BIOL 527 Lecture Notes - Lecture 10: Motor Unit, Inferior Colliculus, Diencephalon
1 Aug 2020
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Neuro lecture 4 descending motor pathways (new for lab exam iii and lecture final: general characteristics. Motor commands issued by the cns are distributed by the somatic nervous system & autonomic nervous system (somatic motor and visceral motor, respectively). We will restrict our discussion to somatic motor pathways. Somatic motor pathways always involve at least 2 motor neurons. Upper motor neuron (umn) - cell bodies lie within a cns processing center. Lower motor neuron (lmn) -cell bodies lie in a nucleus of the brainstem or spinal cord. Upper motor neuron synapses on lower motor neuron. Lower motor neurons innervate a single motor unit in a skeletal muscle_ One lower motor neuron and all of the muscle fibers it innervates. Activity in the upper motor neuron may either facilitate or inhibit the lower motor neuron. Activation of the lmn triggers a contraction in the innervated muscle. Conscious and subconscious motor commands control skeletal muscle by traveling over 2 integrated pathways:
