Anatomy II Exam 1

PELVIC LIMB 8. Tarsus (hock joint) A. Osteology there are 3 rows of tarsal bones but only 2 rows of carpal bones 1. Proximal row - - Talus- has a semicircular ______________ (pulley) that articulates with the tibia. Virtually all movement of the equine hock joint occurs within the __________________ (tarsocrural) joint which has a wide range of motion and therefore the joint capsule has considerable slack. - Ruminants and camelids have both _________________ and ____________ trochleas of the talus so flexion of the hock involves both the tibiotarsal joint and the joint between the distal talus and the _____________ ____________ bone (proximal intertarsal joint). Since these animals spend considerable time lying down with the hock flexed, the double trochlea is probably an aid to flexion for long periods of sternal recumbency. - Calcaneus- a lever arm that is not weight bearing but is responsible for movement. Medial to the lever arm is a groove for the main _________ ___________ tendon. The distal part of the bone is the sustentaculum tali which articulates with the talus. The name comes from the fact that it supports (sustains) the talus in the plantigrade human foot. 2. Middle row- central tarsal bone, Tc 3. Distal row- numbered tarsals, T1+2, T3, T4 correspond with metatarsals.

trochlea; tibiotarsal; proximal and distal; central tarsal; deep flexor

Neurovascular supply (horse) B. Nerves - the medial and lateral palmar/plantar nn. branch at the fetlock to form the: 1. ____________ ____________ n. which supplies the toe and lies dorsal to the palmar/plantar digital a. Since this nerve is not cut for navicular disease the horse can still sense the toe location. 2. _____________/______________ ____________ n. lies on the palmar or plantar (volar) surface of the digital artery and attached to it. This nerve is blocked for the diagnosis of navicular disease and _______ to treat it. Horses so treated still know where their toe is due to the dorsal digital n. If the parent nerve is cut above the fetlock, however, sensation of the toe is lost and the horse is no longer safe to ride on anything other than a flat surface (no more trail riding).

Dorsal digital; Palmar/plantar digital; cut

1. _______________ JOINT = metacarpophalangeal joint Name derivation: may come from "feet lock" for the lock of hair that may be prominently seen on the palmar surface of this joint in some breeds of horses. BONES: − cannon bone (Mc3) with _______________ ___________ distally − long pastern bone (P1) with _______________ ____________ that articulates with ridge i.e., increased stability of joint − two proximal sesamoid bones (clinical) ___________________ fracture: fractures of P1 that involve the sagittal groove.

FETLOCK; sagittal ridge; sagittal groove; screwdriver

FORELIMB STAY APPARATUS • FORELIMB STAY APPARATUS = CABLE DOWN THE ______________ OF LEG (PASSIVE SUPPORT) • MORE COMPONENTS TO FORELIMB STAY APPARATUS: o _______________________ _____________________ (SUSPENSORY LIGAMENT + DISTAL SES LGMT) o ______________ LIGAMENT

FRONT; SUSPENSORY APPARATUS; CHECK

Metapodium Osteology 1. Ox - Mc/Mt 3 and 4 (_____________ bone) are fused except at their distal end. In the hind limb the ____________ ___________________ artery lies in the dorsal groove. The same artery is lateral in the horse because Mt3 (cannon bone) is larger than Mt 4.

cannon; dorsal metatarsal

PELVIC LIMB 9. Metatarsus: ____/____ longer than metacarpus, Mt 3 = cannon bone has a round cross section but Mc. is ________ in cross section. The cannon bone of the ox is a fusion of Mt 3 and 4.

1/4; oval

(clinical) __________________ tendons = flexural deformity are one of the most common congenital deformities of foals and calves. In some cases surgical section of the distal check ligament may be needed to straighten the limbs. These three parallel tendons (suspensory apparatus, SDFT, DDFT) form a passive (non-muscular) support system for the fetlock which is the part of the stay apparatus.

contracted

EQUINE FOOT = hoof (aka hoof capsule) + contents of the hoof The ______________ is the junction of skin and hoof - _______________- waxy layer that protects hoof against drying

coronet; periople

fibular nerve paralysis: - this is a common injury of _________ that suffer prolonged recumbency on a hard surface. The result is pressure damage of the common fibular nerve as it passes over the lateral crus.

cows

Bovine foot (other cloven hoof animals are similar) A. Dew claws = hooves of rudimentary digits ____ and ____. They don't touch the ground but are close enough to pick up dew from grass. The dewclaws of bovine hind limbs may cause udder lacerations when cows with big sloppy udders lie down and hence some dairy people remove the hind dewclaws of heifers at a young age when bleeding is minimal. All ruminants have dewclaws except for the _____________ and American pronghorn. Dewclaws are best developed in reindeer (caribou) where they may help prevent feet from sinking in snow. - ________________ lack due claws and this is one of many subtle differences from ruminants.

2 and 5; giraffe; Camelids

Metapodium Osteology 3. Horse a. Mt 3 is usually about ______% longer than Mc 3. Mc 3 is large and bears all the weight. It is often referred to as the cannon bone because the cross section appears like the barrel of a cannon. Mt 3, however, makes a better cannon as it is round in cross section while Mc 3 is oval because it is wider for bearing more weight. b. Mc 2 and Mc 4 are referred to as splint bones and are generally considered to be vestigial. Splint bones should not be confused with "splints" c. The proximal end of the cannon bone has a metacarpal tuberosity on the dorsal surface where the _______________ ___________ _______________ m. inserts. This tuberosity is probably the result of the continual pull of the stay apparatus. d. The distal end of the cannon bone is referred to as the condyle. The distal articular surface is referred to as the trochlea and has a _____________ crest. The sagittal crest fits into a sagittal groove on the first phalanx (P1). Fractures of P1 that involve this groove are referred to as ____________________ fractures.

