IVMI Flashcards
What is a restriction?
A loss of range of motion with the joint surfaces still in contact.
Is a restriction a subluxation?
No.
How can you diagnose a restriction?
Motion Palpation.
True/False: Restrictions involve only bone and cartilage.
False.
What is the paraphysiologic range?
Small space beyond the active and passive ranges of motion, but before anatomical barriers are breached.
True/False: a correct manipulation does not rely on strength, but instead relies on speed and specificity.
True.
What is HVLA?
High Velocity, Low Amplitude.
What are the three components of a listing?
- Segment/Joint
- Reference Point.
- Direction.
What are three general ways a restriction affects the body?
- Local Effects
- Compensatory Effects.
- Nervous System Effects.
Describe the process of local effects caused by a restriction:
Adhesions, cartilage degeneration, and decreased circulation –> decreased ROM –> less imbibition –> cartilage degeneration –> decreased blood flow
What is a compensatory effect of a restriction?
Hypermobility in adjacent joints.
True/False: Adhesions form within the joint after a few days of immobilization.
True
True/False: When the muscular part of the musculotendinous unit is in spasm, it aids in tendon function.
False - the tendon has to stretch more to compensate and is vulnerable to injury.
What are the four ways the nervous system is affected by restrictions?
- Increased pain
- Lack of inhibition of sympathetics and nociception
- Decreased input to the cortex
- Interference with peripheral nerve function
True/False: a restriction can cause an inflammatory environment or create mechanical stress on the nerves.
True - direct cause of pain from a restriction.
True/False: pain is inhibited by movement.
True - movement stimulates Ia afferent fibers.
What are two effects of high sympathetic tone?
- Overloads the adrenals
2. Suppresses the immune system
How are peripheral nerves affected by restrictions?
Mechanical stress, muscle tension, inflammation, changes in blood flow.
True/False: movement is necessary for a healthy cortex.
True
True/False: A restriction cannot affect peripheral nerve function.
False
How is frequency of firing affected by a restriction?
FOF is decreased. Decreased movement = decreased FOF of sensory and motor neurons.
What are the four things neurons need to be healthy?
- Oxygen
- Glucose
- Neurotropic Factors
- Frequency of Firing
Name the five components of a set-up:
- Doctor Position
- Patient Position
- Doctor Contact Point
- Patient Contact Point
- Line of Drive
True/False: the correct line of drive is in the plane of the joint.
True
What are the three commonly used doctor contact points?
- Calcaneal
- Pisiform
- V Trough
What doctor muscles do most HVLA thrusts use?
Pectorals, triceps
True/False: the best way to lower your episternal notch is to bend at the waist and round your back.
False - use a fencer’s stance or bend your knees.
True/False: long lever adjustments are safer than short lever adjustments.
False - short lever are safer because the contact point is very close to the joint being adjusted.
Is HVLA commonly used for long lever adjustments?
No - often allow the patient to make this type of adjustment.
What are the contraindications for spinal manipulation?
- Joint laxity/hypermobility.
- Neurologic signs.
- History of recent trauma/fracture.
- Severe arthritis.
There are two basic parts of the nervous system: the incoming, or __________ information, and the outgoing, or __________ information.
Incoming = sensory Outgoing = motor
What are the three types of motor neurons that carry information to the skeletal muscle?
Alpha, beta, gamma motor neurons
True/False: Alpha motor neurons go to intrafusal fibers to cause muscle action.
False. Alpha motor neurons go to extrafusal fibers to cause muscle action. Beta and gamma motor neurons go to intrafusal fibers to regulate the extrafusal fibers.
Transneuronal degeneration is part of the __________ nervous system (autonomic vs. somatic).
Autonomic
What are four signs of transneuronal degeneration?
Yawning repeatedly
Breathing heavily
Piloerection
Sweating
True/false: action potentials are graded.
False. Action potentials are not graded (they are always the same size). When enough local potentials add together, they cause an action potential.
True/False: alpha motor neurons are large and myelinated.
True
Which cranial nerves are tested with the Doll’s eye?
CN 3 - Oculomotor
CN 4 - Trochlear
CN 6 - Abducens
CN 8 - Vestibulocochlear
Which cranial nerves are tested with the blink reflex?
CN 5 - Trigeminal
CN 7 - Facial nerve
Which cranial nerves are motor and can be tested by observing muscle mass, tone, or function?
CN 3 - Oculomotor CN 4 - Trochlear CN 5 - Trigeminal CN 6 - Abducens CN 7 - Facial CN 9 - Glossopharyngeal CN 10 - Vagus CN 11 - Accessory CN 12 - Hypoglossal
Does the size of the spinal canal become larger or smaller on extension?
Smaller
T/F: the diameter of the IVF changes with position.
True - smaller with extension and larger with flexion
What are the borders of the IVF?
Vertebral Facets Vertebral Bodies Vertebral Pedicles Ligamentum Flavum Disk
What are the structures within the IVF?
Fat CSF Ligaments Blood Vessels Lymphatics Dorsal Root Ganglion Spinal Nerve Recurrent Meningeal Nerve Dura
Which motion decreases the diameter of the spinal canal and the IVF?
Extension
What are three reasons that walking a horse with the head elevated changes the gait, even in normal horses?
- Extending the neck causes a decrease in the diameter of the spinal canal/IVF
- Affects visual inputs
- Affects vestibular input/balance
Extrafusal/Intrafusal fibers are the part that contracts to create muscle action.
Extrafusal
True/False: alpha motor neurons are large and myelinated, making them fast and able to carry a lot of information.
True - as many as 10,000 axons converge on each motor neuron to regulate muscle action.
Which motor neurons are larger, alpha or gamma?
Alpha
Which motor neurons go to the extrafusal fibers?
Alpha
Muscle spindles monitor _____________.
Muscle stretch
Which type of motor neuron innervates the muscle spindle cell?
Gamma
True/False: spinal manipulation is designed to stimulate golgi tendon organs.
