78 



SPECIAL ANATOMY OF THE SKELETON 



process. The external angular process is strong, prominent, and articulates 

 with the malar bone; running upward and backward from it are two well-marked 

 lines, which, starting together from the external angular process as the temporal 

 crest, soon diverge from each other and run in a curved direction across the bone. 

 These are the upper and lower temporal ridges ; the upper gives attachment to the 

 temporal fascia, the lower to the Temporal muscle. Beneath them is a slight 

 concavity that forms the anterior part of the temporal fossa and gives origin to 

 the Temporal muscle. The internal angular process is less marked than the 

 external, and articulates with the lacrimal bones. 



With maxilla'. 



With nasal'. 

 With perpendicular plate of ethmoid. 



Fin. 45. Frontal bone. Inner surface. 



Frontal sinus. 



Under surface of nasal process, 

 forming part of roof of nose. 



Internal Surface (cerebral surface, fades cerebralis) (Fig. 45). Along the median 

 line is a vertical groove, the sulcus sagittalis, the edges of which unite below to 

 form a ridge, the frontal crest (crista frontalis}] the groove lodges the superior 

 sagittal sinus, while its margins afford attachment to the falx cerebri. The 

 crest terminates below at a small notch which is converted into a foramen by 

 articulation with the ethmoid. It is called the foramen cecum, and varies in 

 size in different subjects; it is sometimes partially or completely impervious, 

 lodges a process of the falx, and when open transmits a vein from the mucous 

 membrane of the nose to the superior sagittal sinus. On either side of the groove 

 the bone is deeply concave, presenting depressions for the convolutions of the 

 brain, and numerous small furrows for the ramifications of the anterior branches 

 of the middle meningeal arteries. Several small, irregular fossa? are seen also on 

 either side of the groove, for the reception of the arachnoid villi. 



The border of the vertical portion is thick, deeply serrated, bevelled at the 



