MUSCLES OF THE BACK. 401 



these insertions; the upper fibres descend, the lower ascend, 

 and the middle are horizontal.* 

 It draws the scapula towards the spine. 



In the cervical portion of these muscles, formed by the ori- 

 gins of both united, is an elliptical expanse of tendon, lying over 

 the ligamentum nuchse, and extended on each side. The liga- 

 mentum nuchse itself, as mentioned elsewhere, is a vertical 

 septum of ligamentous matter, extending from the central line. 

 of the occipital bone, to the spinous processes of all the verte- 

 bras of the neck. At its upper part, where the spinous pro- 

 cesses of the neck are short, this septum is very broad, and di- 

 vides completely the muscles of the two sides of the neck. 



The Latissimus Dorsi, 



Is situated under the skin at the lower part of the back, so 

 as to cover the whole posterior portion of the latter. It arises 

 by a thin tendinous membrane, from the seven inferior spinous 

 processes of the back ; and by a thick tendinous membrane from 

 all those of the loins and sacrum. Its origin also extends along 

 the outer inferior margin of the sacrum, and from the posterior 

 third of the spine of the ilium.t Besides which, the latissimus 

 dorsi has from the sides of the three or four inferior false ribs, 

 as many fleshy heads which are connected with the inferior 

 heads of the obliquus externus abdominis. 



From this extended origin the fibres converge, so as to form 

 the posterior fold of the axilla; and to terminate in a flat, thick 

 tendon, of two inches in breadth, which is inserted into the 

 posterior ridge of the bicipital groove of the os humeri. The 

 upper part of tins muscle passes over the inferior angle of the 

 scapula, and derives a fasciculus of fibres from it. It is there 

 behind the teres major, but as it advances it winds around the 

 inferior edge of the latter so as to get before it. Afterwards 



* Varieties. It is sometimes short of the origin described, by from one to 

 four, of the lower spinous processes of the back. Also the lower fasciculus is 

 sometimes disjoined from the rest of the muscle, by a large triangular space. 



j- This origin frequently is tendinous at the back part of the ilium, and fleshy 

 in front. 



34* 



