DISSECTING MANUAL. 



between the sphenoid and occipital, below the parietals ; each 

 consists of three parts, squamous, tympanic, and petro-mas- 

 toid. The squamous part is thin, shell-like, and vertical. The 

 tympanic part lies below the squamous and forms the lower 

 part of the external auditory meatus. The petro-mastoid part 

 joins the inner aspect of the squamous and tympanic parts 

 and extends behind their junction as a nipple-like (mastoid) 

 process. Its petrous portion is an elongated and three-sided 

 pyramid, which is attached by its base to the inner aspect of the 

 squamous and tympanic parts postero-inferiorly, and extends 

 nearly horizontally inward and forward. [114] 



The sphenoid bone lies at the base in front of the occipital 

 mesially and the temporals at either side. It somewhat re- 

 sembles a bat and presents a cubical body with three pairs of 

 processes. The lesser (orbital) wings are small and flattened 

 triangular plates which extend horizontally outward from the 

 fore and upper part of the body. The greater (temporal) wings 

 are large and, as seen from above, crescentic plates which ex- 

 tend outward from the lower part of the body, between the 

 frontal and temporal bones. The pterygoid processes each 

 consist of two plates (external and internal pterygoid) ; these 

 descend vertically from the roots of the great wing and under 

 surface of the lateral part of the body on each side and are 

 fused in front, except inferiorly. [122] 



The ethmoid bone lies in front of the sphenoid, occupying 

 the ethmoidal notch of the frontal and projecting below this. 

 It is cubical and consists of two cellular (lateral masses) parts, 

 which are united superiorly to a mesial (vertical) plate by a 

 thin horizontal lamina (cribriform plate). [128] 



The two superior maxillary bones form the upper jaw; each 

 consists of a hollow pyramidal body with four surfaces and 

 four processes. The malar (zygomatic) process springs from 

 the outer surface high up; the frontal (nasal) process is a 

 plate ascending vertically from the upper and fore part; the 

 alveolar process is a curved projection from the under surface; 



[2] 



