibers extending through the cribriforme plate of the ethmoid bone.

Infections in the nasal cavity should be managed carefully, as the infection can be transmitted to the cranial cavity via meningeal sheaths covering the nerve fibers traversing the cribriforme plate.

Diminished or absent sense of smell can present in animals as loss of drives / responses.  Cats, particularly, will not eat what they cannot smell, even though they may be hungry.  What presents as inappetance may actually be an absence of olfactory input recognition.

Decreased stimulation of the amygdala by CN I can present as flatness of mood or “depression.”  Decreased stimulation of the cortex by CN I leads to decreased output, i.e. “laziness,” “lethargy,” “depression.”

CN II – Optic Nerve

ANATOMY AND FUNCTION 

CN II  is a photoreceptor.  Anatomically it terminates at the optic chiasm.  The optic tract carries information from the optic chiasm to (mainly) the thalamus / lateral geniculate body and to the superior colliculus in the midbrain (mesencephalon.)  From the thalamus the information travels through the internal capsule and the corona radiata to the primary visual cortex in the occipital lobe.

TESTING AND LESIONS 

CN II lesions generally present as loss of a visual field.  The field of loss can be indicative of the location of the lesion.  Visual field diagrams and their interpretation are outside the scope of this course, but can be found in any thorough neurology text.

CN III – Oculomotor Nerve

ANATOMY AND FUNCTION 

CN III contains both somatic motor and preganglionic parasympathetic fibers.  The nucleus for the motor portion of the nerve is near the midline, in the rostral mesencephalon.  The Edinger-Westphal nucleus, also in the mesencephalon, is the nucleus for the parasympathetic preganglionic portion.

CN III travels through the cavernous sinus and the superior orbital fissure.  The Edinger-Westphal nucleus lies between the CN III nucleus and the cerebral aqueduct.  The surrounding topography should be considered when compression of CN III is suspected.

Structures innervated / major actions:  (Major actions listed are those that occur with eye focused frontally)

• Levator palpebrae – elevates the eyelid
• Medial rectus – adduction
• Superior rectus – elevation
• Inferior rectus – depression
• Inferior oblique – extorsion (top of eye rotates laterally)
• Pupillary sphincter – constriction of the pupil

TESTING AND LESIONS 

Somatic Motor Component 

Dysfunction of the following muscles innervated by CN III can present as…

• Levator palpebrae – evident as lid lag (Note:  Eyes that are either retracted or protruding can create the illusion of lid dysfunction.  It is prudent to examine the position of the eye within the orbit from above the head if lid lag is suspected.  Eyelids are often injured during interactions with other animals.  If a lid seems to show laxity, examine it carefully for small puncture wounds or swelling/redness.)
• Medial rectus – abduction
• Superior rectus – depression
• Inferior rectus – elevation
• Inferior oblique – intorsion (top of the eye rotates medially)

Parasympathetic Component

A lesion in this system will effect function of the pupillary sphincter muscle.

• Anisocoria may be sympathetic, parasympathetic, optic nerve or mesencephalic in origin
• Swinging flashlight test can rule in a prechiasmal CN II lesion:  Consensual constriction is present when shown in functional eye, but both eyes dilate when light is shown in non-functional eye.
• Pupillary light response (PLR) shows response from Edinger-Westphal nucleus to light in the eye.  Afferent information is transferred from the CN II pretectal olivary nuclei to the EW Nuclei bilaterally, as well as having been previously shared at the optic chiasm.  An easily fatiguing PLR in one eye can indicate weak parasympathetic output (perhaps hemisphericity) from the ipsilateral mesencephalon, or overwhelming output from sympathetic innervation from the cranial thoracic chain.  Because the proportion of the optic nerve decussating at the optic chiasm in animals is greater than 50% (horses  > 80%, cats and dogs 65-75%) some dynamic contraction anisocoria upon testing is expected and considered normal.

CN IV – Trochlear Nerve

ANATOMY AND FUNCTION 

CN IV is a somatic motor nerve.  Its nucleus lies near midline in the mesencephalon.

CN IV innervates the contralateral (say most sources) superior oblique muscle, which:

• In forward gaze -  intorts (top of the eye rotates medially)
• In adduction – depresses the eye

TESTING AND LESIONS 

Lesions can present as…

• In forward gaze – extorsion (In animals with round pupils, extorsion can be difficult to identify.  Testing of CN IV in these animals should be done with the gaze in adduction.)
• In adduction – elevation
• If lesion is due to weak nucleus / mesencephalon, the results will show on the contralateral side due to contralateral innervation.

CN V – Trigeminal Nerve

ANATOMY AND FUNCTION 

CN V has general sensory and motor components.  The sensory portion is divided into three segments that sense tactile stimulation, proprioception, pain and temperature from different parts of the face.

V1 – Opthalmic division

V2 – Maxillary division

V3 – Mandibular division

Trigeminal sensory nuclei are lateral, but still medial to the vestibular nucleus.  These nuclei are relatively long, nearly continuous from the rostral mesencephalon to the upper cervical spinal cord.

The motor efferents of CN V are mainly to muscles of mastication.  The motor nucleus is located in the mid-pons, near the attachment of CN V to the brainstem.  The motor fibers travel with V3.

TESTING AND LESIONS 

Increased or decreased sensitivity on the face – tests various branches, depending on area of face tested.

Deterioration of the cornea may be seen in CN V lesions due to the nerve’s contribution to maintenance of the corneal epithelium. (V1)

Corneal reflex – has been noted as useful for testing V1 in an unconscious patient.

Palpebral reflex – at medial (V1) and lateral (V1 / V2) canthus

Jaw Jerk Reflex – Downward tap on the chin causes reflex contraction of the masseter muscles. Can be exaggerated in upper motor neuron lesion.  (V3)

Hypo- or hypertonia in masseter muscles (V3)

Dropping food while eating (V3)

Slack-jawed appearance, increased drooling (V3)

Atrophy of temporalis muscle (V3)  – May first present as increased prominence of the sagittal crest.

CN VI – Abducens Nerve

ANATOMY AND FUNCTION 

CN VI is a somatic motor nerve.  Its nucleus is located near midline in the caudal pons.

Structures Innervated:  Ipsilateral lateral rectus muscle, rectractor bulbi muscle and membrana nictitans (3^rd eyelid)

TESTING AND LESIONS 

Weakness of the CN VI can present as medial strabismus.  The eye may be able to move to midline by relaxation of the medial rectus, but not laterally past midline.  If the abducens nucleus is destroyed this will occur AND the contralateral eye will not adduct past midline due to the influence of the CN VI nucleus on the contralateral CN III nucleus, via the medial longitudinal fasciculus.  This phenomenon is called lateral gaze paralysis.

Retraction will not happen on Menace Response Test if retractor bulbi is weak, and abnormalities may be noted with the 3^rd eyelid.

