THE SKULL THE CKANIUM 239 



os tympanieum ; in French as la par tie ou caisse tympanique ; in 

 German as das Paukenbein or der Paukentheil. 



Determination. If the temporal be held with the external 

 auditory meatus uppermost and the thin border of the squamous away 

 from the student, the zygomatic process will point to the side, right or 

 left, to which the bone belongs. 



Articulation. The temporal articulates with the occipital, the 

 parietal, the basisphenoid, the alisphenoid, the malar, and the man- 

 dible. 



Muscular Attachments. The principal muscles attached to the 

 temporal are : the temporal, to the outer surface of the squamous ; the 

 inasseter, to the zygomatic process ; the sterno-mastoid, the splenius, 



I 



the trachelo-mastoid, the rectus capitis lateralis, the cleido-mastoid, 

 and the stylo-glossus, to the outer surface of the mastoid ; the stylo- 

 hyoid, to the posterior part of the bulla; the stapedius, the tensor 

 tympani, the levator palati, and the tensor palati, to the inferior 

 surface of the petrous. 



Ossification. The details of the development of the temporal 

 bone have not yet been satisfactorily investigated. We know, however, 

 that the various primary centres of ossification coalesce to form four 

 elements which for some time remain entirely distinct. These are the 

 squamous, the petro-mastoid, the ectotympanic, and the entotympanic. 

 The malleus and incus are developed from the upper part of the primi- 

 tive lower jaw, known as Meckel's cartilage. The stapes is developed 

 from the cartilage surrounding the fenestra ovalis. 



VARIATIONS IN THE TEMPORAL BONE. 

 VARIATIONS IN SIZE. 



The measurements were taken on left temporals only, as follows : 



The maximum length is the distance from the tip of the zygomatic 

 process to the posterior end of the squamo-mastoid upward prolonga- 

 tion projected on ruled paper, the posterior root of the zygoma being 

 horizontal. 



The maximum height is the distance from the lowest point of the 

 bulla to the highest projected point "of the squamous, at right angles 

 with the length measurement. 



The squamous height indicates the distance from the lower edge of 

 the postglenoid process to the highest projected point of the squamous. 



