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The optic nerve has been classified as the second of twelve paired cranial nerves, but it is technically a myelinated tract of the central nervous system, rather than a classical nerve of the peripheral nervous system because it is derived from an out-pouching of the diencephalon (optic stalks) during embryonic development.
The lacrimal bone also contains the nasolacrimal duct. The superior bony margin of the orbital rim, otherwise known as the orbital process, is formed by the frontal bone. [7] The roof (superior wall) is formed primarily by the orbital plate frontal bone, and also the lesser wing of sphenoid near the apex of the orbit. The orbital surface ...
The ganglion cell axons form the optic nerve after they leave the eye. The optic disc represents the beginning of the optic nerve and is the point where the axons of retinal ganglion cells come together. The optic disc in a normal human eye carries 1–1.2 million afferent nerve fibers from the eye toward the brain.
Composition and central connections of the spinal nerves; Pathways from the brain to the spinal cord; The meninges of the brain and medulla spinalis; The cerebrospinal fluid; The cranial nerves. The olfactory nerves; The optic nerve; The oculomotor nerve; The trochlear nerve; The trigeminal nerve; The abducens nerve; The facial nerve; The ...
The eyes sit in bony cavities called the orbits, in the skull. There are six extraocular muscles that control eye movements. The front visible part of the eye is made up of the whitish sclera, a coloured iris, and the pupil. A thin layer called the conjunctiva sits on top of this. The front part is also called the anterior segment of the eye.
Loss of function of any of the eye muscles results in ophthalmoparesis. Since the oculomotor nerve controls most of the eye muscles, it may be easier to detect damage to it. Damage to this nerve, termed oculomotor nerve palsy, is known by its down and out symptoms, because of the position of the affected eye (lateral, downward deviation of gaze).
There are three centers of growth that are important in the development of the eye, and each is associated with a nerve. Hence the subsequent nerve supply (innervation) of the eye muscles is from three cranial nerves. The development of the extraocular muscles is dependent on the normal development of the eye socket, while the formation of the ...
The ophthalmic nerve (CN V 1) is a sensory nerve of the head. It is one of three divisions of the trigeminal nerve (CN V) , a cranial nerve . It has three major branches which provide sensory innervation to the eye , and the skin of the upper face and anterior scalp , as well as other structures of the head.