200 THE ANATOMY OF THE HORSE. 



the cervical cord, and above it tapers into the ascending offsets with the 

 internal carotid artery. Connecting branches unite the ganglion with 

 the 1st spinal nerve, and with the last four cranial nerves. Communi- 

 cations with some of the other cranial nerves are also established through 

 the carotid offsets of the ganglion. The distributory branches from the 

 ganglion pass to the adjoining vessels and the pharynx. Of the former 

 set, two branches accompany the internal carotid into the skull, and 

 form the carotid and cavernous plexuses. Other branches follow the 

 external carotid, and are continued on the branches of that artery. 



The 1st Cervical Nerve. The inferior primary branch of this nerve 

 descends through the antero-external foramen of the atlas, and appears 

 in company with the occipital vessels, between the rectus capitis lateralis 

 and the obliquus capitis superior. It passes towards the upper ex- 

 tremity of the trachea, and splits into branches that enter the terminal 

 parts of the subscapulo-hyoid, sterno-hyoid, and sterno-thyroid muscles. 

 Beneath the atlas it gives branches to the anterior and lateral straight 

 muscles of the head ; and beyond that point it furnishes a branch 

 w T hich supplies the thyro-hyoid muscle, and gives a twig to join the 

 hypoglossal nerve. It sends a communicating branch to the superior 

 cervical ganglion of the sympathetic. 



THE TONGUE. 



Directions. — With the cavity of the mouth exposed as in Plate 30,. 

 any portions of food found in the cavity should be removed, and the 

 mucous membrane made clean. By moving the tongue about, the 

 following points w T ill be observed. 



The inferior portion of the tongue lies free on the floor of mouth, 

 from w r hich it can be readily drawn out. This part is two-sided, being 

 flattened from before to behind, and rounded at its extremity like a 

 spatula. The superior portion, on the other hand, cannot be displaced^ 

 and is thick and of a three-sided form. The entire organ is invested 

 by the mucous membrane of the mouth, which, in passing on to the 

 tongue, forms certain folds, or doublings. Thus, if the free portion of 

 the tongue be raised from its position on the floor of the mouth, there 

 will be seen on the middle line a double fold of "mucous membrane 

 termed the freeman linguae. At the extreme upper part of the mouth, 

 again, the mucous membrane, in passing between the root of the tongue 

 and the soft palate, forms on each side a fold termed the anterior pillar 

 of the fauces. 



The mucous membrane of the tongue has its surface raised into the 

 form of papilhe, of which there are four varieties : — 



1. The Filiform Papilllce are the most numerous, and are found all 

 over the tongue. In shape they are conical, having a tapering summit, 