True. The golgi tendon organs are proprioceptors noted at the musculotendinous junction, which are stimulated when a muscle contracts. GTO stimulation will cause muscle relaxation.
True/False: Golgi Tendon Organs (GTOs) monitor tension/contraction and stimulate relaxation.
True.
Interneurons are usually _______________ (excitatory/inhibitory).
Inhibitory. GTO receptor –> spinal cord via 1b neuron –> interneuron –> alpha motor neuron of same muscle
Which mechanoreceptors inhibit the muscle they are in?
a. Muscle Spindles
b. Golgi Tendon Organs
b. Golgi Tendon Organs
Why do we need to bring the joint to tension before the HVLA?
To stimulate the GTOs
One GTO monitors tension/contraction of:
a. All the extrafusal fibers
b. Approximately half of the extrafusal fibers
c. Approximately 30% of the extrafusal fibers
d. Approximately 10-20 extrafusal fibers
d. Approximately 10-20 extrafusal fibers
What do GTOs monitor?
a. Gamma neurons
b. stretch
c. 1b neurons
d. Tension/contraction
d. tension/contraction
What are the three parts of the muscle spindle?
Receptor
1a sensory neuron
Gamma motor neuron
True/False: The muscle spindle relaxes synergistic muscles and contracts antagonistic muscles.
False - contracts synergistic muscles and relaxes antagonistic muscles; stimulates gamma motor neurons back to the same muscle spindle
What are the four jobs of the 1a fibers from muscle spindles?
- contract self-muscle
- contract synergistic muscle
- relax antagonistic muscle
- stimulate gamma motor neurons
Where are the muscle spindles located?
In the muscle belly
What do muscle spindles monitor?
a. Gamma neurons
b. stretch
c. 1a neurons
d. Tension/contraction
b. stretch
How many neurons are in between the 1a afferent neuron and the alpha motor neuron?
a. 0
b. 1
c. 2
d. 3
a. 0
The 1a afferent neuron goes to (choose all that apply):
a. The same muscle
b. synergistic muscles
c. antagonistic muscles
d. gamma motor neurons
a, b, c, d
True/False: the gamma motor neuron keeps intrafusal fibers taut and regulates muscle spindle sensitivity.
True
The sensitivity of the muscle spindle is called __________.
Gamma gain
(High/Low) gamma gain is desirable.
High
Gamma motor neurons regulate:
a. Contraction of extrafusal fibers
b. MS size
c. Muscle mass
d. MS sensitivity
d. MS sensitivity
It is desireable to have (high/low) gamma gain
High
Why is it important to keep the intrafusal fibers taut?
a. To improve blood flow
b. So it is sensitive to all muscle lengths
c. To stimulate the 1b fibers
d. So that it takes more stretch to stimulate the MS
b. So it is sensitive to all muscle lengths
A fit athlete:
a. should have clear muscle definition
b. should have muscles with smooth contours
c. should have tight, tense muscles
b. should have muscles with smooth contours
What are the four functions of muscle tone/gamma gain?
- to keep us upright against gravity
- to keep the center of gravity within the base of support
- to store energy
- to allow for smooth movement
True/False: tense muscles put more strain on the tendons
True
To compensate for poor muscle tone:
a. strength is used
b. movement is slower
c. tension is used
d. less energy is expended
c. tension is used
Tense muscles make movement (more/less) accurate.
Less
Tense muscles can lead to tendon injury:
a. with intense work
b. with slow work
c. within the normal range of motion
d. outside the normal range of motion
c. within the normal range of motion
Low gamma gain can lead to tendon injury:
a. with intense work
b. with slow work
c. within the normal range of motion
d. outside of the normal range of motion
d. outside of the normal range of motion
What is the contact point for manipulations of C3-C7?
The Lamina-Pedicle Junction
Which cervical vertebra has long, delicate transverse processes?
C3
True/False: as we move caudally in the neck, the transverse processes of the cervical vertebrae become shorter and thicker.
True - they become more robust to accommodate large muscle attachment.
Which parts of the vertebra surround the spinal canal?
Lamina - roof
Pedicles - walls
Vertebral body - floor
The dorsal plate of the spinal cord carries mostly (motor/sensory) information.
Sensory
The ventral plate of the spinal cord carries mostly (motor/sensory) information.
Motor
True/False: the spinal canal is much larger in diameter than the cord so that the cord is not restricted with flexion and extension.
True
True/False: the dorsal root ganglion is outside the IVF.
False
The dorsal root ganglion contains cell bodies of (motor/sensory) neurons.
Sensory
The denticulate ligaments run from:
a. caudal facet to cranial facet
b. mixed spinal nerve to DRG
c. the pia mater to the dura
d. the dorsal ligament to the dura
c. the pia matter to the dura
How can vertebral restrictions change the tension on the dura?
a. through its attachment at the IVF
b. through the ligamentum flavum
c. through the transverse process
d. through the vertebral body
a. through its attachment at the IVF
The dorsal root ganglion is:
a. made up of motor neuron cell bodies located in the ventral plate
b. made of both sensory and motor neuron cell bodies in the IVF
c. made up of sensory neuron cell bodies in the dorsal plate
d. made up of sensory neuron cell bodies in the IVF
d. made up of sensory neuron cell bodies in the IVF
How can inflammation of the ligamentum flavum affect the spinal nerve?
Strain of the ligamentum flavum can cause swelling and inflammation that can diffuse into the IVF.
The contents of the IVF can be affected by (choose all that apply):
a. Arthritis or DJD of the facets
b. Restrictions
c. Spondylitis
d. Synovitis of the facet joint
a. Arthritis/DJD of the facets
b. Restrictions
d. Synovitis of the facet joint
True/False: restrictions involve the motion unit and have no effect on the IVF.
False
Name 9 things that lie within the IVF.
Dorsal Root Ganglion The Spinal Nerve Recurrent Meningeal Nerve CSF Dura Blood Vessels Lymphatics Ligaments Fat
Can cervical restrictions have an effect on distal limb lameness?
Yes - affects motor function and blood flow
What are the four main ligaments in the neck?
