LECTURES ON HORSES. 
673 
through the medium of attaching muscles. There is one muscle 
especially designed for the performance of this function — the ser - 
ratus magnus — a muscle of vast magnitude and power, which, 
though by anatomists regarded but as one, might with just reason, 
by the physiologist, be described as many ; inasmuch as by such a 
supposition alone can he account for its unwearied discharge of the 
laborious duties assigned it. Its twelve distinct origins from the 
cervical vertebrae and ribs ought to be considered as twelve distinct 
portions of it; some of which are in continual action, while the 
others are recruiting their tone by repose. Another important duty 
performed by this muscle, and one in which it is probable most if 
not all of its divisions are engaged, is that of, during the action of 
the fore-limbs, fixing the central part of the scapula to the ribs 
while its upper and lower ends revolve, in segments of circles, 
backwards and forwards ; the other muscles attaching the scapula 
to the trunk being employed in effecting the revolving movements. 
With the exception of the joint at the shoulder, between the sca- 
pula and humerus, the joints of the fore-limb are so constructed that 
they can hardly be said to admit of any motions beyond those of 
flexion and extension ; and therefore a very proper division of the 
muscles moving them has been made into flexors and extensors. 
It might be imagined that one or two of each sort would be all that 
was required for such simple movements ; when, however, it is 
considered that the knee-joint admits of some trifling lateral motion, 
and that through it some variety is given in progression to the 
direction of the leg, it will be seen that more became necessary 
to give steadiness and precision, as well as due force and effect, in 
action. The flexor muscles are more numerous and powerful than 
the extensors, because all action in the fore-legs consists in flexion : 
during extension the animal is standing still. There is an import- 
ant extensile movement in the arm performed by the extensor bra- 
chii, whose point of insertion is the process we call the elbow, and 
which, in the living animal, is recognized by the remarkable plump- 
ness of flesh immediately above that process, and before the girth- 
ing-place. Every “ judge” of horses knows that prominence at 
this part constitutes an excellent “ point;” it being of the very 
first consequence that the arm should be extended with force, and 
be firmly maintained in this extension, both on account of the pro- 
jection of the limb in action, and for sure and safe alighting and 
standing upon it. When the horse is throwing his fore-legs 
straight out in the gallop, or projecting them, dart-like, in the trot, 
this is the muscle which, as far as the arm is concerned, is chiefly 
employed ; therefore strength of action, if not extent of projecture, 
will mainly depend upon its magnitude or efficiency. 
The muscles designed for the motions of the leg and foot are 
