1. External nose
External nose refers to the part protruding from the face, which is supported by bones and cartilage and covers the skin. The upper end is narrow and located between the eyes, which is called nasal root; The protruding part at the lower end is called the tip of the nose; The central convex part is called the back of the nose; The protruding parts on both sides of the tip of the nose are called the alar.
The skin at the tip of nose and alar is thick, rich in sebaceous glands and sweat glands, closely connected with deep subcutaneous tissue and perichondrium, and prone to furuncle. Therefore, when inflammation occurs, local swelling compresses nerve endings, which can cause severe pain.
2. Nasal cavity
The nasal cavity is based on bony nasal cavity and cartilage, and its surface is lined with mucosa and skin. The nasal cavity is divided into left and right cavities by nasal septum, the front cavity communicates with the outside world through nostril, and the back cavity communicates with pharyngeal cavity through rear nostril. Each nasal cavity can be divided into nasal vestibule and inherent nasal cavity.
Nasal vestibule refers to the enlarged space surrounded by the alar, and its inner surface is lined with skin, which has the function of retaining and inhaling dust. In addition, the skin is tightly attached to the perichondrium, so when the furuncle is swollen, the pain is severe.
The proper nasal cavity refers to the part behind the nasal vestibule, which is connected with the pharynx through the posterior nasal orifice. Its shape is basically the same as that of bony nasal cavity, and it is composed of bone and cartilage covering mucosa. Each nasal cavity has four walls: upper, lower, inner and outer. The upper wall (roof) is relatively narrow, adjacent to the anterior cranial fossa, and consists of nasal bone, frontal bone, ethmoid plate and sphenoid bone. The ethmoid foramen of the sieve plate is penetrated by olfactory nerve, and the lower wall (bottom) is the top of the mouth and consists of hard palate. The medial wall is the nasal septum, which consists of bony nasal septum and nasal septum cartilage. The nasal septum is biased to one side, especially to the left. There are abundant vascular anastomoses in the mucosa of the anterior lower part of the nasal septum, and about 90% of epistaxis (epistaxis) occurs here, which is clinically called bleeding-prone area. There are three prominent turbinates on the side wall, which are called upper turbinate, middle turbinate and lower turbinate respectively from top to bottom, and the gaps below each turbinate are called upper nasal meatus, middle nasal meatus and lower nasal meatus respectively. The recess behind the superior turbinate is called sphenoid recess. The gap between turbinate and nasal septum is called common nasal meatus. After the middle turbinate is removed, a concave upward arc fissure can be seen in the middle of the middle nasal meatus, which is called semilunar fissure, and the round pillow-shaped protrusion above the fissure is called ethmoidal vesicle. The middle and upper nasal meatus and sphenoid recess have sinus openings, and the lower nasal meatus has nasolacrimal duct openings.
Normal nasal mucosa can be divided into olfactory part and respiratory part according to its nature. The olfactory mucosa covers the upper turbinate and the nasal septum opposite it, showing pale yellow or light yellow, containing olfactory cells, which can feel the stimulation of smell. The rest is covered with pink respiratory mucosa, which is rich in capillaries and mucus glands, and the epithelium has cilia, which can purify the air and improve the temperature and humidity of the inhaled air.
3. Accessory sinuses
Accessory sinuses are composed of bony surfaces lined with mucous membranes, which are continuous with nasal mucosa through the opening of each sinus. Accessory sinuses play a role in pronunciation and can also help regulate the temperature and humidity of inhaled air. Because the mucosa of nasal cavity and sinus is continuous, nasal inflammation can cause sinusitis.
Four pairs of paranasal sinuses are located in the maxilla, and the upper wall is the suborbital wall, which is thin. Maxillary sinusitis or tumor often destroys bone and invades orbit. The lower wall is adjacent to maxillary molars and thin roots, so root infection often spreads to maxillary sinus; The anterior wall below the suborbital foramen is thin, which is where the maxillary sinus is cut during surgery. The medial wall is the lateral wall of the nasal cavity, adjacent to the middle and lower nasal passages. The bone in the anterior upper part of the inferior nasal meatus is thin, and maxillary sinus puncture is done here. The maxillary sinus is open behind the semilunar hiatus. Because of the high position of the opening, the maxillary sinus is not well drained when it is inflamed and suppurated, which is easy to cause pus accumulation in the sinus. The frontal sinus opens at the front end of the semilunar hiatus. The ethmoid sinus leads to the middle and upper nasal meatus. The sphenoid sinus leads to the recess of sphenoid ethmoid bone.