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:
- vestibular root (gives rise to the vestibular n, which is responsible for balance & spatial orientation).
- 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 vesible 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 ↳ Sound waves cause the basilar membrane to vibrate & binding the hair cells.
- The bending of the hair cells triggers the releasing of neurotransmitters generatie electric signals in the auditory n. (cochlear n.)
- ② All the central processes of the spiral ganglion comes together to form the cochlear branch of VIII CN.
- ③ The cochlear br. runs through the (6) internal acustic meatus with the facial nerve.
- ④ Then the fibers (SVE) reach the pons-medulla junction where the cochlear nuclei are found.
- There are 2 main types of cochlear nuclei:
- → Dorsal cochlear nucleus
- → Ventral Posterior " "
- → Ventral anterior " ".
located at the junction of the pons & medulla oblongata.
- ⑤ When the auditory signal reach the cochlear nuclei, they give off their axons to process the signals.
lateral leminiscus:
- 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.