The trapezoid body is part of the auditory pathway. It is a bundle of fibers and cells in the pontine tegmentum. It consists of fibers arising from the ventral cochlear nucleus. A collection of nerve cells inside forms a trapezoid nucleus. The superior olivary nucleus is situated on the dorsal surface of the trapezoid body. Most nerve fibers pass directly from the superior olivary nuclei to the inferior colliculus.
Axons leaving the ventral cochlear nucleus (VCN) form a broad pathway that crosses under the brain stem in the trapezoid body. A thin pathway, the intermediate acoustic stria, also leaves the VCN, merging with the trapezoid body close to the superior olivary complex, where many of its axons synapse. Axons leaving the dorsal cochlear nucleus (DCN) form the dorsal acoustic stria, which reaches primarily the contralateral dorsal nucleus of the lateral lemniscus and the central nucleus of the inferior colliculus.
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Human brain, rhombencephalon, metencephalon: pons (TA A14.1.05.101–604, GA 9.785)
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Dorsal/
(tegmentum) |
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Surface
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Cerebellopontine angle · Superior medullary velum · Sulcus limitans · Medial eminence · Facial colliculus
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White: Sensory/ascending
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Trapezoid body/VIII · Trigeminal lemniscus (Dorsal trigeminal tract, Ventral trigeminal tract) · Medial lemniscus · Lateral lemniscus
MLF, III, IV and VI: Vestibulo-oculomotor fibers
Anterior trigeminothalamic tract · Central tegmental tract
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White: Motor/descending
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ICP (Vestibulocerebellar tract)
MLF, III, IV and VI: Vestibulospinal tract (Medial vestibulospinal tract, Lateral vestibulospinal tract)
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Grey: Cranial nuclei
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afferent: GSA: Principal V/Spinal V · VIII-c (Dorsal, Anterior)/VIII-v (Superior)
efferent: SVE: Motor V · VII · GSE: VI · GVE: VII: Superior salivary nucleus
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Other grey
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Apneustic center · Pneumotaxic center (Medial parabrachial nucleus) · Lateral parabrachial nucleus · Superior olivary nucleus · Caerulean nucleus
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Ventral/
(base) |
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Grey
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Pontine nuclei
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White: Motor/descending
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Corticospinal tract · Corticobulbar tract · Corticopontine fibers
MCP (Pontocerebellar fibers)
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Surface
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Basilar sulcus
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Other grey: Raphe/
reticular |
Reticular formation (Caudal, Oral, Tegmental, Paramedian) · Raphe nuclei (Median)
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M: CNS
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anat(n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp
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noco(m/d/e/h/v/s)/cong/tumr, sysi/epon, injr
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proc, drug(N1A/2AB/C/3/4/7A/B/C/D)
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Auditory and vestibular pathways
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| Auditory |
- inner ear: Hair cells → Spiral ganglion → Cochlear nerve VIII →
- pons: Cochlear nuclei (Anterior, Dorsal) → Trapezoid body → Superior olivary nuclei →
- midbrain: Lateral lemniscus → Inferior colliculi →
- thalamus: Medial geniculate nuclei →
- cerebrum: Acoustic radiation → Primary auditory cortex
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| Vestibular |
- inner ear: Vestibular nerve VIII →
- pons: Vestibular nuclei (Medial vestibular nucleus, Lateral vestibular nucleus)
- cerebellum: Flocculonodular lobe
- spinal cord: Vestibulospinal tract (Medial vestibulospinal tract, Lateral vestibulospinal tract)
- thalamus: Ventral posterolateral nucleus
- cerebrum: Vestibular cortex
- Vestibulo-oculomotor fibers
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M: EAR
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anat(e/p)/phys/devp
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noco/cong, epon
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proc, drug(S2)
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