SPHENOID BONE 107 



mandible and internal to the root ; the styloid process, a slender 

 process of bone, projects vertically downwards. The mastoid 

 process is a stout conical-shaped process behind the opening of 

 the ear, its apex pointing forwards and downwards. 



The temporal bone articulates by means of the upper border 

 of the squamous part with the sphenoid (great wing), parietal^ 

 and occipital bones, and by the zygomatic process with the 

 malar bone. 



The Sphenoid bone consists of a small body with several 

 paired processes, the important ones being the great wings and 

 the pterygoid plates. The latter, four in number, project 

 downwards behind the nose. The great wings have at their 

 extremities triangular surfaces, which articulate with the 

 frontal, parietal, and temporal bones ; these lock the sides of the 

 cranium anteriorly. The body lies between* the ethmoid (which 

 articulates with the nasal parts of the frontal bone) and the 

 basilar process of the occipital bone, so locks the cranium in 

 the antero-posterior direction. The great wings also form part 

 of the orbital cavity, and between the great wing and the lesser 

 wing is the sphenoidal fissure at the back of the orbital 

 cavity through which the first part of the fifth nerve passes. 

 The foramen rotundum and foramen ovale are in the great 

 wing. 



Bones of the Face. 



The MaxillSB unite to form the upper jaw; the body is pyram- 

 idal in form, and hollow, and has on it the infra-orbital foramen, 

 through which part of the fifth nerve emerges. On the anterior 

 border is a deep notch the nasal notch ; above the nasal notch 

 the edge of the bone is rough to articulate with the nasal and 

 frontal bones, below which it unites with its fellow of the 

 opposite side. The inferior or alveolar border is ridged ex- 

 ternally, and from it project the upper row of teeth; on the 

 inner surface the palatal process, a flat plate of bone, projects 

 horizontally inwards to form the roof of the mouth. The 

 upper border is smooth and rounded, and forms the inner 

 half of the lower border of the orbjtal margin, and ends in 

 a rough process for articulation with the malar bone ; the pos- 



