1, interior wall
That is, the nasal septum consists of nasal septum cartilage, median plate of ethmoid bone, also known as vertical plate of ethmoid bone and vomerous bone (figure 1-4).
Fig. 1-4 nasal septum stent
The perichondrium and periosteum are covered with mucosa, and the mucosa in the anterior lower part of the nasal septum is rich in blood vessels. The capillary network formed by the close anastomosis of nasopalatine, anterior ethmoid bone, upper lip and branches of the great palatine artery is called Little's area. Here, the mucosa is thin, the blood vessels are shallow, the mucosa is closely connected with the perichondrium, the blood vessels are not easy to contract after rupture, and the position is in the front, so it is the most prone to nosebleeds.
2. External wall
The outer wall of the nasal cavity is very irregular, and there are three bony turbinates protruding in the nasal cavity, which are called upper, middle and lower turbinates respectively. The space below each turbinate is called nasal meatus, that is, upper, middle and lower nasal meatus. The gap between the medial surface of each turbinate and the nasal septum is called the common nasal meatus. The cavity between the superior and middle turbinates and the nasal septum is called olfactory cleft or olfactory groove (Figure 1-5, 1-6).
Figure 1-5 Nasal wall
(1) Superior turbinate: located in the posterior upper part of the external wall of nasal cavity, with the highest and smallest position. Because the middle turbinate covers the front and lower part, it is difficult to see the front rhinoscope. The ethmoidal recess is located in the posterior upper part of the superior turbinate, where the ethmoidal sinus opens.
Fig. 1-6 lateral wall of nasal cavity (partial resection of upper, middle and lower turbinates)
(2) Superior nasal meatus: There is a posterior ethmoid sinus orifice. (3) Middle turbinate: it is the protruding part of ethmoid bone, and the ethmoid sinus air cavity often grows in the middle turbinate, which obviously narrows the upper part of the nasal cavity. There is a mound on the side wall of the nasal cavity above the front end of the middle turbinate, which is a rich reflection area formed by trigeminal nerve and olfactory nerve.
(4) Middle nasal meatus: There are two protrusions on the outer wall, the ethmoidal vesicle is the atmospheric cavity of ethmoidal sinus, there is an arc-shaped ridge protrusion under the ethmoidal vesicle called uncinate process, and there is a half-moon hole between the uncinate processes of ethmoidal vesicle. There is an arc groove on the outside called ethmoidal funnel, and the frontal sinus is mostly opened in the front upper part of the semilunar hiatus, followed by the anterior ethmoidal sinus and finally the maxillary sinus.
(5) Inferior turbinate: it is an independent bone mass attached to the inner wall of maxilla, with the front end about 2cm away from the anterior nostril and the rear end about 1cm away from the mouth of eustachian tube. It is the largest turbinate, which is about the same length as the bottom of the nose, so when the inferior turbinate swells, it is easy to cause nasal congestion or affect the ventilation and drainage of the tympanic tube.
(6) Inferior nasal meatus: There is an opening in the upper front of nasolacrimal duct, and the outer bone wall near the attachment of inferior turbinate is thin, which is the best needle insertion site for maxillary sinus puncture (Figure 1-7).
Figure 1-7 Right nasal cavity
Step 3 put on the plate
It is a narrow arch, and the front part is composed of frontal nasal process and nasal bone. The middle part is a sieve plate that separates the anterior cranial fossa from the nasal cavity. This plate is thin and brittle, with many fine holes and a sieve shape. The olfactory nerve passes through it and enters the anterior cranial fossa. Trauma or fracture can easily lead to cerebrospinal fluid rhinorrhea, which becomes the way for infection to enter the skull.
Step 4 lower the plate
That is, the hard palate is separated from the mouth. The anterior 3/4 is composed of the palatal process of the maxilla, and the posterior 1/4 is composed of the horizontal part of the palatal bone. The two sides meet at the midline, forming the nasal ridge of the maxilla, which is connected with the lower edge of the vomer. The front of the bottom wall is close to the nasal septum. When these two machines are used, there are openings for dental canals through which the great palatal artery, vein and anterior palatal nerve pass. According to the difference of tissue structure and physiological function, it is divided into olfactory mucosa and respiratory mucosa.