20; extensor carpi radialis; sagittal; screwdriver

Bovine foot B. Claws are the hooves of digits ____ and ____. In many ways they are like a half of an equine foot except: 1. Body weight is borne on the ________ as well as the wall. The bovine bulb is distinct from the wall and is weight bearing while the equine bulb of the heel does not bear weight. Pigs have a soft digital pad in place of the hard bulb of ruminants. 2. Bovine feet have a wall and sole but no homologue of the ________ or _________________ ___________________. 3. The laminae lack secondary (microscopic) laminae. This probably relates to the fact that in the horse the wall bears all the weight but in cattle less than half of the weight is borne by the wall. Therefore, laminitis in cattle is not as painful as in the horse. 4. The terms __________ and ______________ are used to refer to the "sides" of bovine claws. • ___________________ space (cleft) is the space between the claws. The interdigital ligaments cris-cross between the digits to prevent excessive spreading of the digits.

3 and 4; bulb; frog or collateral cartilages; axial and abaxial; Interdigital

PELVIC LIMB 4. Stifle joint: C. Patellar ligaments- horse and cow have ____ rather than one as in the dog - Lateral = ______________ _______________ tendon - Middle and Medial -- probably represent split of a single ligament. - Note regarding the patellar ligament/tendon - the same structure is both a tendon and a ligament depending on the context and reference. To the physiologist and neurologist it is a tendon, hence the patellar tendon reflex uses a rubber hammer to tap the patellar tendon to test the ________________ reflex. The patella is considered a sesamoid bone in the quadriceps tendon which inserts on the tibial tuberosity. Anatomists and surgeons refer to the patellar ligament which connects the patella to the tibia since the quadriceps m. is considered to insert on the patella (rather than the tibia). D. Patellar locking mechanism fixes the stifle joint so that flexion due to gravity is limited. A loop engages with a bony "hook" and limits flexion. 1. Loop- _____________ and _____________ patellar ligaments joined by the patella. 2. "Hook"- ____________ lip (ridge) of the femoral trochlea is considerably larger than the _____________ counterpart - Patella fixation is a clinical condition characterized by an irregular gait due to intermittent failure of the patella to unlock. The old treatment was medial patellar desmotomy (to cut a ligament) which gave immediate relief but poor long term results. Now the treatment involves exercise therapy.

3; biceps femoris; myotatic; medial and middle; medial; lateral

Pig foot: • digits 3 and 4 are of similar size in ruminants but in pigs ____ is larger than ____. The bulb of the hoof is hard in cattle but soft in the pig. • Pigs have dewclaws and they are often __________________, apparently due to lack of abrasion from ground contact. However, bovine dewclaws don't show overgrowth and they lack ground contact. Pigs on concrete show wear on the palmar surface of overgrown dewclaws where there is ground contact when lying in sternal recumbency.

4; 3; overgrown

PELVIC LIMB 1. General Comments: connection to the trunk; extrinsic muscles for forelimb, bony for hind limb. A. Muscle mass comparison hind limb _____ forelimb propulsion vs. support and turning B. Muscle concentration - Proximal most muscle, __________ range of motion, hence less energy to move it. - Distal least muscle, _______________ range of motion. Distal joints are flexed and extended by long tendons from muscle bellies located proximal in the limb.

>>; least; greatest

PELVIC LIMB 10. Equine hind limb stay apparatus- fixes one leg alternately to relieve muscular strain and conserve energy since horses spend most of their lives standing. _________________ muscles support the body weight and are usually extensors and stronger than their non weight-bearing antagonists. The digital flexors are also antigravity muscles. A. ___________ _________ mechanism- triggers the whole mechanism. When the stifle is fixed and the forelimbs limit cranial/caudal movement and the hip is passively fixed. B. Superficial digital flexor m.- mostly tendinous in horse fixes _________. The SDFT both attaches to the point of the hock and also slides over the point of the hock where a calcanean bursa facilitates the sliding. The attachment of the SDFT to the point of the hock is responsible for the _________________ apparatus and the fixation of the hock by the stay apparatus. - NOTE: although the hind limb does not have check ligaments it does have the suspensory apparatus as previously described for the forelimb.

Antigravity; Stifle lock; hock; reciprocal

3. _____________ JOINT = distal interphalangeal joint (DIP joint) • Name derivation: the hoof is the 'coffin' that surrounds the DIP joint. • BONES: − short pastern bone (P2) which is partially surrounded by the hoof − coffin bone (P3, pedal bone) • (clinical) rotation of coffin bone with ______________ due to the deep digital flexor tendon's pull on its insertion on P3. During early stages of this condition, cutting the ___________ ___________ ligament may prevent the rotation of P3.

COFFIN; laminitis; distal check

PELVIC LIMB 6. ________________ (Achilles) tendon is a collective term for the group of tendons derived from the superficial digital flexor m. and the gastrocnemius mm. that acts on the calcaneus bone.

Calcanean

____________________: (metacarpus or metatarsus = a collective term that covers both). __________ is a collective term that means either palmar or plantar so can be used with either limb.

Metapodium; Volar

2. _________________ JOINT = proximal interphalangeal joint (PIP joint) • Name derivation: Before the use of fences, horses were pastured by attaching a rope between a stake and a clamp around the pastern (narrow area between foot and fetlock) hence the name is derived from this old practice. • BONES: − long pastern bone (P1) − short pastern bone (P2) • (clinical) ________ bone: a pathological bone that forms a ring around the pastern bones.