Ventral Longitudinal Ligament
Dorsal Longitudinal Ligament
Ligamentum Flavum
Nuchal Ligament
Which of these ligaments runs within the spinal canal?
a. Supraspinous
b. Dorsal Longitudinal
c. Ventral Longitudinal
d. Lamina-pedicle ligament
b. dorsal longitudinal
Why is there no ventral longitudinal ligament in the lower cervical region?
a. to allow for more lateral bend
b. to allow for greater extension
c. to allow for greater flexion
b. to allow for greater extension
Injury or inflammation of which ligament can affect the cord?
a. ventral longitudinal
b. dorsal longitudinal
c. ligamentum flavum
d. nuchal ligament
b. dorsal longitudinal
Injury or inflammation of which ligament can affect the contents of the IVF?
a. ventral longitudinal
b. dorsal longitudinal
c. ligamentum flavum
d. nuchal ligament
c. ligamentum flavum
The TMJ is a (simple/complex) joint.
Complex. A complex joint has two articular surfaces and a disc.
What are the two compartments of the TMJ?
Dorsal
Ventral
The (dorsal/ventral) TMJ compartment is responsible for open and close motion, while the (dorsal/ventral) TMJ compartment is responsible for lateral excursion.
Ventral compartment = open/close
Dorsal compartment = lateral excursion
True/False: restrictions of the TMJ can affect the hyoid.
True.
Name the four bones of the hyoid apparatus:
Stylohyoid
Ceratohyoid
Epihyoid
Basihyoid
The hyoid apparatus has muscular connections to the:
a. First Rib
b. Humerus
c. C5
d. Sternum
d. Sternum
Which cranial nerve innervates the temporalis muscle?
CN5
Name three muscles that attach to the basihyoid.
Omohyoideus
Stylohyoideus
Sternothyrohyoideus
What are two muscles that close the mouth?
Masseter
Temporalis
What are three possible presenting signs of a hyoid restriction?
Lack of lateral bend
Short stride in front end
Protrusion of tongue when riding
True/False: the atlanto-occipital joint moves only in flexion and extension.
False. A large portion is flexion/extension, but there is some lateral movement as a result of translation.
The capitis muscle is located:
a. over the dorsal arch of the atlas
b. over the nuchal crest
c. ventral to the occipital condyles
d. on the rostral aspect of the skull
a. over the dorsal arch of the atlas
Which foramina of the atlas carries blood vessels and where is it located?
Transverse foramen, located on the caudal wing of the atlas.
Note: the alar and lateral foramina carry nerves.
True/False: the atlanto-occipital joint is shallow and appears very close to the nuchal crest on radiographs.
False
What behavior problems can be associated with restrictions at C0-1?
Spookiness
Fear
Aggression
Depression
Other signs: lack of lateral bend or flexion, hard mouth, head tilt.
Which joint is responsible for most of the rotation of the neck?
C1-C2. Accounts for 73% of the rotation of the neck.
Some horses will rotate their poll when asked for even a slight lateral bend; what can this mean?
Indicates restrictions elsewhere in the neck. A horse should be able to laterally bend to the axilla without rotation.
In the cervical vertebrae, what foramen is mainly used for blood vessels?
a. jugular
b. lateral
c. transverse
d. lamellar
c. transverse
The angle of the facets at C2-3 are __________.
45 degrees
What is the contact point for C3 through C7?
Lamina-pedicle junction
Name two ways that C7 differs from the other cervical vertebrae.
Demi-facets on the caudal aspect to articulate with the first rib. (8 articular surfaces vs. 6)
Lacks a transverse foramen.
What are two ways a lower cervical restriction can affect the distal limb?
- Directly affects the brachial plexus (comes from nerve roots of C5-T2)
- Diminished blood flow
Muscle tension lines in the lower cervical region often come from the _______ muscle.
Serratus ventralis cervicus
What are the attachment sites for the serratus ventralis cervicus?
Transverse processes of C4-7 to medial scapula
Development of the __________ muscle should not be confused with a muscle tension line in the cervical region.
Splenius
What are the attachment sites for the splenius muscle?
Skull, atlas, and nuchal ligament to the transverse processes of C3-5 and dorsal spinous processes of T3-5.
What two muscles help flatten the lower cervical curve (i.e. lift the base of the neck)?
Serratus ventralis cervicus
Scalenes
What are the attachment sites of the scalenes?
Transverse processes of C4-7 to the first rib.
When the horse lifts the base of his neck, what is the action of the splenius muscle?
Support the head
What are the attachment sites for the obliquus capitis caudalis?
Temporal bone and nuchal crest to the wing of the atlas.
Changes in the obliquus capitis caudalis are felt when palpating:
a. the atlas
b. the axis
c. the occiput
d. C7
a. atlas
What are the attachment sites of the subclavius muscle?
Ventral sternum to supraspinatus muscle.
What are the attachment sites of the trapezius muscle?
Nuchal ligament to spine of the scapula.
Clearing restrictions and relaxing what three muscles will increase ROM of the front limb?
Subclavius
Brachiocephalic
Rhomboideus
True/False: to motion palpate C7 we need to be medial to the subclavius and near the attachment of the rhomboideus muscle.
False
What are the attachments of the brachiocephalic muscle?
Skull and transverse processes of C1-4 to the deltoid tuberosity of the humerus.
Name one pro and one con for an arched, flexible thoracolumbar spine.
Pro: allows for quick turns/speed
Con: Requires a great amount of muscular effort and energy to keep the back stable
What are three adaptations of the modern horse for running over relatively flat open terrain?
- Stiff thoracolumbar spine (little lateral bend/rotation)
- Small joint capsules in lumbar region with broad, horizontal transverse processes
- Fused radius/ulna to prevent supination
- Long cannon bones and one toe
Intentionally stiffening a joint that has a large range of motion is accomplished by:
a. ligaments
b. arthritis
c. tendons
d. muscular efford
D. Muscular Effort
How many curves are there in the horse’s cervical region?
Two - primary kyphotic and secondary lordotic
Which cervical curve develops after birth?