CN VII – Facial Nerve

ANATOMY AND FUNCTION

CN VII is a mixed motor / sensory nerve, which utilizes five different nuclei for its various functions.  The majority of the nuclei utilized are located in the ventrolateral tegmentum of the caudal pons; the pontine trigeminal nucleus (for tactile sensation), the nucleus solitarius (for taste), the superior salivatory nucleus (for parasympathetic stimulation to the pterygopalatine and submandibular ganglia), and the motor nucleus of CN VII (for the somatic motor component.)  CN VII utilizes the spinal nucleus of the trigeminal nerve, located in the cranial medulla, for pain sensation.   Fibers of the somatic motor portion of the nerve course dorsally around the abducens nucleus, into the floor of the 4^th ventricle (creating the facial colliculus,) and loop back around ventrally.  All CN VII fibers exit the ventrolateral pons together and travel through internal auditory meatus.  From there the fibers separate and travel through various foramen to reach their end organs.

Structures Innervated:

• motor to muscles of facial expression
• taste from anterior 2/3 of tongue
• tactile and pain sensation for portions of the ear
• preganglionic parasympathetics to salivary glands and lacrimal glands

TESTING AND LESIONS 

• Blinking will be reduced or absent, evident in menace response, corneal blink response and tapping of medial or lateral canthus.
• Tears may leak from the eye because sufficient tone in CN VII is required to maintain patency of lacrimal duct.
• The eye may be dry or mattery due to decreased production from the lacrimal gland.
• Gentle whistling may reveal weakness in muscles that move the ears, as will tickling the ear hairs.  Whistling tests CN VIII as afferent, tickling the ear hair tests CN V / CN VII / CN X (and according to some sources CN IX) as afferent.

Due to patterns of decussation and non-decussation, weakness of muscles of facial expression will be most evident in:

• Ipsilateral side of the entire face if facial nerve itself is affected post-nucleus.
• The lower half of the contralateral side of the face if the lesion is supranuclear (cortex or corticobulbar fibers.)

CN VIII – Vestibulocochlear Nerve

ANATOMY AND FUNCTION

CN VIII is a sensory nerve, involved in balance and hearing.

In the chiropractic treatment of animals, our focus is usually on the balance component.

Sensory information from the vestibule of the semicircular canals is transmitted to the vestibular nuclei in the pons.  Within these nuclei, information from the vestibular apparatus is coordinated with afferent input from the spinal cord, cerebellum, and visual system, all with the goals of coordinating eye and somatic movement, maintaining proper head position, and maintaining the body upright against gravity.  CN VIII travels through the internal auditory meatus with CN VII and enters the posterior cranial fossa.  It joins the brainstem at the pontomedullary junction.

TESTING AND LESIONS 

Dysfunction related to CN VIII often presents as as “vestibular syndrome / disease,” which is quite common in older dogs, but can be seen in cats as well.  Symptoms of the syndrome are representative of severe vertigo.  They include nystagmus, nausea (inappetance, vomiting or drooling,) head tilt / turn, falling, complete inability to stand, inability to walk a straight line.  Veterinary focus is often on otitis media / interna, abnormal flow of the endolymph within the semicircular canals or disease / inflammation of CN VIII.  As chiropractors, we can add to treatment of this syndrome by normalizing input from the paraspinal muscles via chiropractic adjustments.

Acoustic neuroma (a.k.a. vestibular schwannoma) is a tumor that arises from the nerve sheath of CN VIII.  If it grows large enough, it can effect CN VII (ipsi facial paralysis), CN V (numbness, pain) and even CNs IX and X.  Well known in human medicine, it is not a common diagnosis in veterinary medicine.  One paper (see references – Ottinger, et. al.) reports a case in a 12 year old golden retriever. This dog presented with  acute severe neck pain and pain when opening the mouth.  Mild hind limb ataxia was also present.

CN IX – Glossopharyngeal Nerve

ANATOMY AND FUNCTION 

CN IX  is a mixed sensory and motor nerve.

Most CN IX sensory information enters the nucleus of the solitary tract in the medulla.  Pain sensation may travel via spinal trigeminal tract, ending in the spinal trigeminal nucleus, also in the caudal medulla.

Structures innervated:

• Sensory from carotid body and sinus, chemoreceptors and baroreceptors, respectively
• Sensory from middle ear cavity and walls of the pharynx
• Taste from the posterior 1/3 of the tongue
• Preganglionic parasympathetic to the parotid glands originating in the inferior salivary nucleus in the rostral medulla, and to the internal carotid artery, sinus and carotid body

TESTING AND LESIONS 

Touching one side of the pharynx should elicit a gag reflex that is symmetrical.  This reflex involves CNs IX and X, sensory and motor, respectively.  CN IX lesions can present as difficulty swallowing, decreased saliva production (dry mouth,) and deviations in blood pressure, or blood oxygen, carbon dioxide or pH levels.

CN X – Vagus Nerve

ANATOMY AND FUNCTION

CN X is a mixed sensory and motor nerve.

Nuclei – dorsal motor nucleus of the vagus nerve in the floor of the 4^th ventricle and the nucleus ambiguus in the ventrolateral medulla (mainly to heart, thorax and neck).  Sensory fibers mainly terminate in the nucleus of the solitary tract.

Structures Innervated:

• Preganglionic parasympathetic to thoracic and abdominal viscera
• Sensory fibers from these same organs

TESTING AND LESIONS 

Decrease in CN X’s parasympathetic effect on the body can present as:

• Increased heart rate (Normalin adult resting animals:  dog – 70-120, cat 110-130, horse 32-44.)
• Decreased gut motility and secretions – poor digestion, diarrhea
• Panting
• Thick, frothy saliva (mucous heavy)
• Laryngeal or esophageal dysfunction

CN XI – Accessory Nerve

ANATOMY AND FUNCTION 

CN XI is mainly motor, but may include some sensory input from the muscles innervated.

Nucleus – caudal medulla and upper cervical spinal cord

Structures Innervated:

• portions of the trapezius, omotransversarius, sternocephalicus, brachiocephalicus

In humans, innervation of sternocleidomastoid (SCM) muscle is from the ipsilateral cerebral cortex (according to some authors the input to the SCM is bilateral from the cerebral cortex) and innervation of trapezius is from the contralateral cerebral cortex.  This mixed ipsilateral/contralateral origin can be explained functionally.  In order to rotate the gaze to the right, the left SCM and the right upper trapezius muscles are involved – this coordinated action is under the control of the left cortex.

In animals, the sternocephalicus, omotransversarius and brachiocephalicus muscles are largely responsible for the function of the SCM in humans.

TESTING AND LESIONS 

Hypo or hypertonia in trapezius, omotransversarius, sternocephalicus, and brachiocephalicus muscles.  Perhaps the crossed pattern of innervation that exists in the human also exists in animals.  This is worth considering, but a reference confirming this was unavailable.

CN XII – Hypoglossal Nerve

ANATOMY AND FUNCTION 

CN XII is a somatic motor nerve.

