Anatomy of Inner Ear MCQs

The sensory end organ of utricle and saccule are called as macula . They are responsible for linear Balance. The sensory end organ of semicircular canals are called cristae . They are responsible for angular Balance. Each semicircular canal have one narrow end and one dilated end. The dilated end is called ampulla. Cristae are present inside ampulla Cristae contains Gelatinous layer which contains cupula.

Explanation: Inner hair cells (IHCs): IHCs are single row cells responsible for transmitting auditory impulses to the brain via afferent fibers . Outer hair cells (OHCs): OHCs are arranged in 3-4 rows and modulate the function of inner hair cells via efferent pathways, amplifying cochlear sensitivity. Outer hair cells and tectorial membrane movement: OHCs do not primarily move the tectorial membrane . Their role is mainly cochlear amplification ; tectorial membrane motion is a passive mechanical response. (Statement 3 is incorrect) Ratio of Outer: Inner hair cells: OHCs (~12,000) outnumber IHCs (~3,500), approximately a 3:1 ratio.

Travelling wave theory of hearing has been given by Von Bekesy which states that - A sound wave depending on its frequency, reaches maximum amplitude on a particular place in the basilar membrane and stimulates that segment. Therefore, higher frequencies are sensed in the basal turn and low frequencies are sensed in the apex of cochlea. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8th Edition, Page Number- 20.

Utricle and saccule are also called VESTIBULE or OTOLITHIC ORGANS. Utricle and Saccule – Linear balance (Receptor: Macula) Utricle – Horizontal balance Saccule – Vertical balance Semicircular canals – Angular balance(Receptor:Crista) Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8th Edition, pg. no - 20