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 Trochlear 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[1] Opens in new window.
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].

The Olfactory Nerve (Cranial Nerve I)

This is located in the brain in what’s known as the forebrain.
The Olfactory Nerve or Cranial Nerve I is what gives you your sense of smell.