Saccule
Sacculus
Also known as: sacculus, macula of saccule
The smaller, globular otolith organ in the spherical recess of the vestibule; its vertically oriented macula senses vertical linear acceleration and head tilt in the sagittal plane.
Overview
The saccule lies anteroinferior to the utricle, close to the stapes footplate. It is connected to the cochlear duct by the ductus reuniens and to the utricle and endolymphatic duct by the utriculosaccular duct.
Its macula is hook-shaped and oriented vertically on the medial wall (in a near-sagittal plane). It therefore responds to vertical linear acceleration — standing up, sitting down, lifts and jumping — and to forward–backward tilts. Like the utricle it has a striola dividing hair cells of opposite polarity.
Phylogenetically the saccule is an ancient hearing organ in fish, and in humans it remains sensitive to loud low-frequency sounds and bone-conducted vibration, which is exploited clinically in vestibular evoked myogenic potential (VEMP) testing.
- Location
Spherical recess of the vestibule, anteroinferior to the utricle and near the oval window.
Anatomy
- Innervation
Saccular nerve → mainly the inferior vestibular nerve (a small part to the superior division).
- Histology
Macula with type I and II hair cells and an otoconia-laden otolithic membrane.
- Development
Derived from the ventral (saccular–cochlear) part of the otocyst, from which the cochlear duct grows out.
Function
- Sense vertical linear acceleration
- Sense head tilt in the sagittal plane
- Respond to loud sound/vibration (basis of cervical VEMPs)
Clinical significance
Tumarkin otolithic crisis
In late Ménière disease, sudden saccular/utricular stimulation can cause drop attacks without loss of consciousness.
Compiled from standard anatomy and physiology references — see the Special Senses sources. For education only; not medical advice.