MUSCULAR SYSTEM. 109 



sternum, above the preceding muscle: anteriorly, to the spur 

 process of the os hyoicles : also, by a detached slender tendon, to 

 the lower border of the thyroid cartilage. 



llelations. — Inferiorly, with the sterno-maxillaris ; superiorly, 

 with the trachea, and on the left side with the oesophagus like- 

 wise : along its outer border, with the recurrent nerve; along its 

 inner, or mesian line, with its fellow. 



Structure. — Sternal end, tendinous and fleshy, and united in 

 one belly ; at the other end, there are two fleshy bellies ; and the 

 three are connected contiguous to the trachea, about the middle 

 of the neck, by an intermedinte, short, and slender tendon. 



Action. — To draw the os hyoides, and along with it, the larynx, 

 downwards and backwards. 



SUBSCAPULO-IIYOIDEUS. 



Situation. — Continued from the levator humeri, and spread 

 over the antero-superior parts of the neck. 



Form. — A broad, thin, elongated band; thicker and broader 

 anteriorly than posteriorly. 



Attachment. — In connection with the levator humeri, to the 

 inner surface of the scapula ; anteriorly, to the middle of the body 

 of the OS hyoides. 



Relations. — Its course lies between the carotid artery and the 

 jugular vein, between which it forms a fleshy partition ; having on 

 its outer side, the sterno-maxillaris; on its inner, the sterno- 

 thyro-hyoideus ; and at its anterior termination, becoming em- 

 bedded between the submaxillary glands. 



Structure. — The scapular end consists of a thin flattened ten- 

 don : the remaining part is fleshy. It forms altogether a sort of 

 fleshy involucrum for the next muscle. 



Action. — It will draw the os hyoides downwards and back- 

 wards. 



SCALENUS . — Costo-cervicalis. 



Situation. — Postero-infcrior part of the neck. 



Form. — Pyramidal : base cut slantwise and turned down- 

 wards. 



Jttachment. — Posteriorly, to the middle of the first rib ; an- 

 teriorly, to the bodies and transverse processes of the 5th and 6th 

 cervical vertebrae. 



Relatiom. — Along its upper margin, with the transversalis 

 colli; along its lower, with the sterno-maxillaris: on the outer 

 side, with the levator humeri; on the inner, with the trachea; 

 and on the left side, also with the oesophagus. In the interspace 

 between one scalenus and the other, run the carotid artery, par 



