MUSCLES OF THE BODY. 145 



able number of not always clearly separated bundles in the cat. 

 We shall distinguish by name four such bundles; these might 

 be, and frequently are, further subdivided. 



M. pectoantibrachialis (Fig. 65, m). — This is a small flat 

 bundle about one or two centimeters wide, forming the most 

 superficial portion of the pectoralis group. 



Origin on the lateral surface of the manubrium. The 

 muscle passes laterad onto the arm and is inserted by a flat 

 tendon into the superficial fascia of the dorsal border of the 

 forearm, near the elbow-joint. The tendon is continuous 

 craniad with the border of the clavobrachial {k), so that a bundle 

 of fibres may pass from this muscle to be inserted with the 

 clavobrachial, or a bundle from the clavobrachial to be inserted 

 with this. -The tendon is continuous caudad with that of the 

 epitrochlearis (;-), The fascia of insertion may be traced to an 

 attachment into the dorsal border of the ulna. This muscle 

 usually receives near its insertion a slip, sometimes called its 

 caudal division, from the deep layer of the pectoralis major. 



Relations. — Outer surface with the integument. Inner sur- 

 face with both divisions of the pectoralis major (/) on its medial 

 two-thirds, and with the biceps (/) and bicipital arch (/') in its 

 lateral one-third. The cranial border is closely applied to that 

 of the clavobrachial (/('), except at the two ends. 



Action. — Draws the arm mediad. 



M. pectoralis major, or ectopectoralis (Fig. 65, /, /'). — 

 In this it is usually possible to distinguish a superficial and a 

 deep layer. 



The superficial (/') layer is a flat band of fibres one or two 

 centimeters wide. 



Origin from a raphe in the midventral line, along the 

 cranial half of the manubrium and for five to ten millimeters 

 craniad of it. 



Insertion (Fig. 81,/). — The pectoral ridge of the middle 

 third of the shaft of the humerus, slightly dorsad of the line of 

 insertion of the deep portion. 



Relations. — Outer surface with the clavobrachial (Fig. 

 65, /') and integument, the medial end caudally with the 

 pectoantibrachialis (w), and the distal end with the brachialis 



