158 THE POCKET ANATOMY 



To the upper cervical ganglion of the sympathetic. 



To the loop between ist and 2nd cervical. 



To the lingual branch from the pharyngeal plexus. 



To the lingual of the 5th, on the hyo-glossus. 



Distributing : 



Descendens cervicis vel hypoglossi : a slender branch, given 

 off as the nerve hooks round occipital artery, passes down 

 over carotid sheath, joining in a loop with branch from 2nd 

 and 3rd cervical (communicans hypoglossi) ; from this loop 

 muscular branches are given to sterno-hyoid, sterno-thyroid, 

 and the two bellies of the omo-hyoid. This branch, and those 

 to thyro-hyoid and genio-hyoid, do not arise from hypoglossal 

 nucleus, but are derived from communication above with ist 

 and 2nd cervical, and merely pass down with hypoglossal. 



Thyro-hyoid : passes round great cornu of hyoid bone to 

 supply thyro-hyoid. 



Muscular : to stylo-glossus, hyo-glossus, genio-hyoid, genio- 

 hyo-glossus and intrinsic muscles of the tongue. 



THE SPINAL NERVES. 



There are 31 pairs of spinal nerves, viz. : 8 cervical, 

 12 dorsal, 5 lumbar, 5 sacral, and i coccygeal. Each nerve 

 arises from the spinal cord by an anterior (motor) and a 

 posterior (sensory) root, the latter having a ganglion developed 

 upon it. These roots join together in the inter vertebral 

 foramen, and upon issuing from it immediately split up again 

 into two parts, the anterior and posterior primary divisions, 

 each containing fibres from the two roots. The anterior 

 primary divisions supply the parts in front of the spine, the 

 posterior primary divisions the parts behind that column. 



The posterior primary divisions of the spinal nerves are 

 generally smaller than the anterior, and pass directly back- 

 wards, each quickly dividing into an external and an internal 

 branch, to supply the muscles and integuments behind the 

 spine. To this general rule there are a few exceptions, as 

 posterior primary divisions of the ist cervical, the 4th and 

 5th sacral, and the coccygeal nerves do not thus subdivide. 



THE CERVICAL NERVES. 

 THE POSTERIOR PRIMARY DIVISIONS. 

 The first cervical nerve. The posterior primary division 

 of the ist cervical or sub-occipital nerve passes backwards 



