Wednesday, May 18, 2011

Oculomotor nerve palsy

Eye muscles are innervated by three nerves: common oculomotor nerve (cranial nerve III), trohlear nerve (cranial nerve IV) and abducens nerve (cranial nerve VI).
Common oculomotor nerve or cranial nerve III puts into action the following muscles of the eyeball: superior right muscle, the muscle as lower national muscle and inferior oblique muscle. It also innervating the striated muscle portion of the upper lid raised. The vegetative branch innervating the circular muscle of iris and ciliary body circular muscle. Cranial nerve nucleus III has its roots in the depth of the ventral portion of the brainstem, the midbrain, as higher coliculul. The structure of the nucleus in several cell groups:- Core that coordinates the movement of convergence of the eyeballs, the origin innervating muscle fibers that national- Caudal central nucleus- Dorsolateral nucleus which is the starting point of the muscle fibers innervating the right superior and inferior oblique muscle of upper eyelid raised- Edinger-Westphal nucleus, the origin of autonomic parasympathetic fibers for the circular muscles of the iris and ciliary body muscles
This core fibers are grouped into a nerve trunk that crosses the red nucleus, pyramidal way black substance, having originated in the ditch pontopeduncular apparent on the underside of the brain stem. III nerve crosses the subarachnoid space, cavernous lodge ring and Zinn.
IV trohlear nerve or cranial nerve innervating superior oblique eye muscle. VI nerve nucleus originates in the upper protuberantei in the midbrain (the upper brain stem). Fiber crosses the nucleus of the opposite side. The nerve leaves the brainstem to the dorsal face, under coliculul lower. It is the only cranial nerve fibers whose crosses and which apparently originated on the dorsal part of the brainstem. The nerve crosses the subarachnoid space, external wall of the cavernous lodge and enters the orbit through the sphenoidal slot. Trohlearul innervating superior oblique muscle, with the effect of eye movement down and out.
Or VI cranial nerve abducens nerve innervating external eye muscles right. Cranial nerve is the thinnest. Nerve has its origin in a nucleus below the fourth ventricle floor. VI nerve leaves the brainstem to the ventral face, bulbopontin the trench above the bulbar pyramid. Cross subarachnoid space, passes over the top rock temporal bone, enters the cavernous lodge (with direct relationships with internal carotid artery) and enters the orbit through the sphenoidal slot. National innervating muscle whose action is to move outside the eyeball.
Oculomotor nerve nuclei have connections with the vestibular nuclei, the nucleus of nerve VII, spinal cord, the posterior longitudinal strip with higher coliculul and visual cortex.

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