Human ear
Structure of ear is an important concept to learn in detail from exam perspective. The hair cells present in the inner ear of mammals help in sensing the position of the body, in accordance with gravity and maintain the equilibrium. Let’s learn in detail about the anatomy and physiology of ear.Table of Contents
The three anatomical regions of the ear are – the outer ear, the middle ear and the inner ear. Outer Ear – Parts of Outer earThe outer or external ear anatomy comprises the following parts –
Tympanic membrane or eardrum is made up of connective tissue. Skin covers the outer portion and from inside, it is covered by mucous membrane. The tympanic membrane separates the outer ear from the middle ear. Read more: Anatomy of Tympanic Membrane Outer ear AnatomyAuricle is found closed to the side of the head and comprises of a fine plate of yellow elastic cartilage which is molded into distinct ridges, furrows and hollows forming an irregular shallow funnel. The concha is the deepest depression leading to the external auditory canal. The helix emerges from the base of the concha continuing as the rim of the upper part of the auricle. The antihelix in the inner ridge engirdles the concha and is separated by the scapha from the helix. The external auditory canal is somewhat curved tube extending inwards from the base of the concha and blindly terminates at the tympanic membrane. In its exterior third, the wall of the canal comprises the cartilage and inner comprises the bone. The stretched passage is lined with skin covering the exterior surface of the tympanic membrane. Thin hair directed to the exterior and modified sweat glands producing earwax line the canal and prevent entry of foreign particles. Pinna receives the sound in the form of vibration. The sound waves reach and vibrate the eardrum through the external auditory canal. Also see: NEET 2022 Answer Key Pdf Middle Ear – Parts of the Middle EarThe middle ear anatomy is as follows –
The middle ear amplifies the sound waves and transmits to the inner ear. The middle ear cavity is an air-filled, narrow space. The upper and lower chamber, the tympanum and epitympanum are as a result of a small constriction. The chambers are called atrium and attic. The space of the middle ear somewhat appears as a rectangular room having 4 walls, a roof and a floor. The lateral wall is formed by the tympanic membrane while the superior wall is a bone separating the cranial and middle ear cavity and the brain. The inferior wall is a thin plate separating the middle ear cavity from the jugular vein and that of the carotid artery. The posterior wall somewhat separating the middle ear cavity from the mastoid antrum. In the anterior wall the eustachian tube opening can be found, connecting the middle ear to the nasopharynx. The inner wall separating the middle from the inner ear forms a section of the otic capsule of the inner ear. Explore more: What is the function of eustachian tube? Inner Ear – Parts of the Inner EarThe inner ear anatomy consists of the following parts – Inner ear is the part of the ear containing the structures of the senses of equilibrium and hearing. A cavity in the temporal bone – the bony labyrinth is split into 3 sections – the semicircular canals, vestibule, and the cochlea.
Cochlea (Auditory organ)
Also see:
Vestibular apparatus (Equilibrium organ)
Semicircular canals The three semicircular canals of the bony labyrinth are delegated as per its position – posterior, horizontal, superior. The posterior and superior canals are in diagonal vertical planes intersecting at right angles. Each canal has the ampulla opening into the vestibule. Ampullae or superior and horizontal canals are found above the oval window however, the ampulla of the posterior canal leads to the opposite side of the vestibule. The vestibular aqueduct is near the mouth opening into the cranial cavity. The vestibule completes the circle for every semicircular canal. Physiology of EarEars perform two main functions, hearing and equilibrium maintenance.
Mechanism of Hearing
To summarize the events in the mechanism of hearing: Read more: Auditory Pathway Flowchart Mechanism of Maintaining EquilibriumWe all know that hearing ability is due to ears. Other than hearing, ears are also responsible for maintaining equilibrium. The vestibular apparatus is the main organ for maintaining equilibrium. Static equilibrium is maintained by macula of saccule and utricle. Otoliths press against stereocilia due to gravitational pull and stimulate the initiation of a nerve impulse. When the head is tilted or moves in a straight line with increasing speed, otoliths press on stereocilia of different cells. The brain interprets the nerve impulses resulting in the awareness of body position with respect to ground, irrespective of the head position. Utricle responds to the vertical movement and Saccule responds to the sideways movement of the head. Dynamic equilibrium is detected by cristae of semicircular canals. This was in detail about Structure of Ear. Test your understanding with MCQs on Structure of Ear, only at BYJU’S. Frequently Asked QuestionsThe three main structures of the ear are the outer ear, middle ear and inner ear. Which structure of the ear is responsible for the balance?The vestibular apparatus present above the cochlea in the membranous labyrinth is the main organ for maintaining equilibrium and body balance. It has two sac-like chambers called saccule and utricle and three semicircular canals. The static equilibrium is maintained by macula of saccule and utricle and the dynamic equilibrium is detected by the cristae of semicircular canals. Which structure of the ear contains the auditory receptors?The cochlea is a coiled portion of the membranous labyrinth (inner ear), which looks like a snail. It contains auditory receptors. It contains the organ of Corti present on the basilar membrane, which has auditory receptors. Which structure of the ear contains the hair cells?The cochlea contains hair cells in the organ of Corti. Each organ of Corti contains ~18000 hair cells. They detect pressure waves, there are sensory receptors (afferent nerves) present at the base of hair cells that send signals to the brain. Which structure is found in the middle ear?The middle ear contains three ear bones or ossicles known as malleus (hammer-shaped), incus (anvil-shaped) and stapes (stirrup-shaped). They are named after their shapes in Latin. Stapes is the smallest bone of the human body. Related Articles: What division of the temporal bone contains the organs of hearing and equilibrium?inner ear, also called labyrinth of the ear, part of the ear that contains organs of the senses of hearing and equilibrium. The bony labyrinth, a cavity in the temporal bone, is divided into three sections: the vestibule, the semicircular canals, and the cochlea.
Which part of the temporal bone is related with hearing and balancing?The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance.
Where are the sensory apparatus of both equilibrium and hearing contained?The internal ear, or labyrinth of the ear, houses the organs of hearing and balance. The internal ear is composed of the vestibule, semicircular canals, and cochlea. The vestibule functions to sense linear acceleration, while the semicircular canals sense rotational movements.
What is temporal bone in ear?The temporal bone is comprised of four distinct osseous segments including tympanic, mastoid, petrous, and squamous. The pinna attaches to the lateral surface of the temporal bone and opens up into the external auditory canal (EAC), which is an S-shaped tube that has a cartilaginous and osseous component.
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