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Extrapyrimidal system

Extrapyrimidal system - spinal cord Functions •...

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Extrapyrimidal system Comprises the remaining motor system; do not enter medullary pyramids The descending tracts from brain stem to spinal cord, the basal ganglia, and the cerebellum Descending motor pathway through reticulospinal and vestibulospinal tracts Synaptic interruption in basal ganglia, brain stem, and/or reticular formation Four major extrapyramidal tracts: o Rubrospinal tract: Originates in the red nucleus of the midbrain, crosses within the brain stem, and extends to the lateral gray horns (lateral interneurons and motor neurons) of the spinal cord Functions: Mediation of voluntary movement Large muscle movement and fine motor control Facilitates flexion/inhibits extension in upper extremities o Tectospinal tract: Originates in the superior colliculus (tectum) of the midbrain, crosses with the brain stem, and enters the anterior gray horns (anterior/medial interneurons and motor neurons) of the
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Unformatted text preview: spinal cord Functions: • Coordinates head and eye movements • Motor impulses from one side of the midbrain to muscles on the opposite side of the body • Mediates reflex postural movements of the head in response to visual/auditory stimuli o Vestibulospinal tract: Originates in the vestibular nucleus of medulla, uncrosses, and descends and terminates in the anterior gray horns Functions: • Medial: CN 3, 4, 6 in eye movements; controlling head and neck position and gaze control • Lateral: excitatory to motor neurons; antigravity muscles o Reticulospinal tract: Originates in the medulla, uncrossed, and terminates in the anterior gray horns Functions: • Integrates information to coordinate automatic locomotion/posture movements • Facilitates/inhibits voluntary movement • Autonomic functions • Pain impulses • Blood flow...
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