Utricle (ear)
The utricle is a small membranous sac (part of the membranous labyrinth) and paired with the saccule lies within the vestibule of the inner ear. It has an important role in orientation and static balance, particularly in horizontal tilt.
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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 utricle lies on the medial wall of the vestibule and is in contact with the recessus ellipticus 2. It is larger in size compared to the saccule. The utricle communicates with the saccule via the utriculosaccular duct 1.
Lying horizontally on the floor of the utricle lies a projection known as the macula, the sensory organ of the utricle 4. This sensory epithelium is lined by vestibular cells which are mechanoreceptors, containing stereocilia and kinocilia (hair cells and supporting cells respectively) 2. These cells project into the membranous labyrinth called the statoconial membrane, a gelatinous layer beyond containing otoliths (calcium carbonate particles) 2,4. Cilia from the hair cells are attached to these otoliths 2.
Function
Any change in the orientation of the head results in stimulation of the utricle, via movement in the otolith-cilia-macula complex, releasing signals that the brain interprets 2,4. The utricle is more sensitive to horizontal acceleration in comparison to the saccule, which is more sensitive to vertical acceleration 1,4.
Arterial supply
The anterior vestibular artery is the second branch of the labyrinthine artery. This artery supplies the utricle 1.
Innervation
The mechanoreceptors of the utricle are connected to the nervous system by fibers of the vestibular division of the vestibulocochlear nerve (VIII) 1.
Radiographic features
The utricle 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 utricle, 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)
-
sutures
- calvarial
- facial
- frontozygomatic suture
- frontomaxillary suture
- frontolacrimal suture
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- 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
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cranial vault
- muscles of the head and neck
- muscles of the tongue (mnemonic)
- muscles of mastication
- muscles of facial expression
- muscles of the middle ear
- orbital muscles
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- pharyngeal muscles
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- infrahyoid muscles
- intrinsic muscles of the larynx
- muscles of the neck
- deep cervical fascia
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deep spaces of the neck
- anterior cervical space
- buccal space
- carotid space
- danger space
- deep cervical fascia
- infratemporal fossa
- masticator space
- parapharyngeal space
- 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
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- larynx
- viscera of the neck
- blood supply of the head and neck
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arterial supply
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common carotid artery
- carotid body
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- variants
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common carotid artery
- venous drainage
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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)
- 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
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cervical plexus
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- geniohyoid
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ansa cervicalis
- omohyoid (superior and inferior bellies separately)
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- 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
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