n8 HEAD AND NECK 



the maxillae. On either side of the nose are the sockets 

 for the eyeballs, each of which is bounded above by the 

 supra-orbital margin of the frontal bone and below by the 

 orbital margins of the maxilla and the zygomatic bone 

 (O.T. malar). The supra- and infra-orbital margins meet 

 laterally in the region of the cheek bone (zygomatic). From 

 the posterior part of the zygomatic bone, the zygomatic 

 arch, formed partly by the zygomatic and partly by the 

 temporal bone, extends posteriorly to the ear. Above the 

 zygomatic arch is the region of the temporal fossa, which 

 is bounded superiorly by the temporal line. The line 

 terminates anteriorly in the lateral part of the supra-orbital 

 margin. Above the medial part of the supra-orbital margin 

 the superciliary arch can be felt, and at a higher level, 

 above the lateral part of the supra-orbital margin, lies the 

 frontal tuber. The region above the nose and between 

 the medial ends of the superciliary arches is the glabella. 



Below the zygomatic arch lies the ramus of the mandible 

 covered by the masseter muscle ; and extending anteriorly 

 from the lower end of the ramus is the body of the mandible. 

 A line dropped vertically through the junction of the medial 

 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 margin. 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 

 and nerve. 



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 arch 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, 



