REGION OF THE NAPE OF THE NECK. 103 



several vessels of importance in the maintenance of the 

 collateral circulation after ligature of the subclavian or 

 carotid arteries namely, the occipital, vertebral, pro- 

 funda, and princeps cervicis. The occipital enters the 

 region between the splenius capitis and obliquus superior, 

 and lies between the splenius and the complexus, and is 

 afterwards distributed to the scalp; its descending branch, 

 the princeps cervicis, which inosculates with the vertebral 

 and the profunda cervicis branch of the superior inter- 

 costal, passes between the complexus and semi-spinal is 

 colli muscles. The profunda cervicis enters the region 

 by passing backwards between the transverse process of 

 the seventh cervical vertebra and the first rib. The 

 nerves found here are branches of the suboccipital and 

 the posterior branches of the great occipital, and third 

 and fourth cervical nerves. Beneath the integument are 

 a number of lymphatic ganglia, which become engorged 

 in constitutional syphilis. Beneath the cellulo-fatty layer 

 are the muscles forming the suboccipital triangle, the 

 recti capitis postici, internally, the obliquus superior and 

 the obliquus inferior, the floor of which triangle contains 

 the curve of the vertebral artery perforating the pos- 

 terior occipito-atlantoid ligament, before it takes its 

 course through the foramen magnum ; and between this 

 vessel, and the groove in the atlas, is the trunk of the 

 suboccipital nerve. 



Owing to the curvature of the cervical spine, the 

 prominence of the second and third cervical vertebra is 

 seen in the pharyngeal cavity, and can be readily recog- 

 nized from the mouth. 



The cervical spine is liable to dislocation from the 

 great mobility of the articulations ; and from the fact 

 that the articular surfaces are nearly horizontal, disloca- 



