380 MUSCLES. 



dinous and fleshy into the upper face of the first rib, in all the 

 space from its middle to its tubercle. 



7. Scalenus Posticus. 



The scalenus posticus arises from the transverse process 

 of the fifth and sixth cervical vertebrae, and is inserted into the 

 upper face of the second rib, just beyond its tubercle. 



The last three muscles are concealed by the sterno-cleido 

 mastoideus and the anterior edge of the trapezius. The scale- 

 nus posticus is best seen in dissecting the muscles of the spine, 

 and resembles very much one of the class to which Albinus 

 gives the name of Levatores Costarum. 



All the Scaleni elevate the ribs and bend the neck to one 

 side. They are particularly interesting as connected with the 

 course of the large blood vessels and nerves of the upper ex- 

 tremity.* 





CHAPTER H. 



MUSCLES OF THE TRUNK. 

 SECT. I. MUSCLES ON THE FRONT OF THE THORAX. 



The PectoraHs Major, 



Is superficial, and forms the large swelling cushion of flesh 

 under the skin of the breast. It arises tendinous from the ante- 

 rior face of the first two bones of the sternum, their whole length, 

 fleshy from the cartilages of the fifth and sixth ribs, and by a 

 fleshy slip from the upper part of the tendon of the external ob- 



* Varieties. Besides the three scaleni which are described, there are frequent- 

 ly supernumerary muscles or fasciculi. One of these, called the Scalenus Mini- 

 mus Albini, is between the first two, and occasionally appears as a fasciculus of 

 the scalenus anticus, separated from it by one or more of the brachial nerves; it 

 is sometimes double. Another fasciculus, called the Scalenus Lateralis, is be- 

 twecn the scalenus medius and posticus; it comes from the posterior part of the 

 rirst rib, and is inserted into the transverse process of the fourth, fifth, and sixth 

 vertebrae. 





