Kinesiology 1080A/B Lecture 13: Kin lecture 13 - February 10

• School: Western University
• Department: Kinesiology
• Course: Kinesiology 1080A/B
• Professor: Matthew Heath

Document Summary

Important difference between ventral and lateral corticospinal tracts. Lateral corticospinal tract connects (synapses) with an alpha motor neuron: ventral corticospinal tract connects to propriospinal neurons which ultimately synapse with motorneurons. Innervation ratios are dependent on how precise your movements need to be: gama motor neurons (aka. fusimotor) innervate intrafusal muscle fibers tell the intrafusal muscle fibers how sensitive they need to be to stretch. Intrafusal muscle fibers oriented in parallel with extrafusal fibers (inside the muscle: motor unit types physique changes what type of motor units you have. Innervate fast twitch muscle fibers (extrafusal muscle fiber) lots of force a weightlifter would have: highly myelinated. Characterized by medium conduction velocity (60m/s: medium fiber diameter. Slow twitch, fatigue resistant (sr) (slow motor unit) Sprinter: 80% fast and 20% slow motor units: marathoner 20% fast and 80% slow motor units, average person: 50% fast and 50% slow motor units. Couch potato: 60% fast and 40% slow motor units.