Cranial nerves III, IV, and VI - the Oculomotor, Trochlear, and Abducens nerves

Signs and Symptoms of Lesions

Squinting; double vision; tilting of head; conjugate deviation of the eyes; jerky eye movement; lid drop (Ptosis, possible Horner’s Syndrome); dizziness; limitation of movement; intermittent pupil dilation and constriction without light stimuli; oscillating vision.

(Horner’s Syndrome: caused by a brain stem lesion which effects descending  sympathetic nerves ipsilateral to lesion resulting in  face flushing with dryness; narrowing of the palpebral fissure; upper eyelid drooping; lower eyelid elevation; pupil dilates and is unresponsive to light (positive red eye reflex); with the entire eyeball retracting or sunken.)

Oculomotor, Trochlear, and Abducens Nerve Test

There are two steps to test Cranial Nerves III, IV, and VI:

1. This maneuver monitor’s conjugate eye movement. The practitioner, utilizing either a finger or an object, such as a pen, from approximately one foot away, translates the object through at least 8 planes of the individual’s visual field. With the individual maintaining a fixed head, the practitioner requests that the individual follow the object with their eyes only. The practitioner is observing the individual’s ability to follow the object with their gaze.

The practitioner should note the ability of the individual to maintain their gaze on the object with both eyes through all ranges.  Inability to concentrically follow an object is a crude indicator of a lazy eye (amblyopia), multiple sclerosis or occasionally attributed to increased intracranial pressure.

2.  If one eye appears to have the inability to track the motion of the object, repeat the procedure as listed above after covering the eye that was able to track the motion.

If the abnormal eye (the one that was unable to track) is able to track after covering the normal eye, there is a possibility that there is a problem with the medial and/or longitudinal fasciculi of the brainstem, which is responsible for conjugate movement.

If the inability to track is not remedied by covering the normal eye, determine that motion was non-responsive.

Loss of downward medial tracking, consider cranial nerve IV or the superior oblique muscle.

Loss of lateral tracking, consider cranial nerve VI or the lateral rectus muscle. 

With any other deviation, consider cranial nerve III or extraocular muscles, inferior oblique, medial rectus, superior rectus and/or inferior rectus.

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