THE MUSCULATURE 43 



267. Between and dorsal to these, the hyoglossus. Ori- 

 gin from hyoid: insertion in tongue. 



268. Laterad, the deltoideus passes to the arm. It has 

 three portions originating from the sternum, clavi- 

 cle and scapula respectively and inserted on the 

 humerus. 



269. Overlying this and caudad, the great pectoralis 

 extends from the sternum to the humerus. It has 

 three origins, the epicoracoid, sternum, and the 

 sheath of the rectus abdominis (270). 



270. Caudad to the pectoralis, the rectus abdominis 

 extends longitudinally on each side of the mid-line 

 from the pubis to the sternum. Note the white trans- 

 verse tendonous inscriptions. At the sides the ob- 

 liquus externus (256) may be seen. 



Pull the deltoideus cephalad and the pectoralis caudad, 

 exposing between them, 



271. the coraco-radialis, with its broad origin along the 

 episternum and insertion on the radial portion of the 

 radio-ulna. 



Cut through the deltoideus and the pectoralis and identify: 



272. the coraco-brachiales, two slender transverse mus- 

 cles. Origin from coracoid: insertion on humerus. 



273. Anconeus (triceps). This great muscie of the 

 upper arm has one head originating from the scapula 

 and three from the humerus. The insertion is on the 

 ulnar side of the radio-ulna. (The dissection of the 

 muscles of the lower arm and hand are omitted in 

 this manual.) 



Cut through the submaxillaries in the median line, exposing 



274. the submentalis, uniting the tips of the lower jaws. 

 Retract the sternum, exposing 



