40 THE BONES OF THE HEAD. 



The inner surface is marked by cerebral impressions, and by memngeal grooves. 

 At its upper border the outer table is prolonged considerably beyond the inner, 

 forming a thin, scale with the fluted surface looking inwards and overlapping the 

 corresponding bevelled edge of the parietal bone. But in front, at its lower part, 

 the border is thicker, looks forwards and inwards, is bevelled slightly on the outer 

 side, and serrated for articulation with the great wing of the sphenoid. 



The outer surface is in its greatest extent vertical, with a slight convexity, and 



SOUAMOUS PORTION 



AT. SULCUS 



STYLOIO PROC. 



PETROUS PORTION 



Fig. 41. RIGHT TEMPORAL BONE: INNEK VIEW. (Drawn by D. Gunn.) 

 The bone is rotated slightly about a sagittal axis, the upper border being moved inwards. 



forms part of the temporal fossa. Above the aperture of the ear it is marked by a 

 small, nearly vertical furrow for the middle temporal artery. From the lowest 

 part of this surface a long process, the zygoma, takes origin. 



The zygoma, or zygomatic process, is connected with the lower and outer part of 

 the squamous portion, and is of considerable breadth at its base, which projects 

 outwards. It then turns forwards, becomes narrower, and is twisted on itself so as 

 to present outer and inner surfaces and upper and lower borders. The superior 

 margin is thinner, and prolonged farther forwards than the inferior. The extremity 

 is serrated, and articulates with the malar bone. At its base the zygoma presents 

 two roots : the anterior, continuous with the lower border, is a broad convex ridge, 

 directed inwards on the under aspect of the bone : the posterior, also called the 

 supramastoid crest, is prolonged from the upper border ; it passes backwards above 

 the external auditory meatus, marking the line of division between the squamous 

 and mastoid portions of the bone, and turning upwards posteriorly forms the 

 boundary of the temporal fossa. At the place where the two roots diverge is a 

 slight tubercle, which gives attachment to the external lateral ligament of the lower 

 jaw. Between the two roots is the glenoid fossa } a considerable hollow, elongated 



