**Core Concept**
The 8th cranial nerve, also known as the vestibulocochlear nerve, plays a crucial role in transmitting sensory information from the inner ear to the brain. This nerve is responsible for processing sound and maintaining balance and equilibrium.

**Why the Correct Answer is Right**
The vestibulocochlear nerve consists of two divisions: the cochlear nerve, which is responsible for hearing, and the vestibular nerve, which is responsible for balance. The cochlear nerve contains sensory neurons that transmit sound information from the cochlea to the auditory cortex in the temporal lobe. The vestibular nerve contains sensory neurons that transmit information about head position, movement, and acceleration from the vestibular apparatus to the brainstem. This information is essential for maintaining balance and preventing falls.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the 8th cranial nerve is not responsible for controlling facial expressions or taste. The 7th cranial nerve (facial nerve) is responsible for controlling facial expressions, while the 9th and 10th cranial nerves (glossopharyngeal and vagus nerves) are involved in taste.

**Option B:** This option is incorrect because the 8th cranial nerve is not responsible for transmitting motor signals to the muscles of the face or head. The 7th cranial nerve (facial nerve) is responsible for transmitting motor signals to the muscles of the face.

**Option C:** This option is incorrect because the 8th cranial nerve is not responsible for transmitting sensory information from the skin or joints. The 5th cranial nerve (trigeminal nerve) is responsible for transmitting sensory information from the face, while the 2nd and 3rd cranial nerves (optic and oculomotor nerves) are involved in transmitting sensory information from the eyes.

**Clinical Pearl / High-Yield Fact**
The vestibulocochlear nerve is often affected in patients with Ménière's disease, a disorder of the inner ear that causes vertigo, hearing loss, and tinnitus. The symptoms of Ménière's disease can be managed with vestibular rehabilitation therapy and medications that reduce vertigo and hearing loss.

**Correct Answer: C. The function of 8th cranial nerve is related to hearing and balance.**