What is the primary function of the abducens nerve?

The primary function of the abducens nerve is to control the lateral movement of the eye. It is the sixth cranial nerve and specifically innervates the lateral rectus muscle of the eye, which is responsible for moving the eyeball outward, away from the midline of the body. This action allows for proper visual tracking and coordination when the eyes move together.

The abducens nerve's role in eye movement is crucial for maintaining visual clarity and proper binocular vision. Dysfunction or injury to this nerve can lead to conditions such as strabismus, where the eyes do not properly align, affecting depth perception and overall vision.

Other options mention functions that are associated with different cranial nerves; for example, facial expression and control are managed by the facial nerve, hearing and equilibrium are functions of the vestibulocochlear nerve, while swallowing and salivation are primarily controlled by the glossopharyngeal and vagus nerves. This distinction highlights the specialized roles of individual cranial nerves in the body's functioning.