Secondary lordotic
Which cervical joint has the most rotation?
C1-2; 73% of total rotation
What three muscles commonly create muscle tension lines in the neck?
Splenius
Brachiocephalic
Serratus ventralis cervicus
A horse that rotates prematurely when asked for lateral bend may have (choose all that apply):
a. Restrictions
b. Cervical facet DJD
c. Hip Pain
d. Cervical Muscle Soreness
e. An Injection Site Reaction
f. Exceptionally Good ROM at C1-C2
a - restrictions
b - cervical faced DJD
d - cervical muscle soreness
e - injection site reaction
Normal musculature should:
a. have clear definition
b. feel very hard
c. have smooth contour
d. feel very soft and relaxed
c. have smooth contour
True/False: Movement of the vertebrae affects the spinal canal and IVF.
True
Neck (flexion/extension) decreases the diameter of both the spinal canal and the IVF.
Extension
When movement in one plane is always accompanied by movement in a second plane, we term it ____________.
Coupled motion
The diameter of the spinal canal and IVF decreases with:
a. flexion
b. extension
c. lateral bend
d. rotation
b. extension
Why do normal horses change their gait when walked with the head elevated?
Neck extension decreases the diameter of the spinal canal and IVF, potentially affecting the peripheral nerves and balance systems.
What is coupled motion?
Movement in one plane is always accompanied by movement in a second plane.
Why does a horse heavily weight the inside front limb when turning with the neck in extension?
With extension and lateral bend the dorsal spinous processes rotate to the inside of the bend.
The dorsal spinous processes of a horse in flexion and right lateral bend will rotate toward:
a. Left
b. Right
a. left
A(n) (arched/straight/ewe) necked hrose has limited ability to “lift” the base of the neck (i.e. flatten the lower cervical curve).
Ewe
True/False: A joint with good muscle support is less likely to develop DJD.
True
Why is it important to maintain good muscle tone around the lower cervical curve?
To help support the joints
It is difficult for a horse with a ewe neck to flatten the lower cervical curve because:
a. they have inherently weak scalenes
b. the lower cervical curve is long and deep
c. the lower cervical curve is naturally flat
d. they have very strong splenius muscles
b. the lower cervical curve is long and deep
Good muscle tone:
a. does not affect the joints.
b. makes the joints have less than normal ROM
c. pulls the joints past the normal ROM
d. helps to support the joints and keep them within normal ROM
d. helps to support the joints and keep them within normal ROM
What muscles are used when cervical flexion is done incorrectly?
Brachiocephalic and sternohyoideus muscles
True/False: incorrect cervical flexion closes the airway and restricts the hyoid apparatus.
True
Which muscles should the horse use to flatten the lower cervical curve and keep the airway open?
Scalenes
Serratus ventralis
To round the back the _________________ muscles need to be strong in contraction and the __________ muscles need to be strong in an elongated position.
Contract: abdominal and psoas muscles
Elongate: longissimus
How long should be hold a stretch to relieve tension in the muscle?
20-30 seconds
Why does holding a muscle in a stretched position relieve muscle tension?
Resets muscle spindle cells to a longer length.
What exercises help strengthen the abdominal muscles?
Cavaletti
Aquatred
Working in a round frame
Why do horses lower the center of mass during the stride before the jump?
Reduces the amount of downward force that the hindlimbs need to overcome
Elevating the head and neck before a jump begins the upward rotation of the trunk and it stretches the brachiocephalic muscle. What effect does stretching the brachiocephalic have on the front limbs?
Stimulates muscle spindle cells and causes contraction that helps to bring the front limbs forward.
When is the trajectory of the jump determined?
At take-off
Which forelimb absorbs more force at landing from a jump?
The trailing forelimb. Therefore, a horse that consistently lands on one particular lead may have discomfort in the leading forelimb (points the way to St. James).
Define dysafferentiation:
Abnormal afferent input as a result of joint restriction that involves a functional decrease in the activity of large diameter mechanoreceptor afferent fibers and a simultaneous functional increase in the activity of nociceptive afferent nerve fibers.
Describe the ideal stance and posture for an equine athlete.
Horses should stand square and place their feet with confidence. They should have relaxed posture and good muscle tone.
A deficit of the blink reflex on the left medial canthus, atrophy of the left temporalis, and masseter indicate a deficit of which cranial nerve? This reflects a deficit on which side of the brain? How can we address this deficit?
CN5 (Trigeminal)
Deficit on left side of the brain
Stimulate proprioceptors on the right side
What is the definition of dysafferentiation?
a. Severing of the nerve supply
b. An atrophy of the cortex leading to atrophy of the muscles
c. A decrease in Ia afferent activity coupled with an increase in nociceptive fiber activity, often due to a restriction.
d. The Ia afferent fibers change their connection to the other side of the cortex.
c. A decrease in Ia afferent activity coupled with an increase in nociceptive fiber activity, often due to a restriction.
You are presented with a patient that is strongly negative on static sway but positive on dynamic sway. What are your conclusions and why?
UMN problem - UMN dysfunction causes a lack of synchronicity of muscle contraction, which causes weakness.
Why is the dynamic sway test positive with UMN disease?
UMN dysfunction causes a lack of synchonicity of muscle contraction, which causes weakness.
Why does LMN disease cause rapid muscle atrophy?
LMN causes loss of alpha and gamma fibers so muscle atrophies very quickly.
Which balance systems are affected when the horse is walked with the head elevated and the neck extended?
Vision Vestibular Cervical Hyoid TMJ
What are three ways a restriction can adversely affect nerve function?
- Direct effect on dorsal root ganglion, nerve root, or peripheral nerve
- Inflammation defusing into the nerve
- Decreased circulation to the nerve
A horse that walks slowly and carefully is more likely to have a __________ problem.
a. Neurologic
b. Musculoskeletal
a. Neurologic
Circumduction due to a PI ilium is often seen with what other gait changes?
The pelvis will tilt to contralateral side; hock in, toe out appearance on the contralateral side
Why do neurologic signs improve as speed is increased?
