Development of nasal cavities and nasal septum along with the related anomalies скачать в хорошем качестве

Development of nasal cavities and nasal septum along with the related anomalies

Nasal cavities are formed by extension of nasal pits. These pits are at first in open communication with the stomodeum, medial and lateral nasal prominences fuse to form a partition between the pit and stomodeum which is named as primitive palate. Nasal pits deepen to form nasal sacs which expand both dorsally and caudally. Dorsal part is at first separated from the stomodeum by a thin membrane called the bucconasal membrane. It then breaks down and the nasal sac now has a ventral orifice that opens on the face called as anterior/external nares and a dorsal orifice that opens into the stomodeum called as posterior nares/posterior nasal aperture. The 2 nasal sacs are initially widely separated from each other by the frontonasal prominence. This FNP becomes progressively narrower. This narrowing of the FNP and enlargement of the nasal cavities brings them closer together . The intervening tissue thins down to form nasal septum. Ventral part of the septum is attached below to the primitive palate. More posteriorly, the septum is at first attached to the bucconasal membrane and when membrane disappears, it has a free lower edge. Lateral wall of nose is derived from lateral nasal prominences and nasal conchae appear as elevations on it. Olfactory placodes form the olfactory epithelium that lies in the roof and adjoining parts of the walls of nasal cavity. Anomalies Atresia at the external or posterior nares or in the cavity. May be uni/bilateral/complete absence Congenital defects in the cribriform plate leads to communication between cranial cavity and nose. Nasal septum may not be in the middle leading to DNS May communicate with the mouth.