ENT Anatomy Basics

E.N.T is an abbreviation for Ear, Nose and Throat. In this article we present the basic anatomy of ear, nose and throat.

Anatomy of ear:

Anatomically the ear is divided into three parts:
External ear or outer ear
Middle ear or tympanic cavity
Inner ear

External ear consists of:

Pinna or auricle: This is outmost visible part of the ear. It is directed towards outer ear canal or external auditory canal.

External auditory canal or tube: This is the tube that connects the outer ear to the middle ear. This is the tube through which the sound travels to the eardrum.

Eardrum or Tympanic membrane: Eardrum divides the external ear from the middle ear. It transmits sound to the ossicles inside the middle ear. Malleus bone is sited adjacent to eardrum which bridges the gap between the eardrum and the other ossicles.

Middle ear or tympanic cavity:
It consists of ossicles and eustachian tube.

Ossicles: Also called as auditory ossicles. Literally ossicles means ‘tiny bones.’ Malleus, incus and stapes are collectively known as auditory ossicles. These bones transmit the sound waves to the inner ear.

Eustachian Tube: It is a canal-like stucture that links the middle ear with the throat area. The main function of eustachian tube is the equalize the pressure between the outer and the middle ear. During swallowing and chewing the eustachian tube open up for the equalization of the pressure. It is lined with the mucous membrane just as the nose and throat.

Inner ear, also called labyrinth of the ear:
This part of the ear consists of the senses of hearing and equlibrium. It consists of

Cochlea: It is a snail-like structure that contains nerves for hearing. Cochlea has still deeper anatomy. The functional part of cochlea are the sensitive hairs that trigger the generation of the nerve signals that are transmitted to the brain.

Vestibule: It is an oval cavity in the middle of the bony labyrinth. The main function of vestibule is balance and coordination.

Semicircular canals: There are three semi-circular interconnected tubes located in inner ear. They are named anterior, posterior and horizontal canals which are placed almost orthogonally to each other. Each canal is lined with hairs called cilia and a fluid called endolymph. These are sensory parts of semicircular canal.

Anatomy of nose:

Nose is located in the middle of the face and is responsible for smell and ventilation. Nose consists of:

External meatus: The triangular-shaped projection in the center of the face is called external meatus of the face.

Nostrils: Nose has two nostrils that are divided by the septum. These are the chambers from which the air enters into the nose.

Septum: Septum divides nostrils and give shape to the nose. It is made up of cartilage and small bones and is covered by mucous membranes. It also gives support to the outer part of the nose.

Turbinates and nasal passages: Tubinates are shelf-like structures which help trap particles entering the nasal passages. Nasal passages are the air ways in the nose. These passages are lined with mucous membranes and hairs called cilia.

Sinuses: Sinuses are the air-filled cavities surrounding the nose. There are four sinuses which are also called paranasal sinuses. They are lined with mucous membranes.

Anatomy of Throat:

The throat is a ring-like muscular tube with fairly complex anatomy. It acts as the passageway for air, food and liquid and also helps in forming speech. Throat consists of

Larynx: It is also known as the voice box. Larynx is a group of cylindrical muscles, cartilages and soft tissues. Apart from producing sound these muscles allow food to pass only down the esophagus, preventing to enter trachea and lungs.

Pharynx: It is considered as the upper part of the airway tract that begins at the back of nasal passages and ends at the top of the esophagus. It is considered as the part of both respiratory system and digestive system.

Epiglottis: It is the piece of cartilage that lies above the vocal cords. It is the important part of throat as it causes the larynx to be blocked off during swallowing to prevent the food and liquid entering the lungs. It acts exactly as valve that closes every time there is need to swallow, even while swallowing the saliva.

Adenoids and Tonsils: They are lymphatic tissues and therefore are the part of immune system. Tonsils are found at the back of nasal passages and adenoids are situated at the back of the throat. They protect against infections. As they are in proximity of nasal passages they are considered as part of throat.

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