188 



OSTEOLOGY 



is the incisive fossa, and beneath the second premolar tooth the mental foramen 

 which transmits the mental nerve and vessels. The oblique line runs upward from 

 the mental tubercle and is continuous behind with the anterior border of the ramus. 

 The posterior border of the ramus runs downward and forward from the condyle 

 to the angle, which is frequently more or less everted. 



The Orbits (orbitae) (Fig. 190). The orbits are two quadrilateral pyramidal cavi- 

 ties, situated at the upper and anterior part of the face, their bases being directed 

 forward and lateralward, and their apices backward and medialward, so that their 

 long axes, if continued backward, would meet over the body of the sphenoid. 

 Each presents for examination a roof, a floor, a medial and a lateral wall, a base, 

 and an apex. 



Anterior 

 ethmoidal forame) 



Posterior ethmoidal foramen 

 Orbital process of palatine 

 Optic foramen 



Sphenopalatine foramen 



Bella turcica 

 Probe inforamenrotundum 



Fossa for 



lacrimal sac 



Uncinate process 

 of ethmoid 

 Openings of 

 maxillary sinus 

 Inferior nasal 

 concha 



Probe, in pterygoid canal 

 "Probe in pterygopalaline canal 



Palatine bone 

 Lateral pterygoid plate 



Pyramidal process of palatine 



FIG. 192. Medial wall of left orbit. 



The roof is concave, directed downward, and slightly forward, and formed in 

 front by the orbital plate of the frontal; behind by the small wing of the sphenoid. 

 It presents medially the trochlear fovea for the attachment of the cartilaginous 

 pulley of the Obliquus oculi superior; laterally, the lacrimal fossa for the lacrimal 

 gland; and posteriorly, the suture between the frontal bone and the small wing 

 of the sphenoid. 



The floor is directed upward and lateralward, and is of less extent than the 

 roof; it is formed chiefly by the orbital surface of the maxilla; \nfront and laterally, 

 by the orbital process of the zygomatic bone, and behind and medially, to a small 

 extent, by the orbital process of the palatine. At its medial angle is the upper 

 opening of the nasolacrimal canal, immediately to the lateral side of which is a 

 depression for the origin of the Obliquus oculi inferior. On its lateral part is the 

 suture between the maxilla and zygomatic bone, and at its posterior part that 

 between the maxilla and the orbital process of the palatine. Running forward 

 near the middle of the floor is the infraorbital groove, ending in front in the infra- 

 orbital canal and transmitting the infraorbital nerve and vessels. 



