FACE AND FRONTAL REGION OF HEAD 3 



third with the lateral two-thirds of the supra-orbital margin, 

 will cut through the supra-orbital notch of the frontal bone, 

 the infra-orbital foramen of the maxilla, and the mental foramen 

 of the mandible, all three of which may be felt if firm pressure 

 is made in the proper situations. The first, which lies in the 

 supra-orbital margin, transmits the supra-orbital vessels and 

 nerve. The second is placed about half an inch below the 

 infra-orbital jnargjn ; it transmits the infra-orbital vessels and 

 nerve. The third lies midway between the second premolar 

 tooth of the mandible and the lower border of the mandible ; 

 it transmits the mental branches of the inferior alveolar vessels 

 andjierve. 



After the bony points of the region have been studied, 

 the surface anatomy of the ocular appendages should be 

 examined. Under this head are included (i) the eyebrows ; 

 (2) the eyelids; (3) the conjunctiva. 



The eyebrows are two curved tegumentary projections 

 placed over the supra-orbital arches of the frontal bone ; they 

 intervene between the forehead above and the ocular regions 

 below. The short stiff hairs which spring from the eyebrows 

 have a lateral inclination. 



'The eyelids (palpebrae) are the semilunar curtains provided 

 for the protection of each eyeball. The upper lid is the 

 longer and much the more movable of the two. When the 

 eye is open, the margins of the two lids are slightly concave 

 and the interval between them, rima palpebrarum, is elliptical 

 in outline. When the eye is closed, and the margins of the 

 lids are in apposition, the rima palpebrarum is reduced to a 

 nearly horizontal line. Owing to the greater length and 

 mobility of the upper lid, the rima, in the closed condition, is 

 placed at the level of the lower border of the cornea, which 

 is the transparent front part of the eyeball. 



At the extremities of the rima palpebrarum the eyelids 

 meet and form the palpebral commissures. Immediately 

 lateral to the medial commissure the rima expands into a 

 small triangular space, called the locus lacrimalis. If the 

 dissector now examines the free margins of the lids he will 

 note that, to the lateral side of the lacus lacnmalis, they 

 are flat, and that in each lid the cilia or eyelashes project 

 from the anterior border, whilst the tarsal glands open, 

 by a series of minute apertures, along the posterior border, 

 a distinct interval intervening between the cilia and the 