Nucleus – near midline, rostral to caudal medulla, in the floor of the 4^th ventricle

Structures innervated:  Ipsilateral intrinsic and extrinsic muscles of the tongue

TESTING AND LESIONS 

Weakness and atrophy of the tongue, may be unilateral or bilateral.  Tongue will deviate toward the side of a unilateral lesion, or show wrinklier appearance on the side of the unilateral lesion when at rest if the lesion is lower motor neuron (LMN) in character.  If the lesion is cortical or corticobulbar, deviation will be away from the side of the lesion.  Unilateral or bilateral lesions may present as difficulty drinking or eating (dropping food.)

Other Anatomical Structures Useful for Locating Lesions

Cavernous Sinus

The cavernous sinus is located between the sphenoid bone and the temporal bone, lateral to the pituitary fossa and the sphenoidal air sinus.  Cranial nerves III, IV, V(1), V(2), VI  and the internal carotid artery course through the cavernous sinus.  It is also filled with an anstomoses of veins draining the face.  CN VI is immediately adjacent to the internal carotid artery here.

Superior Orbital Fissure

The superior orbital fissure is located in the superior lateral quadrant of the posterior orbit, within the lesser wing of the sphenoid bone.  Cranial nerves III, IV, V(1), and VI course through this fissure.   V(2) has split off from the bundle passing through the cavernous sinus to traverse the foramen rotundum.

Cavernous Sinus vs. Superior Orbital Fissure

Differential diagnosis for space occupying lesions in these two areas… Is the lateral palpebral reflex (V2) present while CNs III, IV, V1 and VI are showing signs of deficit?  If yes, the then lesion has higher probability of being near the superior orbital fissure than in the cavernous sinus.

Brain Stem and Cranial Nerves – NeuroGeography

Having an understanding of the anatomy of the brain stem, the layout of the cranial nerve nuclei, and the courses the cranial nerves take will help you localize lesions.  As mentioned before, this can be important for focusing effective treatments.  Highly recommended resources for visualizing and gaining a thorough understanding of this “neuro-geography” include:   Purves’ NeuroScience; Haines’ Neuroanatomy: An atlas of structures, sections, and systems; and Wilson-Pauwels’, et. al., Cranial Nerves: Function & dysfunction.

THERAPEUTIC IN-ROADS USING THE CRANIAL NERVES 

Therapeutic Target – Cerebral Cortex

• Use CN I – Olfactory Nerve

Stimulation of certain areas of the cerebral cortex can be used to distract from unwanted behaviors and/or to stimulate parasympathetic responses.  Anxiety may be combated with an engaging food smell.  There are also some diffuser-type products which contain calming pheromones.

The potential exists that seizures can be interrupted with olfactory stimulation, particularly stimulation that encourages GABA release.  Stimulating one area of the cerebral cortex often dampens surrounding areas to some extent.  This GABA release and dampening effect would be the mechanisms for interrupting the seizure.

Therapeutic Target – Mesencephalon 

• Use CN II / CN III / CN IV – Optic, Oculomotor and Trochlear Nerves

If the PLR has shown imbalanced responses, direct light therapy into the eye with the weaker PLR can be used to gently ramp up activity in the olivary and/or Edinger-Westphal nuclei on the weakened side.  Stimulating the Edinger-Westphal nucleus (by eliciting pupillary contraction) stimulates the ipsilateral mesencephalon AND the parasympathetic nervous system.  The Edinger-Westphal nucleus is the cranial-most aspect of the parasympathetic nervous system.

The nasal half of retina will stimulate the contralateral superior colliculus.  The temporal half of retina stimulates the ipsilateral superior colliculus.  So, a light stimulating both eyes at an angle from the side of the animal’s head will target the mesencephalon opposite the light source, as will lateral eye movements away from the sluggish side (via CN III) and diagonal movements moving down toward the sluggish side (via CN III and CN IV.)

Note:  The periaqueductal gray matter is also located in the mescencephalon.  It  has been implicated in pain modulation, as stimulation of parts of it can produce analgesia.  

Therapy Target – Pons / Cerebellum

Use CN V, CN VI, CN VII, CN VIII – Trigeminal, Abducens, Facial and Vestiubulocochlear Nerves

The pons is intimately connected to the cerebellum, both in location and function.  The middle cerebellar peduncle, the largest of the three cerebellar peduncles, is made up almost exclusively of fibers sending information from the pontine nuclei to the contralateral cerebellum.

The vestibular system controls the vestibulo-ocular and vestibulospinal reflexes. There are strong connections between the vestibular nuclei, extraocular muscles, semicircular canals and the cerebellum.  Vestibulospinal pathways send information to extensors, a.k.a. the postural muscles – those charged with keeping the organism upright against gravity.

The posture of the carpus and hock reveal a lot about extensor weakness on one side relative to the other.  Wide based stance can also indicate cerebellar weakness in general, because it may be related to a challenged perception of balance.

One rule of thumb to remember (pathways involved are beyond the scope of this course):  The cerebellum PUSHES the eyes away – therefore, lateral eye movements AWAY from the weak cerebellum should be used to strengthen it.  Cerebellar support to the postural muscles is ipsilateral.  Therefore, gaze should be lured away from the sinking hock or carpus.

Other methods of targeting the pons include stimulation of CN V by tickling whiskers and massaging the skin over the masseter muscle.  Stimulation of CN VII can be added by tapping the medial and lateral canthus, eliciting blink response, and by tickling ear hairs to elicit ear movement.  Basically, what is used for testing can also be used therapeutically.

Therapy Target – Medulla / Autonomics

Muscles innervated by CN XI are generally neck flexors / scapula advancers / shoulder extensors.  Use “shake” or “high five” behaviors and carrot stretches between the front legs to stimulate CN XI bilaterally.  Peanut butter on the roof of the mouth will get at CN IX, X and XII.

Skin of the outer ear contains sensory fibers from CNs VII, IX and X.  Two of which are located in the medulla, and all of which have parasympathetic influence.  Stroking an ear will support the ipsilateral medulla and help improve the parasympathetic input to the body.  Some of your clients may be familiar with “ear glides” used in T-Touch for animals – a strategy used for calming.

Special thanks to Rachel Huseby for her contribution in creating these online courses.”

Take the test to complete this course.

References

Bagley, Rodney S. Fundamentals of Veterinary Clinical Neurology.Ames,IA: Blackwell Pub., 2005. Print.

Beckwith, Chris S. “Chiropractic Neurology Examination Procedures.” Advanced Veterinary Neurology Program. HealingOasisWellnessCenter,Sturtevant,WI. 01 May 2010. Lecture.

Brooks, Wendy C. “Laryngeal Paralysis.” VeterinaryPartner.com. Veterinary Information Network, Inc.,19 June 2006. Web.27 Oct. 2010. <http://www.veterinarypartner.com/Content.plx?P=A>.

Collins, B. Keith. “Comparative Neuro-opthalmology.” Advanced Veterinary Neurology Program. HealingOasisWellnessCenter,Sturtevant,WI.27 Feb. 2010. Lecture.

