Vestibulocochlear nerve
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Updates to Article Attributes
The vestibulocochlear nerve is the eighth (CN VIII) cranial nerve (TA: nervus vestibulocochlearis or nervus cranialis VIII). It exits the brainstem through the cerebellopontine angle, passing into the internal acoustic meatus as part of the acousticofacial bundle. Within the internal acoustic meatus, the nerve branches into cochlear and vestibular nerves to supply the cochlea and vestibule respectively. From these special sensory organs of the inner ear, the vestibulocochlear nerve transmits afferent impulses to the central nervous system encoding auditory stimuli, static (gravitational) equilibrium, and dynamic (rotational) equilibrium.
Terminology
Vestibulocochlear nerve is the preferred term nowadays but older texts may employ the archaic synonym, acoustic nerve. The Federative Committee on Anatomical Terminology decided decades ago that the nerve's name should more accurately reflect its main functions 6.
Gross anatomy
Nucleus and intraparenchymal portion
The dorsal and ventral cochlear nuclei are located in the dorsolateral upper medulla, deep to the lateral angle of the rhomboid fossa. Situated medial to the cochlear nuclei are the four vestibular nuclei, which form two columns extending rostrally into the lower pons 1,2. Fibres from the vestibular and cochlear nuclei pass around the inferior cerebellar peduncle, exiting the brainstem through the cerebellopontine angle at the pontomedullary junction in the form of distinct vestibular and cochlear roots 2.
Cisternal portion
In the cerebellopontine angle, the two roots quickly converge to form a single vestibulocochlear nerve. The nerve makes up the most lateral component of the acousticofacial bundle, the other components of which include the facial nerve, nervus intermedius and labyrinthine artery. The vestibulocochlear nerve passes laterally and slightly anterosuperiorly through the cerebellopontine angle cistern, superior to the petro-occipital fissure, inferior petrosal sinus and posterior aspect of the petrous temporal bone 3. It exits the posterior cranial fossa as part of the acousticofacial bundle, passing through the internal acoustic meatus 1,3.
Intrameatal portion
Travelling laterally within the internal acoustic meatus, the vestibulocochlear nerve divides again into vestibular and cochlear roots, which further divide to supply a number of different targets.
Branches
Cochlear nerve
The cochlear nerve passes through the anteroinferior quadrant of the fundus (most lateral part) of the internal acoustic meatus. It spirals towards the spiral ganglion located in the modiolus of the cochlea. It is here that first-order neurones projecting from the hair cells of the organ of Corti synapse with second-order neurones of the cochlear nerve 4.
Vestibular nerve
At the fundus of the internal acoustic meatus, the vestibular nerve expands to form the vestibular ganglion, from which the following bundles emerge 2,3:
- superior division (utriculo-ampullary nerve): courses in the posterosuperior quadrant of the internal acoustic meatus, carrying sensory fibres from the utricle and hair cells of the superior and lateral semicircular canals
- inferior division (saccular nerve): courses in the posteroinferior quadrant of the internal acoustic meatus to enter the vestibule, carrying sensory fibres from the saccule
- singular nerve (posterior ampullary nerve): courses in the posteroinferior quadrant of the internal acoustic meatus and through the foramen singulare, carrying sensory fibres from the posterior semicircular canal 5
Related pathology