PASTERN; ring

B. Dermis (formerly corium) 1. _______________ dermis- The narrow transitional region between hairy skin and coronary dermis, the epithelium covering this region produces a __________ covering of the hoof that prevents drying and cracking of the hoof wall. The coronet is a common name for the transition line from skin to hoof. 2. ________________ dermis (coronary band)- in this region of dermis there are long conical ______________ covered by epithelium that produce tubular horn which forms the bulk of the hoof wall. The wall grows out at a rate of about _______ mm/day (1/4 inch/month). The toe is the slowest part of the hoof wall to be replaced because it is longest part of the wall. Thus it dries out more and is less flexible than the heel. 3. ____________ dermis- is firmly attached to P3 = coffin bone. It bears about ________ primary (sensitive) laminae. Each primary lamina contains >100 secondary laminae. The function of these laminae is to bind the horny (insensitive) hoof wall laminae to the coffin bone whereas the function of the coronary region is to produce the wall. As the wall grows out the horny laminae "slide" slowly over the sensitive laminae. The horn of the wall is often pigmented but the horny (insensitive) laminae are unpigmented and as they are pushed distally they become the ___________ _________. 4. _________ dermis- short papillae produce tubular horn.

Perioplic; waxy; Coronary; papillae; 0.2; Laminar; 600; white line; Sole

PELVIC LIMB 8. Tarsus (hock joint) D. ____________ ligament = strong ligament on the plantar surface of the calcaneus extending to Mt 4. Great force is put on the calcaneus by the tendons of the gastrocnemius. This force can result in tearing of the plantar ligament causing a rounded swelling know as _________ (French, curve)

Plantar; curb

FOOT DEFINITIONS − ___________________ - primate and standing bear. The bear's hind foot is modified for this with a tarsal pad − ___________________ - stands on digital pads - carnivores and camelids. − ___________________ - stands on the hoof. Note that camelids are "digitigrade ungulates", or, hoofed animals without hooves, rather they have a non weight-bearing claw similar to the dog. Pig feet are a transitional form since they have a hoof like toe in front of a soft pad. In the horse the pad (digital cushion) is inside the hoof where it is between the digit bones and the hoof.

Plantigrade; Digitigrade; Unguligrade

PELVIC LIMB 8. Tarsus (hock joint) B. ____________- a general term for equine lameness originating in the hock joint. Bone spavin is an arthritis in the region of ______/______ and ______/_______ in the horse. Radiographically these bones have fuzzy edges due to inflammation. The so called _____________ tendon is often cut to treat this condition because it puts pressure on the painful area which is deep to it. Cunean tendon = medial tendon of the cranial tibial muscle, (also, there is a dorsal tendon).

Spavin; Tc/T3 and T3/Mt3; cunean

PELVIC LIMB 2. Hip region: the __________________ is deep to facilitate force transfer from hind limb to pelvis. In contrast, the shoulder joint is shallow (less force transfer) and easily dislocated. A. Accessory ligament of horse extends from ________________ ligament to the head of the femur. It is accessory to the ligament of the femoral head which is very short. Hip luxation (dislocation) is common in ___________ but rare in ____________ and thus the accessory ligament of the femoral head probably protects horses from hip luxation. Lack of equine side kicking may be due to accessory ligament. B. ____________ _____________ muscle- main extensor of hip. Responsible for the rounded croup of horse. There is no medial gluteal m., the confusion comes from gluteus medius (L. medius = middle). Horses have an _________________ head of the middle gluteal on the deep surface. This head differs from the piriformis of the dog in that it has a distinct femoral insertion separate from the main insertion of the middle gluteal on the greater trochanter. The ___________________ bursa under this insertion is the site of trochanteric bursitis which results in a characteristic "dog like" gait.

acetabulum; prepubic; cattle; horses; Middle gluteal; accessory; trochanteric

- Normal maturation of the digital cushion leads to less ______________ tissue and more cartilage and fibrous tissue joining the digital cushion to the foot cartilages. This maturation depends on environmental factors and aids the foot in dissipating concussive forces. Proper maturation of the foot cartilages and the digital cushion protects the foot from chronic heel pain (________________ syndrome). - Traditionally the wall was thought to bear all of the weight of a horse and that is the case in the horse with shoes on. In the unshod horse some of the weight is born by the ________ and the ________. Dr. Bowker thinks this "natural" condition aides in development of "healthy feet".

adipose; navicular; sole; frog

PARTS of the HOOF 1. Wall- divided into toe, quarters and heel. The _________ are continuous with the wall at the heel. The wall is strong and supports most of the weight of the horse via the ___________________ _______________ which interdigitate with the sensitive laminae of the dermis. The wall is flexible enough to bend in at impact thereby absorbing some of the concussive force of foot impact with the ground. The __________ _________ is the junction of the wall and sole which is best seen when the foot is trimmed. The toe is the _______________ part of the wall and least flexible. Horseshoe nails are mainly put in the toe and quarter so that the heel can remain flexible to enhance blood circulation. The ___________ of the heel are the rounded palmar surface of the heel adjacent to the skin and not in contact with the ground. 2. The sole is soft and less suited to bear weight. 3. The _________ (cuneus) is very soft. It is between the bulbs of the heel and separated from the bars by the _________________ sulci (paracuneal grooves) which are often filled with manure. A sulcus is a groove.