DeToledo, J. C., and D. J. Noble. “Innervation of the Sternocleidomastoid and Trapezius Muscles by the Accessory Nucleus.” Journal of Neuro-Opthalmology 21.3 (2001): 214-16. Print.

Dyce, K. M., W. O. Sack, and C. J. G. Wensing. Textbook of Veterinary Anatomy.Philadelphia: Saunders, 2002. Print.

Jersild, Dena. “Cranial Nerves.” Veterinary Spinal Manipulative Therapy Certification Program. HealingOasisWellnessCenter,Sturtevant,WI.11 Oct. 2007. Lecture.

“Laryngeal Paralysis in Dogs and Horses.” Vet 4 Petz. Web.28 Oct. 2010. <http://www.vet4petz.com/articles/laryngeal_paralysis.htm>.

Nolte, John. Elsevier’s Integrated Neuroscience. Mosby, 2007. Print.

Nolte, John. The Human Brain: an Introduction to Its Functional Anatomy.Philadelphia,PA: Mosby/Elsevier, 2009. Print.

Ottinger, T., Et Al., “Malignant Acoustic Schwannoma in a Dog.” J Vet Diagn Invest 21 (2009): 129-32. Print.

“Pain Modulation.” AnaesthesiaUK.19 June 2004. Web.29 Oct. 2010. <http://www.frca.co.uk/article.aspx?articleid=100119>.

“Posterior Cricoarytenoid Muscle.” Wikipedia, the Free Encyclopedia. Web.02 Oct. 2011. <http://en.wikipedia.org/wiki/Posterior_cricoarytenoid_muscle>.

Purves, Dale, and S. Mark Williams. Neuroscience.Sunderland,MA: Sinauer Associates, 2001. Print.

Reece, William O. Functional Anatomy and Physiology of Domestic Animals.Ames,IA: Wiley-Blackwell, 2009. Print.

Tilley, Lawrence P., and Francis W. K. Smith. Blackwell’s Five-minute Veterinary Consult: Canine and Feline.Ames,IA: Blackwell, 2007. Print.

The theory of yin and yang was used for analysis of the material world in ancient China. The application of this theory was deeply rooted in all schools of thought. It is a theoretical method for observing and analyzing life. The philosophy of yin and yang is a means (way) to generalize two opposite principles which may be observed in all related phenomena within the natural world. They may represent different and opposite aspects within the same phenomenon, or two separate phenomena with opposing natures. It is a way to interpret Nature in a positive way and to use natural laws to man’s advantage, not through attempting to control and subdue Nature (as in Modern Western science), but by acting in harmony with its laws. Water and fire are examples of what would be considered yin and yang. They represent two primary opposite aspects of a contradiction.

So, in short, yin and yang are:
1.  philosophical constructs of two polar complements.
2.  neither forces nor material entities
3.  convenient labels used to describe how things function in relation to each
other and to the universe
4.  an explanation for the continuous process of natural change
5.  how all things are seen as parts of a whole
6.  examples of how no entity can be isolated from its relationship to other entities

The Chinese characters (letters) for yin and yang are related to the dark and sunny side of a hill.
YIN – shady side of the slope
- qualities include: cold, rest, responsiveness, passivity, darkness, interiority,
downwardness, inwardness, decrease, satiation, tranquility, and quiescence
- it is the end, completion and realized fruition
YANG – sunny side of the slope
- qualities include: brightness, heat, stimulation, movement, activity,
excitement, vigor, light, exteriority, upwardness, outwardness, and increase
- it is arousal, beginning, and dynamic potential

The Five Principles of Yin and Yang

The aspects of yin and yang can be summarized into five main points.

A.) The opposition of yin and yang:

All things have 2 facets: yin and yang aspects.
- night/day                                    – fall and winter/spring and summer
- earth/heaven                               - woman/man
- cold/hot                                      – light/heavy

Willfullness, desire and assertiveness = yang.
Acceptance, responsiveness, repose and responsibility = yin.
It is wrong to say something is yang or yin. They are opposites, describing relative aspects of the same phenomena. Everything only pertains to yin or yang in relation to something else. This opposition is not absolute, meaning nothing is totally yin or yang; although everything contains yin and yang, these are never present in a static equal proportion, but in a dynamic and constantly changing balance. For example, hot pertains to yang and cold to yin, so we might say the climate in Colorado is yang in relation to Canada, but it is yin in relation to Mexico.
The opposition of yin-yang is mainly reflected in their ability to struggle with, and thus control, each other. For example, warmth and heat (yang) may dispel cold, while coolness and cold (yin) may lower a high temperature.
The yin or yang aspect within any phenomenon will restrict the other through opposition. Under normal conditions in the human body, therefore, a relative physiological balance is maintained through the mutual opposition of yin and yang. If this mutual opposition results in an excess or deficiency of yin or yang, the relative physiological balance of the body will be destroyed, and disease will arise.

B.) The interdependence of yin and yang:

Although yin and yang can be distinguished, they cannot be separated; they depend on each other for definition and cannot exist without each other.
The things in which yin and yang are distinguished could not be defined without the existence of yin and yang qualities. For example, one cannot speak of temperature apart from its yin and yang aspects, cold and heat; one could not speak of height unless there were both tallness and shortness; there cannot be activity without rest, energy without matter, or contraction without expansion; such opposite aspects depend on and define each other. Both yin and yang are the condition for the other’s existence, and this relationship is known as the interdependence of yin and yang.
Applied to the physiology of the human body, yin corresponds to nutrient substances, and yang to functional activities. Nutrient substances remain interior, therefore “yin remains inside,” while the functional activities manifest on the exterior, so “yang remains outside.” The yang on the exterior is the manifestation of the substantial movement in the interior, so it is known as “the servant of yin.” The yin on the interior is the material base for functional activities and is therefore called “the guard of yang.”

C.) The inter-consuming-supporting relationship of yin and yang:

They are in a constant state of dynamic balance, which is maintained by a continuous adjustment of the relative levels of yin and yang. Although a diagram of a normal balanced state shows yin and yang in equal proportion, this should not be interpreted literally: the balance is achieved with different dynamic proportions of yin and yang.
The inter-consuming-supporting relationship of yin and yang is described as follows. The 2 aspects of yin-yang within any phenomenon are not fixed, but in a state of continuous mutual consumption and support. For example, the various functional activities (yang) of the body will necessarily consume a certain amount of nutrient substance (yin), which is the consumption of yin leading to the gaining of yang. On the other hand, the production of various nutrient substances (yin) will necessarily consume a certain amount of energy (yang), which is the consumption of yang leading to the gaining of yin. If the balance of the relationship goes beyond normal physiological limits, yin and yang will not be maintained, resulting in excess or deficiency and occurrence of disease.
If yin is excessive, then yang will be too weak and vice-versa. If temperature is neither too cold or hot, then both cold and hot aspects are mutually controlled and held in check. They remain balanced.

