FRONTAL BONE. 27 



tween the two internal angular processes, is a rough excavation which 

 receives the nasal bones, and a projecting process, the nasal spine. 

 Upon each orbital plate, immediately beneath the external angular 

 process, is a shallow depression which lodges the lachrymal gland ; 



Fig. 15.* 



and beneath the internal angular process a small pit, sometimes a 

 tubercle to which the cartilaginous pulley of the superior oblique 

 muscle is attached. 



Internal Surface. Along the middle line of this surface is a 

 grooved ridye, the edges of the ridge giving attachment to the falx 

 cerebri and the groove lodging the superior longitudinal sinus. At the 

 commencement of the ridge is an opening, sometimes completed by 

 the ethmoid bone, the foramen ccecum. This opening lodges a process 

 of the dura mater, and occasionally gives passage to a small vein which 

 communicates with the nasal veins. On each side of the vertical ridge 

 are some slight depressions which lodge the glandulae Pacchioni, and 

 on the orbital plates a number of irregular pits called digital fossae, 



* The external surface of the frontal bone. 1. The situation of the frontal 

 eminence of the right side. 2. The superciliary ridge. 3. The supra-orbital 

 ridge. 4. The external angular process. 5. The internal angular process. 

 6. The supra-orbital notch for the transmission of the supra-orbital nerve and 

 artery ; in the figure it is almost converted into a foramen by a small spiculum 

 of bone. 7. The nasal tuberosity; the swelling around this point denotes the 

 situation of the frontal sinuses. 8. The temporal ridge commencing from the 

 external angular process (4). The depression in which the figure 8 is situ- 

 ated is a part of the temporal fossa. 9. The nasal spine. 