bars; insensitive laminae; white line; thickest; bulbs; frog; collateral

Humerus 1. Equine intertubercular groove has an intermediate tubercle that keeps the _______________ ______________ "on track", not present in other domestic species except camelids. 2. Brachial groove deep in ungulates and deltoid tuberosity is prominent 3. Medial and lateral epicondyles are the sites of ____________________ flexor and extensor mm. origins respectively (sometimes called flexor and extensor epicondyles).

bicipital tendon; antebrachial

B. Intrinsic muscles of the forelimb act to stabilize or move individual joints of the limb 1. Shoulder muscles function primarily as so called "active" collateral ligaments to hold the shoulder joint together. The shoulder lacks typical collateral ligaments. 2. Both the _________________ and ______________ ______________ mm. flex the elbow but their structure is considerably different. While the brachialis is fleshy, the biceps of the horse has a central tendon that extends from the ________________________ ________________ of the scapula. The central tendon of the biceps continues as a distinctly palpable structure, the _______________ _________________, to then unite with the fibrous covering of the extensor carpi radialis m. This final insertion is on the proximal metacarpus (metacarpal tuberosity). This continuous tendinous connection from scapula to metacarpus is called the forelimb stay apparatus. In a standing horse, muscle energy is conserved through stabilization of the shoulder and carpal joints via this __________ __________________. 3. The ________________ ____________ _______________ m. is large and is the main extensor of the carpus.

brachialis and biceps brachii; supraglenoid tubercle; lacertus fibrosus; stay apparatus; extensor carpi radialis

Metapodium Osteology 2. Sheep - the distal cannon bone (Mc/Mt 3 and 4) physis of sheep is the so-called "___________ __________". If this physis can be broken in the slaughter house the animal is considered to be a lamb, if not, it is an adult and the value/pound is much less. Physeal closure occurs at about ____ year(s) of age.

break joint; 1

D. Navicular bone = distal sesamoid bone, (named for its boat like shape, L. naves) 1. Navicular __________- on the palmar surface, separates the navicular bone from the _________ ____________ ___________ tendon. Elevation of the toe or a low heel puts pressure on the bursa by the DDFT. The bursa provides lubrication for the DDFT as it passes over the navicular bone. 2. Dorsal surface- is straddled over the palmar surface of the coffin joint. The navicular bone separates the ___________ joint from the navicular bursa.

bursa; deep digital flexor; coffin

Carpus 2. The flexor retinaculum extends from the medial collateral ligament to the palmar aspect of the accessory carpal bone forming the ___________ ___________ (proximal carpals + retinaculum). The carpal canal contains both ____________ ____________ tendons, the _____________ nerves and the major vessels of the region. 3. The accessory carpal bone (Ca) acts as a lever arm like the calcaneous and thus has considerable force exerted on it. It has four ligaments that stabilize it by binding to other carpal bones and the lateral splint (Mc4).

carpal canal; digital flexor; palmar

Scapula -- Scapula ________________ is well developed in ungulates, not in dog. __________________ absent in horse

cartilage; Acromion

Surface structures. (covered in lab). - The _______________ is located higher in the forelimb than the hind limb where it is on the medial side of the distal tarsus. In the forelimb it is on the medial side of the antebrachium (forearm) about the middle of its length. While the chestnut is often considered to be a remnant of the _________ _________, it is more likely a remnant of the ____________ ________. The hind limb chestnut would correspond to the tarsal pad which is not present in dogs but is found in bears. - The ergot is located on the palmar (or plantar) surface of the ______________. It is considered to be a remnant of the _____________________ _________. The ergot is best developed in heavy horses and zebras. - The so-called chestnuts of llamas/alpacas are not homologs and are better named metatarsal pads. They are only on the hind limb where they are more distal and on both sides of the metatarsus

chestnut; first digit; carpal pad; fetlock; metacarpal pad

Carpal osteology: carpal ________ and _________ fractures (fxs) are common in athletic horses. A. Proximal row- radial, intermediate, ulnar and accessory carpal bones (Cr, Ci, Cu, Ca). The accessory carpal bone is lateral and projects palmarly to form a ___________ similar to the calcaneous of the hind limb.

chip and slab; lever

Forelimb: In contrast to the firm bony attachment of the hind limb to the sacrum, the forelimb has no bony attachment to the axial skeleton (no ______________) and therefore a limb that can more freely move forward. The resultant longer ____________ length afforded by this increase in mobility makes for a faster animal i.e., a huge survival advantage when fleeing from predators.

clavicle; stride

E. Digital cushion - corresponds to the digital pad of the dog. It is composed of a mixture of ________________, _______________ tissue and pieces of ________________. It lies under (distal to) the deep digital flexor tendon, deep to the frog and between the collateral cartilages. The digital cushion along with the collateral cartilages acts as a pump to push _______________ ___________ out of the hoof and up the leg against gravity. It compresses veins between the hoof wall or skin and the cartilages and forces the blood proximally. At ground contact the bars and frog push up on the axial projections of the foot cartilages causing them to move abaxially. Also, the digital cushion serves as a ___________ _________________.

collagen, adipose; cartilage; venous blood; shock absorber

1. FETLOCK JOINT LIGAMENTS: support fetlock joint • suspensory ligament (palmar aspect of cannon bone), Origin on the proximal palmar aspect of cannon bone, distally splits into medial and lateral branches which insert (mainly) on the outer surfaces of the sesamoid bones except for a small extensor branch on either side that ties in with the _____________ ________________ tendon • ___________________________ ligament (between sesamoid bone). Digital flexor tendons traverse the palmar aspect of this ligament. • distal sesamoidean ligaments (oppose the _____________ pull of the suspensory ligament on the sesamoid bones. • (clinical) fracture of sesamoid bones (pull apart) due to severe downward translation of the fetlock joint.

