BIOL 031 Lecture Notes - Lecture 27: Gamma Motor Neuron, Alpha Motor Neuron, Muscle Spindle
19 Aug 2020
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**spindles are tonically active and ring even when muscle is relaxed. Alpha motor neurons to extrafusal bers receive tonic input from muscle spindles. Extrafusal bers maintain a certain level of tension even at rest. Muscle stretch can trigger a stretch re ex. When muscles stretch and lengthen, muscle spindle sensory afferent neurons re more. The re ex response is muscle contraction to prevent damage from over-stretching. Alpha-gamma coactivation keeps the spindles stretched when the muscle contracts. it maintains spindle function when muscle contracts. Alpha motor neuron res and gamma motor neuron res. Stretch on centers of intrafusal bers unchanged. Without gamma motor neurons, muscle contraction causes the spindle neurons remains constant. Golgi tendon organ: a type of muscle proprioceptor that is found at the junction of tendons and muscle bers, placing them in series with the muscle bers. Respond to muscle tension during an isometric contraction and are insensitive to muscle stretch.