D.) Yin and yang transform into each other:

Yin and yang are always subtly supporting, repairing, and transforming into each other; this constant transformation is the source of all change; it is a give-and-take relationship that is life activity itself. This change does not happen at random, but only at a certain stage of development, for example: summer to winter, day to night, life to deat

There are two conditions for this to happen:

1.) Internal Conditions; things can only change through internal causes
primarily, and external causes secondarily; change only takes place when the
internal conditions are ripe. For example, an egg requires heat to become a chick,
and only because the egg has the capacity within itself to turn to a chick…heat a
stone and it becomes a stone!

2.) Time Factor; yin and yang can only transform into each other at a certain
stage of development, when conditions are ripe for change.

When considering the dynamics of the body, the nature of transformation can be illustrated by the manner in which inhalation is followed by exhalation, or periods of activity and exertion must be succeeded by nourishment and rest.
When considering human interactions and relationships, assertion and responsiveness alternate…in normal life, such regular transformations occur smoothly, maintaining a proper, healthy balance of yin and yang. If a relationship has unbalanced yin and yang for prolonged periods of time or in an extreme manner, the resulting transformations may be quite drastic.
Disharmony means that the yin-yang are in unequal proportion and there is imbalance. A deficiency of one aspect implies an excess of the other. Extreme disharmony means that the deficiency of one aspect cannot continue to support the excess of another aspect, and the resulting change may be rebalancing or, if that is not possible, either the transformation into opposites or the cessation of existence.
Using a “romantic couple” as an example, assume a lack of harmony in their relationship…one partner is overly aggressive while the other is overly passive.

There are three possible outcomes:

1.) They sit down and talk it out, agreeing to change their attitudes (rebalancing
their relationship).

2.) They separate (putting an end to the relationship).

3.) One day the passive partner gets fed up and waits for the other with an ax or
other lethal object (radical transformation of yin into yang occurs).
In clinical practice, one of three kinds of transformation is always possible. For example, a patient presents with a pattern of high fever and much sweating (excess yang, or fire), and may be in danger of suddenly going into shock (extreme yin, or cold condition); this is because yang cannot continue to exist in such extreme relation to yin without some transformation occurring. Either gradual transformation (rebalancing) must take place (medication and healing), or a radical transformation (into opposites – yang to yin) will occur (shock), or yin and yang will separate and existence will cease (death).

E.) Any yin or yang aspect can be further divided into yin and yang:

Temperature can be divided into cold (yin) and hot (yang), but cold can be divided further into icy cold (yin) and moderately cold (yang).
Within a yin illness characterized by coldness, there may be aspects of yang, such as sharp, forceful contractions. Within a yang illness of heat and hyperactivity, there may be weakness and loss of weight, both yin qualities.
Yin and yang have infinite divisibility, and can be further divided into 3 subcategories:

1.) Yin

a.) Declining Yin is called Jueyin (the first yin)
b.) Lesser Yin is called Shaoyin (the second yin)
c.) Greater Yin is called Taiyin (the third yin)

2.) Yang

a.) Scanty Yang is called Shaoyang (the first yang)
b.) Extreme Yang is called Yangming (the second yang)
c.) Greater Yang is called Taiyang (the third yang)

The differentiation of syndromes applied to the development of febrile diseases is analyzed with the application of the Taiyang, Yangming, Shaoyang, Taiyin, Shaoyin, and Jueyin divisions.

The interdependent relationship of yin and yang are represented well in the Traditional Chinese Taoist symbol seen below:

The main points of this symbol of interdependence are:

1.) Although they are opposite stages, yin-yang form a unity and are complementary.

2.) Yang contains the seed of yin and vice-versa represented by the small black
and white dots (illustrating that within yin there is yang, and vice-versa)

3.) The dynamic curve dividing them indicates yin and yang are continuously
merging and nothing is totally yin or totally yang; this illustrates the opposition
and interdependence of the yin-yang inter-consuming-supporting relationship

4.) Thus, yin and yang create, control, and transform into each other (yang
changes into yin and vice-versa).

The Application of Yin and Yang to Medicine

The whole of Traditional Chinese Medicine (TCM), including its physiology, pathology, diagnosis and treatment, may all be reduced down to the basic fundamental theory of yin and yang. All physiological processes and symptoms can be analyzed with yin and yang theory. Ultimately, every treatment modality is aimed at one of these four strategies:

1.) tonify yang
2.) tonify yin
3.) sedate yang
4.) sedate yin

This concept is very important to TCM. One can say that there is no Chinese Medicine without yin-yang. It serves to explain the organic structure, physiological functions, and pathological changes of the human body, and in addition guides clinical diagnosis and treatment.

A.) Yin-yang and the organic structure of the human body.

Every part of the human body has either predominantly yin or yang characteristics. However, it is always relative to what is being compared. For example, the shoulders are yang in relation to the chest, but yin in relation to the head.
As a general rule, the following are the descriptions of various body structures:

1.) yang – superior, exterior, posterior-lateral surfaces, back, function
2.) yin – inferior, interior, anterior-medial surfaces, front, structure

Yin and yang characteristics of the body structures, organs and energies are:
Yang                                                   Yin
back                                                    front (chest and abdomen)
head                                                    body
exterior (skin/muscles-protect)               interior (organs-nourish)
above the waist                                     below the waist
posterior/lateral surfaces of the limbs      interior/medial surface of the limbs
yang organs                                         yin organs
function of organs                                 structure of organs
Qi                                                       blood and body fluids
Defensive Qi                                        Nutritive Qi

Within the meridian system there are also 2 categories: yin meridians and yang meridians…so…the opposition of yin and yang manifests within all the upper, lower, internal and external organic structures.

B.) Yin-yang and the physiological functions of the human body.

The theory holds that normal vital activities of the human body are based on the coordination of yin and yang in a unity of opposites.
Functional activities pertain to yang and nutrient substances to yin. Various functional activities depend on the support of nutrient substances. The nutrient substances sustain the functional activities, and the functional activities are the motive power for production of the nutrient substances. Again, another example of their interdependence!
For example, without the functional activities of the zang-fu organs (see next paragraph), water and food would not be transformed into nutrient substance…yin and yang are mutually supportive in this way…acting together to protect the organism from invasion by pathogenic factors and to maintain a relative balance…if yin and yang fail to support each other and become separated, the vital activities of the body will cease.
An explanation of the zang-fu organs: a general term for the internal organs of the human body, and includes the six zang organs (heart, lung, spleen, liver, kidney, pericardium), six fu organs (gallbladder, stomach, small intestine, large intestine, bladder, triple energizer) and the extra fu organs (brain, marrow, bones, vessels, gallbladder, uterus). The main physiological functions of zang organs are to manufacture and store essential substances, including vital essence, qi, blood, and body fluid. The main physiological functions of the fu organs are to receive and digest food, and transmit and excrete wastes.

C.) Yin-yang and pathological changes in the body.

TCM considers the occurrence of disease resulting from the loss of relative balance between yin and yang, and subsequent excess or deficiency of either.
The occurrence or development of disease is related to both the antipathogenic qi and to pathogenic factors. There are two types of pathogenic factors: yin and yang. Antipathogenic qi involves yin fluid and yang qi. The following are four examples:

1.) When yang pathogenic factors cause disease, this may lead to an excess of
yang which consumes yin and gives rise to heat syndromes.

