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The nasal cavity is divided in two by the vertical nasal septum. On the side of each nasal cavity are three horizontal outgrowths called nasal 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 septum grows down from the roof of the nasal cavity and fuses with the developing palates along the midline. The septum divides the nasal cavity into two nasal passages opening into the pharynx through the definitive choanae. [48] [49] At ten weeks, the cells differentiate into muscle, cartilage, and bone.
The upper airways or upper respiratory tract includes the nose and nasal passages, paranasal sinuses, the pharynx, and the portion of the larynx above the vocal folds (cords). The lower airways or lower respiratory tract includes the portion of the larynx below the vocal folds, trachea, bronchi and bronchioles.
The canal containing the duct is called the nasolacrimal canal.It is formed by indentations in the inferior nasal conchae, maxilla and lacrimal bone.The canal drains into the nasal cavity through the anterior portion of the inferior meatus, which is between the inferior concha and the floor of the nasal cavity.
Illustration of upper respiratory system. In anatomy, a nasal concha (/ ˈ k ɒ n k ə /; pl.: conchae; / ˈ k ɒ n k iː /; Latin for 'shell'), also called a nasal turbinate or turbinal, [1] [2] is a long, narrow, curled shelf of bone that protrudes into the breathing passage of the nose in humans and various other animals.
It consists of a nasal cavity inside the head, and an external nose on the face. The external nose houses the nostrils, or nares, a pair of tubes providing airflow through the nose for respiration. Where the nostrils pass through the nasal cavity they widen, are known as nasal fossae, and contain turbinates and olfactory mucosa.
Back-flow into the gill chamber during the inhalatory phase is prevented by a membrane along the ventroposterior border of the operculum (diagram on the left in Fig. 23). Thus the mouth cavity and gill chambers act alternately as suction pump and pressure pump to maintain a steady flow of water over the gills in one direction. [58]
The neurons' dendrites project towards the nasal cavity while their axons ascend through the cribriform plate [1] as the olfactory nerves. [ 3 ] The part of the nasal cavity that is lined with olfactory mucosa is known as the olfactory region ( pars olfactoria tunicae mucosae nasi ), [ 2 ] while the rest of the nasal cavity that is lined by ...