Which cranial nerves have Parasympathetic fibers?

The oculomotor nerve, identified as cranial nerve III, is critically associated with parasympathetic functions. It carries parasympathetic fibers that innervate the sphincter pupillae muscle of the iris, which controls pupil constriction, and the ciliaris muscle for lens accommodation. These actions are essential for controlling the amount of light entering the eye and for focusing on near objects, respectively.

In contrast, the olfactory nerve (cranial nerve I) is responsible for the sense of smell and does not have any parasympathetic fibers. The abducens nerve (cranial nerve VI) primarily controls lateral eye movement and lacks parasympathetic function as well. The trigeminal nerve (cranial nerve V) is mainly focused on sensory functions of the face and motor control of mastication, and while it has some autonomic functions, it does not have parasympathetic fibers associated with its main branches. Thus, among the cranial nerves listed, the oculomotor nerve is the notable one that embodies parasympathetic innervation.