6 THE ANATOMY OF THE HOBSB. 



The Levator Anguli ScAPULiE (Plate 4) arises from the trans- 

 verse processes of the last four cervical vertebrae ; and its fibres converge 

 to be inserted into the triangular area on the ventral surface of the 

 scapula near its cervical angle, in common with the anterior fibres of 

 the preceding muscle, from which it is not distinct. The two muscles, 

 taken together, have a well-marked fan-like arrangement, having an 

 extensive convex border where they take origin, while they converge to 

 a comparatively narrow point at their insertion. 



Action. — The levator anguli scapulae carries the articular angle of the 

 scapula backwards by pulling the cervical angle forwards ; but when 

 the scapula is fixed, the right and left muscles, acting together, can 

 raise the cervical portion of the spinal column, or the single muscle can 

 incline it to one side. 



The SuBSCAPULO-HTOiD. This muscle, which arises from the sub- 

 scapular fascia; is described with the dissection of the neck. 



THE OUTEH SCAPULAE BEGION. 



Position. — The muscles which pass between the shoulder and the 

 trunk, on the outer aspect of the former, must next be dissected ; and, 

 to permit this, the subject must be placed in an entirely new position. 

 The standing posture of the animal is the best for this purpose ; and it 

 may be imitated by suspending the subject to a stout iron rod provided 

 with chains and hooks, and capable of being raised or lowered by means 

 of a system of pulleys or a small windlass. 



Surface-marking. — About the centre of the region to be dissected the 

 student will feel the spine of the scapula, the most prominent part of 

 which is its tubercle. In a well-nourished, sound horse the spine should 

 not be very distinctly visible, but in an emaciated animal, or in one 

 whose scapular muscles are atrophied as an accompaniment of joint- 

 disease, it forms a very prominent ridge. 



Directions. — An incision through the skin is to be made along the 

 spine of the scapula from the withers to the middle of the arm, where 

 a transverse incision is to be made from the anterior to the posterior 

 border of the Umb. Another incision is to be carried along the middle 

 line of the back, and prolonged forwards along the neck by the dissector 

 of that region, and backwards to the lumbar region by the dissector of 

 the back. The dissectors of the three regions should here work 

 together, the skin being turned down as a single flap from the neck and 

 anterior half of the shoulder, and as another flap from the back and 

 posterior half of the shoulder. The skin, it will be observed, is thicker 

 .than in the pectoral region, and it has the panniculus carnosus attached 

 to its inner surface. Care must be taken not to remove this panniculus 

 with the skin. 



The Panniculus Caenosus is the muscle which enables the horse to 



