146 THE MUSCLES. 



(?'). Inner surface with the deep portion (/), the fibres of 

 which it crosses obliquely. 



The deep portion (/) is a flat band of parallel fibres about 

 three times as broad as the superficial portion. 



Origin. The ventral surface of the manubrium and of the 

 first three divisions of the sternum, and the median raphe for 

 about one centimeter craniad of the manubrium. It passes 

 directly laterad. 



Insertion (Fig. 81, e} along a line which begins at the 

 infraspinatus fossa of the great tuberosity, and runs parallel to 

 the deltoid ridge until it reaches the pectoral ridge at the junc- 

 tion of the second and third fourths of the humerus and then 

 continues in the direction of the pectoral ridge as far as the 

 junction of the third and fourth fourths of the humerus. Some 

 of its fibres may pass caudad of the biceps and be inserted with 

 the epitrochlearis. Into the part of the line which is parallel 

 to the deltoid ridge the muscle is inserted by a flat tendon ; 

 into the remainder of the line it is usually inserted directly by 

 muscle-fibres, though at its caudal end its insertion may again 

 be tendinous. 



Relations. Outer surface with the cutaneus maximus, the 

 outer layer of the pectoralis major (Fig. 65, /'), the pectoanti- 

 brachialis (;), and the clavobrachial (). Inner surface with 

 the pectoralis minor (0), the proximal end of the humerus, the 

 coracobrachialis (Fig. 77, /"), and the supraspinatus (Fig. 

 77, d} at the insertion of the latter. At the cranial part of its 

 origin it touches the sternomastoid (Fig. 65, g) and sternohyoid 

 (Fig. 65, e}. 



Action. Draws the arm mediad and turns the foot forward. 



M. pectoralis minor, or entopectoralis (Fig. 65, o). This 

 is a fan-shaped mass of fibres, flat but thicker than the pec- 

 toralis major. 



Origin from the lateral half of the first six divisions of the 

 body of the sternum and sometimes from the xiphoid process. 

 The fibres are divisible into several bundles which vary in 

 extent and distinctness and are sometimes described as separate 

 muscles. They pass craniolaterad and converge so that the line 

 of insertion is about one-half as long as that of the origin. 



