Chap. VII] 



MUSCULAR TISSUE 



103 



-OCCIPITALIS 



LAST 



CERVICAL " 

 VERTEBRA 



I 



.#^ 



i\ 



/ 



rLATISSIMUS 



to their insertion in the clavicle, the acromion process, and 

 the spine of the scapula. It is a very large muscle, and cov- 

 ers the other muscles of the upper part of the back and neck, 

 also the upper portion of the latissimus dorsi. 



Action. — It lifts the 



shoulder and rotates the ^ 



angle of the scapula back- - If M ^ 



ward. / ' ,r 



Latissimus dorsi. — / '/ 



The latissimus dorsi 

 arises from the last six 

 thoracic vertebree, and 

 through the medium of 

 the lumbar aponeurosis, 

 from the lumbar and 

 sacral part of the spine 

 and from the crest of 

 the ilium. It covers the 

 lower part of the back. 

 The fibres pass upward 

 and converge into a 

 thick, narrow band, 

 which winds around and 

 finally terminates in a 

 flat tendon, which is in- 

 serted into the front of 

 the humerus just below 

 its head. 



Action. — It draws the humerus backward, the body forward, 

 and keeps the scapula close to the chest, as in using crutches or 

 climbing. If the arm is elevated, it draws it down, back, and 

 rotates it in, as in swimming. 



Muscles of the chest. — The chief bulk of the anterior mus- 

 cular wall of the chest is made up of the pectoral muscles. 



Pectoralis major. — The pectoralis major arises from the sternal 

 end of the clavicle, the sternum, and the six upper ribs. The fibres 

 converging form a thick mass, which is inserted by a tendon of 

 considerable breadth into the upper part of the humerus. 



Action. — It draws the arm downward and forward. 



Fig. 74. 



Muscles in the Superficial Later 

 OF THE Back. (Gerrish.) 



