Question

Which cranial nerve provides taste sensation in the anterior ${{\displaystyle \frac{2}{3}}}^{rd}$ part of the tongue?
A. Vagus
B. Facial
C. Glossopharyngeal
D. Hypoglossal

Answer 1

Hint: Tongue is a muscular organ present in the mouth which helps in mastication of food, speaking and also swallowing of food. It is supplied with blood vessels, nerves and blood.The cranial nerves are 12 pairs of nerves that can be seen on the ventral surface of the brain.

Complete answer:
Let us analyse each given option to find out the correct answer.

Option A: Vagus nerve is the longest and most complex of the 12 pairs of cranial nerves. It transmits information to or from the surface of the brain to tissues and organs elsewhere in the body. Therefore, this is an incorrect option.

Option B: The tongue is divided into three parts called anterior two third parts, posterior one third part and the base of the tongue. Different nerves for taste and sensation are present in the parts of the tongue. The nerve responsible for taste in the anterior two third part of the tongue is the chorda tympani branch of the facial nerve. This nerve is responsible for sensation in this part is a lingual branch of the mandibular division of the trigeminal nerve. Therefore, this is the correct option.

Option C: Glossopharyngeal nerve is a mixed nerve that consists both of the motor and sensory fibers that rise from its nuclei. It supplies sensory innervation to the oropharynx, and thus carries the afferent information for the gag reflex. Therefore, this is an incorrect option.

Option D: The hypoglossal nerve arises from the hypoglossal nucleus in the medulla oblongata of the brainstem. It is mainly a somatic efferent (motor) nerve. It innervates the tongue musculature. The nerve also contains some sympathetic postganglionic fibers from the cervical ganglia, which innervates tongue vessels and some small glands in the oral mucosa.Therefore, this is an incorrect option.

Thus, the correct option is B, Facial.

Note: The facial nerve is the seventh cranial nerve and can be denoted as VII. It arises from the pons of the brainstem and is involved in controlling the muscles of facial expression.