The Facial Nerve (Cranial Nerve VII)

The seventh cranial nerve comes from the pons of the brainstem[1]. The facial nerve is responsible for facial expression and conveyance of taste sensation for the front two thirds of the tongue[1]. This is both a motor and sensory nerve[2]. Facial nerve testing can be done by showing your teeth, puffing your cheeks, wrinkling your brow, frowning, and closing your eyes tightly[2]. Essentially, this nerve controls all the funny faces you can make!

The Abducens Nerve (Cranial Nerve VI)

The sixth cranial nerve is the abducens nerve. This nerve is a somatic efferent nerve, otherwise called a motor nerve[1]. The abducens nerve is responsible for innervating the lateral rectus muscle which laterally moves the eyes[2]. The sixth cranial nerve runs a lengthy path from the pons, in the brainstem, to the eyes[2].

The Trigeminal Nerve (Cranial Nerve V)

The trigeminal nerve, or fifth cranial nerve, is responsible for sensation in the face as well as chewing and biting[1]. This nerve originates on the pons, which is part of the brainstem[2]. It splits into three separate nerves; the ophthalmic, the maxillary, and the mandibular nerve[1]. The main functions are to receive sensation from the face, and control the four main muscles required for chewing[2].

The Oculomotor Nerve (Cranial Nerve IV)

The trochlear nerve, also called the fourth cranial nerve or CN IV, is a motor nerve Opens in new window (a somatic Opens in new window efferent nerve) that innervates only a single muscle: the superior oblique muscle Opens in new window of the eye, which operates through the pulley Opens in new window-like trochlea Opens in new window[1].
Homologous Opens in new window trochlear nerves are found in all jawed vertebrates Opens in new window. The unique features of the trochlear nerve, including its dorsal exit from the brainstem and its contralateral innervation, are seen in the primitive brains of sharks[2 Opens in new window].

The Oculomotor Nerve (Cranial Nerve III)

The somatic motor component of CN III plays a major role in controlling the muscles responsible for the precise movement of the eyes for visual tracking or fixation on an object[1].
The visceral motor component is involved in the pupillary light and accommodation reflexes[1]. This is related to parasympathetic innervation[1].