As speed increases, maintenance of gait relies more on the release of stored energy from tendons and ligaments, and less on muscle contraction.
The basic rhythmic pattern of gait is located in __________.
The spinal cord
What are central pattern generators and where are they located?
CPGs are neural networks located in the spinal cord that are capable of generating rhythmic activity in the absence of sensory feedback; they only generate rhythmic activation of muscles - cannot adapt to terrain or disruptions of balance.
The step generated by CPGs can be altered by sensory input. Is this a:
a. feed-forward mechanism
b. feed-back mechanism
b. feed-back
What is the primary goal of the vestibular system?
To maintain the correct orientation of the head and neck
Define phase-dependent reflex reversal.
The effect of stimulation changes depending on the phase of stride.
Where are the second order sympathetic cell bodies located? What joints are they near?
Located in the sympathetic trunk just outside the vertebrae in the thoracolumbar region. Located very close to rib heads (two near first rib and one near TMJ)
How can a restriction cause local patchy sweating?
Stimulation of the sympathetic nervous system
What are four effects of chronic sympathetic stimulation?
Immune system depression
Adrenal fatigue
GI problems
Chronic pain
What effect does nociception have on the sympathetics?
Nociception and sympathetics stimulate each other
True/False: the lumbar vertebrae can move in all three axes.
True, but lateral bend is extremely limited. Most of the ROM is in flexion/extension.
When is flexion/extension of the lumbar vertebrae at its greatest?
At the canter, and increases as speed increases.
Intertransverse joints are usually found at ____________.
L5-6 and L6-S1; occasionally at L4-5
Ankylosis of the intertransverse joints is found in _____% of horses.
50%
Describe three common anatomical variations in the lumbar region.
L1 may have rib remnant instead of transverse process
Intertransverse joints
L6 may be fused to sacrum - sacralization
L5 DSP occasionally slants caudally
How can a lumbar restriction affect the ribs? The pelvis?
Ribs - via lumbocostal ligament
Pelvis - via psoas muscle
Why is it difficult to palpate S1?
The S1 DSP is very short and lies between the tuber sacrale
What is the patient contact point to adjust a sacral apex in a 3 year old?
S4 - the sacral vertebrae fuse at 4-5 years of age, so contact point for a younger horse is S4, vs. older horse is S5
How many joints are at the cranial sacrum?
a. 3
b. 7
c. 9
d. 6
b. 7
2 facets
2 intertransverse
2 sacroiliac
1 vertebral body
What is the role of the ventral sacroiliac ligament?
To hold the SI joint together - extends around the dorsal aspect of the sacral wing and the wing of the ilium, and fills in the space between the ventral ilial wing and the sacrum
The dorsal sacroiliac ligament is like:
a. intertransverse ligament
b. ventral longitudinal ligament
c. suspensory ligament
d. nuchal ligament
d. nuchal ligament
What are the three main functions of the pelvis?
To transfer force from the hindlimbs to the trunk
To protect and support the GI tract and urogenital system
To serve as a point of attachment for spinal, abdominal, and hindlimb muscles
What are three muscles that attach at the tuber ischium?
Biceps femoris
Semimembranosus
Semitendinosus
What are three muscles that attach to the tuber coxa?
Superficial gluteal
Tensor fascia lata
Abdominal obliques (internal and external)
What are the centers of rotation for the pelvis?
Coxofemoral joint
Sacroiliac joint
A PI ilium is restricted in which directions?
Dorsal and caudal
An AS ilium is restricted in which directions?
Ventral and cranial
A pelvic restriction can affect the lumbar vertebrae via two structures. What are they?
Iliolumbar ligament
Psoas muscle
What is the largest epaxial muscle?
Longissimus
True/False: atrophy of the longissimus and multifidus muscles can begin within 24 hours of injury.
True; longissimus and multifidus have segmental innervation
What are the functions/responsibilities of the longissimus/multifidus muscles?
Extend the back and stabilize the spine. They work isometrically to stabilize joints.
The __________________ epaxial muscle runs down and forward while the _________________ epaxial muscle runs up and forward.
Longissimus - down and forward
Multifidus - up and forward
The attachments of the longissimus are:
a. lumbar DSP to ribs
b. Mamillary processes to preceding DSP
c. sacrum, ilium, and DSPs to transverse processes of preceding vertebrae
d. dorsal arch of the ribs to sacrum
c. sacrum, ilium, and DSPs to transverse processes of preceding vertebrae
What can focal atrophy of the longissimus indicate?
Vertebral pathology in a certain area - the longissimus has segmental innervation
What are the attachments of the multifidus?
Lateral sacrum, articular and mamillary processes inserting on DSP of preceding vertebra
Why is the multifidus and important postural muscle?
High concentration of muscle spindle cells
What are 6 muscles that flex the hip?
Psoas major Iliacus Tensor fascia lata Superficial gluteal Sartorius Pectinius
What muscle causes ventral displacement of the tuber coxa when it fractures?
Tensor fascia lata
Name two hip flexors that attach at the lesser trochanter of the femur.
Psoas major
Iliacus
Name two hip flexors that attach at the third trochanter.
Tensor fascia lata
Superficial gluteal
The cranial gluteal nerve innervates the ______________ and _________________.
Tensor fascia lata
Superficial gluteal
What two hip flexors assist in adduction of the hind limb? What is their innervation?
Sartorius and pectinius
Femoral nerve for both, pectineus also innervated by obturator nerve
Name four hip extensor muscles:
Middle gluteal
Biceps femoris
Semimembranosus
Semitendinosus
What nerve innervates the middle gluteal muscle?
Cranial gluteal nerve and lumbar segments L6-2
What nerve(s) innervate the biceps femoris, semitendinosus and semimembranosus?
Caudal gluteal
Sciatic
What muscle attaches at the caudal sacral and first coccygeal vertebrae to the tuber ischium and then on to the cranial tibia and calcaneus?
Semitendinosus
What muscle attaches at the sacral DSPs to the tuber ischium and then on to the patella, tibia, and calcaneus?
