Human Ear: Structure, Function, Parts, Balance, Anatomy, Hearing

Hearing and balance are two important functions of the human ear. It has three different parts the outer ear, the middle ear, and the inner ear. It also maintains the balance through the vestibular system in the inner ear. This topic is important in biology, especially for exams like NEET and AIIMS BSc Nursing that also focus on the sensory systems.

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This Story also Contains

1. Human Ear
2. Structure of the Ear
3. Function of the Ear

Human Ear

The human ear is a complex organ responsible for hearing and balance. There exist three parts of the human ear, the outer ear, which collects the sound, the middle ear, in which the collected sound gains amplification, and the inner ear, where the sound vibrations are changed into signals that reach to be read by the brain. The inner ear also helps the body maintain its balance. These structures work together for us to hear sounds and balance ourselves.

• Practice MCQ on the Structure of Human Ear
• Neural Control and Coordination
• Diagram of Ear
• Chemical Coordination and Integration

Structure of the Ear

The human ear consists of three main parts:

1. External Ear

2. Middle Ear

3. Internal Ear

External Ear

The external ear is divided into the following parts:

Auricle (Pinna)

• The auricle, or pinna, is a thin plate of elastic cartilage covered by a layer of skin.

• Its funnel-like curves collect sound waves and transmit them to the middle ear. The lobule consists of adipose and fibrous tissues supplied with blood capillaries.

External Auditory Meatus

• The external auditory meatus is a slightly curved canal supported by bone in its interior part and cartilage in the exterior part.

• The canal is lined with stratified epithelium and wax glands.

Tympanic Membrane

• The tympanic membrane separates the middle ear from the external ear.

• This membrane receives and amplifies sound waves. Its central part is known as the umbo.

Middle Ear

The middle ear comprises the following parts:

Tympanic Cavity

• The tympanic cavity is a narrow, air-filled cavity separated from the external ear by the tympanic membrane and from the inner ear by a bony wall.

• It contains an auditory tube known as the eustachian tube in its anterior wall.

Eustachian Tube

• The eustachian tube is a 4 cm long tube that equalizes air pressure on either side of the tympanic membrane.

• It connects the tympanic cavity with the nasopharynx.

Ear Ossicles

The ear ossicles transmit sound waves from the eardrum to the middle ear. There are three ear ossicles:

• Malleus: A hammer-shaped part attached to the tympanic membrane through its handle and to the incus through its head. It is the largest ear ossicle.

• Incus: An anvil-shaped ear ossicle connected with the stapes.

• Stapes: The smallest ossicle and the smallest bone in the human body.

Inner Ear

The inner ear comprises two main parts:

• Bony labyrinth
• Membranous labyrinth

Bony Labyrinth

• The bony labyrinth consists of a vestibule, three semi-circular canals, and a spirally coiled cochlea. It is filled with perilymph.

Membranous Labyrinth

• The bony labyrinth surrounds the membranous labyrinth, which contains sensory receptors responsible for balance and hearing.

• The membranous labyrinth is filled with endolymph and includes three semi-circular ducts, the cochlear duct, saccule, and utricle.

• The sensory receptors are cristae, the organ of Corti, and ampullary maculae.

Human Ear Diagram

The ear structure diagram is given below:

Function of the Ear

The human ear performs two primary functions: hearing and maintaining balance.

Hearing

The mechanism of hearing involves the following steps:

• Sound waves pass through the auditory canal and reach the eardrum.
• The vibrations produced pass through the tympanic membrane to the tympanic cavity.
• The ear ossicles in the tympanic cavity receive the vibrations, and the stapes push the oval window in and out.
• This action is transmitted to the organ of Corti, the receptor of hearing, which contains tiny hair cells that translate the vibrations into electrical impulses transmitted to the brain by sensory nerves.

Balance

The eustachian tube and the vestibular complex are crucial for maintaining balance.

• Eustachian Tube: It equalizes air pressure in the middle ear, helping to maintain balance.

• Vestibular Complex: This complex contains receptors that maintain body balance.

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