NEfi VES 159 



beneath the vertebral artery on the posterior arch of atlas, 

 and, entering the sub-occipital triangle, divides into branches 

 to supply the inferior oblique, which branch communicates 

 with the 2nd cervical nerve, the recti postici major and minor, 

 the superior oblique, and the complexus. 



With the exception of the sub-occipital nerve, the posterior 

 primary divisions of the cervical nerves divide into : 



External branches : for the muscles behind the spine. 



Internal branches are larger than the external branches, 

 and, with the exception of that from the 2nd cervical nerve 

 (great occipital), pass to spinous processes, supplying the 

 muscles on their way, and become cutaneous. The branch 

 from the 3rd cervical nerve supplies the integument at the 

 base of the occiput (third or least occipital}. The internal 

 branches from the 6th, yth, and 8th end in the muscles. 



The great occipital nerve is the internal branch of the posterior 

 primary division of the 2nd nerve. It passes through the 

 complexus and trapezius, and ascends with the occipital 

 artery to the back of the scalp, communicating with the 

 small occipital nerve. It usually has an auricular branch. 



THE ANTERIOR PRIMARY DIVISIONS. 



The anterior primary divisions of the first four cervical 

 nerves form the cervical plexus, and those of the lower four, 

 with part of that of the ist dorsal nerve, compose the brachial 

 plexus. 



The anterior primary divisions of the ist and 2nd cervical 

 nerves differ in form from the rest. 



The anterior primary division of the 1st cervical nerve 

 passes outwards in the groove on the outer side of the upper 

 articular process of the atlas, lying behind* the vertebral 

 artery, and giving a branch to the rectus lateralis and recti 

 antici capitis major and minor. It joins the 2nd nerve, and 

 communicates with the sympathetic on the vertebral artery, 

 with the superior cervical ganglion, the pneumogastric, and 

 with the hypoglossal nerves. 



The second cervical nerve : the anterior primary division 

 of this nerve winds forward outside the vertebral artery, and 

 divides into an ascending part which joins the ist cervical, 

 and a descending part, which joins the 3rd cervical nerve. 



The Cervical Plexus is formed by the union of the anterior 

 primary divisions of the first four cervical nerves after each 

 has communicated with the superior cervical ganglion. It is 

 situated between the sterno-mastoid and the middle scalene 

 muscles. Each nerve except the ist divides into an ascending 



