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The motor system is the set of central and peripheral structures in the nervous system that support motor functions, i.e. movement. [ 1 ] [ 2 ] Peripheral structures may include skeletal muscles and neural connections with muscle tissues. [ 2 ]
A neurological examination is the assessment of sensory neuron and motor responses, especially reflexes, to determine whether the nervous system is impaired. This typically includes a physical examination and a review of the patient's medical history, [1] but not deeper investigation such as neuroimaging.
Exaggerated (brisk) deep tendon reflexes such as this can be found in upper motor neuron lesions, hyperthyroidism, [6] anxiety or nervousness. The test itself assesses the nervous tissue between and including the L2 and L4 segments of the spinal cord. [1] The patellar reflex is often tested in infants to test the nervous system. [7]
The PNS includes motor neurons, mediating voluntary movement; the autonomic nervous system, comprising the sympathetic nervous system and the parasympathetic nervous system and regulating involuntary functions; and the enteric nervous system, a semi-independent part of the nervous system whose function is to control the gastrointestinal system.
Peripheral neurons receive input from the central nervous system and innervate the muscles. In turn, muscles generate forces which actuate joints. Getting the pieces to work together is a challenging problem for the motor system and how this problem is resolved is an active area of study in motor control research.
The patellar reflex (knee jerk) is an example of the stretch reflex and it is used to determine the sensitivity of the stretch reflex. Reflexes can be tested as part of a neurological examination, often if there is an injury to the central nervous system. To test the reflex, the muscle should be in a neutral position.
Glutamate released from the upper motor neurons triggers depolarization in the lower motor neurons in the anterior grey column, which in turn causes an action potential to propagate the length of the axon to the neuromuscular junction where acetylcholine is released to carry the signal across the synaptic cleft to the postsynaptic receptors of the muscle cell membrane, signaling the muscle to ...
Motor NCS are obtained by stimulating a nerve containing motor fibers and recording at the belly of a muscle innervated by that nerve. The compound muscle action potential (CMAP) is the resulting response and depends on the motor axons transmitting the action potential, the status of the neuromuscular junction, and muscle fibers.