212 MYOLOGY. 



are either flexors^ extensors, abductors, adductors, or rotators, but 

 in the horse the last are comparatively few, limited in their 

 action, and nearly all extrinsic, the joints of the horse's limbs 

 below the shoulder and hip allowing very slight rotatory motion. 



Muscles of the Pectoral Limb, 

 These may be conveniently divided 



Scapular . 

 Brachial . 

 Antibrachial 

 Metacarpal 



nto the following regions; 



The shoulqler. 

 The arm. 

 The fore-arm. 

 The foot (hand). 



Scapular Region. 



Externally the region is covered by the strong scapular fascia, 

 and comprises an external group of four and an internal of three 

 muscles. 



External Scapular Group. 



Teres externus. f Postea-spinatus. 



Antea-spinatus. ' Postea-spinatus minor. 



TERES EXTERNUS. 



(ScOipido-humeralis Magnus.) 



(Fig. 78. c.) 



This is the long abductor of the arm, which corresponds to 

 the deltoid of man. Situated on the outer and posterior part 

 of the shoulder, it consists of two portions, anterior and posterior. 

 The posterior or larger portion is triangular in form, and very 

 fleshy, the fibres extending obliquely downwards and forwards ; it 

 is lodged in a depression in the caput magnum. The anterior 

 or superior portion is thin, and aponeurotic above, extending 

 over the postea-spinatus muscle, to which it is adherent. 



Attachonents. — The posterior section arises from the dorsal 

 angle and posterior costa of the scapula ; the anterior by strong 

 fascia from a tubercle on the spine of the scapula, and the 

 scapular fascia. They unite inferiorly, and by tendinous and 

 fleshy fibres are inserted to the deltoid ridge of tte humerus 

 below the insertion of the postea-spinatus minor. • 



r 



