54 ANATOMY IN A NUTSHELL. 



are interposed between similar processes of the External oblique muscle. The 

 upper fibers pass longitudinally outward, the middle fibers obliquely upward, 

 and ihc lower fibers vertically upward, converging at the inferior angle of the 

 scapula. ( Plate XX.) 



Insertion.- Into the bottom of the bicipital groove of the humerus, its 

 insertion extending higherthan that of the Pectoralis major. (Plate XXIII.) 



A' riON.- Draws the arm down and hack, raises the lower ribs, and draws 

 the trunk forward. 



Nerve Supply.- Middle or long subscapular. 



Blood Supply. Subscapular artery. 



Serratus magnus. — Description. — (Plates XV-XVI1I.) — This is a thin irreg- 

 ularly quadrilateral muscle situated between the ribs and scapula at the upper 

 and lateral part of the chest. It is partly covered in front by the Pectoral 

 muscles, behind by the Subscapulars. The axillary vessels and nerves lie 

 upon its upper part, while its deep surface rests upon the ribs and intercostal 

 muscles. 



Origin.- By nine digitations or slips from the outer surface and upper 

 border of the eight upper ribs (the second rib giving origin to two slips,) and 

 from the aponeurosis covering the corresponding intercostal muscles. The 

 fiber- pass backward closely applying the chest wall and the vertebral border of 

 the scapula. The lower four slips interdigitate at their origin with the upper 

 five slips of the External oblique muscle of the abdomen. 



Insertion. — The slips from the first and the higher of the two from the 

 second rib. converge to be inserted into the triangular area on the ventral 

 aspect of the superior angle of the scapula. The next two slips spread out to 

 form a thin triangular -heath, the base of which is directed backward and is in- 

 serted into nearly the whole length of the ventral aspect of the vertebral border 

 of the scapula. The lower slips converge as they pass backward from the ribs 

 and form a fan-shaped structure, the apex of which is inserted, partly by mus- 

 cular and partly by tendinous fibers, into the triangular impression on the ven- 

 tral aspect of the inferior angle. (Plate XXI.) 



\< tion. — A pushing muscle. It also raises the point of the shoulder. 



Xi:i;\ i. SUPPLY. Posterior thoracic which is derived from the fifth, sixth, 

 and seventh cervical nerves. 



Blood Supply, [ntercostals, long and short thoracic 



LESSON XI. 



Levator angull scapulae. — Description.— (1'late XVIII.) — This muscle lies 

 jusl beneath the Trapezius at the back part and side of the neck. 



Origin. By tendinous -lips from the transverse process of the atlas, and 

 from the posterior tubercle- of the transverse processes of the second, third, 

 and fourth cervical vertebras. These slips become fleshy and unite so as to 

 form a flat muscle which passes downward and backward to its insertion. 



Insertion. Into the posterior border of the scapula between the superior 



