Final answer:
When assessing extraocular eye movements to check cranial nerves, the examiner typically examines horizontal movements first, followed by vertical movements, convergence, and pupillary reactions. The test looks for conjugate movements and proper function of the extraocular muscles controlled by the oculomotor, trochlear, and abducens nerves.
Step-by-step explanation:
When assessing extraocular eye movements to check cranial nerves, the movements that are examined first are typically the horizontal movements. This involves having the patient follow a visual target like the tip of a pen through the visual field. Watchful for conjugate movements, the examiner tests for proper function of the oculomotor, trochlear, and abducens nerves which control the extraocular muscles, and looks for any signs of internuclear ophthalmoplegia which would be apparent if there's failure in the coordinated movement of both eyes. The corresponding horizontal movement test includes abduction by the lateral rectus muscle, controlled by the abducens nerve, and adduction by the medial rectus muscle, controlled by the oculomotor nerve.
Following the horizontal movement assessment, vertical movements, convergence, and pupillary reactions are examined. In convergence, the medial recti muscles cause the eyes to move inward. This should be accompanied by accommodation, where the shape of the lens changes, controlled by the parasympathetic fibers of the oculomotor nerve.
The sixth nerve, or abducens nerve, specifically controls the lateral rectus muscle responsible for abduction. The third nerve, or oculomotor nerve, controls most of the rest of the extraocular muscles including the medial rectus muscles for convergence and accommodation.