168 THE ANATOMY OF THE HORSE. 



the superficial temporal and internal maxUlary veins. It passes out 

 throiigh the substance of the parotid, and then lies in a groove on 

 its surface, where it receives maxillo-musctdar and posterior auricular 

 branches. 



The 7th Cranial Nerve (Portio dura) (Plate 28) emerges from 

 the aqueduct of Fallopius by the stylo-mastoid foramen of the petroiis 

 temporal bone. It passes dowTiwards and forwards at the inner face of 

 the parotid or within its substance ; and txirning round the inferior 

 maxilla, it reaches the fece with the transverse facial vessels. In this 

 course it is crossed superficially by the posterior auricular artery, and 

 passes over the angle of division of the superficial temporal artery. As 

 it turns roiind the inferior maxilla, it is joined by the sensory sub- 

 zygomatic branch from the inferior maxillary division of the 5th cranial 

 nerve. In this part of its course the 7th nerve detaches the following 

 branches : — 



1. The Anterior, Middle, and Posterior Aiiricular Nerves. — The first two 

 are given off at the st3do-mastoid foramen, the last is detached midway 

 between the foramen and the edge of the ramus. The nerves ascend in 

 or beneath the parotid gland, and their distribution is given at page 163. 



2. Nerves to the occipito-styloid, stylo-hyoid, digastricus (upper 

 belly), and stylo-maxillaris muscles. These are given off at the stylo- 

 mastoid foramen. 



3. The Cervical Branch, which is given off at nearly the same point as 

 the anterior auricular, but from the opposite side of the trunk. It 

 passes through the parotid, and reaches the surface of the gland (see 

 page 163). 



4. Numerous small and irregular branches to the parotid gland and 

 guttural pouch. 



The Subzygomatic Nerve {Auriculo-temporal of man) is a branch 

 of the inferior maxillary division of the 5th nerve, given off at 

 the foramen lacerum basis cranii. It descends behind the capsular 

 ligament of the jaw ; and crossing over the termination of the super- 

 ficial temporal artery, it joins the 7th as it turns round the ramus. It 

 sends a branch to accompany the transverse facial vessels (Plate 29). 



THE REGION OF THE POLL. 



Directions. — It will be convenient at this stage to dissect a group of 

 muscles (with their nerves and vessels) placed above the occipito-atlantal 

 and atlanto-axial joints (fig. 18, page 156). The cervico-auricular muscles 

 of one side having been cleared away, the mastoid tendon of the 

 mastoido-humeralis (page 152) will present itself. Beneath that, again, 

 is the mastoid tendon common to the splenius and trachelo-mastoideus 

 (page 153); and still deeper, there is the occipital insei'tion of the 

 complexus. Each of these, having been identified, may be cut away; 



