TEMPORAL BONE. 



6T 



THE TEMPORAL BONES. 



The Temporal Bones are so called because they occupy that part of the head 

 on which the hair first begins to turn gray, thus indicating the age. They are 

 situated at the side and base of the skull, and present for examination a squamous, 

 mastoid, and petrous portion. 



The Squamous Portion (squama, a scale), the most anterior and superior part of 

 the bone (fig. 30), is scale-like in form, thin and translucent in texture. Its outer 

 surface is smooth, convex, and grooved at its back part for the deep temporal 

 arteries ; it affords attachment to the Temporal muscle, and forms part of the 

 temporal fossa. At its back part may be seen a curved ridge, part of the tem- 

 poral ridge ; it serves for the attachment of the temporal fascia, limits the origin 

 of the Temporal muscle, and marks the boundary between the squamous and 

 mastoid portions of the bone. Projecting from the lower part of the squamous 



Fig. 30. Left Temporal Bone. Outer Surface. 



portion is a long arched outgrowth of bone, the zygomatic process. It is at first 

 directed outwards, its two surfaces looking upwards and downwards ; it then appears 

 as if twisted upon itself, and takes a direction forwards, its surfaces now looking 

 inwards and outwards. The superior border of this process is long, thin, and 

 sharp, and serves for the attachment of the temporal fascia. The inferior, short, 

 thick, and arched, has attached to it some fibres of the Masseter muscle. Its outer 

 surface is convex and subcutaneous ; its inner is concave, and also affords attachment 

 to the Masseter. The extremity, broad, and deeply serrated, articulates with the 

 malar bone. This process is connected to the temporal bone by three divisions, 

 called the roots of the zygomatic process, an anterior, middle, and posterior. The 

 anterior, which is short, but broad and strong, runs transversely inwards into a 

 rounded eminence, the eminentia articularis. This eminence forms the front 

 boundary of the glenoid fossa, and in the recent state is covered with cartilage. 

 The middle root forms the outer margin of the glenoid cavity ; running obliquely 



