PECTORAL GROUP. 



195 



PECTORALIS TRAXSVERSUS. 

 (Stemo-aponeuroti 



(FiG. 75. d.) 



Situated on the latero-inferior part of the thorax, this muscle 

 is quadrilateral, the fibres extending outwards and downwards. 



FIG. 75. 



Ptctoral muscles, and inferior deep muscles of the neck, a, Longus colli ; b, Bectus capitis 

 latertlis ; c, Eectus capitis anticus minor ; d, Pectoralis transversus ; e, Pectoralis auticua ; //, 

 Pectoralis niagnas ; y. Pectoralis panrus. On the left side the pectoralis transversus and anticus 

 have been removed. 



Near its origin it is fleshy, mixed with tendon, but afterwards 

 becomes aponeurotic. 



Origin. By fleshy fibres usually from the first four bones of 

 the sternum, meeting its fellow at a white central line. 



Insertion. To the olecranon, by fascia covering the inner side 

 of the arm, and to the anterior part of the humerus. 



Relation. Externally with the skin ; anteriorly with the 

 pectoralis anticus ; superiorly with the pectoralis magnus. 



Action. X adduct the arm, and especially to tense the 

 brachial fascia. 



