Frontal Bone 1 1 



the lower parts of the sterno-mastoid, sterno-hyoid, and sterno-thyroid, 

 though, with the internal jugular vein and the pneumogastric nerve, 

 it is popularly believed to be contained in it. Then, by only a very 

 little more imagination, the inferior thyroid artery, the recurrent laryn- 

 geal nerve (p. 70), and the cord of the sympathetic are seen within the 

 space all of which are behind the carotid sheath. The trachea and 

 the thyroid gland are similarly given in the triangle. 



THE BONES OF THE HEAD 



The frontal bone. The vertical part is marked by the frontal 

 eminences, which correspond to the frontal lobes of the brain. Below 

 them are the superciliary ridges, which are continuous internally with 

 the root of the nose. They correspond with the frontal sinuses and 

 give origin at their inner end to the corrugator supercilii and the 

 orbicularis. In the case of fracture the external table may be driven 

 into the sinus without the inner table being damaged, and on the man 

 coughing, or blowing his nose, air may escape into the scalp and cause 

 extensive emphysema. 



The frontal sinuses are absent in childhood, and they are com- 

 paratively small in women. They communicate with the middle 

 meatus by the infundibulum. A chronic abscess of the sinus which 

 has opened externally must -be drained into the nose. 



Below the superciliary ridge comes the margin of the orbit, with 

 the supra-orbital notch or foramen to the inner side of the middle. 

 As the supra-orbital vein traverses this notch it receives a small diploic 

 vein. 



The supra-orbital arch ends at the strong external angular process, 

 which articulates with the malar, and the 

 temporal ridge ascends from it. This pro- 

 cess overhangs the fossa for the lachrymal 

 gland. The internal angular process 

 articulates with the nasal process of the 

 superior maxilla and the lachrymal ; a 

 hernial protrusion of the dura mater a 

 meningocele sometimes occurs at that 

 spot. Close behind the internal angular 

 process is the fossa for the pulley of the 

 superior oblique. 



On the cerebral aspect, where the 

 lateral halves join, is a ridge for the attach- 

 ment of the falx cerebri, and the groove W 



for the Superior longitudinal sinus. Anterior Meningocele (BRYANT). 



The horizontal part of the frontal con- 

 sists of the thin plates for the roof of the orbit, the notch between them 



