<unk>  anatomy The term<unk> " can refer to each of the two<unk> es of the nose, or to the two sides combined. CT scan in the coronal plane, showing the ostiomeatal complex (green area). The lateral wall of each<unk>  mainly consists of the maxilla. However, there is a deficiency that is compensated for by the perpendicular plate of the palatine bone, the medial pterygoid plate, the labyrinth of ethmoid and the inferior concha. The paranasal sinuses are connected to the<unk>  through small orifices called ostia. Most of these ostia communicate with the nose through the lateral<unk>  wall, via a semi-lunar depression in it known as the semilunar hiatus. The hiatus is bound laterally by a projection known as the uncinate process. This region is called the ostiomeatal complex. The roof of each<unk>  is formed in its upper third to one half by the<unk>  bone and more inferiorly by the junctions of the upper lateral cartilage and<unk>  septum. Connective tissue and skin cover the bony and cartilaginous components of the<unk>  dorsum. The floor of the<unk> es, which also form the roof of the mouth, is made up by the bones of the hard palate: the horizontal plate of the palatine bone posteriorly and the palatine process of the maxilla anteriorly. The most anterior part of the<unk>  is the<unk>  vestibule. The vestibule is enclosed by the cartilages of the nose and lined by the same epithelium of the skin (stratified squamous, keratinized). Within the vestibule this changes into the typical respiratory epithelium that lines the rest of the<unk>  and respiratory tract. Inside the nostrils of the vestibule are the<unk>  hair, which filter dust and other matter that are breathed in. The back of the<unk>  blends, via the choanae, into the nasopharynx. The<unk>  is divided in two by the vertical<unk>  septum. On the side of each<unk>  are three horizontal outgrowths called<unk>  conchae (singular "concha") or turbinates. These turbinates disrupt the airflow, directing air toward the olfactory epithelium on the surface of the turbinates and the septum. The vomeronasal organ is located at the back of the septum and has a role in pheromone detection. Segments The<unk>  is divided into two segments: the respiratory segment and the olfactory segment. * The respiratory segment comprises most of each<unk> , and is lined with ciliated pseudostratified columnar epithelium (also called respiratory epithelium). The conchae, or turbinates, are located in this region. The turbinates have a very vascularized lamina propria (erectile tissue) allowing the venous plexuses of their mucosa to engorge with blood, restricting airflow and causing air to be directed to the other side of the nose, which acts in concert by shunting blood out of its turbinates. This cycle occurs approximately every two and a half hours. * The olfactory segment is lined with a specialized type of pseudostratified columnar epithelium, known as olfactory epithelium, which contains receptors for the sense of the smell. This segment is located in and beneath the mucosa of the roof of each<unk>  and the medial side of each middle turbinate. Histological sections appear yellowish-brown due to the presence of lipofuscin pigments. Olfactory mucosal cell types include bipolar neurons, supporting (sustentacular) cells,<unk>  cells, and Bowman's glands. The axons of the bipolar neurons form the olfactory nerve (cranial nerve I) which enters the brain through the cribriform plate. Bowman's glands are serous glands in the lamina propria, whose secretions trap and dissolve odoriferous substances. Blood supply There is a rich blood supply to the<unk> . In some animals, such as dogs, the capillary beds flowing through the<unk>  help cool the blood flow to the brain. Blood supply comes from branches of both the internal and external carotid artery, including branches of the facial artery and maxillary artery. The named arteries of the nose are: * Sphenopalatine artery and greater palatine artery, branches of the maxillary artery. *Anterior ethmoidal artery and posterior ethmoidal artery, branches of the ophthalmic artery *Septal branches of the superior labial artery, a branch of the facial artery, which supplies the vestibule of the<unk> . Nerve supply Innervation of the<unk>  responsible for the sense of smell is via the olfactory nerve, which sends microscopic fibers from the olfactory bulb through the cribriform plate to reach the top of the<unk> . General sensory innervation is by branches of the trigeminal nerve (V1 & V2): *Nasociliary nerve (V1) *Anterior Ethmoidal nerve from the Nasopalatine nerve (V2) *Posterior<unk>  branches of Maxillary nerve (V2) The<unk>  is innervated by autonomic fibers. Sympathetic innervation to the blood vessels of the mucosa causes them to constrict, while the control of secretion by the mucous glands is carried on postganglionic parasympathetic nerve fibers originating from the facial nerve.
Nasal cavity
Oropharyngeal airway
Hemotympanum
Nasopharyngeal airway
Lacrimal sac
Mouth
Craniopharyngeal canal
Orbital septum