496 MUSCLES ON POSTERIOR KECK AND BACK. 



Sixth layer, (Fig 151.) Dissection. Eemove tlie semi- 

 spinales. This layer consists of the deeper and more deli- 

 cate muscles of the back and ribs. 



The inter-spinales , as their name implies, are situated 

 "between the spinous processes of contiguous vertebras. 

 They consist of a succession of small, short muscles, which, 

 in the neck, are in pairs, owing to the bifid state of the 

 cervical spines. In the back they are quite indistinct, and 

 in the loins they are mostly ligamentous, having a few 

 muscular fibres intermixed. Function. To extend the 

 spine and keep it erect. 



The intertransversales are also short muscles, and as 

 their name indicates, are situated between the transverse 

 processes. They are double and distinct in the neck, very 

 indistinct in the back, and feeble in the loins. 



Function. To bend the spine laterally. 



The multifidus spince consist of a multitude of small, 

 fleshy and tendinous fasciculi, which are parallel to each 

 other, and extend from transverse to spinous processes, the 

 whole length of the spine. They arise each from the trans- 

 verse or oblique piocess of one vertebra, and are inserted 

 into the spinous process of the vertebra above, the fasci- 

 culi sometimes extending to the second or third vertebra 

 above. 



At the lower part of the spine the multifidus spinaa 

 have also an attachment, tendinous and fleshy, to the back 

 part of the sacrum, and the posterior part of the ilium. 

 Function. To support the spine and bend it to one side. 



The levatores costarum are twelve in number, on each 

 side of the chest, and are parallel to the external intercos- 

 tal muscles. Each arises from the transverse processes of 

 the dorsal and the last cervical vertebra, and is inserted into 

 the ribs below, between the tubercle and angle. Func- 

 tion. To elevate the ribs and assist in inspiration. 



The supra-spinales are little fleshy fasciculi,, or bands, 

 described as being situated exclusively upon the spinous 

 processes of the cervical vertebrae 



It will be seen from the above description of the muscles 