2.) When yin pathogenic factors cause disease, this may lead to the
preponderance of yin which damages yang and gives rise to cold syndromes.

3.) When deficiency of yang fails to control yin, deficiency and cold syndromes
may appear, in which yang is deficient and yin excessive.

4.) When deficiency of yin fluid fails to restrict yang, deficiency and hot
syndromes may appear, in which yin is deficient and yang hyperactive.

From the above it can be seen that although pathological changes are complicated and subject to change, they can be generalized/explained by an imbalance of yin and yang; excess yin or deficient yang equals cold syndromes, excess yang or deficient yin equals hot syndromes.

In addition, deficiency of either yang qi or yin fluid may lead to consumption of the other, known as “the mutual consumption of yin and yang.” Here are two examples:

1.) Prolonged poor appetite is mainly attributed to weakness of SP-Qi (yang),
leading to insufficiency of blood (yin). This is deficiency of both qi and blood
due to weakness of yang affecting yin.

2.) Hemorrhage, where considerable loss of yin blood usually leads to the
syndrome of deficiency of yang, manifesting as chilliness and cold limbs. This is
a deficiency of both yin and yang resulting from deficiency of yin affecting yang.

D.) Yin-yang as a guide to clinical diagnosis and treatment.

Yin-yang is the basis for the differentiation of syndromes by the eight principles: yin, yang, interior, exterior, cold, heat, deficient, and excess. Interior, cold and deficient are yin and exterior, heat and excess are yang. Using the eight principles makes it possible to simplify complicated clinical situations, giving a correct diagnosis and appropriate treatment.
Keeping in mind the general principles of the Yin and Yang character of symptoms and signs, we can list the main clinical manifestations as follows:
Yin                                                             Yang
Chronic disease                                           Acute disease
Gradual onset                                              Sudden onset
Lingering disease                                         Sudden pathological changes
Cold                                                            Heat
Sleepiness, listlessness                               Restlessness, insomnia
Likes to be covered                                      Throws off bedclothes
Likes to curl up                                            Likes to lie stretched out
Cold limbs and body                                     Hot limbs and body
Pale face                                                     Red face
Likes hot drinks                                            Likes cold drinks
Weak voice, dislikes talking                           Loud voice, talks a lot
Shallow, weak breathing                                Coarse breathing
No thirst                                                       Thirst
Profuse, pale urine                                        Scanty, dark urine
Loose stools                                                 Constipation
Pale tongue                                                  Red tongue with yellow coating
Empty pulse                                                 Full pulse
Since the basic cause of disease is imbalance between yin and yang, the acupuncture treatment would be used to adjust yin and yang to restore harmony and balance. THE BASIC FUNCTION OF NEEDLING IS TO ADJUST THE QI (ENERGY) OF YIN AND YANG!!
In the clinical application of acupuncture, the theory of yin-yang is applied to determine not only the principles of treatment, but also the selection of points and the technique of needling and Moxibustion to be used. For example, in clinical practice, combining Yuan-Primary and Luo-Connecting points with externally and internally related meridians is used extensively. The Back-shu and Front-mu points are often selected to treat diseases of the zang-fu organs, respectively. The associated Back-shu points are usually used for the zang diseases, and Front-mu points for the fu diseases. Alternatively, Front-mu points may be selected for yang diseases, and Back-shu points may be selected for yin diseases.
From the above paragraph, we can see that in acupuncture and Moxibustion, the points, meridians and techniques for Moxibustion and needling are all closely related to the principles of yin and yang, again emphasizing the vital role that yin and yang have in both theory and practice.
In closing, I would like to quote The Web that has No Weaver: “Because of the influence of yin and yang theory on Chinese thought and culture, the Chinese explain events differently than does the West. The idea of causation, central to Western thinking, is almost entirely absent. The Chinese believe phenomena occur independently of an external act of creation, and there is not great need to search for a cause. In Chinese thought, events and phenomena unfold through a kind of spontaneous cooperation, an inner dynamic in the nature of things.
“The Chinese assume that the universe is continuously changing. Its movement is the result not of a first cause or creator, but of an inner dynamic of cyclical patterns. Just as the sun maps out four distinct seasons in its yearly round, so all biological organisms go through four seasons in a lifetime: birth, maturation, decline, and death. The constancy of the cosmos is in these patterns of change, which are regular. The cosmos itself is an integral whole, a web of interrelated things and events. Within this web of relationships and change, any entity can be defined only by its function, and has significance only as part of the whole pattern.
“This metaphysics that emphasizes the perception of patterns is basic to Chinese thinking. It results in part from Taoism, which altogether lacks the idea of a creator, and whose concern is insight into the web of phenomena, not the weaver. For the Chinese, that web has no weaver, no creator; in the West the final concern is always the creator of cause and the phenomena is merely its reflection. The Western mind seeks to discover and encounter what is beyond, behind, or the cause of the phenomena. Knowledge, within the Chinese framework, consists in the accurate perception of the inner movement of the web of phenomena. The desire for knowledge is the desire to understand the interrelationships or patterns within that web, and to become attuned to the unfolding dynamic.”

References
Chinese Acupuncture and Moxibustion. Liangyue, et. al. Published by: Foreign Language Press, Beijing, China. 1999.
The Foundations of Chinese Medicine. Maciocia, Giovannie. Published by: Churchill Livingston. 1989.
The Web That Has No Weaver. Kaptchuk, OMD, Ted J. Pulblished by: Contemporary Books. 2000.

The purpose of this course is to help you understand chi (or qi) and how it relates to the human body.  We will look at Qi, Jing, and Shen to understand how they affect the body.  I have practiced acupuncture for 7 years and have been a chiropractor for 14 years.  I have found that the two compliment each other so well, and when we use them together our patients receive the best results.  I hope the passion that has engulfed me to help people with chiropractic and acupuncture will be contagious.  I was not the most skilled when I began using acupuncture, but with time and practice I became more and more comfortable with using acupuncture and understanding the power of qi.

QI (CHI), GENERALLY SPEAKING, IS THE INTRINSIC SUBSTANCE THAT MAKES UP EVERYTHING AND PRODUCES ALL THINGS THROUGH ITS MOVEMENT AND VARIATIONS.

Let us begin by trying to understand what qi is.  In the simplest meaning qi is energy. You may see it referenced as chi or qi.  The Chinese term qi is used to refer to all types of energy.  Qi is the vital force behind everything in the universe. The physiological explanation of qi is that it is the intrinsic substance that flows in the human body and is the impelling force for all of its activities. All humans are immersed in qi.  When we discuss qi in a medical sense, it is how we strengthen the patient’s qi so that pathogenic influences are not allowed to overtake the body and cause disease and pain.  How do we affect qi so that there is a balance of yin and yang energy and help the body to restore its “normal physiologic state”.