1, olfactory mucosa
It is distributed on the medial surface of the upper turbinate and part of the middle turbinate and the corresponding nasal septum. It is a pseudostratified columnar epithelium without cilia, which consists of olfactory cells, supporting cells and basal cells. Its inherent layer contains olfactory glands that secrete serous fluid, thus dissolving particles of odorous substances and producing sense of smell. Olfactory cells are bipolar nerve cells. The central axon of olfactory cells gathers most olfactory filaments and reaches the olfactory bulb through the sieve plate. Peripheral axons protrude from the epithelial surface and become slender olfactory hairs (figure 1-8).
Figure 1-8 olfactory nerve
2, respiratory mucosa
The nasal cavity, except the olfactory region, is covered by the mucous membrane of the respiratory region, which belongs to stratified or pseudo-stratified columnar ciliated epithelium, and its cilia mainly move from front to back in the direction of nasopharynx. Mucosa is rich in serous glands, mucous glands and goblet cells, which can produce a lot of secretions, so that the surface of mucosa is covered with a mucus blanket that moves backwards with cilia movement. There are abundant venous plexus in mucous membrane, which constitutes sponge tissue, has elastic contractility, can quickly change its congestion state, and is the main part of regulating air temperature and humidity. The mucosa on the inferior turbinate is the thickest, which is very important for the physiological function of the nasal cavity, so it is not advisable to remove it too much during surgery. Arteries mainly come from ophthalmic artery, a branch of internal carotid artery system, and maxillary artery, a branch of carotid artery system.
1. The posterior branches of ophthalmic artery from optic canal into orbit are anterior ethmoidal artery and posterior ethmoidal artery. Both of them enter the ethmoid sinus through the corresponding anterior and posterior ethmoid foramen, cling to the tip of ethmoid sinus, run through the groove and bone canal formed by the bone crest, then leave ethmoid sinus, enter the anterior cranial fossa, and enter the nasal cavity along the sieve plate through a small incision beside the cockscomb.
2. In pterygopalatine fossa, the branches of maxillary artery are discoid palatine artery, infraorbital artery and great palatine artery, among which sphenopalatine artery is the main artery supplying blood to nasal cavity.
3. The veins flowing back to the front, back and lower parts of the nasal cavity flow into the internal and external jugular veins, while the superior nasal vein flows into the cavernous sinus through the ophthalmic vein, or flows into the intracranial vein and dural sinus through the ethmoidal vein. Include olfactory nerve, sensory nerve and autonomic nerve.
1. The olfactory nerve is distributed in the mucosa of the olfactory region. The central protuberance of olfactory cells gathers into a plurality of olfactory filaments, which pass through the sieve holes on the sieve plate and reach the olfactory bulb. The olfactory nerve sheath is a continuation of dura mater, which can damage the mucosa of olfactory region or cause secondary infection, and can enter the skull along the olfactory nerve, causing rhinogenic intracranial complications.
2. Sensory nerve comes from the first branch (ophthalmic nerve) and the second branch (maxillary nerve) of trigeminal nerve.
Ophthalmic nerve: Anterior ethmoidal nerve and posterior ethmoidal nerve, which are separated by its branch nasociliary nerve, enter the nasal cavity with the same name artery, and are distributed in a small part of the nasal septum and the upper part of the lateral wall of the nasal cavity.
Maxillary nerve: the sphenopalatine nerve branches after passing through or bypassing the sphenopalatine ganglion, and then enters the nasal cavity through the sphenopalatine orifice, where it is divided into posterior superior lateral branch and posterior superior medial branch, which are mainly distributed in the posterior part of the lateral wall of the nasal cavity, the nasal roof and the nasal septum.
3. The vasodilation and glandular secretion of autonomic nerve nasal mucosa are controlled by autonomic nerve.