Lecture_15 - Motor Systems I Spinal Control Skeletal...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Motor Systems I: Spinal Control Skeletal muscles or striated muscles (fig13.1) -Voluntary control -Work as synergists or as antagonists - Synergists : group of muscles that work together in motion (ex. Triceps) - Antagonists : group of muscles that work opposite to contract or flex body (ex. Quadriceps and hamstring) Lower motor neurons (fig 13.3) -Cell bodies in ventral horn and project out ventral root - Inhibit = relax muscle - Excite = contract muscle Ventral Horn Enlargement -Becomes larger because there are more motor neurons in certain areas - Cervical enlargement : because of arm muscles - Lumbar enlargement : because of leg muscles Neuron topography -Location of motor neurons in ventral horn is related to muscle groups innervated -Flexors (contracting) and extensors (relaxing) neurons are opposite in ventral horn 2 kinds of motor neurons - Alpha motor neurons -drive contraction of muscles o Also makes all muscle fibers contract when it is stimulated - Gamma motor neuron Motor unit and pool (fig 13.6) - Motor unit = ONE alpha motor neuron and one or more fibers - Motor pool = ALL alpha motor neurons innervating a muscle - Twitch -momentary contraction and release with in that muscle fiber Twitch Summation (fig 13.7) -Spike an AP in a Motor Neuron -More current = smoother contraction (sustained) because the twitch doesn't relax between other twitches - Size principle : the motor unit with the smallest number of muscle fibers gets turned on first -We only turn on enough muscle fibers to do the job -The more muscle fibers turned on the less fine motor control you have
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 4

Lecture_15 - Motor Systems I Spinal Control Skeletal...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online