Page 140 - Anatomy and Physiology of Farm Animals, 8th Edition

Anatomy of the Muscular System / 125

VetBooks.ir g

h
i
b
a
j

k e c

m d
l
f

Figure 7-2. Attachments of muscles are predictive of their main actions. a, extensors of shoulder and
flexors of elbow; b, flexors of shoulder and extensors of elbow; c, extensors of carpus; d, extensors of carpus
and digits; e, flexors of carpus; f, flexors of carpus and digits; g, extensors of hip; h, flexors of hip and exten­
sors of stifle; i, extensors of hip and flexors of stifle; j, flexors of stifle and extensors of hock; k, flexors of hock; l,
flexors of hock and extensors of digits; m, extensors of hock and flexors of digit.

Triceps brachii muscle

Biceps brachii muscle

Figure 7-3. Functional grouping of muscles. The lines denote the long axes of the humerus in the bra­
chium and radius in the forearm of the horse. On the left, the elbow joint is fully extended; as the angle
between the bones is decreased, the joint is being flexed. The m. biceps brachii is a flexor of the elbow, and
the m. triceps brachii is an extensor. In this case, the m. biceps brachii is an agonist for elbow flexion
(right), and the m. triceps brachii acts as an antagonist for that movement. Any muscles that assist elbow
flexion indirectly by stabilizing other joints are considered synergists of that movement.

an action directly opposite that of the ago­ m. triceps brachii, the agonist for extension
nists. Synergists are muscles that oppose of the elbow), the m. biceps brachii and
any undesired action of the agonists. For m. brachialis are antagonists because their
example, in extension of the elbow (a move­ contraction produces the opposite action,
ment produced by contraction of the flexion of the elbow. Since the long head