66 



THE SKELETON. 



runs from the upper border of the zygoma backward over the external auditory 

 rneatus. It is termed the supra-mastoid crest, and forms the posterior part of the 

 lower temporal ridge. At the junction of the anterior root with the zygoma is 

 a projection, called the tubercle, for the attachment of the external lateral liga- 

 ment of the lower jaw ; and between the anterior and middle roots is an oval depres- 

 sion, forming part of the glenoid fossa (yAjywy, a socket), for the reception of the 

 condyle of the lower jaw. This fossa is bounded, in front, by the eminentia 

 articularis ; behind, by the tympanic plate, which separates it from the external 

 auditory meatus ; it is divided into two parts by a narrow slit, the G-laserian 

 fissure. The anterior or mandibular part, formed by the squamous portion of 

 the bone, is smooth, covered in the recent state with cartilage, and articulates 

 with the condyle of the lower jaw. This part of the glenoid fossa presents 

 posteriorly a small conical eminence, the post-glenoid process, already referred to. 

 This process is the representative of a prominent tubercle which, in some of the 

 mammalia, descends behind the condyle of the jaw, and prevents it being 

 displaced backward during mastication (Humphry). The posterior part of the 

 glenoid fossa, which lodges a portion of the parotid gland, is formed chiefly by 

 the tympanic plate, which constitutes the anterior wall of the tympanum and 

 external auditory meatus. The plate of bone terminates above in the Glaserian 

 fissure, and below forms a sharp edge, the vayinal process, which gives origin to 

 some of the fibres of the Tensor palati muscle. The Glaserian fissure, which 

 leads into the tympanum, lodges the processus gracilis of the malleus, and 

 transmits the tympanic branch of the internal maxillary artery. The chorda 

 tympani nerve passes through a separate canal, parallel to the Glaserian fissure 

 (canal of Huguier), on the outer side of the Eustachian tube, in the retiring 

 angle between the squamous and petrous portions of the temporal bone. 1 



Aquseductiis restibnli. 



Depression for dura mater. 



Meatus auditorius intern us. 



Great 



Eminence for superior semicircular canal. 



Hiatus Fallopii. 



Opening for smaller petrosal nerre. 

 __ Depression for Gasserian Ganglion. 

 Bristle passed through carotid canal. 



FIG. 32. Left temporal bone. Inner surface. 



The internal surface of the squamous portion (Fig. 32) is concave, presents 



1 This small fissure must not be confounded with the large canal which lies above the Eustachian 

 tube and transmits the Tensor tympani muscle. 



