THE TEMPORAL BONES. 65 



The Temporal Bones. 



The Temporal Bones (tempus, time) are situated at the sides and base of the 

 skull, and present for examination a squamous, mastoid, and petrous portion. 



The sctuamous portion (squama, a scale), the anterior and upper part of the 

 bone, is scale-like in form, and thin and translucent in texture (Fig. 31). 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 temporal 

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

 the Temporal muscle. The boundary between the squamous and mastoid portions 



Masloid 

 foramen. 



Glenoid fossa.- 



> DIGASTRIC 



STVLO-GLOSSUS. 



Styloid proc. 



Auditory pi'oc. 



STYLO-HYOID. 



FIG. 31. Left temporal bone. Outer surface. 



of the bone, as indicated by traces of the original suture, lies fully half an inch 

 below this ridge. Projecting from the lower part of the squamous portion is a 

 long, arched process of bone, the zygoma or zygomatic process. This process is 

 at first directed outward, its two surfaces looking upward and downward ; it then 

 appears as if twisted upon itself, and runs forward, its surfaces now looking 

 inward and outward. The superior border of the 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 attach- 

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

 with the malar bone. The zygomatic process is connected to the temporal bone 

 by three divisions, called its roots an anterior, middle, and posterior. The 

 anterior, which is short, but broad and strong, is directed inward, to terminate in 

 a rounded eminence, the eminentia artieularis. This eminence forms the front 

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

 The middle root is known as the post-glenoid process, and is very prominent in 

 young bones. It separates the mandibular portion of the glenoid fossa from the 

 external auditory meatus, and terminates at the commencement of a well-marked 

 fissure, the Glaserian fissure. The posterior root, which is strongly marked, 



