Equine Forelimb - Comparative Anatomy

Question 1

What structure on the scapula is not present in the equine species?

Answer 1

acromion process

Question 2

Is there communication between the intertubercular bursa and the shoulder in the equine species?

Answer 2

no (horse and cow)

Question 3

Why is the horse incapable of pronation and supination of the forelimb?

Answer 3

the radius and ulna are fused

Question 4

What is unique to the collateral ligaments of the cubital joint in the horse that is not seen in small animals?

Answer 4

medial collateral ligament has two parts
long, more cranial part that is a remnant of the pronator teres muscle
short, more caudal and deep part

Question 5

What is unique about the suspensory ligament in the fetlock joint of the horse?

Answer 5

becomes completely tendinous upon maturity

Question 6

What pectoral muscle is unique to the horse?

Answer 6

subclavius muscle (additional pectoral muscle)
present in the ox but less developed than the horse

Question 7

Describe the origin of the biceps brachii muscle in the horse

Answer 7

originates from the supraglenoid tubercle via the fibrocartilaginous tendon molded onto the intermediate tubercle of the humerus

Question 8

Describe the insertion of the biceps brachii muscle in the horse

Answer 8

inserts onto the radial tuberosity and continues as the lacertus fibrosus, finally inserting onto metacarpal 3

Question 9

Name the heads of the triceps brachii muscle

Answer 9

long, lateral and medial
note: NO accessory head

Question 10

Describe the manica flexora of the horse

Answer 10

tibelike enclosure formed by SDFT around DDFT proximal to metacarpophalangeal joint

Question 11

Describe the stay apparatus in the horse

Answer 11

tendinous ligamentous support mechanism
assists rest of equine forelimb (hindlimb too) while standing

Question 12

Name the parts of the stay apparatus

Answer 12

pastern joint
fetlock joint
carpal joint
elbow joint
shoulder joint

Question 13

What is unique about the musculocutaneous nerve of the horse?

Answer 13

only has branches

Question 14

What nerves innervate the dorsal aspect of the distal limb?

Answer 14

dorsal branches of the ulnar nerve
medial cutaneous antebrachial nerve
dorsal branches from medial and lateral palmar digital nerve

Question 15

Which nerve is the main nerve of the equine mannus?

Answer 15

median nerve

Question 16

How does the median nerve travel down the equine forelimb?

Answer 16

travels distally
bifurcates to the carpus forming the medial and lateral palmar nerve

Question 17

How does the ulnar nerve travel down the equine forelimb?

Answer 17

travels distally
overlaps with the median nerve
gives a dorsal and palmar branch

Question 18

Where do the palmar nerves of the equine manus lie?

Answer 18

within the metacarpal grooves on both sides of the palmar aspect of the distal forelimb

Question 19

Describe the medial palmar nerve of the equine forelimb

Answer 19

extends distally past the carpus between the interosseous muscle and flexor tendons

Question 20

Describe the communicating branch of the palmar nerves in the equine forelimb

Answer 20

medial palmar nerve detaches a communicating branch to join the lateral palmar nerve at the mid-metacarpal region

Question 21

Describe the lateral palmar nerve of the equine forelimb

Answer 21

has ulnar contribution
detaches a deep brach to supply the interosseus muscle - producing lateral and medial palmar metacarpal nerve

Question 22

Above the fetlock, the palmar nerve becomes

Answer 22

medial and lateral palmar digital nerves

Question 23

Describe the dorsal branches of the palmar digital nerves

Answer 23

pass over the abaxial aspect of the proximal sesamoid bones and the level of P1 and P2

Question 24

Name the main artery of the manus

Answer 24

medial palmar artery

Question 25

Describe how the arteries of the equine manus terminate

Answer 25

at the terminal arch dorsal and palmar branches anastomose and pass through the sole foramine into the sole canal