The septum of the nose divides the cavity into narrow chambers – the right and the left cavity of the nose. The septum nasi (nasal septum) is seldom placed exactly in the medial plane, but almost invariably bulges or deviates to one side or the other (more frequently to the right). Immediately above the nostril, the septum shows a slight depression. That portion of the septum is the medial wall of the vestibule of the nose, and is covered with skin from which a number of stiff hairs, called vibrissae, project into the cavity. The rest of the septum is covered with mucous membrane which is closely adherent to the subjacent periosteum and perichondrium; and it is separable into two regions: a lower or respiratory area, and a much smaller upper or olfactory area (comprising not more than the upper third of the septum) in which branches of the olfactory nerve spread out. The respiratory mucous membrane is very thick and spongy. It is highly vascular and contains numerous mucous glands, the orifices of whose ducts can be detected by the unaided eye. Over the olfactory area, the mucous membrane is softer and more delicate, and the glands are smaller.
The main parts of the skeleton of the septum nasi are: (1) the vomer, below and behind; (2) the perpendicular plate of the ethmoid, above and behind; and (3) the septal cartilage, below and in front. Small portions of other bones take a minor part in its construction.
Vessels and nerves of the septum nasi
The nerves of the septum nasi are the olfactory (the nerve associated with smell), and the spheno-palatine, branches of the anterior ethmoidal nerve, and twigs from the nerve of the pterygoid canal (all nerves of common sensation).
The long sphenopalatine nerve is a long, slender nerve that can easily be detected on the deep surface of the mucous membrane of the septum. It springs from the spheno-palatine ganglion, and enters the nasal cavity through the spheno-palatine foramen accompanied by the sphenopalatine branch of the maxillary artery. It first runs medially across the roof of the cavity; then, changing direction, it passes downward and forward, in a groove on the surface of the vomer, to reach the floor of the nose, and then on through the incisive canal and median incisive forman to end in the mucous membrane of the anterior part of the hard palate.
The short sphenopalatine nerves from the spheno-palatine ganglion and the twigs from the nerve of the pterygoid canal send slender filaments to the posterosuperior part of the septum.
The medial nasal branches of the anterior ethmoidal nerve descend over the anterior part of the nasal septum, and may be traced as far as the vestibule.
The arteries which convey blood to the septum are branches of the spheno-palatine, ethmoidal, and superior labial arteries.