Traditional Chinese Medicine believes that disease is due to an imbalance of energy within the body.  Disease, illness and pain are caused by the body’s fight between qi in the body and pathologic influences.  It is believed that to heal the body you can either remove the pathologic influences or strengthen and balance the qi.

Under normal conditions the human body has balanced energy and is capable of maintaining the physiological functions of the body, adjusting to any changes it is exposed to.  If the body is exposed to pathological influences that are beyond the normal functioning of the body, the qi can be destroyed or blocked and illness can occur.  So to protect the body from illness, it must be adaptable and able to withstand the pathological influences it is exposed to.

If the body’s qi is strong, it will be difficult for the pathogenic influences to negatively affect it.  The abundance of qi will increase the immunity of the body and prevent disease from occurring.  Only when qi is weak will pathogenic influences be able to cause illness and or disease.

A way of removing the physical manifestations of illness is to balance the patient’s qi.  As healthcare practitioners, we can help our patient’s balance their qi by prescribing herbs, nutritional supplements, acupuncture, massage, and teaching our patient’s qigong.  You may need to use one or many of the above methods to help your patient’s achieve balanced qi.  It is very important for humans to regularly work at keeping their qi balanced.  External assistance (performing acupuncture) is not a permanent solution to illness caused by qi imbalance. We can, as doctors performing acupuncture, help our patient?s learn how to boost their qi and keep it balanced.

When we study acupuncture, we look at the twelve meridians or pathways and the extra meridians as an integral system of interrelated networks with different physiological functions. The system uses the pathways to link organs and other human systems into a unified whole, making the communication and interaction between parts of the body possible. As you already know, the energy that flows in the pathways is the qi (or chi).  Qi extends internally to the organs and externally throughout the body, which completes an interrelated system of networks.

Some sources credit Dr. Wang Wei-Yi (987-1067 A.D.) as being the first person to accurately chart the energy meridians.  Dr. Wang was an acupuncturist in the Northern Dynasty.  He was in charge of compiling the Manual of the Illustrated Points for Acupuncture and Moxibustion.  This manual helped to facilitate the research and development of acupuncture.  This manual was also used to help teach acupuncture.

Energy Meridians

The qi pathways in the human body include 12 channels (meridians), 8 extraordinary vessels, 15 main branches, and the collaterals.  Channels (meridians) refer to energy pathways that connect to the organs internally and extend to the limbs externally.  These channels have accessible acupuncture points on the surface of the body.  Vessels are energy pathways that connect to the channels, but they do not have direct connections to the organs nor the acupuncture points.  The 15 main branches include the branches of the 12 channels (meridians) plus the Governing Vessel, Conception Vessel and an additional one from the Spleen Channel (meridian).  The collaterals are small netlike energy pathways that branch out of the larger energy pathways.  The energy pathways (or meridians) are the connectors between the organs and the limbs.  They link the upper and lower body.  They regulate and balance the entire body which helps make the human body an integrated whole.

The acupuncture points on the external body allow you to have a direct connection to the twelve energy channels, the Governing Vessel and the Conception Vessel.  In some texts they are referred to as the 14 Channels and Vessels.   Six of the energy channels have a direct connection to the viscera and six to the bowels.  The additional two are the

Conception Vessel and the Governing Vessel.  Below you will find a picture of the tsing points of the twelve channels or meridians.  As you know the tsing points are some of the most powerful points in the body.  They are where the 12 meridians begin or end and are located on the hands or feet.

Acupuncture points are located on the surface of the skin and are connected to the channels.  This gives you direct access to the bowels and organs.  The acupuncture points have a greater accumulation of qi and are points for draining or nourishing qi.  They are also important passages for the energy pathways.  These points have a direct relationship to the flow of qi through and from the organs.  By stimulating the acupuncture points with needles, massage, moxibustion or qigong exercises, a person who is ill can regulate and balance their chi to maintain and regulate their health.

There are two main functions of the energy pathways.  The first is their ability to reflect symptoms when the body is ill or diseased. The second is to help conduct normal physiological activities when the body is functioning normally.

As you probably learned during your study of acupuncture, qi manifests itself when the body is showing signs of illness through qi-deficiency and qi-stagnation.  Qi-deficiency is when there is a weakness in the functioning of the body or organ systems.  Qi-stagnation is when there is restricted flow, or blockage, of qi in the body.  Qi should normally flow smoothly throughout the body.  If the body is injured, or there is an illness a restriction of qi and blood will occur.  Think of the garden hose that has a kink in it. The water will not be able to flow as freely out of the open end of the hose if there is a kink in it.  The water gets backed up behind the kink and it trickles out of the open end.  This is the same concept with qi flowing throughout the pathways (meridians).

Jing, Qi, Shen

When talking about qi , it is important to understand how Jing, Qi, and Shen work together to help the body stay in natural balance and healthy.  The three work together and influence one another.  They have been called the Three Treasures.

Jing

Jing is considered the essence of life and is the fundamental material that makes up the human body.  It is broken down into two categories, innate-jing and acquired-jing.  We inherit the innate-jing form our parents when we are conceived.  Acquired-jing we get from food and water which is converted by the stomach and spleen. When we eat and drink food and beverage, it is converted by our stomach and spleen into Jing and any excess Jing is stored in the kidneys.  The innate-jing we receive when we are born is also stored in the kidneys. Innate and acquired jing are not stored separately in the kidneys, they exit together and nourish one another.

• Mother + Father= Innate Jing
• Food + Water→ Stomach & Spleen=Acquired Jing (excess jing is stored in the Kidneys)

Innate-jing has another function.  It includes the reproductive essence or semen (the original substance needed for the construction of the human body).   The jing stored in the kidneys is closely related to reproduction and sexual function.  The body’s metabolism and all bodily functions require us to replenish our jing with what we eat and drink.  Jing is continually being used and replenished.  When we have an abundance of jing the body will be vital and strong and able to adapt to its’ environment, preventing illness.  When jing is deficient, the body will be weak and unable to prevent or fight illness.

Qi

As we learned earlier, qi in the body is the intrinsic substance that is the driving force for all functions.  Qi includes the energy derived from the air, other external sources (ie. the sun), food and water, as well as the innate energy source we inherit from our parents.  People do not necessarily feel qi directly.  It is felt indirectly and manifested in their bodies interactions within itself and to its surroundings.

Qi is also classified as innate-qi or original-qi (congenital-qi) and acquired-qi.  Innate-qi (congenital qi) we get from our parents and are born with it.  Innate-qi is converted from innate-jing.  Acquired-qi is converted from food, water, air and external energy sources.  Energy surrounds us in the form of radio waves, microwaves, sunlight, etc. When we eat, drink,or go outside in the sun, our bodies take that energy that is brought into it and convert it into acquired-qi.  The relationship between innate and acquired-qi is interdependent. An example of this is when a train takes coal and burns it to create heat and steam that creates energy to move the train. The coal is the food, the heat and steam are the energy, and the train is the body. The food we eat, the water we drink, and the external forms of energy we are exposed to are taken in by the body and converted into acquired-qi.  The human body needs to keep its level of qi abundant so it can  function optimally and ward off disease.

