The nose consists of three parts: external nose, nasal cavity and sinus. The external nose is located in the center of the face. The nasal cavity is a cavity between two lateral skulls, and its upper part, rear part and side are surrounded by paired left and right sinuses, and it is closely adjacent to the anterior cranial fossa, middle cranial fossa, oral cavity and orbit, and separated from each other only by a thin bone plate, so severe nasal trauma can be accompanied by trauma of its surrounding structures, and nasal diseases can also spread to neighboring organs. The opening of the sinus enters the nasal cavity, and the mucous membranes of the two move together to form a whole.

The external nose consists of bone and cartilage and is covered with soft tissue.

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And has a slightly conical shape with a nasal root, a nasal tip, a bridge of the nose, a nasal wing, a front nasal opening, a nasal columella and the like. Skeletal support of external nose: it consists of nasal bone, frontal nasal process and maxillary frontal process.

The nasal bones are paired left and right, and the midline is connected. The nasal process of the frontal bone is connected on the upper side, and both sides are connected with the frontal process of the maxilla. The lower edge of nasal bone, the inner edge of maxillary frontal process and the free edge of maxillary palatal process form pear-shaped holes.

External nasal cartilage scaffold: it consists of nasal septum cartilage, lateral nasal cartilage and alar cartilage. Cartilage is connected by connective tissue.

The alar cartilage is left and right, and the bottom is horseshoe-shaped, each with inner and outer feet. The lateral foot forms the support of the alar, and the two medial feet clamp the anterior lower part of the nasal septum cartilage, forming the main support of the nasal columella.

The skin of nose tip, alar and nasal vestibule is thick, closely attached to subcutaneous tissue and perichondrium, and rich in sebaceous glands and sweat glands, which are the prone parts of acne, acne and rosacea. When boils are inflamed, there will be slight swelling and pain.

The external nasal vein flows into the internal and external jugular veins through the internal canthus vein and facial vein, and the internal canthus vein communicates with the superior ophthalmic vein and the inferior ophthalmic vein, and finally flows into the intracranial cavernous sinus. There is no valve in the facial vein, so blood can circulate up and down. If the furuncle on the nose or upper lip (called the danger triangle) is not handled properly or squeezed at will, it may cause the risk of serious intracranial complications such as cavernous sinus thrombophlebitis.

The nose structure of vertebrates is different, but it is generally composed of external nose, nasal cavity and sinus. The mucosal blood vessels in the lower part of the nasal cavity are rich, which can adjust the air temperature and humidity. Accessory sinuses are several bone cavities communicating with the nasal cavity, which can help regulate the temperature, humidity and timbre of the air. Some animals have nose hair in the front of the nasal cavity, which plays a role in filtering dust in the air. Liver cirrhosis has an external nostril and an olfactory sac, but it still receives nerves from a pair of olfactory lobes. Fish usually have external nostrils and paired olfactory sacs. The external nostril of cartilaginous fish is located on the ventral surface of snout, while teleost fish is located on the dorsal surface. Terrestrial vertebrates breathe air, and the olfactory organs communicate with the oral cavity, which leads to the appearance of internal nostrils. After the appearance of the inner nostril, the nasal cavity has both olfactory and respiratory functions. In amphibians, the inner nostril is open in front of the mouth, and the olfactory mucosa in the nasal cavity is flat, and part of it is transformed into vomeronasal organ, which is a taste receptor. Reptiles have a developed sense of smell, and the nasal cavity and olfactory mucosa are enlarged. The nasal cavity structure of birds is similar to that of reptiles. Mammals have a second jaw and the internal nostril moves back to the pharynx. Because the sense of smell is highly developed and the structure is complex, it is characterized by enlarged nasal cavity and turbinate bone. The turbinate is a thin bone block with complex coils, which is covered with olfactory mucosa covered with olfactory nerve, greatly increasing the olfactory surface area. The olfactory degeneration of aquatic species, such as whales and manatees; Some animals, such as dogs, have a keen sense of smell because their olfactory mucosa extends beyond the nasal cavity.

There are nasal mucosa in the nasal cavity, and there are abundant capillaries and mucus glands in the nasal cavity, which can secrete mucus. These structures can make the air inhaled into the nasal cavity warm and moist, and reduce the stimulation to the lungs. There are also olfactory cells in the mucosa of the upper nasal cavity that receive odor stimulation.

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