234 THE HORSE. 



beino- able to move the limbs, exerts its power in enlarging the cavity 

 of tlfe chest, and thus materially assists in the act of breathing. There- 

 fore, as we have stated when treating of that disease, a horse labouring 

 under inflammation of the lungs will obstinately stand night and day, that 

 he may obtain the assistance of this muscle in respiration, which is become 

 laborious and painful ; and we regard his lying down as one of the most 

 favourable symptoms that can occur, because it shows us that the 

 breathing is so much relieved that he needs not the assistance of this 

 muscle. 



At e is a small portion of the splenius muscle, of which we have spoken 

 when describing the neck, p. 154. 



/represents a muscle sometimes described as a portion of the raiser of 

 the shoulder, arising from the nipple-shaped process of the temporal bone, 

 running down the somewhat lateral but fore-part of the neck, inserted into 

 the upper and middle part of the lower bone of the shoulder, and thence 

 continued down to the arm. Its office is to bend the head ; or, the head 

 and neck being fixed, to elevate and bring forward the arm. It is fn 

 powerful action when the horse is running at his speed with the head pro- 

 jected. 



At g is a portion of the sterno-maxillaris, or muscle common to the fore- 

 part of the chest and the lower jaw, and described at p, 156. 



h o-ives the principal muscle extending from the shoulder to the lower bone 

 of the shoulder, and employed in drawing this bone towards the shoulder- 

 blade, and bending the w hole of the limb. Exceedingly powerful action is 

 required from this muscle, therefore it is very tendinous, and inserted in 

 such a direction as to act with great mechanical advantage, and that 

 advantage increased in proportion to the slanting of the shoulder. 



The muscle at i, aiitea spinatus (before the spine) is situated, as its name 

 would intimate, on the external part of the shoulder before the spine or 

 ridge, and fills the whole of that space. It proceeds towards the bone of the 

 arm, and, dividing into two parts, is inserted into the two prominences in 

 front of that bone. It is a very strong muscle, and extends the arm and 

 carries it forward. 



Themuscleatj, ^;o5/m sp27zr/f2fs (behind the spine or ridge), occupies 

 that space. It likewise goes to the lower bone of the shoulder, and is in- 

 serted into the outer and upper head of the bone. It draws this bone out- 

 ward and upward. 



At k is a muscle common to the breast and the shoulder-blade, and 

 called the little jjectoral, or breast muscle. It arises from the breast-bone, 

 and reaches to the covering of the shoulder-joint, and the muscles of the 

 shoulder. Its action, in common with tliat of a larger muscle, seen at 771 

 {the great pectoral), is to draw back the head of the lower bone of the 

 shoulder and the lower part of the shoulder-blade, and to make the latter 

 bone more upright. 



At q is the tendon of a very important muscle, the long extensor of the 

 arm, extending from the upper angle, and the posterior border of the 

 shoulder-blade, to the point of the elbow, and the inside of the arm, 

 and which will be presently described; and at r and s are the three divi- 

 sions of another muscle concerned in the same office, arising from the 

 shoulder-blade and the lower bone of the shoulder, and likewise attached 

 to the point of the elbow by a very strong tendon. 



This cut represents the muscles on the inside of the slioulder and fore- 

 arm, a is a very prominent one. It is called the pectoralis transversus 

 (the muscle crossing the breast). It arises from the first four bones of 

 the chest, and runs across to the inner part of the arm, and is inserted 



