THE EXTERIOR OF THE SKULL 185 



sphenoid; below, by the lateral border of the orbital surface of the maxilla and the 

 orbital process of the palatine bone; laterally, by a small part of the zygomatic 

 bone : l medially, it joins at right angles with the pterygomaxillary fissure. Through 

 the inferior orbital fissure the orbit communicates with the temporal, infratem- 

 poral, and pterygopalatine fossae; the fissure transmits the maxillary nerve and 

 its zygomatic branch, the infraorbital vessels, the ascending branches from the 

 sphenopalatine ganglion, and a vein which connects the inferior ophthalmic vein 

 with the pterygoid venous plexus. 



The pterygomaxillary fissure is vertical, and descends at right angles from the 

 medial end of the preceding; it is a triangular interval, formed by the diver- 

 gence of the maxilla from the pterygoid process of the sphenoid. It connects 

 the infratemporal with the pterygopalatine fossa, and transmits the terminal part 

 of the internal maxillary artery. 



The Pterygopalatine Fossa (fossa pterygopalatina; sphenomaxillary fossa). The 

 pterygopalatine fossa is a small, triangular space at the angle of junction of the 

 inferior orbital and pterygomaxillary fissures, and placed beneath the apex of 

 the orbit. It is bounded above by the under surface of the body of the sphenoid 

 and by the orbital process of the palatine bone; in front, by the infratemporal 

 surface of the maxilla; behind, by the base of the pterygoid process and lower part 

 of the anterior surface of the great wing of the sphenoid ; medially, by the vertical 

 part of the palatine bone with its orbital and sphenoidal processes. This fossa 

 communicates with the orbit by the inferior orbital fissure, with the nasal cavity 

 by the sphenopalatine foramen, and with the infratemporal fossa by the pterygo- 

 maxillary fissure. Five foramina open into it. Of these, three are on the posterior 

 vail, viz., the foramen rotundum, the pterygoid canal, and the pharyngeal canal, 

 in this order downward and medialward. On the medial wall is the sphenopalatine 

 foramen, and below is the superior orifice of the pterygopalatine canal. The fossa 

 contains the maxillary nerve, the sphenopalatine ganglion, and the terminal part 

 of the internal maxillary artery. 



Norma Occipitalis. When viewed from behind the cranium presents a more 

 or less circular outline. In the middle line is the posterior part of the sagittal 

 suture connecting the parietal bones; extending downward and lateralward from 

 the hinder end of the sagittal suture is the deeply serrated lambdoidal suture join- 

 i ig the parietals to the occipital and continuous below with the parietomastoid and 

 occipitomastoid sutures; it frequently contains one or more sutural bones. Near 

 the middle of the occipital squama is the external occipital protuberance or inion, 

 and extending lateralward from it on either side is the superior nuchal line, and 

 above this the faintly marked highest nuchal line. The part of the squama above 

 the inion and highest lines is named the planum occipitale, and is covered by the 

 Occipitalis muscle; the part below is termed the planum nuchale, and is divided 

 by the median nuchal line which runs downward and forward from the inion to the 

 foramen magnum; this ridge gives attachment to the ligamentum nuchse. The 

 riuscles attached to the planum nuchale are enumerated on p. 130. Below and in 

 front are the mastoid processes, convex laterally and grooved medially by the 

 mastoid notches. In or near the occipitomastoid suture is the mastoid foramen for 

 the passage of the mastoid emissary vein. 



Norma Frontalis (Fig. 190). When viewed from the front the skull exhibits a 

 somewhat oval outline, limited above by the frontal bone, below by the body of the 

 mandible, and laterally by the zygomatic bones and the mandibular rami. The 

 upper part, formed by the frontal squama, is smooth and convex. The lower part, 

 made up of the bones of the face, is irregular; it is excavated laterally by the orbital 



K'avities, and presents in the middle line the anterior nasal aperture leading to the 

 1 Occasionally the maxilla and the sphenoid articulate with each other at the anterior extremity of this fissure; the 

 zygomatic is then excluded from it. 





