134 SPECIAL ANATOMY OF THE SKELETON 



nerve and their branches. In its roof are seen the foramen ovale and the foramen 

 spinosum; on its anterior wall open the posterior dental canals. At its upper and 

 inner part may be observed the sphenomaxillary and pterygo maxillary fissures. 



The sphenomaxillary fissure (fissura orbitalis inferior), horizontal in direction, 

 opens into the outer and back part of the orbit. It is formed above by the lower 

 border of the orbital surface of the greater wing of the sphenoid; below, by the 

 external border of the orbital surface of the maxilla and a small part of the palate 

 bone; externally, by a small part of the malar bone; 1 internally, it joins at right 

 angles with the pterygomaxillary fissure. This fissure permits the orbit to com- 

 municate with three fossae the temporal, zygomatic, and sphenomaxillary fossae; 

 it transmits the superior maxillary nerve and its orbital branch, the infraorbital 

 vessels, and ascending branches from the sphenopalatine or Meckel's ganglion. 



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

 inner extremity of the preceding; it is a V-shaped interval formed by the diver- 

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

 to 'connect the sphenomaxillary fossa with the zygomatic fossa, and transmits 

 the internal maxillary artery. 



The Sphenomaxillary Fossa (fossa pteryyopalatind). The sphenomaxillary fossa 

 is a small, triangular space situated at the angle of junction of the sphenomaxillary 

 and pterygomaxillary fissures, and placed beneath the apex of the orbit. It is formed 

 above by the under surface of the body of the sphenoid and by the orbital process of 

 the palate bone; in front, by the maxilla; behind, by the anterior surface of the base 

 of the pterygoid process and lower part of the anterior surface of the greater wing of 

 the sphenoid; internally, by the vertical plate of the palate. This fossa has three 

 fissures terminating in it the sphenoidal, sphenomaxillary, and pterygomaxillary; 

 it communicates with the orbit by the sphenomaxillary fissure; with the nasal 

 fossa? by the sphenopalatine foramen, and with the zygomatic fossa by the pterygo- 

 maxillary fissure. It also communicates with the cavity of the cranium, and has 

 opening into it five foramina. Of these, there are three on the posterior wall- 

 the foramen rotundum above; below and internal to this, the Vidian canal; and 

 still more inferiorly and internally, the pterygopalatine canal. On the inner wall 

 is the sphenopalatine foramen, by which the sphenomaxillary communicates with 

 the nasal fossa; and below is the superior orifice of the posterior palatine canal, 

 besides occasionally the orifices of the accessory posterior palatine canals. The 

 fossa contains the superior maxillary nerve and Meckel's ganglion, and the termi- 

 nation of the internal maxillary artery. 



The Anterior Eegion of the Skull (norma frontalis}. The norma frontalis 

 forms the face, is of an oval form, presents an irregular surface, and is excavated 

 for the reception of two of the organs of sense, the eyes and the nose. It is bounded 

 above by the glabella and margins of the orbit; below, by the prominence of the 

 chin; on each side by the malar bone and interior margin of the ramus of the man- 

 dible. In the median line are seen from above downward the glabella, and diverg- 

 ing from it are the superciliary ridges, which indicate the situation of the frontal 

 sinuses and support the eyebrow. Beneath the glabella is the frontonasal suture, 

 the mid-point of which is termed the nasion, and below this is the arch of the nose, 

 formed by the nasal bones, and the nasal processes of the maxillae. The nasal 

 arch is convex from side to side, concave from above downward, presenting in the 

 median line the internasal suture (sutura internasalis), formed between the nasal 

 bones, laterally, on either side, the nasomaxillary suture (sutura nasomaxillaris), 

 formed between the nasal bone and the nasal process of the maxilla. Below the 

 nose is seen the opening of the apertura pyriformis, which is heart-shaped, with 

 the narrow end upward, and presents laterally the thin, sharp margins serving 



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

 the malar is then excluded from entering into its formation. 



