The structure of the ear

When we see ears, they are the parts located on both sides of our head. In fact, this is only part of the ear. Another part of the ear is in the brain. Only when the outer ear and the inner ear work together can we hear all the sounds in the world. Many people think that the ear is the part that is exposed outside, but this is actually due to a lack of understanding of the ear. The ear is also an organ with a very complex structure.

Auricle

There is a large hole outside the auricle, called the external auditory meatus, which connects to the external auditory canal. The auricle is funnel-shaped and has the function of collecting external sound waves. Most of it is supported by elastic cartilage under the skin, and the small part below contains only connective tissue and fat under the skin. This part is called the earlobe. In clinical applications, the auricle is the site for auricular acupuncture treatment and auricular acupuncture anesthesia, while the earlobe is also often used as the site for clinical blood collection.

external ear

The external auditory canal is a curved tube from the external auditory meatus to the eardrum, about 2.5 to 3.5 cm long, and its skin is continued from the auricle. The outer third of the auditory canal wall is made of cartilage, and the inner two thirds of the auditory canal wall is made of bone. There are ear hair, sebaceous glands and cerumen glands on the skin of the cartilage part.

eardrum

The tympanic membrane is a translucent membrane that is shallowly funnel-shaped, with the concave side facing outward and its edges fixed to the bone. It is the boundary between the external auditory canal and the middle ear. Sound waves transmitted through the external auditory canal can cause the eardrum to vibrate.

tympanum

The tympanic cavity is located between the eardrum and the inner ear. It is a small air-filled cavity with a volume of about 1 cm3. The tympanic cavity is the main component of the middle ear, which contains three ossicles: the malleus, the incus and the stapes. The base of the stapes is attached to the oval window of the inner ear. The three ossicles are connected by ligaments and joints, forming the ossicular chain. The vibration of the eardrum can be transmitted to the oval window through the ossicular chain, causing the lymph in the inner ear to vibrate.

inner ear

The inner ear consists of three parts: the vestibule, semicircular canals and cochlea. It is composed of complex curved tubes, so it is also called the labyrinth. The labyrinth is filled with lymph, and the vestibule and semicircular canals are home to position receptors, which are related to body balance. The vestibule can sense changes in the position of the head and changes in speed during linear motion, and the semicircular canals can sense the rotational and speed-changing motion of the head. After these stimuli are reflected to the central nervous system, they cause a series of reflexes to maintain the body's balance. The cochlea is the location of auditory receptors and is related to hearing. So how is hearing formed? Human hearing is not very sensitive, but we can hear sound waves ranging from 16 to 20,000 vibrations per second. After the external sound is collected by the auricle, it is transmitted to the eardrum through the external auditory canal, causing the eardrum to vibrate. The frequency of the eardrum's vibration is exactly the same as the amplitude of the sound waves' vibration. The louder the sound, the greater the vibration of the eardrum.