112 THE SKELETON. 



illary nerve and their branches. At its upper and inner part may be observed two 

 fissures, the spheno-maxillary and pterygo-maxillary. 



The Spheno-maxillary Fissure, 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 great wing of the sphenoid ; below, by the external border of the orbital 

 surface of the superior 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 

 pterygo-maxillary fissure. This fissure opens a communication from the orbit into 

 three fossae the temporal, zygomatic, and spheno-maxillary ; it transmits the 

 superior maxillary nerve and its orbital branch, the infraorbital vessels, and 

 ascending branches from the spheno-palatine or Meckel's ganglion. 



The Pterygo-maxillary Fissure is vertical, and descends at right angles from 

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

 the divergence of the superior maxillary bone from the pterygoid process of the 

 sphenoid. It serves to connect the spheno-maxillary fossa with the zygomatic fossa, 

 and transmits branches of the internal maxillary artery. 



The Spheno-maxillary Fossa. 



The Spheno-maxillary Fossa is a small, triangular space situated at the angle of 

 junction of the spheno-maxillary and pterygo-maxillary 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 superior 

 maxillary bone ; behind, by the anterior surface of the base of the pterygoid 

 process and lower part of the anterior surface of the great wing of the sphenoid ; 

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

 terminating in it the sphenoidal, spheno-maxillary, and pterygo-maxillary ; it 

 communicates with the orbit by the spheno-maxillary fissure ; with the nasal fossae 

 by the spheno-palatine foramen, and with the zygomatic fossa by the pterygo-max- 

 illary fissure. It also communicates Avith the cavity of the cranium, and has open- 

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

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

 more inferiorly and internally, the ptery go-palatine canal. On the inner Avail is 

 the spheno-palatine foramen, by which the spheno-maxillary communicates Avith 

 the nasal fossa ; and beloAV 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 Region of the Skull. 



The Anterior Region of the Skull, which 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 eye 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 anterior margin of the ramus of the jaw. In the median line are 

 seen from above downward the glabella, and diverging from it are the superciliary 

 ridges, Avhich indicate the situation of the frontal sinuses and support the eyebrows. 

 Beneath the glabella is the fronto-nasal suture, the mid-point of Avhich is termed 

 the nasion, and beloAV this is the arch of the nose, formed by the nasal bones, and 

 the nasal processes of the superior maxillary. The nasal arch is convex from side 

 to side, concave from above downward, presenting in the median line the inter- 

 nasal suture formed between the nasal bones, laterally the naso-rnaxillary suture 

 formed between the nasal bone and the nasal process of the superior maxillary 

 bone. BeloAV the nose is seen the opening of the anterior nares, which is heart- 

 shaped, with the narrow end upward, and presents laterally the thin, sharp 



1 Occasionally the superior maxillary bone and the sphenoid articulate with each other at the 

 anterior extremity of this fissure; the malar is then excluded from entering into its formation. 



