ANATOMY AND PHYSIOLOGY 3
meatus; the posterior ethmoidal sinuses drain into the superior meatus; the
sphenoidal sinus communicates with the spheno-ethmoidal recess. An
appreciation of the detailed structure of the meatuses will be obtained by
studying Fig. 4 in which the middle concha has been removed, and Fig. 5 in
which the superior concha has also been removed.
The nasal septum (Fig. 6) separates the two nasal cavities and is partly
osseous and partly cartilaginous. The perpendicular plate of the ethmoid and
Fig. 2. The external nose. 1, Nasal bone; 2, Frontal process of maxilla; 3, Lateral cartilage; 4, Greater
alar cartilage; 5, Lesser alar cartilages; <J, Fatty tissue of ala nasi.
the yomer bone constitutesjthe upper and posterior part, while the septal
cartilage completes the septum anteriorly, stretching from the dorsum of the
nose above to the nasal crests of the maxillary and palatine bones below.
The main arterial supply of the nasal septum arises from the septal branch of
the sphenopalatine artery, and this anastomoses with the greater palatine
artery and septal branches of the superior labial and anterior ethmoidal
arteries at the ajnterg-inferior jpart of the septurAr-the so-called 'bleeding area*
or Little's area, whidtTis""of importance in epistaxis (fig. 7). The lateral nasal
wall is supplied by lateral branches from these vessels. Venous drainage from
the nasal cavity is through the sphenopalatine foramen to the pterygoid