168 THE ANATOMY OF THE HORSE. 



The Cervical Branch of the 7th nerve. This nerve comes out 

 through the substance of the parotid gland, near or at the same point 

 as the jugular vein, and under cover of the parotido-auricularis muscle. 

 It supplies that muscle, and is continued down the neck, as already 

 seen (page 148). 



AuEicnLAR Branches of the 1st Cervical Nerve. These, which are 

 derived from the superior primary branch of that nerve, appear in the 

 poll between the obliquus capitis superior and the rectus capitis posti- 

 cus muscles. Crossing the cervico-auriculares muscles, they are distri- 

 buted at tlie inner side of the base of the ear. 



Auriculae Branches of the 2nd Cervical Nerve. These are derived 

 from the stellate group which the inferior primary branch of that 

 nerve forms on the mastoido-humeralis, behind the wing of the atlas. 

 They reach the ear by crossing over the parotid gland, and are 

 distributed mainly to the skin of the concha on its posterior aspect 

 (when the opening is directed outwards), but some branches reach its 

 inner side. 



Auriculae Branch of the Lachrymal Nerve. This nerve, which 

 emerges from the orbital sheath, crosses the direction of the anterior 

 auricular branch of the 7th on the zygomatic arch, and is distributed 

 to the skin in front of the ear. 



Cartilages of the Ear : — 



The CoNCHAL Cartilage. This and the other cartilages are com- 

 posed of yellow (elastic) fibro-cartilage. Although its name expresses 

 some likeness to a shell, it bears more resemblance to a trumpet. The 

 opening of the trumpet is somewhat elliptical, and can be directed 

 forwards, outwards, or backwards. The margins of the opening meet 

 above and below in acute angles. Beneath the lower angle, or commis- 

 sure, the cartilage forms a complete tube, which is slightly inflated in 

 form. At its termination it becomes narrow, and slightly embraces the 

 annular cartilage, over the outer side of which it sends a peaked pro- 

 cess, whose fibrous extremity is attached to the wall of the guttural 

 pouch. 



The Annular Cartilage. This has the form of a ring surrounding 

 the edge of the auditory process ; and it is itself embraced by the con- 

 chal cartilage, the three structures being related to one another like the 

 tubes of a telescope. This connection between the cartilages is main- 

 tained by connecting elastic tissue, and by the lining membrane of the 

 ear in passing from the one structure to the other. 



The ScuTiFORM Cartilage is superposed to the temporal muscle in 

 front of the base of the concha, to which it is connected only by the 

 muscles already described. It is thin, flexible, and irregularly triangular 

 in shape. 



