Anatomy Lecture 3

Question 1

What is the purpose of the stay apparatus of the horse?

Answer 1

Allows the horse to dose while standing up, using minimal muscular activity
- locks joints and limbs to prevent collapse

Question 2

What is another name for the shoulder joint?

Answer 2

Glenohumeral joint

Question 3

What is another name for the elbow joint?

Answer 3

Humeroradioulnar Joint

Question 4

What are the names of the three joints in the Knee?

Answer 4

Antebrachiocarpal Joint
Intercarpal Joint
Carpometacarpal Joint

Question 5

What is another name for the Fetlock?

Answer 5

Metacarpophalangeal Joint

Question 6

What is another name for the Pastern?

Answer 6

Proximal Interphalangeal Joint

Question 7

What is another name for the Coffin?

Answer 7

Distal interphalangeal joint

Question 8

What are the muscles involved in the Fibrous support mechanism?

Answer 8

Tendon of the Biceps brachii, Lacertus fibrosus, Extensor carpi radialis, Triceps brachii, SDF and accessory (proximal check) ligament, DDF and accessory (Distal check) ligament, Common digital extensor tendon, Interosseus, Proximal sesamoid bones and sesamoidean ligaments.

Question 9

The tendon of which muscle prevents the shoulder from flexing (stay apparatus)? How?

Answer 9

Biceps brachii - radial insertion of this muscle is a fixed point since its close to the axis of rotation of the elbow which is stabilized by the weight of the animal.

Question 10

What allows the shoulder joint to lock (stay apparatus)

Answer 10

Molding of the biceps brachii tendon to the intermediate tubercle of the humerus

Question 11

What acts to maintain the extension of the elbow when the actual muscle of the triceps brachii is flaccid? (stay apparatus)

Answer 11

The fibrous components within the muscles maintain extension

Question 12

What muscle at the elbow joint remains engaged during the stance phase?

Answer 12

the anconeus

Question 13

With the shoulder fixed, how does the weight rest?

Answer 13

on a nearly vertical radius

Question 14

How is the stabilization of the shoulder achieved?

Answer 14

• biceps brachii maintains extension of the shoulder

Question 15

How is the stabilization of the Elbow joint achieved?

Answer 15

• fibrous components within the triceps brachii maintain extension of the elbow
• Anconeus remains engaged during the stance phase
• smal corrections made by the carpal and digital flexors to maintain vertical radius of weight

Question 16

How is the stabilization of the Carpus achieved?

Answer 16

• tension exerted on the tendon of the biceps brachii is transmitted to the extensor carpi radialis m. via the lacertus fibrosus. This exerts overall upwards force that prevents buckling
• Strong palmar carpal ligament also prevents hyperextension

Question 17

Which muscles are involved in the stabilization of the fetlock, pastern and coffin joints?

Answer 17

• Suspensory apparatus: Interosseus (lateral and medial branches that unite with comon digital extensor), proximal sesamoids, sesamoidean ligaments (Straight, Oblique, Cruciate)
• SDF and proximal check ligament
• DDF and distal check ligament

Question 18

How is the downward force on the SDF and DDF counteracted?

Answer 18

by the proximal and distal check ligaments respectively

Question 19

What counteracts the flexing of the coffin joint?

Answer 19

the extensor branches of the interosseus

Question 20

What counteracts the hyperextension of the fetlock?

Answer 20

the distal sesamoidean ligaments

Question 21

Where do the distal sesamoidean ligaments attach?

Answer 21

distal attachments to the proximal phalanx, middle phalanx also attached to the middle phalanx

Question 22

How are the structures of the suspensory apparatus able to “spring back” to their normal state so quickly?

Answer 22

they store energy

Question 23

What is a digigrade?

Answer 23

walks/bears weight on digits

Question 24

What is an Unguligrade?

Answer 24

walks/bears weight on the distal phalanx

Question 25

What metacarpal bone is weight bearing in the horse?

Answer 25

the third metacarpal

Question 26

What metacarpal bone is weight bearing in the Ox?

Answer 26

Third and Fourth metacarpals

Question 27

Which metacarpal bones are the medial and lateral splint bones of the horse?

Answer 27

Medial: second metacarpal
Lateral: Fourth metacarpal

Question 28

Which carpal bones are fused in the dog?

Answer 28

the radial and intermediate proximal carpals

Question 29

Which carpal bones are fused in the horse?

Answer 29

The first distal carpal is either fused, very tiny, or non-existant

Question 30

Which carpal bones are fused in the Ox?

Answer 30

The second and third distal carpal bones are fused and the first is missing

Question 31

What muscle gives the horses shoulder a nice rounded appearance?

Answer 31

the subclavius m.

Question 32

Which muscle on the horse forms the ventral border of the jugular groove?

Answer 32

the sternomandibularis m. (synonymous with the sternocephalicus)

Question 33

Which digits are cut when amputating the digit in cattle?

Answer 33

the proximal and distal interdigital ligaments

Question 34

What muscle has ruptured in a horse with a flying scapula?

Answer 34

serratus ventralis

Question 35

Carpal bone II rests entirely on what?

Answer 35

the medial splint bone

Question 36

Carpal bone IV rests on what?

Answer 36

both metacarpals III and IV

Question 37

Where do popped splint lesions in the forelimb usually occur? What does it result in?

Answer 37

on the medial side - results in damage to the interosseus ligament

Question 38

How are proximal sesamoid fractures accomplished?

Answer 38

the accessory bone gets pulled on so hard that pieces of bone rip off