digital extensor; intersesamoidean; upward

CHECK LIGAMENTS also help provide passive support without expenditure of muscular effort i.e., they are part of the stay apparatus functioning to support the fetlock. i.e., deep and superficial _____________ ____________ tendons and their respective check ligaments help support the fetlock. Name derivation = preventing downward movement of the ______________. They are accessory ligaments of the digital flexor tendons. • SDFT with its proximal check ligament inserts on ______. Function: prevent digit from buckling _______________. There is no hind limb counterpart. • DDFT with its distal check ligament inserts on ______. Function to counteract hyperextension of digit. Usually absent in the hind limb.

digital flexor; fetlock; P2; forward; P3

Metapodial region 3. The suspensory apparatus = suspensory ligament + ___________ ____________________ ligaments. The suspensory apparatus is aided by the deep and superficial _____________ ____________ tendons and their respective check ligaments. These three parallel tendons form a passive (non-muscular) supporting system for the fetlock which is the part of the stay apparatus that is very similar in fore and hind limbs but check ligaments are poorly developed or absent in the hind limb. a. The check ligaments provide passive support without expenditure of muscular effort. The name comes from checking = preventing downward movement of the ____________. They are accessory ligaments of the digital flexor tendons. - The proximal check ligament is the __________ head of the superficial digital flexor m. There is no hind limb counterpart. The superficial digital flexor tendon attaches to the _____________ _______________ and by pulling back on the middle phalanx prevents buckling forward of the digit. - The distal check ligament, is an extension of the _____________ ___________ ligament (or tarsal equivalent) but the check ligament is usually absent in the hind limb. In the forelimb, the check ligament is often of the same size as the tendon of the deep digital flexor muscle that it unites with. Since the deep digital flexor muscle inserts on the distal phalanx, it counteracts the extension of this digit by the main extensor tendon and the extensor branches of the suspensory ligament. b. Contracted tendons = ______________ deformity are one of the most common congenital deformities of foals and calves. In some cases surgical section of the distal check ligament may be needed to straighten the limbs. c. The deep flexor tendon insertion on the coffin bone (P3) causes ______________ of P3 when the soft tissue attachment of P3 to the hoof breaks down due to _______________. Surgical section of the distal check ligament in the early stages of laminitis may prevent debilitating coffin bone rotation.

distal sesamoidean; digital flexor; fetlock; radial; middle phalanx; palmar carpal; flexural; rotation; laminitis

- swelling due to excess fluid always follows the path of least resistance. Therefore, the swelling will appear where there is the thinnest covering over the enclosed fluid. - In the case of bog spavin, the ____________ ____________ area of the main (tibial-tarsal) joint pouch has the least and thinnest covering; hence the joint capsule bulges out here and that bulging is referred to as the dorsal-medial pouch of the joint capsule - in the case of thoroughpin (2 slides from now) the tarsal canal is ____________ but the path of least resistance goes to the _____________ side due to thick fascia on the medial side

dorsal medial; medial; lateral

PELVIC LIMB 7. Extensors of digit A. Long digital extensor m.- originates on the _______________ fossa of the femur (with fibularis tertius). In the ox the muscle consists of two parallel bellies and tendons. They are the _________ digital extensor m. which inserts on both major digits (3 & 4) and the _____________ digital extensor m. which inserts on the third digit. B. Lateral digital extensor m.- The lateral digital extensor tendon fuses with the long digital extensor tendon in the horse but it inserts directly on the ___________ digit of the ox. ________________ is a poorly understood spasmodic condition that for unknown reasons can be helped by cutting the lateral digital extensor tendon near where it "inserts" on the long digital extensor tendon.

extensor; long; medial; fourth; Stringhalt

C. Coffin bone = Distal Phalanx = P3, so named because the hoof forms a coffin around it. The main digital extensor tendon attaches on the _______________ process. 1. The __________ ___________ contains a vascular arch where the digital arteries terminate. 2. Collateral cartilages are attached to the _____________ process ("wings") of the coffin bone. TVA uses the term hoof cartilage which is misleading because the cartilage is not attached to the hoof. Numerous large veins lie between the cartilages and the coronary dermis. The cartilages are _____________ in the young animal and become thicker and fibrocartilagenous as the animal matures. An axial projection of the foot cartilages develops with maturity. ___________________ = ossified foot cartilages

extensor; solar canal; palmar; hyaline; Sidebones

PELVIC LIMB 4. Stifle joint: really 3 joints in one; femoropatellar + 2 femorotibial A. Femorotibial joints are separate from each other and connected via _________________________ ____________. - Medial pouch- always communicates with femoropatellar in the horse - Lateral pouch- one fourth communicate with femoropatellar pouch in the horse. B. The _________________ ligaments are merely thickenings of joint capsules, the _______________ are "inner" collaterals, they are not inside the joint but rather lie between the lateral and medial joint pouches. Cruciates are named by their __________ attachment (cranial cruciate = caudal on femur to cranial on tibia)

femoropatellar pouch; collateral; cruciates; tibial

Antebrachium 1. In primates, the radius rotates around the ulna but in carnivores this rotation is limited. 2. In ungulates (animals with hooves) the radius and ulna are __________ to varying degrees so there is no rotation. In the pig there is _____________ fusion of radius and ulna, it is __________ in the cow, and in horse the distal part of ulna is "__________________" into the radius. Occasionally a _____________________ remnant marks the point of fusion between the equine distal ulna and radius and should not be misconstrued as a defect or fracture. 3. In the horse, radiology of the distal radial physis is used to determine when a young horse is mature enough to withstand the stress of training for racing.

fused; fibrous; bony; absorbed; cartilaginous

B. Dermis (formerly corium) - is the dermis of the foot. The outermost layer is adjacent to the _______________ layer of the epidermis which produces the horn of the hoof. The dermis connects the hoof to the ___________ bone. The dermis is covered by epidermis which produces the hoof. Since the epidermis too thin to be seen grossly, we discuss the dermis below.

germinal; coffin;

Carpus - besides the collateral ligaments which are common to most hinge joints, there are numerous __________________ ligaments which bind individual carpal bones together. More specifically, the intercarpal ligaments are especially well developed to unite the bones of the proximal or distal row to others in the same row. The effect of this can be seen when the carpus of a horse is flexed and the individual rows of carpals can be discerned by palpation on the dorsal surface of the carpus.

intercarpal

SUSPENSORY APPARATUS (found in forelimb and hind limb) 1. SUSPENSORY LIGAMENT is the clinical term for the ____________________ tendon (proper term): − While this structure appears to be a ________________ in the horse it is homologous to the interosseous muscles of the dog. − The interosseous tendon originates on the palmar surface of the upper part of the ______________ bone and divides distally to insert on the _______________ sides of the proximal sesamoid bones. − The outer most fibers of the suspensory ligament extend distally and dorsally (extensor branches of suspensory ligament) to insert on the _______________ or __________ digital extensor tendon and therefore it extends the digit as well as supporting the fetlock. − Functionally the suspensory ligament supports the fetlock joint from overextension (dorsiflexion). which is continually stressed towards overextension (dorsiflexion). The suspensory ligament acts as a proximal sesamoidean ligament and is counteracted by the distal sesamoidean ligaments which will be covered later. − The suspensory ligament has an ____________ storing function being deformed during downward translation of the fetlock, it releases stored energy at the end of the retraction phase by _____________ the fetlock. It has been referred to as the metapodial spring ligament.

interosseous; ligament; cannon (metatarsal/metacarpal 3); abaxial; common or long; energy; flexing

Neurovascular supply of the carpal/metacarpal region B. Nerve blocks 1. Nerve blocks are often used to diagnose equine lameness. In general, it is assumed that if a horse "goes sound" after a particular nerve block, the lesion causing the lameness is assumed to be in the area anesthetized by the nerve block. To achieve good localization of the lesion, a series of nerve blocks are made starting distally with a small area of anesthesia. Each progressive nerve block is made more proximal and usually includes a larger area. Once soundness is achieved, it is assumed that the lesion is in the field of the last block but not in the area of the previous blocks. By subtracting out the area of previous blocks, the location of the lesion is narrowed. Besides blocking specific nerves, a __________ or ___________ may be blocked. 2. The _____________ ____________ n. is the most common block because it is used to diagnose navicular disease. To make the block one palpates the groove between the flexor tendons and the _________ _____________ bone (P1) in the pastern region. The nerve lies in this groove adhered to the artery.

joint or a bursa; palmar digital; long pastern

PELVIC LIMB 11. Neurovascular supply - brief comments A. Cranial tibial a.→ dorsal pedal a.→ dorsal Mt. a. which is dorsal in the ox in Mt 3/Mt4 groove but ____________ in the horse due to great reduction in the size of Mt 4 (lateral splint bone). This artery is useful for taking arterial blood for blood gas determination during surgery. B. ____________ saphenous v. is well developed in horse and cat while the ____________ saphenous v. is well developed in dog and ox. In horses, the cranial branch of the medial saphenous v. is vertical as it crosses the cunean tendon and thus vulnerable to damage during cunean tendonectomy. C. Pelvic limb nerve supply summary • _____________ n. → quadriceps femoris m. and medial skin • _______________ n. → adductor muscle group = adductors, pectineus, gracilis • ____________ n. (ischiatic) → supplies the rest of the limb muscles - common fibular n. (peroneal) → cranial lateral muscles of the crus - tibial n. → caudal muscles of the crus. [The obturator n. supplies the external obturator m. but the internal obturator m. is supplied by the sciatic n. The obturator muscles rotate the cranial surface of the femur outward.]

lateral; Medial; lateral; femoral; obturator; sciatic

B. Distal row of carpals- Horse 1. C 1 is small and inconsistent being embedded in the ______________ __________________ ligament but it may be seen in radiographs and should not be confused with a carpal chip. 2. C 2 is mainly situated over the second metacarpal bone and therefore it can be pushed distally when the foot strikes the ground causing a displacement of Mc 2. This is not true for carpal 4 which straddles Mc 3 and 4. Therefore, Mc2 can be pushed down by C2 causing a tearing of the _____________________ ligament which binds the splint bone to the cannon bone (Mc3). 3. Like Mc 3, C 3 is large. It is prone to ________ fractures on the dorsal surface and is the most fracture prone bone of the carpus.

medial collateral; interosseous; slab

Neurovascular supply (horse) A. Arteries - the _____________ _____________ a. or its hind limb counterpart the _____________ ___________________ a. branch above the fetlock to form the medial and lateral digital aa. which are most superficial in the fetlock region where the pulse can be felt in laminitis. Distal to the fetlock they lie in the groove between the ______________ bones and the digital flexor tendons. They terminate by anastomosis in the solar canal of the coffin bone.

