50 TOPOGRAPHIC AND APPLIED ANATOMY. 



turbinate bone. This divides the upper portion of the antral opening into two parts, of which 

 the posterior half is usually closed in by mucous membrane, while the anterior part presents the 

 normal opening leading into the superior maxillary sinus. These openings lead from the antrum 

 into the middle meatus. ED.] 



The skin of the nose, though movable upon the underlying bones, is so firmly adherent to the 

 nasal cartilages that cutaneous defects cannot be closed by approximating the edges of the wound, 

 and the scars following such defects do not undergo very marked contraction. In the vicinity of 

 the alae the skin is particularly rich in sebaceous glands, which through the retention of their 

 secretion and the occasional appearance of the demodex folliculorum may lead to the formation 

 of "black-heads" (comedones). At the nostril the skin with its hairs (vibrissae) and sebaceous 

 glands is continued into the nasal cavity, the glands and hair gradually disappearing, but the 

 epidermic character being maintained as far as the region of the anterior nares. This portion of 

 the nasal cavity is known as the vestibulum nasi. 



The olfactory region is the only portion of the nasal mucous membrane containing olfactory 

 cells; it covers the superior turbinated bone, occasionally a small region of the middle turbinated 

 bone, and the opposite portion of the septum. The mucous membrane of the respiratory region 

 is devoid of a submucous layer and adheres directly to the periosteum. It is predisposed to 

 swellings on account of the cavernous tissue, which is especially developed upon the free borders 

 of the inferior and middle turbinated bones. The mucous membrane also lines the accessory 

 cavities, becoming much thinner and losing almost all of its glands as it passes in through their 

 orifices. 



There are no large arteries of surgical importance within the nasal cavity. Marked hem- 

 orrhages, usually of capillary or venous origin, are consequently controlled by plugging. The 

 largest artery is the spheno palatine, a branch of the internal maxillary, which passes from the 

 spheno-maxillary fossa through the spheno-palatine foramen to the outer and inner walls of the 

 nasal chamber. The other arteries are the small anterior and posterior ethmoidal (from the 

 ophthalmic) and the anastomoses of the facial and of the palatine arteries in the region of the alae 

 of the nose. 



The veins of the nasal cavity are particularly well developed ; they form superficial and deep 

 plexuses as well as the cavernous tissue upon the turbinated bones. The ethmoidal veins (accom- 

 panying the arteries of the same name) empty into the superior longitudinal sinus. The veins 

 of the nose are also connected with the veins of the cranial cavity through the cribriform plate of 

 the ethmoid; the foramen caecum transmits an emissary vein in the child but not in the adult. 

 The connection of the veins of the nasal cavity with those of the brain explains the relief afforded 

 in a severe headache after bleeding from the nose. 



The nerves of the nasal cavity, disregarding those of special sense, the olfactory filaments 

 (see page 21), are the sensory nerves supplying the mucous membrane and proceeding from the 

 first and second divisions of the trifacial. The nasal nerve is given off from the ophthalmic or 

 first division of the trifacial, passes through the anterior ethmoidal foramen, pursues a short 

 subdural course in the cranial cavity, and runs through the cribriform plate of the ethmoid toward 

 the vestibulum nasi ; it gives off an external branch which reaches the skin of the nose below the 

 lower border of the nasal bone. The main nervous filaments come from the spheno-palatine 



