As the pair of<unk>  nerves arises from different subnuclei in the midbrain, courses through different structures in the brain and branches into superior and inferior divisions after exiting the cavernous sinuses, any lesions along its path will produce different pathological features of the third nerve<unk> . The parasympathetic aspect of the nerve (which constricts pupils and thicken the lens) is located on the nerve surface, supplied by pial blood vessels. The nerve's core contains the main trunk of the<unk>  nerve, supplied by vasa vasorum. Thus pathologies affecting the nerve's core without affecting the superficial part of the nerve (thus sparing the pupillary reflex) are known as "medical"<unk> . The "surgical" type of<unk>  is caused by external structures compressing on the nerve or trauma, which affects the entire nerve, thus affecting pupillary reflex. Ischemic stroke selectively affects somatic fibers over parasympathetic fibers, while traumatic stroke affects both types more equally. Ischemic stroke affects the vasoneurium, which starts to supply the nerve from outside to inside. As the somatic fibers are located in the inner part of the nerve, these fibres are affected more in the setting of ischemia. A similar mechanism is also accurate for diabetes. Therefore, while almost all forms cause ptosis and impaired movement of the eye, pupillary abnormalities are more commonly associated with trauma and the "surgical third" rather than with ischemia (the "medical third"). A posterior communicating artery aneurysm will generally cause compression of the entire third nerve and will this prevent any nerve signal conduction, affecting the somatic system as well as the autonomic. The compression of the external autonomic fibres renders the pupil nonreactive and leads to the "surgical third" nerve<unk> .<unk><unk>  can be of acute onset over hours with symptoms of headache when associated with diabetes mellitus. Diabetic neuropathy of the<unk>  nerve in a majority of cases does not affect the pupil. The sparing of the pupil is thought to be associated with the microfasciculation of the fibers that control the pupillomotor function located on the outmost aspect of the<unk>  nerve fibres; these fibres are spared because they are outermost and therefore less prone to ischemic damage than are the innermost fibres.
Oculomotor nerve palsy
Nasolacrimal duct obstruction
Optic nerve tumor
Vibroacoustic disease
Auditory neuropathy
Ocular ischemic syndrome
Cat eye syndrome
Phantom eye syndrome