-<p>The <strong>vestibulocochlear nerve </strong>is the <strong>eighth</strong> <strong>(CN VIII) </strong><a href="/articles/cranial-nerves">cranial nerve</a> (<a title="TA (anatomy standard)" href="/articles/terminologia-anatomica-1">TA</a>: nervus vestibulocochlearis or nervus cranialis VIII). It exits the brainstem through the cerebellopontine angle, passing into the <a href="/articles/internal-acoustic-canal">internal acoustic meatus</a> as part of the acousticofacial bundle. Within the internal acoustic meatus, the nerve branches into cochlear and vestibular nerves to supply the <a href="/articles/cochlea">cochlea</a> and <a href="/articles/vestibule-ear">vestibule</a> respectively. From these special sensory organs of the <a href="/articles/inner-ear">inner ear</a>, the vestibulocochlear nerve transmits afferent impulses to the central nervous system encoding auditory stimuli, static (gravitational) equilibrium, and dynamic (rotational) equilibrium.</p><h4>Terminology</h4><p>Vestibulocochlear nerve is the preferred term nowadays but older texts may employ the archaic synonym, acoustic nerve. The Federative Committee on Anatomical Terminology decided decades ago that the nerve's name should more accurately reflect its main functions <sup>6</sup>.</p><h4>Gross anatomy</h4><h5>Nucleus and intraparenchymal portion</h5><p>The dorsal and ventral cochlear nuclei are located in the dorsolateral upper <a href="/articles/medulla-oblongata">medulla</a>, deep to the lateral angle of the <a href="/articles/rhomboid-fossa">rhomboid fossa</a>. Situated medial to the <a href="/articles/cochlear-nuclei">cochlear nuclei</a> are the four vestibular nuclei, which form two columns extending rostrally into the lower <a href="/articles/pons">pons</a> <sup>1,2</sup>. Fibres from the vestibular and cochlear nuclei pass around the <a href="/articles/inferior-cerebellar-peduncle-1">inferior cerebellar peduncle</a>, exiting the <a href="/articles/brainstem">brainstem</a> through the cerebellopontine angle at the pontomedullary junction in the form of distinct vestibular and cochlear roots <sup>2</sup>.</p><h5>Cisternal portion </h5><p>In the cerebellopontine angle, the two roots quickly converge to form a single vestibulocochlear nerve. The nerve makes up the most lateral component of the acousticofacial bundle, the other components of which include the <a href="/articles/facial-nerve">facial nerve</a>, <a href="/articles/nervus-intermedius">nervus intermedius</a> and <a href="/articles/labyrinthine-artery">labyrinthine artery</a>. The vestibulocochlear nerve passes laterally and slightly anterosuperiorly through the <a href="/articles/cerebellopontine-angle-cistern">cerebellopontine angle cistern</a>, superior to the <a href="/articles/petro-occipital-fissure-1">petro-occipital fissure</a>, <a href="/articles/inferior-petrosal-sinus">inferior petrosal sinus</a> and posterior aspect of the <a href="/articles/petrous-part-of-temporal-bone">petrous temporal bone</a> <sup>3</sup>. It exits the <a href="/articles/posterior-cranial-fossa">posterior cranial fossa</a> as part of the acousticofacial bundle, passing through the internal acoustic meatus <sup>1,3</sup>.</p><h5>Intrameatal portion</h5><p>Travelling laterally within the internal acoustic meatus, the vestibulocochlear nerve divides again into vestibular and cochlear roots, which further divide to supply a number of different targets.</p><h4>Branches</h4><h5>Cochlear nerve</h5><p>The <a title="Cochlear nerve" href="/articles/cochlear-nerve">cochlear nerve</a> passes through the anteroinferior quadrant of the fundus (most lateral part) of the internal acoustic meatus. It spirals towards the <a href="/articles/spiral-ganglion">spiral ganglion</a> located in the <a title="Modiolus (cochlea)" href="/articles/modiolus-cochlea">modiolus of the cochlea</a>. It is here that first-order neurones projecting from the hair cells of the <a href="/articles/organ-of-corti">organ of Corti</a> synapse with second-order neurones of the cochlear nerve <sup>4</sup>.