Spinal nerve tracts {spinal cord}| organize basic movements, like running or walking, and control sense input. Spinal cord has inner gray matter cell bodies and outer white matter myelin, in lemnisci.
laminas
Lamina V is for pain and visceral afferents. Lamina VI is for joints and skin positions. Lamina VIII is medial motor neuron column for motor neurons to trunk and limbs. Lamina IX is lateral motor neuron column for motor neurons to arms and legs, with flexor central and extensor peripheral. Lamina X is central canal.
locations
Pain, heat, and cold axon tracts are on spinal-cord lateral sides. Touch and pressure axon tracts are on ventral side. Muscle-sensor axon tracts are on dorsal side.
Axons and dendrites can mix {neuropil}.
Spinal cord has outer white matter {lemnisci} with fascicles grouped into funiculi columns.
Spinal-cord outer white matter has descending and ascending axon tracts {fascicle} grouped into lemnisci.
Spinal-cord lamina I {Lissauer's tract} {Lissauer tract} is for pain.
Spinal-cord dorsal-horn lamina II {substantia gelatinosa} receives touch, pressure, pain, and thermal sensations.
Spinal-cord laminas {lamina III} can be for position and light touch.
Spinal-cord laminas {lamina IV} can be for position and light touch.
Spinal-cord laminas III and IV {nucleus proprius} are for position and light touch.
Spinal-cord laminas {lamina VII} {dorsal nucleus} {Clarke's column} can have intermediolateral nucleus and be for preganglion sympathetic system.
Spinal-cord lamina-VII dorsal nucleus ganglion {intermediolateral nucleus} contains preganglion sympathetic neurons.
Spinal-cord nerve tracts {medial longitudinal fasciculus} can be for head and eye coordination and come from vestibular nuclei.
Spinal-cord tracts {reticulospinal tract} can modulate sensation and spinal reflexes.
Spinal-cord tracts {rubrospinal tract} can be motor.
Spinal-cord back horn {dorsal horn} is for sense input and has ascending sense-connector nerves.
functions
Dorsal column is for fine touch and proprioception from skin, tendon, and joint.
layers
Dorsal horn has five layers. Layer 1 receives axons from skin neurons and sends to neurons higher in spinal cord. Layers 2 and 3 modulate sense input from both skin neurons and neurons in layers 4 and 5. Layer 4 receives axons from skin neurons and sends axons to layer 5. It detects gentle and general pressures. Layer 5 receives axons from skin, viscera, and layer-4 neurons and sends to brain.
nuclei
Neuron nuclei {dorsal column nuclei} receive afferent fibers from skin and send to ventrobasal complex.
tracts
Tracts are spinothalamic tract, dorsal spinocerebellar tract, ventral spinocerebellar tract, and spinoreticular pathway.
neurons
Nociceptive-specific neurons respond to noxious stimuli. Wide dynamic range neurons respond to all mechanical stimuli, but especially to noxious mechanical or thermal stimuli.
Spinal-cord front horn {ventral horn} is for motor output and has descending motor nerves. Tracts are lateral corticospinal tract, anterior corticospinal tract, vestibulospinal tract, rubrospinal tract, reticulospinal tract, and tectospinal tract. Descending autonomic neurons come from hypothalamus and brainstem. Medial longitudinal fasciculus is for head and eye coordination and comes from vestibular nuclei.
Voluntary escape behaviors use small efferent spinal cord fibers with long latencies and variable responses, which react to visual, tactile, and vibratory threats.
Spinal cord and brain have connective tissue layers {meninges}|, dura mater, pia mater, and arachnoid. Cerebrospinal fluid is between layers and in central canal.
Spinal cord has inner connective tissue layer {arachnoid}.
Spinal cord has outer connective tissue layer {dura mater}.
Spinal cord has middle connective tissue layer {pia mater}.
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Date Modified: 2022.0225