THE EXTERIOR OF THE SKULL 



187 



medial part of the circumference of each orbit. Below the nasal bones and between 

 the maxillae is the anterior aperture of the nose, pyriform in shape, with the narrow 

 end directed upward. Laterally this opening is bounded by sharp margins, to 

 which the lateral and alar cartilages of the nose are attached; below, the margins 

 are thicker and curve medialward and forward to end in the anterior nasal spine. 

 On looking into the nasal cavity, the bony septum which separates the nasal 

 cavities presents, in front, a large triangular deficiency; this, in the fresh state, 

 is filled up by the cartilage of the nasal septum; on the lateral wall of each nasal 

 cavity the anterior part of the inferior nasal concha is visible. Below and lateral 

 to the anterior nasal aperture are the anterior surfaces of the maxillae, each 

 perforated, near the lower margin of the orbit, by the infraorbital foramen for the 



Nasal bone 



Lacrtmat sulcus 



Zygomalic bone 

 Maxilla 



Ant. ethmoidal cells 



Nasal septum 



Probe in 



infundibulum 

 Middle ethmoidal cells 



Superior nasal concha 



Post, ethmoidal cells 



Superior meatus 



Sphenoidal sinuses 



Infraorbital groove 



Inferior orbital 

 fissure 



Palatine bone 



Sphenoidal bone 

 Foramen rotundum 



Foramen ovale 

 Foramen spinosum 



Carotid canal 

 FIG. 191. Horizontal section of nasal and orbital cavities. 



passage of the infraorbital nerve and vessels. Below and medial to this foramen 

 is the canine eminence separating the incisive from the canine fossa. Beneath 

 these fossae are the alveolar processes of the maxillae containing the upper teeth, 

 which overlap the teeth of the mandible in front. The zygomatic bone on either 

 side forms the prominence of the cheek, the lower and lateral portion of the orbital 

 cavity, and the anterior part of the zygomatic arch. It articulates medially with 

 the maxilla, behind with the zygomatic process of the temporal, and above with 

 the great wing of the sphenoid and the zygomatic process of the frontal; it is per- 

 forated by the zygomaticofacial foramen for the passage of the zygomaticofacial 

 nerve. On the body of the mandible is a median ridge, indicating the position 

 of the symphysis; this ridge divides below to enclose the mental protuberance, the 

 lateral angles of which constitute the mental tubercles. Below the incisor teeth 





