36 



TEMPORAL BONE. 



rior border is thin, irregular, 



Fig- 13.* and squamous, and articulates 



with the sphenoid bone. 



Developernent. By two cen- 

 tres, one for each lateral half. 

 Articulations. With twelve 

 bones ; the two parietal, the 

 sphenoid, ethmoid, two nasal, 

 two superior maxillary, two 

 lachrymal, and two malar. 



Attachment of Muscles. To 

 four pairs ; occipito-frontalis, 

 orbicularis palpebrarum, cor- 

 rugator supercilii, and tem- 

 poral. 



TEMPORAL BONE. The tem- 

 poral bone is situated at the side 

 and base of the skull, and is di- 

 visible into a squamous, mastoid, and petrous portion. 



The Squamous portion, forming the anterior part of the bone, is 

 thin, translucent, and contains no diploe. Upon its external surface 



it is smooth, to give attachment 

 Fig. 14.t to the fleshy fibres of the tem- 



poral muscle, and has projecting 

 from it an arched and lengthened 

 process, the zygoma. Near the 

 commencement of the zygoma 

 upon its lower border, is a pro- 

 jection called the tubercle, to 

 which is attached the external 

 lateral ligament of the lower 

 jaw, and continued horizontally 

 inwards from the tubercle a 

 rounded eminence, the eminentia 

 articularis. The process of bone 

 which is continued from the tu- 

 bercle of the zygoma into the 



* The internal surface of the frontal bone ; the bone is raised in such a manner as to 

 show the orbito-nasal portion. 1. The grooved ridge for the lodgment of the superior 

 longitudinal sinus and attachment of the falx. 2. The foramen caecum. 3. The su- 

 perior or coronal border of the bone ; the figure is situated near that part which is 

 bevelled at the expense of the internal table. 4. The inferior border of the bone. 5. 

 The orbital plate of the left side. 6. The cellular border of the ethrnoidal fissure. The 

 foramen cascum (2) is seen through the cthmoidal fissure. 7. The anterior and pos- 

 terior ethmoidal foramina ; the anterior seen leading into its canal. 8. The nasal spine. 

 9. The depression within the external angular process (12) for the lachrymal gland. 10. 

 The depression for the pulley of the superior oblique muscle of the eye ; immediately 

 to the left of this number is the supra-orbital notch, and to its right the internal angular 

 process. 11. The opening leading into the frontal sinuses. The same parts are seen 

 upon the opposite side of the figure. 12. The external angular process. 



t The external surface of the temporal bone of the left side. 1. The squamous por- 



