Question

Identify the origin of the vestibulocochlear (VIII) nerve in the brain, the foramen through which it exits the skull, and the functions of each of its branches.

Answer 1

ANSWER---

VESTIBULOCOCHLEAR NERVE ALSO CALLED 8TH CRANIAL NERVE.

ORIGIN

RHOMBOID FOSSA OF THE BRAINSTEM

---VESTIBULOCOCHLEAR NERVE originates near the pontomedullary junction and it leaves the skull and goes into the internal auditory canal near the temporal bone.

--- It has two main component:

1. VESTIBULAR COMPONENT
2. COCHLEAR COMPONENT

--- VESTIBULAR COMPONENT PERFROMS THE BALANCE

----COCHLEAR COMPONENT PERFORMS THE HEARING

There are two main branches of the vestibulocochlear nerve which divides into the component and enters the internal ear and there two component vestibular part performs the balance of the body in the ear and cochlear part performs the hearing function.

This nerve have the root of both component from the origin itself and when it reaches to the internal ear both root divides and goes in there respective part.

They both have there respective nuclei in the brainstem.

After entering into the internal acoustic meatus nerve gets divides into the two part and they both takes the different roots and pathways in the internal ear.

Cochlear root goes near the lower anterior fundus of the internal ascoustic meatus and vestibular root also passes through the vestibular ganglion passes to the fundus of the internal ascoustic meatus and then divides into the three branches:

1. utrico ampulary nerve
2. sacular nerve
3. posterior ampulary nerve

​​​​​​​And of these nerve the utrico ampulary nerve also gets splitted into further three branches:

1. utricular nerve
2. anterior ampulary nerve
3. lateral ampulary nerve

In which the utricular nerve innervates the macula of the utricle and anterior ampulary nerve innervates the crista ampularis of the anterior ampula and lateral ampulary nerve innervates the crista ampularis of the lateral ampula.

Sacular nerves via penetrating the fundus of the internal ascoustic meatus enters the vestibule and there innervates the macula of the saccule and helps in detections of somatosensory stimulis.

While posterior ampulary innervates the crista ampularis of the posterior ampula ,

They are helpful in detection of the somatosensory signals and going balance and hearing the internal ear.​​​​​​​

I hope this is clear please rate it and ask if any doubt in comments.