of the Week:
Two 3rd cranial nerves (oculomotor nerves) are located at the top of the brainstem - one to the right and one to the left. Motor messages from the 3rd cranial nerve nucleus controls eye muscles on the same side, or, ipsilateral (medial rectus, superior rectus, inferior rectus and inferior oblique).
Compression of the 3rd cranial nerve prevents the transmission of the impulse to the pupil, eyelid and eye muscles, on the same side as the nerve compressed.
Compression of the 3rd cranial nerve causes the following problems (on the same side as the compression):