medial palmar; dorsal metatarsal; pastern

Neurovascular supply of the carpal/metacarpal region C. Vascular supply 1. In the horse the main artery of the distal forelimb is the _____________ ____________ a. which is derived from the median a. after passing through the carpal canal. The medial palmar a. lies on the medial side near the groove between the digital flexor tendons and the ____________________ ligament. Distally between the end of the splint bones it curves deep to the flexor tendons and divides into the equal sized _____________ and ______________ _____________ aa. that pass over the fetlock joint to the digit. The pulse is sometimes palpable from the digital arteries as they run over the fetlock and in laminitis the pulse is easily palpated here. Distal to the fetlock the digital aa. lie in a palpable groove between the long pastern bone and the flexor tendons. The digital nerves are adhered to the palmar (plantar) surface of the digital arteries and the two must be separated to safely cut the nerves to relieve the pain of ________________ disease (palmar digital neurectomy). The palpable groove mentioned above is the surgical site for the neurectomy. 2. The ______________ veins, get their name from their drainage to the external jugular v. The larger cephalic v. drains the ____________ side where there is more soft tissue while the smaller accessory cephalic v. drains the ___________ side where soft tissue is scant. [Since the external jugular veins are small in humans it is not surprising that the homologue of the cephalic v. is the radial vein which does not drain to the jugular and is the most frequent site of venipuncture in humans.]

medial palmar; suspensory; lateral and medial digital; navicular; cephalic; palmar; dorsal

Forelimb vessels - While the main arterial distribution is on the _____________ side of the limb, the main muscle mass of the antebrachium is on the lateral (and caudal) side. The _____________ _____________________ artery passes to the lateral side to serve these muscles. While most of the surfaces of the radius and ulna are fused in the ox and horse, an interosseous space between them allows the vessel to pass between the bones to the lateral side

medial; cranial interosseous

PELVIC LIMB 8. Tarsus (hock joint) E. Tarsal canal - formed by a groove on the _____________ side of calcaneus and the flexor retinaculum. - Contents - tendon of the ____________ head of deep digital flexor m. and plantar nerves. - ____________________ = a swelling of the sheath of the tendon of lateral head of the deep digital flexor m. The name comes from shuttle pin since the fluid in the swelling can "shuttle" from proximal lateral to distal medial as the swelling is palpated.

medial; lateral; Thoroughpin

Carpus 4. The 3 carpal joints are the: radiocarpal, ____________ carpal and carpometacarpal. Since the distal row of carpal bones is firmly fixed to the metacarpus, there is virtually no movement in the carpometacarpal joint. There is more movement in the __________________ joint than the _____________ carpal but both allow considerable movement as demonstrated by the wide "opening" of these joints as can be palpated on the dorsal surface of the flexed equine carpal joint. The middle carpal and carpometacarpal joints __________________________ but the radiocarpal joint does not. This similar to the pattern in the tarsus where the proximal and distal joints don't communicate.

middle; radiocarpal; middle; intercommunicate

Carpus 1. On the palmar surface of the carpus is the _____________ ____________ ligament which is a wide ligament that covers most of the palmar aspect of the carpus. The function of the palmar carpal ligament is to prevent overextension of the joint. Since luxation due to overextension is extremely rare, we must conclude that the palmar carpal ligament is very strong and does its job well but carpal chip fractures and fracture of the accessory carpal bone are probably the result of forces which would cause overextension if not prevented by the palmar carpal ligament. Actually, overextension of the carpus occurs in performance horses for a split second in the gallop when one forelimb is vertical and momentarily bears all the weight of the body (Adams). This force produces a vice like trauma on the dorsal part of the carpal bones causing chip or slab fractures. The palmar carpal ligament forms the dorsal wall of the ____________ ____________. The palmar carpal ligament extends beyond the carpus to form the distal (carpal or inferior) __________ ligament.

palmar carpal; carpal canal; check

Neurovascular supply of the carpal/metacarpal region A. Nerve supply - the median and ulnar nerves pass thru the carpal canal where they communicate to form the medial and lateral ____________ nerves of the cannon region. These lie along the ____________ tendons and are connected by a palpable communicating branch (vessels anastomose but nerves communicate). The continuations of these nerves beyond the fetlock are the palmar ____________ nerves.

palmar; flexor; digital

A. Extrinsic muscles attach the forelimb to the body. 1. The serratus ventralis muscle forms a functional sling for the trunk as it runs from a discrete point of attachment on the medial face of the _______________ to a very broad, fanning attachment to the cervical vertebrae and ribs. Tendinous strips provide added passive support, conservation of muscle energy is an important consideration if the horse since it spends most of its life standing. In addition, the serratus ventralis m. acts as a "shock absorber", protecting the chest from excessive "jarring" when running. 2. The __________ ________________ and __________________ ___________ mm. pull back on the limb in the shoulder region (power stroke for forward motion) i.e., effectively pulling the trunk forward when the limb has contact with the ground. 3. After the power stroke the ___________________________ m. pulls the limb forward in preparation for the next power stroke. To do this requires a long muscle to provide enough distance to shorten sufficiently.

scapula; deep pectoral and latissimus dorsi; brachiocephalicus

PELVIC LIMB 3. Thigh region: the large hamstring muscle group forms the caudal thigh region. "Behind" your own knee joint the biceps and _______________________ tendons can be felt as lateral and medial cords. The biceps femoris m. is ___________, the "semi" muscles medial at insertion in stifle region. They separate to pass lateral and medial to the gastrocnemius muscles. The space between the muscles contains the ____________ nerve and ________________ lymph nodes. Hamstring muscles function to: 1. extend the _______ ---> propulsion 2. extend the stifle when foot is fixed ---> propulsion 3. flex the stifle when foot is off the ground (caudal biceps, _________________________) 4. Adduct limb (_____________________________)

semitendinosus; lateral; sciatic; popliteal; hip; semitendinosus; semimembranosus

