Anatomy Bones and Muscles · MU Pleven

175. Vestibular portion of the VIII nerve. Vestibular pathway.

Covers the vestibulocochlear nerve's two divisions and the cochlear (auditory) pathway from the pinna through the cochlea, internal acoustic meatus and cochlear nuclei to the temporal cortex. It then turns to the vestibular pathway: the peripheral semicircular canals, utricle and saccule, the route to the vestibular nuclei, and their four connections with the spinal cord, cerebellum, eye-movement nuclei and thalamus. A table of the vestibular nuclei complex and several diagrams accompany the text.

Inside: 3 sections · 7 labelled pictures · 2 tables · 10 flashcards · 3 min

Topic 174 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 3 sections, about 400 words (3 min of reading), with 10 flashcards.

In this note

  1. VESTIBULOCOCHLEAR NERVE
  2. Cochlear nerve pathway: (auditory pathway)
  3. Vestibular pathway:

VESTIBULOCOCHLEAR NERVE

  • The vestibulocochlear nerve, also known as the eight cranial nerve (CN VIII), responsible for transmitting sensory information related to hearing and balance.
  • It consists of 2 divisions, each emerge from their respective roots:
  1. 1. vestibular root (gives rise to the vestibular n, which is responsible for balance & spatial orientation).
  2. 2. Cochlear root (gives rise to cochlear nerve, which responsible for transmitting auditory information related to hearing )

Cochlear nerve pathway: (auditory pathway)

  • External ear: (1) Pinna (the visible part of the ear) ↳ collect sound waves & direct them into (2) ear canal.
  • Middle ear: (3) Tympanic membrane ↓ (4) Ear bones
  • Inner ear: (5) Cochlea ↳ the basil membrane contains hair cells.
  1. ① Sound waves cause the basilar membrane to vibrate & binding the hair cells.
  • The bending of the hair cells triggers the releasing of neurotransmitters generatic electric signals in the auditory n. (cochlear n.)
  1. ② All the central processes of the spiral ganglion comes together to form the cochlear branch of VIII CN.
  2. ③ The cochlear br. runs through the (6) internal acoustic meatus with the facial nerve.
  3. ④ Then the fibers (SVE) reach the pons-medulla junction where the cochlear nuclei are found.
  • There are 2 main types of cochlear nuclei:
  1. ⑤ When the auditory signal reach the cochlear nuclei, they give off their axons to process the signals.

lateral lemniscus:

  1. ⑥ Finally, the thalamus sends auditory signals to the primary auditory cortex located in the temporal lobe.
  • ↳ Responsible for the initial processing & understanding of auditory information.

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