Biceps femoris
What muscle attaches on the ilium, sacrum and sacrosciatic ligament to the greater trochanter of the femur?
Middle gluteal
What muscle originates on the first coccygeal to the tuber ischium and inserts on the medial condyles of the femur and tibia?
Semimembranosus
Degeneration or inflammation of the ________ joint can cause atrophy of the four main muscles of hip extension.
SI joint
To run faster or jump higher the horse needs to generate _________ ground reaction force.
High
When a horse’s balance, proprioceptive, and nervous systems are working properly, the horse will stand __________.
Square
Define shunt stability:
Engagement of the core muscles prior to limb movement
Two ways to maintain a steady gait against gravity are _____________ and _______________.
Muscular effort
Mechanical limb locking
True/False: A loss of sensation from peripheral receptors can adversely affect balance.
True
What are the three main goals of the postural system?
- Maintain a steady state against gravity
- Anticipate voluntary movement
- Be adaptive
What are three biomechanical reasons a horse should stand square?
- Uses less energy
- Avoids muscle strain
- Allows them to move quickly in any direction
When a horse “sits” on its feed tub it may indicate ______________.
Back pain
Pain and movement:
a. are directly proportional
b. are inversely proportional
b. are inversely proportional
When can nociceptors branch out and attach to 1a receptors?
When movement decreases, there is less stimulation of 1a afferent fibers, allowing nociceptive fibers to branch out and attach to 1a receptors
When 1a fibers are stimulated, they branch out to inhibit _______________ and ______________.
Sympathetics and nociception
1a fibers are stimulated by _________________.
Movement
How can you determine if a horse leans right or left?
Pectoral muscle tension will indicate current lean
Hoof size indicates chronic lean - hoof on the leaning side will be larger
What is the difference between muscle tone and muscle tension?
Muscle tone: Muscles should have good gamma gain (sensitivity of muscle to stretch) but be smooth, relaxed and without tension
Muscle tension: definition of the muscles due to a steady state of contraction
Which muscles are innervated by cranial nerve XI?
Brachiocephalic
Trapezius
Omotransversarius
Sternocephalicus
How can a restriction of the TMJ affect the horse’s ability to collect?
Mandible cannot swing freely –> back held in extension –> longissimus dorsi tense and back hollow –> hindquarters cannot come under the horse properly –> difficulty collecting
Of the six major inputs for balance, which are the four we can affect?
TMJ
Hyoid
Cervical
Hoof Balance
TMJ restrictions may cause (choose all that apply):
a. short stride
b. cranial nerve 7 deficit
c. restriction at C2-3
d. hollow back
a, b, c, d
True/False: Hyoid restrictions are rarely seen with a TMJ restriction.
False
Thy hyoid should move:
a. Rostral/caudal
b. Left/right
c. Dorsal/ventral
d. In all directions
d. In all directions
The stomatognathic system consists of:
a. Teeth and TMJ
b. All the soft tissue in the cervical region.
c. Everything cranial to the shoulders
d. Teeth, TMJ, and soft tissue of the head
c. Everything cranial to the shoulders
A horse that plays with its tongue is likely to have a _______ restriction.
Hyoid
What does positive dissociation mean?
The hind feet contact the ground earlier than usual in the gait pattern
What effect does dissociation have on the pattern of footfalls, for example on the normal two beat diagonal pattern of the trot?
It changes the number of beats - the trot becomes four beat
What effect does using the abdominals and scalenes properly have on the movement of the front limb?
The front limb will have good ROM in the elbow and at full extension the carpus and fetlock will have a slight flexion so that the sole of the hoof is parallel to the ground
Where is the center of gravity in relation to the base of support during movement?
Near the perimiter of the base of support, moving outside the base of support as speed increases
When is the horse most stable, during stance or during movement?
Stance
Tendons are viscoelastic. What does that mean?
The tissue properties change after repeated cyclical loading (i.e. become more elastic after repeated loading)
How does 10-20 minutes of walking before training help prevent injury?
Repeated cyclical loading decreases tendon stiffness, allowing tendons to withstand higher loads because they are more elastic.
Why don’t athletes spend a lot of time stretching before training?
Stretching resets the muscle to a new longer length, which will not provide as much support to the joints and allowing them to go beyond their normal ROM, which predisposes to injury.
How does chronic stretching affect the muscle to increase ROM?
Chronic stretching increases the number of sarcomeres in the muscle, increasing the normal ROM of the muscle.
What are the two basic forms of muscle? Which is best at creating a large range of motion?
Parallel and Pennate
Parallel better for large ROM. Pennate better for isometric action.
Isometric action is often used to ____________________.
Support/stabilize joints and resist joint angle changes
Which type of muscle action can quickly generate the most force?
Eccentric - often used to decelerate joint motion at the end of a movement
Concentric generates more force when acting slowly
What is eccentric action commonly used for?
Decelerating joint motion
Muscles can generate the most force at:
a. full extension
b. full flexion
c. resting length
c. resting length
What is active insufficiency?
At the extremes of range of motion, muscles have less cross-bridging and generate less force
What is the benefit of starting with a counter-movement?
Generates more force
What is reflex potentiation?
Stretch on a muscle stimulates the muscle spindle cells to cause a reflex muscle contraction.
Which muscle action generates more force when loaded slowly?
Concentric
What are four ways the stretch-shortening cycle helps generate more force?
Contractile potentiation
Reflex potentiation
Storage of energy
Increased time to apply force
What is the Force-Motion principle?
Force is increased as ROM is increased (flex arms to make a chest pass vs. passing with arms fully extended)
What are the components of the functional dorsal ligament system?
Nuchal ligament
Supraspinous ligament
Thoracolumbar fascia to dorsal sacral ligament
Hamstring muscles
What role do the abdominals play in the ring of muscles?
The abdominal muscles lift and stabilize the back - vital to preventing back injury
What muscles does the horse use to flatten the lower cervical curve?
Scalenes
Serratus ventralis
How does back pain interfere with using the ring of muscles?
