Question

If a man, abducens nerve is injured. In that case, which one of the following functions will be affected?
a. Movement of the eyeball
b. Swallowing
c. Movement of the tongue
d. Movement of the neck

Answer 1

Abducens or abducens nerve in human beings, is the nerve responsible to regulate the movement of a muscle responsible for outward gaze. It sends signals to the lateral rectus muscle.

Complete answer:
• The abducens or abducens is a somatic efferent nerve.
• It regulates movements of the lateral rectus muscle.
• The abducens nerve goes out from the brainstem around the intersection of the medulla and the pons, which is almost the center-point of the facial nerve. From this location the abducens nerve reaches the eye.
• The nerve goes over the mutual tendinous ring of the four rectus muscles and then arrives at the bottom layer of the lateral rectus muscle. The role of the abducens nerve is to bond the lateral rectus. This further results in movement of the eye away.
• This nerve is indirectly responsible for outward gazing.
So, in a man, the injured abducens nerve will be affecting the movement of the eyeball.

Hence, the correct answer is option (A).

Additional information:
• The cranial nerves originate from the brain. It is evident from the fact that the word “cranial” in cranial nerves comes from the word “cranium”.
• The cranial nerves that are responsible for the process of swallowing are ninth (IX) and twelfth (XII) nerves. These nerves are glossopharyngeal and hypoglossal respectively.
• Movement of the tongue is governed by the hypoglossal (XII) nerve.
• Movement of the neck is governed by the facial nerve.

Note: The abducens or abducens nerve is known to be the 6th cranial nerve in human beings. It is a motor nerve, that is, it carries only motor functions and does not carry any sensory functions. Its functions are very different from that of the oculomotor nerve as well as the trochlear nerve.