62 



THE SKELETON. 



the upper boundary of the orbit and separates the vertical from the horizontal 

 portion of the bone. The outer part of the arch is sharp and prominent, afford- 

 ing to the eye, in that situation, considerable protection from injury; the inner 

 part is less prominent. At the junction of the internal and middle third of this 

 arch is a notch, sometimes converted into foramen, and called the supraorbital 

 notch or foramen. It transmits the supraorbital artery, vein, and nerve. A small 

 aperture is seen in the upper part of the notch, which transmits a vein from the 

 diploe to join the supraorbital vein. The supraorbital arch terminates externally 

 in the external angular process and internally in the internal angular 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, 

 commencing together from the external angular process, soon diverge from eacti 

 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 



-^Internal External 



angular process. angu i ar process. 



Nasal | spine. 

 FIG. 28. Frontal bone. Outer surface. 



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 processes are less marked than the external, and articulate with 

 the lachrymal bones. Between the internal angular processes is a rough, uneven 

 interval, the nasal notch, which articulates in the middle line with the nasal bone, 

 and on either side with the nasal process of the superior maxillary bone. From 

 the concavity of this notch projects a process, the nasal process, which extends 

 beneath the nasal bones and nasal processes of the superior maxillary bones and 

 supports the bridge of the nose. On the under surface of this is a long pointed 

 process, the nasal spine, and on either side a small grooved surface enters into 

 the formation of the roof of the nasal fossa. The nasal spine forms part of the 

 septum of the nose, articulating in front with the nasal bones and behind with 

 the perpendicular plate of the ethmoid. 