If a horse has back pain and can’t lift his back, he can’t tension the dorsal ligament system, flatten the lower cervical curve, or bring his hind end under.
Which is faster, feed-forward or feed-back? Why?
Feed-forward. Works because brain has prior experience of same or similar situations, resulting in very fast muscular control before the intended movement.
Effective feed-back is dependent on high __________.
Gamma gain
Which mechanism compares the intended movement to the actual movement?
a. feed-forward
b. feed-back
b. feed-back
With relation to feed-forward/back, when are injuries likely to occur? How can be protect athletes against this type of injury?
Injuries typically occur when there is a disruption in balance - we can protect athletes by helping to practice controlled disruptions in balance, such as performing movements more rapidly than usual or using a vibration plate.
What happens before a voluntary movement begins?
The brain “sees” the desired outcome
What is motor planning?
The brain “sees” the desired outcome, causing mechanoreceptors throughout his body to send signals to the brain reporting on the body’s position.
What are two things that affect the speed of voluntary movement?
The number of neurons involved
The amount of information processed
What are two things that affect the accuracy of a movement? What is their effect (to increase or decrease the accuracy)?
Prior experience increases the accuracy
Speed decreases accuracy (less time for feed-back correction)
Why are reflexes so fast?
Only two neurons are involved, vs. planned movements that travel through more neurons.
Activation of flexor muscles reflexively _____________ the extensors.
Inhibits
What three types of action make up complex movements?
Reflexes, rhythmic, and voluntary movements
One example of burst neurons that regulate gait is the ______________.
Central pattern generators
What are two types of adaptive pain?
Nociceptive pain
Inflammatory pain
How is neurogenic pain related to injury?
Neurogenic pain is pain that lingers even after an injury is healed; it is maladaptive pain. It is not related to a current injury.
Why do we pull away, yell, and get hot when we hit our thumb with a hammer?
Nociceptors stimulate three parts of the brain: the thalamus (pull away), limbic system (yell), and hypothalamus (get hot)
What stimulus causes pain in all individuals in all situations?
No stimulus causes pain in all individuals in all situations. Pain is a percept of the brain and therefore different for everyone.
Rank these neurons from fastest to slowest:
A-delta
Ia afferent
C fibers
Ia afferent
A-delta
C fibers
Which neurons are responsible for dull throbbing or burning pain?
C fibers
Why do horses with colic sweat?
C fibers travel with sympathetic nerves, so stimulation of C fibers can stimulate the sympathetics
How can stomach ulcers cause pain over the sternum?
Viscero-somatic sensations due to both somatic and visceral nociceptive fibers synapsing on the same part of the dorsal horn of the spinal cord
What is neuronal windup?
Dorsal horn cells become more sensitive and have a bigger response to the same stimulus due to chronic C fiber stimulation
What is neurogenic inflammation?
Inflammation caused by the nerves themselves.
How do neuropeptides differ from neurotransmitters?
Neurotransmitters: released by neurons into the synaptic cleft; they stay close to the synaptic cleft and are taken up very quickly.
Neuropeptides: No re-uptake system, so they travel far away from the synaptic cleft
How do nociceptors contribute to the swelling, heat, and redness of inflammation?
Nociceptive neurons release neuropeptides, such as substance P. Substance P causes vasodilation and edema, as well as mast cell histamine release, contributing to swelling, heat, and redness.
What affect does nociceptor stimulation have on the sympathetics?
Nociceptors are continuously firing and provide 90% of all input to the sympathetic nervous system.
What is the first DSP that can be palpated in the withers?
T3. Note: T1 and T2 are hidden between the scapulae.
What DSP is the highest point of the withers?
T4
What DSPs mark the end of the withers?
T8-9
In which direction do the cranial thoracic DSPs slant? Why?
Caudally - to resist the pull of the nuchal ligament.
Which DSP(s) are vertical?
T15 or 16. After this point, the DSPs slant cranially.
How many articular surfaces are on the thoracic vertebrae?
12 surfaces: 4 facets, 2 body, 4 costovertebral (demi-facets), 2 costotransverse
Describe how the intercapital ligament runs:
Neck of one rib, through the intervertebral foramen, under the dorsal longitudinal ligament, through the opposite IVF, to the neck of the opposite rib.
Why do the ribs have a double curve?
The double curve makes them flexible, strong, and capable of increasing the volume of the thorax during inspiration.
Which direction(s) do the ribs move during inspiration?
Dorsal, cranial, lateral
What are the four muscles of inspiration?
Rectus thoracis
External intercostal
Serratus dorsalis cranialis
Levator costarum
What is the role of the first rib?
The first rib is short and straight and has a tight articulation with the sternum. It serves as a post and the other ribs are pulled toward it during inspiration.
Which muscle has fibers that run caudoventrally and fill in the space between the rib bodies?
External intercostal muscle (note: fibers run in same direction as external abdominal oblique)
Which two muscles of inspiration are on the dorsal aspect of the rib?
Serratus dorsalis cranialis
Levator costarum
What are the four muscles of expiration?
Transversus thoracis
Internal intercostal
Serratus dorsalis caudalis
Retractor costae
Which expiratory muscle attaches to the deep aspect of the sternum and the ventral, medial aspect of ribs 2-8?
Transversus thoracis
Which muscle has fibers that run cranioventrally and lie between the rib bodies?
Internal intercostal (note: fibers run in the same direction as the internal abdominal oblique)
What is the movement of the ribs during expiration.
Caudal, ventral, medial
What are the four abdominal muscles?
Rectus abdominis
External abdominal oblique
Internal abdominal oblique
Transverse abdominal
Which abdominal muscle has fibers that run caudoventral?
External abdominal oblique
What are the attachments for the rectus abdominis muscle?
Lateral aspect of ribs 4-9 and inserts on prepubic tendon and head of the femur
Why is it important for the abdominal muscles to be strong and have good tone?
To provide proper stabilization and support for the back.
Which two abdominal muscles attach to the tuber coxa?
External and internal abdominal obliques
Which abdominal muscle originates at the lumbar transverse processes and medial surface of ribs 7-18?
