Passive Stay Apparatus

Question 1

what is a passive stay apparatus?

Answer 1

skeletal, ligamentous, and tendinous adaptations in equids to minimize muscle effort in maintaining quiet standing/grazing

Question 2

what apparatus is in the fetlock/pastern? (both limbs)

Answer 2

suspensory apparatus

Question 3

what opposes the tendency for body weight to make the scapula fall onto the humerus (flex shoulder joint)?

Answer 3

biceps brachii, lacertus fibrosus, extensor carpi radialis

Question 4

label this image

Answer 4

A: biceps brachii
B: lacertus fibrosus
C: extensor carpi radialis

Question 5

what opposes the force for the fetlock joint to go into flexion?

Answer 5

suspensory apparatus

Question 6

what makes up the suspensory apparatus? what is the most important part?

Answer 6

SDF, DDF, ligaments from interosseus

Question 7

what does the suspensory apparatus do?

Answer 7

pulls digit caudally (extends digit)

Question 8

what is the mechanism at the stifle of the hindlimb?

Answer 8

patellar sling

Question 9

what is the patellar sling?

Answer 9

locking mechanism of patella over medial femoral condyle

Question 10

how does the patellar sling work?

Answer 10

notch on patella hooks over larger medial condyle and lock stifle

quads extend knee for this to happen

Question 11

what is the reciprocal mechanism?

Answer 11

when the knee is locked, the hock can’t move either (one can’t move without the other)

Question 12

what structures are involved in the reciprocal mechanism?

Answer 12

peroneus tertius, common calcaneal tendon, SDF

Question 13

label this image. what mechanism is this?

Answer 13

A: common calcaneal tendon

B: peroneus tertius

reciprocal mechanism

Question 14

broadly speaking, what is the action of the passive stay apparatus?

Answer 14

tripod-support in longer standing

equal load of both forelimbs

alternating load and unloadking of pelvic limbs