What is Ear Coning?

The outer ear includes the ear ear (collecting sound waves) and the external ear canal (transmitting sound waves to the eardrum).

The outer ear includes the ear ear (collecting sound waves) and the external ear canal (transmitting sound waves to the eardrum).

Chinese name

external ear

Foreign name

4waier; TG1u; external ear

Subject

medicine

Physiology

organ

Make up

Ear Guo, external ear canal

Function

Collect sounds and identify directions

Overview of the outer ear

External ear

Most of the ears are made of elastic cartilage covering the skin. Ear Guo has several depressions, of which the ear nails are the deepest. The earlobe (excluding cartilage) is made up of fibrous tissue, fat and blood vessels. It is easy to perforate blood samples and hang earrings. The ear's blood mainly comes from the posterior auricular artery and the superficial temporal artery; the greater auricular nerve and the temporal auricular nerve are distributed on the skin of the auricle: the greater auricular nerve is distributed on the upper part of the ear and outer skin below the ear canal; the temporal auricular nerve (trigeminal nerve) Mandibular branch) is distributed over the ear skin above the external auditory canal. The lymph on the lateral side of the upper part of the ear is drained to the superficial lymph nodes of the parotid gland, and the lymph on the cranial (medial) side is drained to the lymph nodes behind the ear and the deep cervical lymph nodes. Lymphatic drainage of the rest of the ear (including the earlobe) to the superficial cervical lymph nodes.

External ear canal

The external auditory meatus is a curved duct that extends from the external ear door deep in the ear nail cavity to the eardrum inward, and can transmit the sound waves collected by the ear Guo to the eardrum. The direction is first inward and upward, then inward and upward, and then inward and downward. Adults are about 2.5 to 3.5 cm long. Because the tympanic membrane is inclined, the anterior lower wall (3.1 cm) of the external auditory meatus is longer than the posterior superior wall (2.5 cm). The lateral 1/3 of the external auditory canal is based on the external auditory canal cartilage, which is the cartilage external auditory canal, and the medial 2/3 is based on the bone, which is the bony external auditory canal. The junction between the two is narrow; the narrow place is about 2cm from the external ear canal, and the narrowest part of the external ear canal is called the isthmus, which has the effect of preventing foreign matter from entering the external ear canal to invade the eardrum. The cartilage of the external ear canal and the cartilage of the ear are continuous. When clinically examining the eardrum, lifting the ear up and back can straighten the external ear canal for easy observation. Infants and young children's bony external auditory canal is underdeveloped, and the bottom and top of the cartilage external auditory canal are fissure-shaped, and face inward and downward. When examining the tympanic membrane, the ear ear must be pulled down and the tragus pulled forward. The skin of the external auditory canal is thin and closely connected to the perichondrium and periosteum. The skin of the cartilage external ear canal is rich in hair follicles, sebaceous glands, and sacral glands, and is one of the susceptible sites for bloating. Ear hairs and tadpoles are insect-proof, dust-proof, waterproof, and keep the air warm. The four walls of the external ear canal are adjacent to some important structures: the medial part of the anterior wall is connected to the temporomandibular joint; the lateral part of the anterior wall and the inferior wall are adjacent to the parotid gland. The upper wall of the bony external ear canal connects to the middle cranial fossa; the posterior wall is adjacent to the mastoid atrium. Above the deepest part of the external ear canal abuts the upper tympanic recess; the posterior superior abuts the mastoid sinus. These adjacent relationships are related to the spread of disease and the choice of surgical approach.

External eardrum

The tympanic membrane is located on the inner side of the external auditory canal and has a diameter of about 2 cm. It is a thin oval translucent membrane that is the boundary between the external auditory canal and the middle ear (tympanum). The tympanic cavity is an air chamber located in the temporal bone, which contains the ossicles: the malleus, anvil and sacrum. The tympanic membrane is covered with thin skin, and the middle ear is covered with mucous membranes. In otoscope observation, the tympanic membrane is concavely facing the external ear canal, the center of which is tapered, and the apex is the umbilical cord. The tympanic membrane axis is vertical to the tympanic membrane through the tympanic membrane through the tympanic membrane. When the tympanic membrane extends outward, it also moves forward and downward at the same time, like a radar or satellite that collects signals on the front and lateral sides of the head (sound waves). During otoscopy, the eardrum has a cone of light reflecting from the umbilicus forward and downward. The tympanic membrane on the lateral process of the malleus is thinner, and it is the slack part of the tympanic membrane, which forms the outer side wall of the recess in the tympanic cavity. The rest of the tympanic membrane contains tapered and annular fibers, which is the tension part.

The external ear canal transmits sound waves to the tympanic membrane, causing the tympanic membrane to vibrate, and the sound waves are further transmitted to the inner ear through the middle ear hearing bone. The outer surface of the tympanic membrane is mainly distributed in the auriculotemporal nerve, and also in some small branches of the vagus nerve. The glossopharyngeal nerve is distributed on the inner surface of the tympanic membrane.