The nasal fossae, and the various openings into them, with the posterior nares, have been previously described as they exist in the skeleton, and the greater part of that description is also applicable generally to the nose in a recent state; but it is proper to mention certain differences in the form and dimension of parts, which depend on the arrangement of the lining membrane, viz.
Throughout the whole of the nasal fossae it to be observed that - Firstly, owes- to the thickness of the membrane in question, (which not only lines the walls of the fossae, but covers the spongy bones on both sides.) the nasal cavity is much narrower in the recent state. Secondly, in consequence of the prolongations of membrane on their free margins, the tm-binate bones, and more particularly the lower pair, appear in the recent state to be both more prominent and longer in the direction, from before backwards, than in the dried skull. Thirdly, by the arrangement of the mucous membrane aroimd and over the orifices which open into the nasal fossas, some of the foramina in the bones are narrowed, and others completely closed.
In the individual parts of the nasal fossae the following particulars are to be noticed.
In the upper meatus, the small orifice which leads into the posterior ethmoidal cells is lined by a prolongation of the thin mucous membrane which continues into those cavities; but the spheno-palatine foramen is covered over by the Schneiderian membrane, so that no such opening exists in the recent nasal fossa.
In the middle meatus, the aperture of the infundibulum is nearly hidden by an overhanging fold of membrane; it leads directly into the anterior ethmoidal cells, and through them into the frontal sinus. Below and behind this, the passage into the antrum of Highmore is surrounded by a circular fold of the pituitary membrane (sometimes prominent and even slightly valvular), which leaves a circular aperture much smaller than the foramen in the bony meatus.
In the lower meatus the inferior orifice of the nasal duct is defended by one or two folds of membrane; and when there are two, the folds are often adapted so accurately together as to prevent even air from passing back from the cavity of the nose to the lachrymal sac.
In the roof the apertures in the cribriform plate of the ethmoid bone are closed by the membrane, but the openings into the sphenoidal sinuses receive a prolongation from it.
In the roof the incisor foramen is in the recent state generally closed. Some- times, however, a narrow funnel-shaped tube of the mucous membrane descends for a short distance into the canal, but is closed before it reaches the roof of the palate. Vesalius. Stenson and Santorini, believed that this tube of membrane opened generally into the roof of the mouth by a small aperture close behind the interval between the central incisor teeth. Haller, Scarpa, and more recently, Jacobson, find that in man it is usually closed, and often difficult of detection. (See Cuvier’s Report on a paper by Jacobson, "Annales du Museum d’Hist. Naturelle; " Paris, 1811 ; vol. XVIII. p. 412.)
From Quain's anatomy.