Saccule (Ear)
The saccule is a small membranous sac, paired with the utricle, within the vestibule of the inner ear. It is part of the membranous labyrinth and has an important role in orientation and balance, particularly in vertical tilt 1.
On this page:
Gross anatomy
The vestibule is located within the bony labyrinth (temporal bone) of the inner ear 2, inferior to the semicircular canals 1. The utricle and the saccule are co-located within the vestibule 3. The saccule lies in the medial wall of the vestibule, near the opening of the vestibular duct of the cochlea in the recessus sphaericus 1,5. It is smaller in size compared to the utricle and globular in appearance. The saccule is oriented in a vertical plane 2.
The saccule communicates with the cochlear duct through the ductus reuniens and it communicates with the utricle via the utriculosaccular duct 5.
Within the anterior aspect of the saccule lies a projection known as the macula, the sensory organ of the saccule 2. Like the utricle, this sensory epithelium of the saccule is lined by vestibular cells 1. These cells project into the membranous labyrinth called the statoconial membrane, a gelatinous layer beyond containing otoliths (calcium carbonate particles) 1,2. Cilia from the hair cells are attached to these otoliths 5.
Function
Any change in the orientation of the head results in stimulation of the saccule, via movement in the otolith-cilia-macula complex, releasing signals that the brain interprets 2,4. The saccule is sensitive to vertical acceleration in comparison to the utricle, which is more sensitive to horizontal acceleration 2,5. Unlike the utricle, the saccule also provides information about head position even when it is stationary.
Arterial supply
The saccule receives its blood supply from two arteries. The anterior vestibular artery (second branch of the labyrinthine artery) and the posterior vestibular artery both supply the saccule 5.
Innervation
The inferior vestibular nerve supplies the saccule. This nerve is a branch of the vestibular nerve, itself a division of the vestibulocochlear nerve (VIII) 5.
Radiographic features
The saccule itself is too small to be distinguished on high-resolution CT or MRI 6, but sits in the medial portion of the vestibule.
Related pathology
Damage to the otolith-containing organs such as the saccule can result in a reduced ability to sense motion and orientation, leading to vestibular symptoms, e.g. imbalance 5.
See also
Related Radiopaedia articles
Anatomy: Head and neck
- skeleton of the head and neck
-
cranial vault
- scalp (mnemonic)
- fontanelle
-
sutures
- calvarial
- facial
- frontozygomatic suture
- frontomaxillary suture
- frontolacrimal suture
- frontonasal suture
- temporozygomatic suture
- zygomaticomaxillary suture
- parietotemporal suture (parietomastoid suture)
- occipitotemporal suture (occipitomastoid suture)
- sphenofrontal suture
- sphenozygomatic suture
- spheno-occipital suture (not a true suture)
- lacrimomaxillary suture
- nasomaxillary suture
- internasal suture
- basal/internal
- skull landmarks
- frontal bone
- temporal bone
- parietal bone
- occipital bone
- skull base (foramina)
-
facial bones
- midline single bones
- paired bilateral bones
- cervical spine
- hyoid bone
- laryngeal cartilages
-
cranial vault
- muscles of the head and neck
- muscles of the tongue (mnemonic)
- muscles of mastication
-
muscles of facial expression
- occipitalis muscle
- circumorbital and palpebral muscles
- nasal muscles
- buccolabial muscles
- elevators, retractors and evertors of the upper lip
- levator labii superioris alaeque nasalis muscle
- levator labii superioris muscle
- zygomaticus major muscle
- zygomaticus minor muscle
- malaris muscle
- levator anguli oris muscle
- risorius muscle
- depressors, retractors and evertors of the lower lip
- depressor labii inferioris muscle
- depressor anguli oris muscle
- mentalis muscle
- compound sphincter
- orbicularis oris muscle
- incisivus superior muscle
- incisivus inferior muscle
- muscle of mastication:
- elevators, retractors and evertors of the upper lip
- muscles of the middle ear
- orbital muscles
- muscles of the soft palate
- pharyngeal muscles
- suprahyoid muscles
- infrahyoid muscles
- intrinsic muscles of the larynx
- muscles of the neck
- accessory muscles of the neck
- deep cervical fascia
-
deep spaces of the neck
- anterior cervical space
- buccal space
- carotid space
- danger space
- deep cervical fascia
- infratemporal fossa
- masticator space
- parapharyngeal space
- stylomandibular tunnel
- parotid space
- pharyngeal (superficial) mucosal space
- perivertebral space
- posterior cervical space
- pterygopalatine fossa
- retropharyngeal space
- suprasternal space (of Burns)
- visceral space
- surgical triangles of the neck
- orbit
- ear
- paranasal sinuses
- nose
- oral cavity
- pharynx
- larynx
- viscera of the neck
- blood supply of the head and neck
-
arterial supply
-
common carotid artery
- carotid body
- carotid bifurcation
- subclavian artery
- variants
-
common carotid artery
- venous drainage
-
arterial supply
- innervation of the head and neck
-
cranial nerves
- olfactory nerve (CN I)
- optic nerve (CN II)
- oculomotor nerve (CN III)
- trochlear nerve (CN IV)
-
trigeminal nerve (CN V) (mnemonic)
- trigeminal ganglion
- ophthalmic division
- maxillary division
- mandibular division
- abducens nerve (CN VI)
- facial nerve (CN VII)
-
vestibulocochlear nerve (CN VIII)
- vestibular ganglion (Scarpa's ganglion)
- glossopharyngeal nerve (CN IX)
-
vagus nerve (CN X)
- superior laryngeal nerve
- recurrent laryngeal nerve (inferior laryngeal nerve)
- (spinal) accessory nerve (CN XI)
- hypoglossal nerve (CN XII)
- parasympathetic ganglia of the head and neck
- greater occipital nerve
- third occipital nerve
-
cervical plexus
- muscular branches
- longus capitis
- longus colli
- scalenes
- geniohyoid
- thyrohyoid
-
ansa cervicalis
- omohyoid (superior and inferior bellies separately)
- sternothyroid
- sternohyoid
- phrenic nerve
- contribution to the accessory nerve (CN XI)
- cutaneous branches
- muscular branches
- brachial plexus
- pharyngeal plexus
-
cranial nerves
- lymphatic drainage of the head and neck
- embryological development of the head and neck
Unable to process the form. Check for errors and try again.