PELVIC LIMB 8. Tarsus (hock joint) C. Joint capsules and pouches (pouch = bulging of joint capsule between ligaments or tendons) 1. Tibiotarsal (tarsocrural) joint- most movement so most __________ in joint capsule. ________ ___________ is a joint capsule swelling on dorsal side between the fibularis tertius/cranial tibial tendons and the medial collateral ligament (swelling of the main tibiotarsal joint or proximal intertarsal joint; and bone spavin is arthritis in the distal intertarsal joint or tarsometatarsal joint with no swelling but lots of pain) 2.,3. Proximal and distal intertarsal joints- on either side of the central tarsal bone (Tc) 4. Tarsometatarsal- between T3/Mt3 (and also, T4/Mt4 and T1+2/Mt2)

slack; Bog spavin

Metapodial region (cannon region). Metapodium = metacarpus or metatarsus. 1. The splint bones of the horse are bound to the cannon bone by the interosseous ligaments. These ligaments can be torn by a shearing force resulting from upward or downward displacement of the splint bones. The result is inflammation followed by new bone formation resulting in a swelling known as a "_________". Therefore, all horses have splint bones but not all have "splints". Mc 2 is pushed down (distal) by _______ which is not supported by Mc3. Care must be taken to never confuse the interosseous ligaments with the interosseous tendon.

splint; C2

PELVIC LIMB 5. Equine reciprocal apparatus: movement of hock reciprocates with movement of the __________ joint. This allows a ________________ concentration of the muscle mass. The reciprocal apparatus consists of two mostly tendinous muscles. A. __________________ _____________ ____________ m. extends the hock. This mostly tendinous muscle extends the hock by attachment of the edge of the tendon to the tuber calcis. This tendon also slides over the tuber calcis and ____________ the digit as well as extending the hock. Extension of the hock combined with flexion of the digit are both propulsive actions. B. _______________ (peroneus) _____________ - flexes the hock. [the fibularis longus and brevis of the dog are the first and second fibularis muscles]. This muscle originates from the deep extensor fossa on the lateral side of the distal end of the femur. The _________ _____________ ________________ m. also originates from the extensor fossa of the femur. In the crus the long digital extensor m. covers over the fibularis tertius m. - If the foot is caught and stifle flexion puts tension on the fibularis (peroneus) tertius tendon it will rupture if the hock joint is not able to flex

stifle; proximal; Superficial digital flexor; flexes; Fibularis tertius; long digital extensor

SUSPENSORY APPARATUS (found in forelimb and hind limb) 2. DISTAL SESAMOIDEAN LIGAMENTS: − ________________ (straight) sesamoidean ligament extends from the distal ends of the sesamoid bones to the proximal ridge of the _________ pastern bone. − ____________ (oblique) sesamoidean ligament extends to the ____________ side of the long pastern.

superficial; short; middle; palmar

Nerves of the upper forelimb. Brachial and lumbosacral plexuses have numbered input (ventral spinal nn.) and after a mixing of fibers, the output is named nerves. The input to the brachial plexus is C6,7,8 and T1 and the output includes: A. The _____________________ n. wraps around the cranial edge of the scapula in the neck region where it is vulnerable to pressure damage resulting in an atrophy of the supra- and infraspinatus mm. which results in a more prominent scapula spine. Classically it is caused by a horse collar on a pulling horse and is called _____________. B. The ___________ n. supplies ALL the intrinsic extensors of the forelimb. The distal part is vulnerable to damage where it wraps around the humerus caudal to the brachialis m. and therefore special precautions must be taken when a horse is positioned in lateral recumbency for surgery. Radial n. paralysis results in stumbling and fetlock flexion due to inability to extend the digit. C. _______________ ____________ paralysis is vulnerable to pressure damage from the rib cage when a large animal is placed in lateral recumbancy. This may be confused with radial n. paralysis. When you dissect the brachial plexus you find it _____________ to the shoulder region. This problem is more so in cattle which have proportionately wider ribs. Some years ago in the Veterinary Teaching Hospital a cow came off a surgery table with a paralyzed left forelimb after being down 2+ hours for repair of lacerated teats. Despite extensive supportive therapy, she never recovered and eventually went to post mortem. In dogs brachial plexus paralysis is usually due to being hit by a vehicle.

suprascapular; sweeny; radial; Brachial plexus; medial

Metapodial region The interosseous tendon is the proper term for the ____________________ _________________, a clinical name. a. While this structure appears to be a ligament in the horse it is homologous to the ____________________ muscles of the dog. b. The interosseous tendon originates on the palmar surface of the upper part of the ____________ bone and divides distally to insert on the abaxial sides of the _________________ ________________ bones. c. The outer most fibers of the suspensory ligament extend distally and dorsally (extensor branches of suspensory ligament) to insert on the common or long digital extensor tendon and therefore it ______________ the digit as well as supporting the fetlock. d. The name suspensory ligament comes from the function of supporting the fetlock joint which is continually stressed towards overextension (dorsiflexion). The suspensory ligament acts as a proximal sesamoidean ligament and is counteracted by the distal sesamoidean ligaments which will be covered later. e. The suspensory ligament has an energy storing function being deformed during downward translation of the fetlock, it releases stored energy at the end of the retraction phase by flexing the fetlock. It has been referred to as the ___________________ ____________ ligament.

suspensory ligament; interosseous; cannon; proximal sesamoid; extends; metapodial spring