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However, most typically, the optic nerve is grouped with the other eleven cranial nerves and is considered to be part of the peripheral nervous system. The optic nerve is ensheathed in all three meningeal layers (dura, arachnoid, and pia mater) rather than the epineurium, perineurium, and endoneurium found in peripheral nerves.
II Optic: Sensory Retinal ganglion cells: Located in the optic canal. Transmits visual signals from the retina of the eye to the brain. [3] III Oculomotor: Mainly motor Anterior aspect of Midbrain: Located in the superior orbital fissure.
Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs.Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck, including the special senses of vision, taste, smell, and hearing.
Light from a single point of a distant object and light from a single point of a near object being brought to a focus. The accommodation reflex (or accommodation-convergence reflex) is a reflex action of the eye, in response to focusing on a near object, then looking at a distant object (and vice versa), comprising coordinated changes in vergence, lens shape (accommodation) and pupil size.
Odd-numbered segments 1, 3, 5, and 7 are on the left. Even-numbered segments 2, 4, 6, and 8 are on the right. Segments 1 and 2 each includes both the retina and the optic nerve (cranial Nerve #2). Segments 3 and 4 are nerve fibers that cross from the pretectal nucleus on one side to the Edinger-Westphal nucleus on the contralateral side.
Loss of the sense of smell is called anosmia and can be either unilateral or bilateral. Bilateral loss can occur with rhinitis, smoking, or aging. Unilateral loss indicates a possible nerve lesion or deviated septum. This test is usually skipped on a cranial nerve exam. [1] The short axons of the first cranial nerve regenerate on a regular basis.
The latest research looked at a part of the brain called the olfactory bulb, which processes information about smell. Humans have two olfactory bulbs, one above each nasal cavity. Humans have two ...
Beyond the optic chiasm, with crossed and uncrossed fibers, the optic nerves are called optic tracts. The optic tract inserts on the optic tectum (in mammals known as superior colliculus) of the midbrain. In mammals they also branch off to the lateral geniculate body of the thalamus, in turn giving them to the occipital cortex of the cerebrum. [5]