Oculomotor nerve

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Scheme of the oculomotor nerve, autonomous part yellow
Nerves around the eyes
Eye locomotor nerve plan

The paired oculomotor nerve ( eye movement nerve ), also known as the third cranial nerve , N. III , innervates four of the six outer eye muscles and two inner eye muscles as well as the eyelid lifter .

Course and function

The oculomotor nerve arises in the anterior part of the midbrain and leaves it in the interpeduncular fossa . Its cranial nerve nuclei are the Ncl. nervi oculomotorii (somatomotor) and the Ncl. accessorius nervi oculomotorii ( Edinger-Westphal core ) ( parasympathetic ) and the core of Perlia for accommodation. It moves ventrally to the sella turcica ( Turkish saddle ), where it breaks through the dura and enters the cavernous sinus . In its roof and later on its side wall, it pulls towards the superior orbital fissure . After passing through the superior orbital fissure into the eye socket , it runs in the common tendinous annulus and then splits into a superior and an inferior ramus .

In addition to the levator palpebrae superioris muscle (eyelid lift), the motor fibers innervate the medial rectus muscle (straight, inner eye muscle), the superior rectus muscle (straight, upper eye muscle), the inferior rectus muscle (lower, lower eye muscle) and the inferior obliquus muscle (oblique, lower eye muscle).

The parasympathetic fibers of the oculomotor nerve move to the ciliary ganglion , where they are switched to its second neuron . The nerve fibers of the second neuron innervate the sphincter pupillae muscle , which is responsible for the constriction ( miosis ) of the pupil , and the ciliaris muscle , which regulates accommodation .

The unpaired Ncl. perlia n. oculomotorii specifically innervates the M. ciliaris, which is responsible for the accommodation of the eye.

Failure symptoms

Damage to the oculomotor nerve or its core areas leads to paralysis, the so-called oculomotor paresis . It triggers disorders of the eye muscle balance ( strabismus ) and restricted movement of the affected eye, which is accompanied by a corresponding double vision ( diplopia ). In addition, the upper eyelid may sag ( ptosis ), dilated pupils ( mydriasis ) and blurred vision in the vicinity ( accommodation disorder). Depending on the localization of the disorder, various diseases are known, which are often triggered by aneurysms or other space-consuming processes. These include the cavernous sinus syndrome and the Clivuskanten syndrome . There is also damage to the oculomotor nerve in the area of ​​the cerebral arteriosis ( Circulus Wilissi ).

Individual evidence

  1. ↑ Martin Trepel : Neuroanatomy - Structure and Function . 4th edition. Elsevier, Munich 2008, ISBN 978-3-437-41298-1 , pp. 61 f .
  2. ↑ J. Fanghänel (Ed.): Waldeyer Anatomie des Menschen. 18th edition. de Gruyter, Berlin et al. 2009, ISBN 978-3-11-019353-4 , p. 463, re. Ncl. Perlia.

See also

literature

  • Martin Trepel: Neuroanatomy. Structure and function. 3rd, revised edition. Urban & Fischer, Munich a. a. 2004, ISBN 3-437-41297-3 .
  • Franz-Viktor Salomon: nervous system, systema nervosum . In: Franz-Viktor Salomon, Hans Geyer, Uwe Gille (Ed.): Anatomy for veterinary medicine. Enke, Stuttgart 2005, ISBN 3-8304-1007-7 , pp. 464-577.