</p><h5>Vestibular nerve</h5><p>At the fundus of the internal acoustic meatus, the vestibular nerve expands to form the <a href="/articles/vestibular-ganglion">vestibular ganglion</a>, from which the following bundles emerge <sup>2,3</sup>:</p><ul>- +<p>The <strong>vestibulocochlear nerve </strong>is the <strong>eighth</strong> <strong>(CN VIII) </strong><a href="/articles/cranial-nerves">cranial nerve</a> (<a href="/articles/terminologia-anatomica-1">TA</a>: nervus vestibulocochlearis or nervus cranialis VIII). It exits the brainstem through the cerebellopontine angle, passing into the <a href="/articles/internal-acoustic-canal">internal acoustic meatus</a> as part of the acousticofacial bundle. Within the internal acoustic meatus, the nerve branches into cochlear and vestibular nerves to supply the <a href="/articles/cochlea">cochlea</a> and <a href="/articles/vestibule-ear">vestibule</a> respectively. From these special sensory organs of the <a href="/articles/inner-ear">inner ear</a>, the vestibulocochlear nerve transmits afferent impulses to the central nervous system encoding auditory stimuli, static (gravitational) equilibrium, and dynamic (rotational) equilibrium.</p><h4>Terminology</h4><p>Vestibulocochlear nerve is the preferred term nowadays but older texts may employ the archaic synonym, acoustic nerve. The Federative Committee on Anatomical Terminology decided decades ago that the nerve's name should more accurately reflect its main functions <sup>6</sup>.</p><h4>Gross anatomy</h4><h5>Nucleus and intraparenchymal portion</h5><p>The dorsal and ventral cochlear nuclei are located in the dorsolateral upper <a href="/articles/medulla-oblongata">medulla</a>, deep to the lateral angle of the <a href="/articles/rhomboid-fossa">rhomboid fossa</a>. Situated medial to the <a href="/articles/cochlear-nuclei">cochlear nuclei</a> are the four vestibular nuclei, which form two columns extending rostrally into the lower <a href="/articles/pons">pons</a> <sup>1,2</sup>. Fibres from the vestibular and cochlear nuclei pass around the <a href="/articles/inferior-cerebellar-peduncle-1">inferior cerebellar peduncle</a>, exiting the <a href="/articles/brainstem">brainstem</a> through the cerebellopontine angle at the pontomedullary junction in the form of distinct vestibular and cochlear roots <sup>2</sup>.</p><h5>Cisternal portion </h5><p>In the cerebellopontine angle, the two roots quickly converge to form a single vestibulocochlear nerve. The nerve makes up the most lateral component of the acousticofacial bundle, the other components of which include the <a href="/articles/facial-nerve">facial nerve</a>, <a href="/articles/nervus-intermedius">nervus intermedius</a> and <a href="/articles/labyrinthine-artery">labyrinthine artery</a>. The vestibulocochlear nerve passes laterally and slightly anterosuperiorly through the <a href="/articles/cerebellopontine-angle-cistern">cerebellopontine angle cistern</a>, superior to the <a href="/articles/petro-occipital-fissure-1">petro-occipital fissure</a>, <a href="/articles/inferior-petrosal-sinus">inferior petrosal sinus</a> and posterior aspect of the <a href="/articles/petrous-part-of-temporal-bone">petrous temporal bone</a> <sup>3</sup>. It exits the <a href="/articles/posterior-cranial-fossa">posterior cranial fossa</a> as part of the acousticofacial bundle, passing through the internal acoustic meatus <sup>1,3</sup>.</p><h5>Intrameatal portion</h5><p>Travelling laterally within the internal acoustic meatus, the vestibulocochlear nerve divides again into vestibular and cochlear roots, which further divide to supply a number of different targets.</p><h4>Branches</h4><h5>Cochlear nerve</h5><p>The <a href="/articles/cochlear-nerve">cochlear nerve</a> passes through the anteroinferior quadrant of the fundus (most lateral part) of the internal acoustic meatus. It spirals towards the <a href="/articles/spiral-ganglion">spiral ganglion</a> located in the <a href="/articles/modiolus-cochlea">modiolus of the cochlea</a>. It is here that first-order neurones projecting from the hair cells of the <a href="/articles/organ-of-corti">organ of Corti</a> synapse with second-order neurones of the cochlear nerve <sup>4</sup>.</p><h5>Vestibular nerve</h5><p>At the fundus of the internal acoustic meatus, the vestibular nerve expands to form the <a href="/articles/vestibular-ganglion">vestibular ganglion</a>, from which the following bundles emerge <sup>2,3</sup>:</p><ul>
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Image 2 Diagram (Vestibulocochlear nerve) ( create )
Image 4 MRI (T2) ( update )
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