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The sensory decussation or decussation of the lemnisci is a decussation (a crossing over) of axons from the gracile nucleus and cuneate nucleus, known together as the dorsal column nuclei. The dorsal column nuclei are responsible for fine touch , vibration, proprioception and two-point discrimination .
This article is about the optic chiasm of vertebrates, which is the best known nerve chiasm, but not every chiasm denotes a crossing of the body midline (e.g., in some invertebrates, see Chiasm (anatomy)). A midline crossing of nerves inside the brain is called a decussation (see Definition of types of crossings).
In the brain, where nerve fibers obliquely cross from one lateral side of the brain to the other, that is to say they cross at a level other than their origin. See for examples decussation of pyramids and sensory decussation. In neuroanatomy, the term chiasma is reserved for crossing of- or within nerves such as in the optic chiasm.
A sensory nerve, or afferent nerve, is an anatomic term for a nerve that contains exclusively afferent nerve fibers. [1] Nerves containing also motor fibers are called mixed . Afferent nerve fibers in a sensory nerve carry sensory information toward the central nervous system (CNS) from different sensory receptors of sensory neurons in the ...
The pyramidal tracts include both the corticobulbar tract and the corticospinal tract.These are aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (corticobulbar) or spinal cord (corticospinal) and are involved in the control of motor functions of the body.
Upon decussation (crossing over) from one side of the medulla to the other, also known as the sensory decussation, they are then called the medial lemniscus. The internal arcuate fibers are part of the second-order neurons of the posterior column-medial lemniscus system , and are important for relaying the sensation of fine touch and ...
The optic nerve leaves the orbit (eye socket) via the optic canal, running postero-medially towards the optic chiasm, where there is a partial decussation (crossing) of fibers from the temporal visual fields (the nasal hemi-retina) of both eyes.
A nerve tract is a bundle of nerve fibers connecting nuclei of the central nervous system. [1] [2] [3] In the peripheral nervous system, this is known as a nerve fascicle, and has associated connective tissue. The main nerve tracts in the central nervous system are of three types: association fibers, commissural fibers, and projection fibers.