• Mother + Father = Innate Jing → Innate QI
• Food + Water + External Energy Sources = Acquired Qi

The combination of innate and acquired-qi is sometimes referred to as genuine-qi.  Genuine-qi is the force that supports all human functions.  Qi is distributed to different parts of the body to perform different tasks.

The qi that travels through the meridians is called vital-qi.  The vital qi influences the functions of the blood, qi and organs of the entire body.

Some sources differentiate qi in the body by source, function and distribution. These are primary, pectoral, nutrient and defensive qi.

Primary Qi: is derived from innate qi and nourished by acquired qi.  It is stored in the kidney and spreads through the body via the triple heater (triple energizer or San Jiao). It promotes the function of the twelve meridians and their corresponding organs.  If there is an abundance of Primary Qi, the body will be healthy and able to ward off disease.

Pectoral Qi: is derived from the external qi that is breathed in, combined with the qi the body creates after ingesting food and water (acquired-qi).  The acquired qi we create by what we eat and drink is produced in the spleen and stomach. Pectoral qi is stored in the chest and helps to control respiration and speech. It also helps the heart dominate blood.  Pectoral qi helps with the circulation of qi and blood.  This in turn affects the body’s motor capabilities and the use of the arms and legs.

Nutrient Qi: is derived from the qi of food and water and is created in the stomach and spleen.  Nutrient qi circulates in the vessels.  Nutrient qi helps produce blood and it circulates with the blood.

Defensive Qi:  is derived from the qi of food and circulates outside of the vessels.  Its purpose is to protect the muscular surface, defend the body against pathogenic influences, control the opening and closing of the pores, moisten the skin and hair, readjust the body temperature and warm the organs of the meridians.  The most important function of this type of qi is to protect the body form pathogenic influences.

Because qi is not visible to the human eye, it can be a hard concept to understand and to teach to patients.  But think of electricity, we can not see it but we know it is there and we can see what it does when it is in active use.  There are highly trained masters of TCM (Traditional Chinese Medicine) that are able to see a body’s qi via an aura.  However, you can feel qi and you can train your patients to be aware of qi in their own body.  Qi can be felt in several ways, as warmth, cool, tingling or as a magnetic repulsion sensation. When I perform acupuncture on my patients I always explain they may feel one of the above sensations when the needles are in.  This is what is meant by feeling the “qi come in”.

Shen

In Traditional Chinese Medicine, shen refers to spirit.  It means an expression of one’s vitality of spirit, or mental faculties.  Shen is related to the function of the heart.  Shen comes from innate-jing and depends on acquired-jing and qi for nourishment to keep it functioning.  It is a very important component of the human body.  When shen is scattered, the body’s functions will be weakened.  When shen is strong, the body will function in a state of harmony and balance.

Our vitality of spirit is an expression of our emotional state.  The condition our vitality of spirit is in can affect our ability to be healthy, recover from disease and can impede our bodily functions.  A stable emotional state and positive mental attitude can speed recovery and help us maintain health.  The flip side to this is if you are under constant emotional disturbances or prolonged emotional disturbances, it will scatter your energy and can cause physical disease.  I think we have all seen patients in our practices that are under a lot of stress and develop conditions such as ulcers, migraines or pain.  It is a mechanism of the body to protect itself, to wake up the person to pay attention to their health and make changes.  In TCM it is explained as the vitality of spirit, how a person’s emotions can affect their physical health.

Vitality of spirit is influenced by 7 emotions:

• Joy
• Anger
• Pensiveness
• Worry
• Sorrow
• Shock
• Fear

It is stated in the Yellow Emperor’s Internal Classic that “excessive anger damages the liver; excessive joy damages the heart, excessive pensiveness damages the spleen, excessive sorrow damages the lungs, excessive fear damages the kidneys.” It also states, “excessive anger causes qi to rise, excessive joy causes qi to retard, excessive sorrow causes qi to diminish, excessive fear causes qi to fall, excessive shock causes qi to scatter and excessive pensiveness causes qi to stagnate.”

As stated earlier, emotional trauma can cause disease and the malfunctioning of internal organs.  There are three causes of disease: exogenous (external), endogenous (internal) and neither exogenous nor endogenous. Exogenous causes of disease are usually related to excessive atmospheric influences: wind, cold, summer heat, dampness, dryness and fire.  If our body cannot adapt to the changes in the seasons, its” energy flow will be out of balance and illness can occur.  Endogenous causes of disease relate mainly to excessive emotional trauma: joy, anger, shock, worry, pensiveness, fear and sorrow.  The final cause of disease is neither exogenous nor endogenous: overworking, overeating, excessive drinking and excessive sexual activities.

We have learned that there are two types of qi: innate, which we are born with, and acquired, which is affected by what we eat, drink and external energy sources.  An abundance of qi will help keep the body healthy and disease free.  The body has twelve main meridians, eight extraordinary vessels, 15 branches and the collaterals that qi flows through connecting the organs to the limbs and surface acupuncture points.  Acupuncture points have a greater accumulation of qi and are the points where we can affect the addition of energy or take excess energy away.  Traditional Chinese Medicine teaches that Jing, Qi and Shen  help make up the human physiological system.  If there is a deficiency in jing, qi or shen; illness, pain or disease can occur.

Functions of Qi

1. Promoting Function: The ability of the human body to grow and develop is dependant on qi.  The circulation of blood, distribution of body fluid and, physiological activities of the organs are dependant on the promotion and stimulation of qi.
2. Warming Function:  The temperature of the body is regulated and maintained by the warming function of qi.
3. Defensive Function:  Qi helps the body to defend itself against exogenous pathogenic influences.  It helps the body to ward off pathogenic influences.
4. Checking Function:  Qi checks, controls and regulates bodily substances and metabolic products.  Qi helps control blood by keeping it circulating in the vessels.  It also helps to control sweating, urination, and sexual functions.
5. Qihua (activities of qi): It refers to the mutual transformation among essence, qi, body fluid and blood.  A second function is to help the bladder to discharge urine.
6. Nourishing Function: Yingqi is the nutrient substance formed by food.  It circulates with the blood in the body and helps nourish it.

The six functions of qi are different.  However, they compliment, support and supplement each other.

Practitioners should always perform clean needle technique when performing acupuncture.  Also, NEVER needle through clothing.  Protect your patients from unnecessary risk and use disposable needles or properly autoclave the needles after use.

References:

1997, Qigong Empowerment, Master Shou-Yu Liang and Wen-Ching Wu, The Way of the Dragon Publishing

1989, The Foundations of Chinese Medicine, Maciocia, Churchill Livingstone, New York. 

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Thank you for taking this course. We have several other courses available on different acupuncture topics.  We have quick easy reference manuals available that contain 20 conditions.  Each page has a diagram where to needle and the points to be needled on a human drawing. Where appropriate, also will be included the Auriculotherapy diagram for the same condition.  See our products to order online.