Question

The set of mixed nerves is
A) Optic, auditory, olfactory
B) Auditory, trigeminal, hypoglossal
C) Oculomotor, pathetic, abducens
D) Vagus, facial, trigeminal

Answer 1

Mixed nerves contain both afferent and efferent axons, thus they conduct both incoming sensory information and outgoing muscle commands within the same bundle. They are also composed of both motor and sensory fibers, and transmit messages in both directions at once.

Complete answer:
A nerve is an enclosed and cable-like bundle of nerve fibres called axons, in the peripheral nervous system. A nerve transmits electrical impulses and also it is a basic unit of the peripheral nervous system.
Nerves are categorized into three groups based on the direction that signals get conducted

1. Sensory nerves, also called afferent nerves, carry information from the outside world, such as sensations of heat, cold, and pain, to the brain and spinal cord.
2. Motor nerves, or efferent nerves, transmit impulses from the brain and spinal cord to the muscles.
3. Mixed nerves are composed of both motor and sensory fibers, and transmit messages in both directions at once.

Let us analyze the given options

Option A is incorrect as optic, auditory and olfactory are sensory nerves.
Option B is incorrect as auditory is sensory and hypoglossal is motor nerve.
Option C is incorrect as oculomotor and abducens both are motor nerves.
Option D is correct as Vagus, Facial and Trigeminal nerves as all of them are mixed nerves.

Hence, the correct answer is option (D) i.e., Vagus, Facial and Trigeminal.

Note: Each nerve is covered on the outside by a dense sheath of connective tissue, the epineurium. Beneath this is a layer of fat cells, the perineurium, which forms a complete sleeve around a bundle of axons.