HEAD AND NECK OF THE HORSE 31 



cartilage behind the base of its tapering styloid process, and ter- 

 minates in the skin lining the cavity. 



The auriculo - palpebral nerve (described later) supplies the 

 anterior part of the ear. The great auricular nerve from the second 

 cervical is distributed over the posterior part of the ear. and the 

 occipital branch of the first cervical nerve terminates at the medial 

 part of the base of the ear. Both of the two last-named nerves 

 are connected with branches of the posterior auricular. 



When the first part of the vagus nerve comes to be examined, 

 it will be found that it also furnishes an auricular branch. 



The dissector should now turn his attention to the face, and should 

 begin with an examination of the external parts of the eye. 



The eyelids (Palpebrse). — The eyelids, using the term in the 

 more usual sense, are two in number, upper (palpebra superior) 

 and lower (palpebra inferior) ; but to these must be added a much 

 less obvious third eyelid (palpebra tertia). The upper and lower 

 lids may be described as membranous curtains arranged for the pro- 

 tection of the eyeball. The upper lid is the larger and the more 

 movable, has the more concave free edge, and is provided with a 

 special muscle, the m. levator palpehrce superioris, by which it is 

 raised. The limits of the upper lid cannot be accurately determined 

 by inspection merely ; but an indistinct infrapalpebral groove demar- 

 cates the lower lid from the face in general. Each lid has an outer 

 surface (facies anterior palpebrse) covered with hair-bearing skin, 

 and an inner surface (facies posterior palpebrse) applied to the eye- 

 ball and rendered smooth by the conjunctiva, a membrane that is 

 continued from the lid over the front of the eyeball. Short, fine 

 hairs cover both lids, and in addition tactile hairs, scanty on the 

 upper lid but numerous over the lower part of the lower lid, are 

 present. 



The free borders of the eyelids bound the palpebral fissure 

 (rima^ palpebrarum), which is in the form of a narrow slit, some 

 5 cm. in length when the lids are closed, but assumes an elliptical 

 outline when the eye is open. The border of each lid is flattened 

 in such a fashion as to make it possible to distinguish two margins, 

 an inner and an outer. The outer margin carries the eyelashes, 

 which are few, short, and weak on the lower lid, but much more 

 numerous, longer and stronger on the lateral two- thirds of the upper 

 lid. It should be noted that the upper eyelashes are arranged in 



1 Bima (for rigma; root rig means to split, to cleave) [L.], a crack, fissure, 

 cleft, chink. 



