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The oculomotor nerve, also known as the third cranial nerve, cranial nerve III, or simply CN III, is a cranial nerve that enters the orbit through the superior orbital fissure and innervates extraocular muscles that enable most movements of the eye and that raise the eyelid.
The Edinger–Westphal nucleus also called the accessory or visceral oculomotor nerve, is one of the two nuclei of the oculomotor nerve (CN III) located in the midbrain. [ 1 ] [ 2 ] [ 3 ] It receives afferents from both pretectal nuclei (which have in turn received afferents from the optic tract ). [ 4 ]
The nucleus of the oculomotor nerve does not consist of a continuous column of cells, but is broken up into a number of smaller nuclei, which are arranged in two groups, anterior and posterior. Those of the posterior group are six in number, five of which are symmetrical on the two sides of the middle line, while the sixth is centrally placed ...
The common tendinous ring, also known as the annulus of Zinn or annular tendon, is a ring of fibrous tissue surrounding the optic nerve at its entrance at the apex of the orbit. It is the common origin of the four recti muscles of the group of extraocular muscles. It can be used to divide the regions of the superior orbital fissure. [1]
The medial longitudinal fasciculus is the main central connection for the oculomotor nerve, trochlear nerve, and abducens nerve. It carries information about the direction that the eyes should move. Lesions of the medial longitudinal fasciculus can cause nystagmus and diplopia, which may be associated with multiple sclerosis, a neoplasm, or a ...
The levator palpebrae superioris receives motor innervation from the superior division of the oculomotor nerve. [1] [2] [3] The smooth muscle that originates from its undersurface, called the superior tarsal muscle is innervated by postganglionic sympathetic axons from the superior cervical ganglion.
The short ciliary nerves contain both parasympathetic and sympathetic nerve fibers. The parasympathetic fibers arise from the Edinger-Westphal nucleus and synapse in the ciliary ganglion via the oculomotor nerve, the postganglionic parasympathetics leave the ciliary ganglion in the short ciliary nerve and supply the ciliary body and iris.
Then, it courses posteriorly toward the nuclei of the oculomotor nerve (III), trochlear nerve (IV) and abducens nerve (VI), the three cranial nerves that mediate eye movements. [3] At the level of the caudal midbrain, corticomesencephalic fibers descend through the tegmentum in the medial lemniscus toward the oculomotor (III) and the trochlear ...