THE NASAL CAVITY 



1203 



mobile nasal septum. The postero-superior margin is attached to the perpen- 

 dicular plate of the ethmoid, and the postero-inferior margin joins the vomer and 

 the ventral part of the nasal crest of the maxilla, the cartilage broadening out to 

 obtain a wide though lax attachment to the nasal spine. 



The shape of the septal cartilage varies with the extent of the ossification of the bony 

 septum. Even in the adult a strip of cartilage may extend for a va^^^ng distance postero- 

 superiorly between the vomer and perpendicular plate of the ethmoid, sometimes reaching the 

 body of the sphenoid; it is known as the sphenoidal process of the septal cartilage [proc- 

 essus sphenoidalis septi cartilaginei]. The vomero -nasal cartilage [cartilago vomero-nasaUs 

 Jacobsoni*] is a narrow strip of cartilage firmly attached to each side of the septal cartilage, 

 where this joins the anterior portion of the vomer. 



Muscles. — The muscles are grouped according to function as dilators and 

 contractors, the latter being comparatively feeble in their action. They are 

 described on p. 334. 



The skin covering the external nose is thin and freely movable upon the sub- 

 jacent parts, except at the tip and over the cartilages, where it is much thicker, 



Fig. 965. — Oblique Section passing through the Nasal Cavity just in Front of the 



Choax^. (Seen from behind.) 



Front wall of left 



sphenoidal sinus- 



with orifice below 



Orifice of right 



sphenoidal sinus 



) ,-y:. 



Superior nasal concha—. 





-Crista galli 



A closed anterior 

 ethmoidal cell 



-V^r-:/ Posterior ethmoidal 

 cells 



Pharyngeal ostium of 

 tuba auditiva 



Upper surface of, 

 soft palate 



Pharyngeal ostium 

 of tuba auditiva 



more adherent, and furnished with numerous exceptionally large sebaceous glands. 

 At the nares it is reflected into the nasal cavity, where it passes into the mucous 

 membrane. The hairs on the skin of the nose are very fine, except in the nares, 

 where they may be strongly developed. 



Vessels and nerves. — The arteries of the external nose are derived from the external maxil- 

 lary (facial) artery (pp. 540 and 541), the ophthalmic artery (p. 554), and the infra-orbital 

 artery (p. 549). The veins terminate in the anterior facial vein and the ophthalmic vein (p. 

 644). The lymphatics pass to the submaxillary lymphatic nodes (p. 712). The motor nerves 

 are branches of the facial (p. 946). The sensory nerves are derived from the trigeminal through 

 the frontal and naso-cihary branches of the ophthalmic (p. 936) and infra-orbital branch of the 

 maxillary (p. 939). 



The nasal cavity [cavum nasi] is the ample space situated between the floor of 

 the cranium and the roof of the mouth extending forward into the external nose 

 and backward to the nasal part of the pharyiLX. With the exception of the 

 inferior part of the nose its walls are of bone as already described (pp. 110, 112). 

 The cartilages and membranes of the nose complete the boundaries anteriorly. 

 Here the cavitj^ opens to the exterior by the nares. At the back a free communi- 



*Jacobson: Danish anatomist. B. 1783, D. 1843. 



