PECTORAL GROUP. 



195 



PECTOEALIS TRANSVERSUS. 



{Sterno-cq^oneuroticus.) 



(Fig. 75. d.) 



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

 is quadrilateral, the fibres extending outwards and downwards. 



Fig. 75. 

 Pectoral muscles, .and inferior deep muscles of the neck, a, Longus colli ; h, Eectus capitis 

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

 Pectoralis luaguus ; (/, Pectoralis parvus. Ou 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. 



