MUSCULAR SYSTEM. 113 



Relations. — Externally, with the trapezius and cartilage of the 

 scapula; internally, with the vertebrae and ribs : anteriorly, it is 

 connected with the rhoniboideus longus ; posteriorly, it is crossed 

 by the latissimus dorsi. 



Structure. — Fleshy : enveloped in a cellular expansion. 



Action. — To elevate the scapula. 



2.— PECTORAL REGION. 



These muscles form the breast, or what is vulgarly and ab- 

 surdly called the bosom. 



FECTORALIS T R A N S V ERS U S.- ( "Jf ''""'f ^"^"7^^'^''^- 



t oterno-humeralis. 



Situation. — Lateral, anterior, and inferior parts of the breast. 

 The pair form the fleshy prominences seen directly from the front. 



Form. — An approach to a triangle whose apex has been cut 

 off: broad and thick, superiorly ; narrow, inferiorly. 



Attachment. — On the inner side, to a white tendinous line, 

 and through the medium of that, to its fellow of the opposite side; 

 also to the four first bones of the sternum: on the outer side, to 

 the anterior part of the body of the humerus, and to the faschia 

 covering the arm. 



Relations. — Superiorly, it is connected with the major and 

 minor pectoral muscles ; externally, it is covered by the skin; in- 

 ternally, opposed to the front of the elbow joint; anteriorly, to 

 the levator humeri. 



Direction. — Transverse ; incurvating downwards. 



Structure. — Inner attachments, tendii;ous as well as fleshy ; 

 outer, wholly aponeurotic : intermediate part, fleshy. 



Action. — To adduct the arm ; also to keep it close to the chest 

 during its flexion and extension : this muscle has, probably, more 

 to do in enabling the arm to support weight than to give it motion. 



PECTORALis MAGNUS. — Stcmo- troclijueus. 



Situation. — Infero-lateral part of the thorax. 



Figure. — Trapezoid ; flattened and thick in substance. 



Attachment. — Inwardly, to the 4th, 5th, and 6th pieces of 

 the sternum, and to the cartilages connecting them ; also to the 

 ensiform cartilage, where, through the intervention of a white 

 tendinous line, it becomes united with its fellow ; still more pos- 

 teriorly, to the aponeurosis of the external oblique muscle, and 

 the cartilages of the false ribs : outwardly, it is attached to the 

 lesser tubercle of the humerus and the inner part of the lower 

 end of the scapula. 



