NERVOUS SYSTEM. 345 



inward sides of the coronoid processes. This nerve takes its course 

 obliquely downward, along the branch of the lower jaw, runs 

 between the pterygoideus and the larynx, and afterwards insinu- 

 ates itself between the muscles forming the root of the tongue. 

 Having penetrated the substance of this organ, the nerve per- 

 vades its middle, accompanied by the lingual artery, and ends 

 in a ramous expansion in its tip. The branches of this nerve 

 are — 1. Some small ones in its course to the hyo-glossus longus ; 

 one of which, remarkable for its length, runs to the termination 

 of that muscle, detaching many twigs in its way. 2. Lateral 

 branches, which come off in a half penuiform manner, within 

 the substance of the tongue, and ramify extensively among the 

 fibres of the other lingual muscles. 



Tenth Pair, or Sub-occipital, 



Possessing all the attributes of a spinal nerve, probably 

 should rather be considered as the first of the cervical. It has 

 a filamentous origin from the place of junction of the medulla 

 oblongata with the medulla spinalis, and passes out through 

 a foramen in the anterior part of the body of the atlas. It then 

 splits into a superior and an inferior division. The superior divi- 

 sion, larger than the inferior, we find deeply buried in muscle 

 upon the transverse process of the atlas, where it spreads into 

 several small branches, of which two only are worthy of remark, 

 the others being quickly expended in the contiguous muscles. 

 One of these is a deep muscular branch, which penetrates the 

 mass of muscle upon the occiput. The other ascends over the 

 vertex, and ramifies upon the inner and back part of the ear. 



The inferior division, the longer one, turns round the trans- 

 verse process of the atlas, and runs tlirough a foramen in the 

 anterior wing of the bone; after which it turns down towards 

 the trachea, transmitting its ulterior ramifications to the thyroid 

 gland, top of the trachea, and some lymphatic glands in the 

 vicinity ; also to the sterno-niaxillaris and sterno-thyro-hyoideus. 

 Its branches are — a. Some to the deep-seated muscles in front of 

 the atlas, b. Two or three to the anterior cervical ganglion. 

 c. One of communication with the lingual nerve. 



SPINAL NERVES. 



The thirty-six pairs of spinal nerves are divided into classes 

 correspondent with the vertebree composing the spine, viz. cer- 

 vical, dorsal, lumbar, sacral, and coccygeal. Likewise, the 

 several pairs of nerves in each class are numbered according to the 

 order in which they orioinate, so that the ntmiber and name of 



