ANATOMY IN A NUTSHELL. 507 



and at this point a small vein from the diplce passes into tin' supraorbital vein. 



7. The external angular process is the end of the supraorbital arch 

 and is well marked. It articulates with the malar bone. 



8. The internal angular process is the other end of the supraorbital 

 arch and is not so well marked as the external angular process. It articulates 

 with the lachrymal hone 



9. The temporal ridges run upward and backward from the external 

 angular process. The lower ridge gives attachment to the Temporal muscle, 

 and the upper one gives attachment to the temporal fascia. 



10. The anterior part of the temporal fossa is below these ridges and 

 gives origin to part of the Temporal muscle. 



11. The nasal notch is between the internal angular processes and artic- 

 ulates with the two nasal bones mesially and with the nasal process and the 

 superior maxillary bone ext< rnally. | [ P 



12. The nas\l process passes from this notch under the nasal bones and 

 the nasal processes of the superior maxillary bones. 



13. The nasal spine arises from the under surface of the nasal process 

 and joins the nasal bones in front and the perpendicular plate of the ethmoid 

 behind to form part of the septum. 



The internal surface of the vertical portion has the following points for 

 consideration : 



1. A vertical groove which passes along the middle line for the superior 

 longitudinal sinus, and the edges of this groove give attachment to the falx 

 cerebri. 



2. The frontal crest is formed by the edges of this groove muting an- 

 teriorly. 



3. The foramen cecum is formed by a notch in the lower end of the 

 frontal crest by its articulation with the ethmoid. This foramen lodges a pro- 

 cess of the falx cerebri, and when open a vein from the nose passes through it 

 to the superior longitudinal sinus. 



4. Eminences and depressions are found on this surface of the frontal 

 bone external to the median line for the cerebral convolutions. 



5. Furrows which are for branches of the anterior meningeal arteries. 



6. Depressions for the Pacchionian bodies are near the vertical groove. 

 The frontal sinuses are two spaces at the anterior inferior part of the bone 



between its layers. They are lined with mucous membrane and open into the 

 middle meatus of the nose by the ini'undibula. 



The inferior surface of the horizontal portion has the following point- for 

 consideration: 



1. The ETHMOID NOTCH separates two thin plates which forms the vaull 

 of each orbit. This notch is filled by the cribriform plate of the ethmoid, and 

 edges of this notch present half cells which with half cells of the ethmoid make 

 the ethmoidal cells. 



2. The lachrymal fossa, which is for the lachrymal gland, is near the 

 external angular process. 



3. A depression or tubercle for the fibrous pulley "\ the Superior oblique 

 muscle is at the nasal margin of this surface. 



