102 



THE SKELETON 



the temporal, the great wing of the sphenoid perforated by the foramen ovale and foramen 

 spinosum; helow by the alveolar border of the maxilla; laterally by the ramus of the mandible 

 and the zygoma formed by zygomatic and temporal; medially by the lateral pterygoid plate, a 

 line from which to the spine of the sphenoid separates the infratemporal fossa from the base of 

 the skull. It contains the lower part of the temporal muscle and the coronoid process of the 

 mandible, the external and internal pterygoids, the internal maxiUary vessels, and the mandibular 

 division of the fifth nerve with numerou;3 branches. At its upper and medial part are seen the 

 inferior orbital and pterygo-palatine fissures. 



The inferior orbital (or spheno-maxillary) fissure is horizontal in position, and lies between 

 the maxilla and the great wing of the sphenoid; laterally it is usually completed by the zygo- 

 matic, though in some cases the sphenoid joins the maxilla, and in this way excludes the zygo- 

 matic bone from the fissure; medially it is terminated by the infratemporal surface of the orbital 

 process of the palate bone. Through this fissure the orbit communicates with the pterygo- 

 palatine (spheno-maxillary), infratemporal, and temporal fossae. It transmits the infra- 

 orbital nerve and vessels, the zygomatic nerve, ascending branches from the spheno-palatine 

 ganglion to the orbit, and a communicating vein from the ophthalmic to the pterygoid plexus. 



Fig. 127. — The Skull. (Norma lateralis.) 



Lambda 



Inion 



The pterygo-palatine f[)tGrygo-maxillary) fissure forms a right angle with the inferior 

 orbital fissure and is situated between the maxilla and the anterior border of the pterygoid 

 process of the sphenoid. At its lower angle, where the two lips of the fissure approximate, the 

 lateral pterygoid plate occasionally articulates with the maxilla, but they are usually separated 

 by 'a thin portion of the pyramidal process of the palate. The pterygo-palatine fissm-e, which 

 .servos to coriner-t the infratemporal fo.ssa with the ptorygo-palaiine fo.ssa, is bounded medially 

 by the i)erpon(licul;i,r f)art of the palate; it transmits bram^hos of the internal maxillary artery, 

 and the c()rros|)Oii(iiiig veins, to and from the pt(;rygo-palatine fossa. 



(c) The pterygo-palatine (spheno-maxillary) fossa is a small space, of the form of 

 an inverted pyrainid, situated at the angle of junction of the inferior orbital (spheno-maxil- 

 lary) with the pterygo-palatine (pt(>rygo-maxillary) fissure, below the apex of the orbit. It is 

 boundofl infrniil. by the infratemporal surface of the maxilla; l>rhi)i.d, by the base of the pterygoid 



CrocesH and the lowtsr part of the anterior surface of the great wing of the sphenoid; medially 

 y the perpendicular part of the palate with its orbital and sph(Mioi(lal processes; above by the 

 lower surface of the body of tlie sphenoid. Three fissures terminate in it — viz., the superior 

 orbital, pterygo-palatine, and inferior orbital; through the sii[)erior orbital fissure it communi- 

 cates with the cranium, through the |)t(!rygo-palatine fissure with the infratemporal fossa, 

 through the inferior orbital fissure with the orbit, and through the spheno-palatine foramen 

 on the medial wall it communicates with the upper and back part of the nasal fossa. In- 



