The part of the mammalian ear responsible for the maintenance of balance is the

Step 1: Analyze the question The question asks which part of the mammalian ear controls balance (equilibrium), not hearing.

Step 2: Explain the concept The mammalian ear has three main regions:

• Outer ear: pinna and ear canal. They collect sound waves.
• Middle ear: eardrum and three ear ossicles (malleus, incus, stapes). They transmit and amplify vibrations.
• Inner ear: cochlea, and the vestibular system (semicircular canals, utricle and saccule). The cochlea is for hearing and the vestibular system is for balance.

The vestibular system contains fluid (endolymph) and sensory hair cells.

• The semicircular canals detect rotational movement of the head.
• The utricle and saccule detect the position of the head relative to gravity and straight-line movement.

When you move, the fluid shifts and bends the hair cells. Nerve impulses then travel to the brain, which adjusts your posture and keeps you balanced.

Step 3: Evaluate the options

• A. Cochlea: A coiled tube for hearing. It converts sound vibrations into nerve impulses. Not for balance.
• B. Pinna: The external ear flap that collects sound. Not for balance.
• C. Perilymph: A fluid in the inner ear that cushions and transmits vibrations. It is not an organ responsible for balance.
• D. Vestibular system: Contains the semicircular canals, utricle and saccule, which maintain balance. Correct.

Step 4: Answer The correct answer is D. vestibular system.

Exam tip: Remember "Cochlea = Concert (hearing); Vestibular = Vertical (balance)." Also, if you see "semicircular canals" or "utricle and saccule" in an option, think balance right away.