Transverse abdominal oblique
Name three muscles that attach to the front limb and are innervated by cranial nerve XI:
Trapezius
Brachiocephalicus
Omotransversarius
What are two muscles that lift the scapula?
Trapezius
Rhomboideus
The brachiocephalic and the ______________ are closely associated.
Omotransversarius
The _____________________ muscle helps to advance the limb and the _______________ helps to flex the shoulder joint.
Brachicephalic - advance
Latissimus dorsi - flex shoulder
Of the seven muscles that attach the thoracic limb to the trunk, three attach along the dorsal midline. Name these three muscles.
Trapezius
Rhomboideus
Latissimus dorsi
What muscle has a thoracic part that attaches on the medial scapula and to the ventral aspect of ribs 1-9? What is the action of this muscle?
Serratus ventralis. Serves to suspend the trunk and flatten the lower cervical curve/lift the withers
All of the pectorals have similar actions - what are they?
Support the trunk and adduct the limb
What are the attachments of the transverse pectoral muscle?
Costal cartilages of ribs 1-6 and sternum, inserting on the antebrachial fascia
Which of the muscles that attach the thoracic limb to the trunk also flexes the shoulder?
Latissimus dorsi
What shoulder flexors attach to the deltoid tuberosity of the humerus?
Deltoid
Teres minor
Which shoulder flexor attaches to the olecranon?
Long head of the triceps
What shoulder flexors attach to the medial side of the humerus?
Teres major
Latissimus dorsi
What is the only shoulder flexor that attaches to the supraspinous ligament from T3 to the thoracolumbar fascia?
Latissimus dorsi
Which head of the triceps flexes the shoulder and extends the elbow?
Long head of the triceps
True/False: The biceps brachii, coracobrachialis, and the subscapularis all insert on the medial side of the leg.
True
Which muscle runs from the coracoid process of the scapula to the medial humerus?
Corachobrachialis
Which shoulder extensor inserts on the radius?
Biceps brachii
Which shoulder extensor has a huge and distinctly shaped tendon that curves over the proximal humerus?
a. brachiocephalic
b. coracobrachialis
c. subscapularis
d. omotransversarius
e. biceps brachii
e. biceps brachii
Which shoulder muscle is multipennate and acts like a medial collateral ligament?
Subscapularis - best for isometric contraction
List the shoulder extensors:
Biceps brachii Coracobrachialis Subscapularis Supraspinatus Brachiocephalic Omotransversarius \+/- infraspinatus depending on the angle of the joint
Name the elbow flexors - both their names start with “B”
Biceps Brachii
Brachialis
Which muscle wraps around the humerus?
Brachialis
All elbow extensors insert on the ___________.
Olecranon
Which head of the triceps has an action in addition to elbow extension?
Long head
Which two muscles extend the elbow?
Triceps
Tensor fascia antebrachii
The rider’s weight makes the horse’s back extend. How do young horses compensate for this? How does that change as they become accustomed to carrying a rider?
Young horses will retract their forelimbs to help support a rider, until their abdominal muscles are strong enough to balance the additional weight.
When looking at a horse’s stance, what can indicate back pain?
Bringing the hind limbs forward toward the forelimbs, sitting on the wall or water bucket
What comments may a a rider make that indicate the horse may have back pain?
Reluctant to turn, saddle slipping (slips to opposite side of back pain), behavior issues (nervous, spooky)
How does back pain affect the horse’s gait?
Pain will decrease the ROM of the back, and therefore decrease stride length. As pain becomes chronic, the horse will begin to drag the back toes and have a wider gait behind.
Can back pain affect the horse’s behavior? If so, how?
Yes - spooky, nervous
What is an undesirable but common appearance of the lumbars and hindquarters?
peak-dip-peak (kyphosis of cranial lumbar vertebrae with dip in the caudal lumbar region and a peak at the tuber sacrale)
For a horse that works in collection a __________ lumbar conformation is desired.
a. long
b. short
b. short
Thoroughred racehorses often have a __________ lumbar region.
a. long
b. short
a. long
What is viscous friction?
The friction between the blood and blood vessels
How does the speed of blood flow affect the amount of viscous friction?
Faster blood flow = more friction
Where is there a concentration of proprioceptors in the hoof? Why are they important?
Heel - They are important in sensing the location of the body relative to the ground and send input to the central pattern generators
Describe hoof mechanics.
The priority at impact is for the coffin joint to land flat and for the whole hoof to land flat or heel first. As the hoof is loaded the dorsal wall moves back, the quarters flare outward, and the frog and sole move downward.
Steep hoof angle = heel first landing
Low hoof angle = toe first landing (undesirable)
The oscillations of impact in the foot are absorbed mostly between the ____ and ______.
Hoof wall and P3
What aids in controlling the sliding of the hoof at impact?
Translation of the coffin joint and extensor branches of the suspensory ligament.
How does a horse change its stance to compensate for a low hoof angle?
The horse will retract its front feet to stand over its breakover and align the cannon bone with the heels.
How does a low hoof angle affect the shoulder? The scapula?
A low hoof angle will cause extension of all the joints of the limb; the shoulder will move caudal and the scapula will rotate cranially.
How can restrictions affect hoof quality and angle?
Restrictions can affect blood flow to the hoof and chronic low heels
A low hoof angle in the rear feet can cause muscle soreness in the _______ and ________.
Low back and hindquarters
How does a low hoof angle affect the DDFT?
Increases strain in the DDFT
How does raising the hoof angle affect the suspensory and SDFT?
Increases tension in the SL and SDFT
Ideally, the palmar angle should be:
a. Negative
b. Positive
b. Positive
A line drawn along the coronary band of the hind foot from heel to toe should meet the front limb at the _____________.
Carpus
Describe the likely appearance of the frog in a hoof with a negative palmar angle:
Recessed apex
The axis of the cannon bone should align with the __________, with respect to hoof balance.
Heel bulbs
True/False: Shoes help to dampen impact oscillations.
False. Increase by 15%
