Oculomotor nerve

The oculomotor ( eye movement nerve) is the third of twelve paired cranial nerves. It innervates four of the six extraocular muscles, two inner eye muscles and the levator.

Flow and function

The oculomotor nerve originates in the anterior part of the midbrain and leaves it in the interpeduncular fossa. His cranial nerve nuclei are the Ncl. nervi oculomotorii ( somatomotorisch ) and the Ncl. accessory nerve oculomotorii ( Edinger - Westphal nucleus) ( parasympathetic) and the core of Perlia for accommodation. He pulls anteriorly to the sella turcica ( Turkish saddle), where it breaks through the dura and enters the cavernous sinus. In the roof, and later on the side wall pulling towards the superior orbital fissure. After it passes through the superior orbital fissure into the orbit it runs in the tendinous communis and splits after inferior into a superior ramus and ramus on.

The motor fibers innervate adjacent to the levator palpebrae superioris ( Lidhebung ) the musculus rectus medialis (straight, inner eye muscle ), the musculus rectus superior (straight, upper eye muscle ), the rectus inferior ( straight, lower eye muscle ) and the abdominal inferior ( oblique, lower eye muscle ).

The parasympathetic fibers of the ciliary ganglion N. oculomotoris draw where they are switched to their second neuron. The nerve fibers of the second neurons innervate the sphincter pupillae, which for the constriction ( miosis ) of the pupil is responsible, and the musculus ciliaris, which regulates the accommodation.

The unpaired Ncl. Perlia n oculomotorii innervated specifically the ciliary muscle, which is responsible for the accommodation of the eye.

Failure symptoms

When damage to the oculomotor nerve or its nuclei, there is a paralysis of the so-called third nerve palsy. It dissolves eye muscle incoordination of ( squint) and restricted movement of the affected eye, what with the corresponding double vision ( diplopia) is associated. In addition, there may be a drooping of the upper eyelid (ptosis ), dilated pupils ( mydriasis) and blurred near vision ( failure of accommodation ) may occur. Depending on the location of the fault is known various diseases that are often caused by aneurysms or other space- occupying lesions. These include inter alia the cavernous sinus syndrome and Clivuskanten syndrome. Also in the area of the circle of Willis ( circulus Wilissi ) there is damage to the oculomotor nerve.