8 HUMAN ANATOMY. 



THE FRONTAL BONE forms the anterior portion of the 

 cranium and consists of two portions, a vertical or frontal por- 

 tion and a horizontal or orbito-nasal portion. 



The vertical portion consists of two surfaces,, external and 

 internal. 



The external surface is convex, and presents the frontal emi- 

 nence on either side of the median line, the superciliary ridges, 

 produced by the frontal sinuses, beneath, below which is the 

 supra-orbital arch, forming the upper boundary of the orbit, and 

 terminating on either side in the external angular process, articu- 



FIG. 2. 



2, foramen caecum; 4, articulates with lesser wing; 6, articulates 

 with ethmoid; 7, anterior and posterior ethmoidal foramina; 9, 

 lachrymal fossa; 10, depression for pulley of superior oblique; 11, 

 frontal sinus. 



lating with the malar bone, and the internal angular process, ar- 

 ticulating .with the lachrymal bone, and having at its inner third 

 a notch or foramen, the supra-orbital foramen, for passage of 

 supra-orbital artery, nerve, and vein. 



Ascending from the external angular process is the tem- 

 poral ridge for attachment of temporal fascia. Between the 

 internal angular processes is the nasal notch, for articulation 

 with the nasal bone, and nasal process of superior maxilla, 

 terminating below in the nasal spine, and above it projects the 

 nasal eminence, or glabella, marking the location of the frontal 

 sinuses. 



The posterior or internal surface is concave and lodges the 

 anterior lobes of the brain. 



