PECTORAL GROUP. 



195 



PECTORALIS TRANSVERSUS. 

 (Stemo-aponeuroticus. ) 

 (Fig, 75. d.) 



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

 is quadrilateral, the fibres extending outwards and- downwards. 



Fto. 75. 



Pectoral mtwcles, and inferior deep muscles of the neck, a, Longus colli ; 6, Rectus capitis 

 lateralis ; c, Rectus capitis anticus minor ; d, Pectoralis transversus ; e, Pectoralis anticus ; //, 

 Pectoralis magnus ; g, 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. — To adduct the arm, and especially to tense the 

 brachial fascia. 



