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George E. Carvell, PhD, PT   University of Pittsburgh
 
THE MOTOR UNIT
A single alpha motoneuron (anterior horn cell), its dendrites, and its axon are shown. Note the extensive distribution of the dendrites into ventral and intermediate gray and white matter of the lateral columns adjacent to the spinal gray. This is the location of a portion of the propriospinal tract
Nolte, Fig 10-7 p 224
C. S. Sherrington described the alpha motoneuron and its innervated muscle fibers as the motor unit. The motor unit is the functional unit of contraction in skeletal muscle. Normally, once an action potential is conducted from the axon hillock to the muscle all the muscle fibers contacted by the axon collaterals will be activated; this assumes the periphery is intact and muscles are unfatigued.
Sherrington referred to the alpha motoneuron (anterior horn cell) as the final common pathway for all movements involving skeletal muscle.
Labeled Alpha Motoneuron
GMOMM  2001