This patient has a left abducens nerve (cranial nerve 6) palsy with resultant lateral rectus weakness. She moves her eyes well to the right, but upon left gaze, cannot abduct the left eye. The sixth cranial nerve originates in the pons, travels through the meninges along the bony clivus, and innervates the lateral rectus muscle. Among cranial nerves, it is particularly susceptible to the effects of increased intracranial pressure. Neuromuscular junction disease may also cause extraocular muscle weakness.