Question

Which group of cranial nerves controls eyeball movements?
(a)Optic, Abducens, Pathetic
(b)Optic, Oculomotor, Trochlear
(c)Oculomotor, Abducens, Auditory
(d)Oculomotor, Abducens, Trochlear

Answer 1

Hint: The cranial nerves consist of 12 paired nerves that arise from the brainstem. Three cranial nerves carry signals from the brain to control the extraocular muscles, one of them controls the majority of the muscles, another controls the superior oblique muscle, and one nerve controls the lateral rectus muscle.

Complete answer:
Via the superior orbital fissure, an oculomotor nerve enters the orbit and innervates extrinsic eye muscles that enable most movements of the eye and also raise the eyelid is the third cranial nerve (CN III). Also, pupillary constriction enabled with the help of fibers present in it that innervate the intrinsic eye muscles that enable an accommodation (ability to focus on near objects as in reading). The basal plate of the embryonic midbrain is the origin of the oculomotor nerve. The fourth and sixth cranial nerves also participate in the control of eye movement. And the CN IV(a motor nerve) which operates through the pulley-like trochlea is the fourth or trochlear nerve and also innervates only a single muscle: the superior oblique muscle of the eye. And the other one that is a somatic efferent nerve called the sixth pair of nerves or the abducens nerve (or abducens nerve/CN VI) controls the movement of the lateral rectus muscle, responsible for outward gaze in humans.

Additional information:
1) The oculomotor nerve may be easier to detect damage as it controls most of the eye muscles. If any damage occurs to this nerve, this leads to oculomotor nerve palsy, this disease is known by its down and out symptoms, because of the position of the affected eye (lateral, downward deviation of gaze).
2) At the junction of the pons and the medulla, the abducens nerve leaves the brainstem, medial to the facial nerve. From this position, the sixth nerve runs upwards and forwards from this position to reach the eye.
3) Homologous trochlear nerves are found in all jawed vertebrates, and the dorsal exit from the brainstem is the unique feature of the trochlear nerve, which includes its contralateral innervation that can be seen in the primitive brains of sharks.

So, the correct answer is, ‘Oculomotor, Abducens, Trochlear’.

Note: Three types of voluntary eye movement are used by primates and many other vertebrates to track objects of interest: smooth pursuit, vergence shifts, and saccades, which appear to be initiated by a small cortical region in the brain's frontal lobe and corroborated by the removal of the frontal lobe. Though the voluntary control is obliterated, the reflexes like shifting the eyes to moving light, in this case, are intact. Congenital fourth nerve palsy is reported by patients with eye movement disorders, Duane syndrome, Internuclear ophthalmoplegia, Nystagmus, Ophthalmoparesis, Opsoclonus, Sixth (abducent) nerve palsy.