THE NERVES. 403 



to the extremities, in particular. In the back (nn. intercostales) 

 they pass singly, without forming a plexus. 



c. The posterior branches, much smaller than the anterior, pass 

 between the transverse processes (foram. intervertebrr. posterr. 

 Cruveilhier), and through the foram. sacralia posit, backwards, 

 divide into several branches, and soon terminate in the muscles 

 and the skin of the back from the occiput to the coccyx. 



650. 1. The cervical nerves, Nervi cervicales (eight pairs). 



Their posterior branches pass at first transversely inwards be- 

 tween m. complexus and semispinalis, perforate the trapezius from 

 before backwards, and take a retrograde course beneath the skin 

 transversely outwards ; they also unite with the plexus. Those of 

 the two first are larger than the anterior. The anterior branches 

 form, principally, the plexus cervicalis brachialis. 



651. a. The four superior cervical nerves 



supply the skin and muscles of the occiput, nape of the neck and 

 cervical region, and form the plex. cervicalis, from which n. phre- 

 nicus arises. 



1. Nerv. cervicalis 1. s. infra occipitalis Aschii, one of the 

 smallest spinal nerves, passes forth under art. vertebralis (rarely 

 over it) between occiput and atlas, behind proc. obliquus, and di- 

 vides below the curvature of the art. vertebralis. Its larger ante- 

 rior root contains from three to four fasciculi, the smaller posterior 

 from two to three. It is situated farther forwards than the rest of 

 the posterior roots, applies itself to the n. accessorius, and is said 

 to be sometimes wanting. Its ganglion lies in the foram. inverte- 

 brale. 



a. Ramus anterior, passes on the inner side of art. vertebral, in 

 a sulcus of the Atlas, and bends downwards to form a loop 

 with the second cervical nerve. Branches to the articulation 

 of the occiput, hypoglossus, gangl. cervicale I., vagus and 

 sympath., art. vertebralis, mm. recti capitis antici and late- 

 ralis, between which it pierces 



b. Ramus posterior, larger than a, passes in the space between 

 mm. capitis obliqui and rect. postic., supplies these and m. 

 later alis, biventer and complexus. 



652. 2. N. cervicalis II., 



far larger than I., passes through between atlas and dentatus, far- 

 ther backwards than the rest of the spinal nerves, arid divides be- 

 neath m. capit. obliq. inferior, into : 



