248 DETAILED SYNTHESIS. 



9entre of the inner surface of the lower jaw, and the 

 back part extends up to the temporal bone. This mus- 

 cle can therefore draw down the jaw if the hyoid bone 

 is firmly held, or if the jaw is firmly held the hyoid will 

 be raised. It is a curious muscle on account of its cen- 

 tral tendon and its arrangement. 



510. Remark. Other neck-muscles may best be described, so far 

 as they need to be mentioned, in connection with the throat and larynx. 



Muscles of the Trunk-walls. 



511. THE MUSCLES OP THE TRUNK-WALLS MAYBE 

 CLASSED as those adapted to act on the upper extremities, 

 to elevate the ribs, to depress them, to compress the or- 

 gans of the abdomen, and to bend or sustain the spinal 

 column. 



512. THE MUSCLES ADAPTED TO ACT ON THE UPPER 

 EXTREMITIES MAY BE CLASSED as those acting on the 

 blades and on the arms, and both may be classed as 

 front and back, or anterior and posterior. 



513. THE PECTORALIS MAJOR, as its name signifies, 

 is the largest of the breast, and is worthy of notice from 

 the curious arrangement of its fasciculi, where they are 

 attached to the arm (14, PI. 20, Fig. 1). The lower ones 

 extend up under the upper ones, to be attached as near 

 the joint as possible, since their use is to draw the arm 

 downward, while the upper fasciculi extend over the 

 upper ones and are attached as far as possible down 

 from the joint, a very extraordinary and ingenious ar- 

 rangement for gaining important results by simple means. 

 This muscle forms the inside of the armpit. 



514. THE SERRATUS MAGNUS (Fig. 1, PI. 21) is a 

 broad, not very thick muscle, that extends from several 

 of the ribs under the shoulder-blade, to the under sur- 

 face of the back edge or base of which it is attached ; 



510. What said of other neck-muscles? 511. How ? 512. How ? 518. De- 

 scribe . Why is this muscle curious and interesting? 514. Describe . 



