Equine Thoracic Stay Apparatus Flashcards
Functions of the stay apparatus
Reduce energy required to stand
Increase efficiency in movement
About __% of the animal’s weight is on the thoracic limb.
60
Common name for the proximal interphalangeal joint
Pastern
Common name for the distal interphalangeal joint
Coffin
Common name for the carpal joint
Knee
Common name for the metacarpophalangeal joint
Fetlock
Anatomic name for the shoulder joint
Glenohumeral joint
Anatomic name for the elbow joint
Humeroradioulnar joint
Anatomic name for the knee joint and it’s three internal joints)
Carpus (antebrachiocarpal joint, middle carpal joint, carpometacarpal joint)
Anatomic name for the fetlock joint
Metacarpophalangeal joint
Anatomic name for the pastern joint
Proximal interphalangeal joint
Anatomic name for the coffin joint
Distal interphalangeal joint
When a horse is standing on the limb, is the metacarpophalangeal joint flexed, extended, or hyperextended?
The metacarpophalangeal joint is hyperextended normally when th
e horse is standing on the limb.
With no support from muscles, what would happen at each joint of the thoracic limb of the horse?
Glenohumeral: marked flexion
Humeroradioulnar: flexion
Carpus: flexion (buckles forward)
Metacarpophalangeal: marked hyperextension
Proximal interphalangeal: marked hyperextension
Components of the stay apparatus in the thoracic limb
Tendon of biceps brachii
Lacertus fibrosus
Extensor carpi radialis
Triceps brachii
SDF and proximal check (accessory) ligament
DDF and distal check (accessory) ligament
Common digital extensor tendon
Interosseus (medial and lateral extensor branches)
Proximal sesamoid bones and sesamoidean ligaments: cruciate, oblique, and straight
Function of the tendon of the biceps brachia muscle in the stay apparatus
Prevents shoulder flexion (tendon of origin engages on intermediate tubercle)
“Locks” the shoulder joint
Stabilization of the elbow joint:
No muscles actively engaged all the time to provide balance of weight on the nearly vertical radius. Triceps muscle is quite relaxed.
Stabilization of the carpus:
Tension transferred from biceps brachia muscle to the extensor carpi radials muscle via lacerates fibrosis, palmar carpal ligament prevents hyperextension of the carpus
