PSYC 280 Lecture Notes - Lecture 9: Intrafusal Muscle Fiber, Dorsal Root Ganglion, Alpha Motor Neuron

• School: Simon Fraser University
• Department: Psychology
• Course: PSYC 280
• Professor: Evan Caldbick

Document Summary

Psyc 280 - lecture 9 - motor control. Encompasses major contribution regarding why animals have nervous systems at all. Unlike plants or fungi, most animals need to move themselves to new locations to take advantage of ecological opportunities. Requires means of locomotion & precise control system. Innervation w/i muscles - distinguishable b/w extrafusal & intrafusal muscle fibers of muscle spindles. Extrafusal fibers - innervated by alpha motor neurons where intrafusal fibers innervated by gamma motor neurons. Feedback info about state of muscle comes from primary afferent fibers which innervate central portion of intrafusal muscle fibers in spiral fashion. Secondary afferent fibers innervate thin distal end of intrafusal fiber. Like touch info, travels through dorsal root ganglia while motor fibers extend from ventral spinal root to innervate muscles. Both transmit info to & from brain. Inhibition & more complex motor plans are some of modifications to circuit transmitted from brain down to spinal cord.