Human Anatomy
Organs of Hearing and Equilibrium
Ear anatomy for MBBS: external, middle and inner ear, ossicles, auditory tube, cochlea and vestibular apparatus, mapped to NMC codes AN40.1 to AN40.5.
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Organs of Hearing and Equilibrium
Ear anatomy for MBBS: external, middle and inner ear, ossicles, auditory tube, cochlea and vestibular apparatus, mapped to NMC codes AN40.1 to AN40.5.
The organs of hearing and equilibrium chapter covers the external, middle and inner ear, the ossicles, the auditory tube and the cochlear and vestibular receptors. It underpins the anatomy of middle ear infection, hearing loss and balance disorders.
High-yield: Organs of Hearing and Equilibrium
- The ear is divided into the external, middle and internal ear, each with a distinct role in hearing.
- The tympanic membrane separates the external ear from the middle ear and vibrates in response to sound.
- The middle ear contains three ossicles, the malleus, incus and stapes, which transmit vibration to the inner ear.
- The stapes fits into the oval window and passes vibrations to the fluid of the cochlea.
- The tensor tympani is supplied by the mandibular nerve and the stapedius by the facial nerve, both damping loud sounds.
- The facial nerve runs in a bony canal in the medial wall of the middle ear and can be injured in ear disease or surgery.
- The auditory tube connects the middle ear to the nasopharynx and equalises pressure across the tympanic membrane.
- Infection can spread from the throat to the middle ear along the auditory tube, especially in children whose tube is more horizontal.
- The inner ear consists of the bony labyrinth containing the cochlea, vestibule and semicircular canals.
- The cochlea houses the organ of Corti, the receptor for hearing, supplied by the cochlear nerve.
- The semicircular canals detect rotational movement and the utricle and saccule detect linear acceleration and gravity.
- The vestibulocochlear nerve carries hearing and balance information to the brainstem.
- The chorda tympani crosses the middle ear over the tympanic membrane and can be affected in middle ear surgery.
- Otitis media, or middle ear infection, is a common childhood condition linked to the anatomy of the auditory tube.
The three parts of the ear
- **External ear:** Auricle and external acoustic meatus, ending at the tympanic membrane.
- **Middle ear:** Air-filled cavity with the three ossicles, facial nerve, chorda tympani and auditory tube.
- **Inner ear:** Cochlea for hearing and the vestibular apparatus for balance.
- **Nerve:** Vestibulocochlear nerve carries hearing and balance to the brainstem.
NMC competencies in this chapter
- **AN40.1:** External ear: auricle and external acoustic meatus
- **AN40.2:** Middle ear: walls, ossicles and contents
- **AN40.3:** Auditory tube and its clinical importance
- **AN40.4:** Internal ear: bony and membranous labyrinth
- **AN40.5:** Applied anatomy of the ear
Frequently Asked Questions
Why is middle ear infection common in children?
The auditory tube is shorter and more horizontal in children, so infection spreads more easily from the nasopharynx to the middle ear, causing otitis media.
How do the ossicles help hearing?
The malleus, incus and stapes form a chain that transmits vibrations from the tympanic membrane to the oval window, amplifying and passing sound into the cochlear fluid.
Which structures in the middle ear are at risk in ear surgery?
The facial nerve in its bony canal and the chorda tympani crossing the cavity are both close to the surgical field and can be injured.
How does this chapter help in NEET-PG?
Middle ear anatomy, the facial nerve course and the vestibular apparatus are core ENT topics, so ear anatomy is directly high-yield for PG.
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