Question

Which of the following cranial nerves is mixed in function?
(a) Olfactory
(b) Vagus
(c) Oculomotor
(d) Trochlear

Answer 1

Hint: Cranial nerves mainly have two functions, motor and sensory. Some are purely sensory, some are purely motor while others have mixed functions. The tenth cranial nerve is one of the nerves with mixed functions.
Complete answer: Mixed cranial nerves are the cranial nerves that perform both sensory and motor functions as they have both afferent and efferent fibres. There are four such cranial nerves in our peripheral nervous system
- Trigeminal nerve (CN V)
- Facial nerve (CN VII)
- Glossopharyngeal nerve (CN IX)
- Vagus nerve (CN X)
The Vagus nerve is the tenth cranial nerve (CN X) , and is the longest and most complex cranial nerve. The Vagus primarily supplies the organs of the chest and abdomen, and not the head and neck. The name “Vagus” is given as it has a vague or wandering course going towards the abdomen.
Except for the adrenal glands, the Vagus supplies motor parasympathetic fibres to all the organs, from the neck down to the second segment of the transverse colon. The Vagus also controls a few voluntary muscles.
Different nerve fibres of the Vagus innervate the pharynx and back of the throat and are responsible for the gag reflex. Stimulation of the Vagus in the cervical portion of the uterus can lead to a vasovagal response. The Vagus also plays a role in satiation after food consumption i.e. the feeling of satisfaction or a full belly. It is seen that if the vagal response is suppressed, people eat a lot more than they would otherwise.
So, the answer is, “Vagus.”

Note: The other three nerves which perform mixed-function are also very important nerves. The trigeminal nerve supplies the pulp of all the teeth by its maxillary and mandibular branches. The facial nerve supplies the facial muscles, muscles of mastication, and also the tongue.