Motor systems (1) Control of Body Movement

Know the basic organization of the motor systems.

3 level hierarchy tht plans, coordinates and execute movements while also having sensory feedback

1. Highest Level (Sensorimotor Cortex, Association Areas, Limbic Areas): Generates the overall goal and intention to move

2. Middle Level: The sensorimotor cortex, basal nuclei, thalamus, brainstem, and cerebellum turn a movement goal into a motor program. They use sensory information like vision, vestibular sense, and proprioception to decide which muscles contract, in what order, when, and how strongly.

3. Local Level (Brainstem and Spinal Cord Interneurons, Motor Neurons, Afferent Neurons): Receives the motor programs from the middle level and determines the exact activation or inhibition of motor neurons to produce coordinated movement

Basic Functions of Neural & Muscular Components;

Know the basic functions of afferent neurons, efferent

neurons, interneurons, motor neurons, and muscles in

the motor systems.

1. Afferent Neurons: Carry sensory feedback from peripheral receptors To to the CNS to continuously refine movements and make real-time adjustments

2. Interneurons: Comprise ~90% of spinal cord neurons; they receive inputs from higher centers and sensory receptors to act as switches that excite or inhibit motor neurons.

3. Motor Neurons: Represent the final common pathway out of the CNS. Their action potential frequencies directly dictate the strength, timing, and duration of muscle contractions

4. Efferent Neurons: Include alpha motor neurons (innervate extrafusal fibers for force generation) and gamma motor neurons (innervate intrafusal fibers to maintain spindle sensitivity during contraction).

5. Muscles: Contract and relax to generate mechanical force and movement across joints (they can pull, but cannot push).

Know the basic functions of muscle spindles and Golgi

tendon organ.

Muscle Spindles: It monitors muscle length & the rate of change in muscle length.

• Location/structure: has Intrafusal muscle fibers surrounded by afferent nerve endings located within the extrafusal muscle fibers

• Mechanism : when muscle gets stretched the spindle fires more. Alpha-gamma coactivation keeps the muscle spindle sensitive to stretch while the muscle contracts

Golgi Tendon Organ: Monitors muscle tension, especially tension caused by muscle contraction or an external load.

• Location & structure: located in tendon near muscle-endon junction, around collagen bundles.

• Mechanism: increased tension straightens the collagen fibers, which deforms the sensory nerve endings causing them to fire

Know the concepts of voluntary, involuntary movements, reflexes, and motor programs.

Voluntary movements: movements you consciously chose to do

Involuntary: your body does it automatically

Reflexes: Rapid involuntary responses; when a muscle is suddenly stretched it contracts automatically

Rhythmic Motor Patterns: movements you start voluntarily but then you continue to do it automatically. Etc walking

Motor Programs: a planned pattern of neural activity that tells speific muscles which muscles to use, when to contract, and how much force to use. (Brains movement plan)

Identify the major brain regions involved in motor control

Sensorimotor cortex: helps decide what movement you want to make and creates a motor program for that movement. Also sends motor commands down to lower levels

Basal Nuclei: Helps plan and start movements, creates motor programs, and helps control movement through the thalamus

Thalamus: relays motor info form the basal nuclei and cerebellum back to the sensorimotor cortex

Cerebellum: combines sensory info like vision with intended motor program to find and correct movements that have errors and adjust timing (fixed mistakes while you move)

Brainstem: controls postural reflexes and helps related and carry out motor pathways

Explain the sensory systems that maintain posture and balance.

Maintenance of posture relieves on 3 main things

1. Proprioceptive system

   1. Muscle spindles: Provide info on muscle length and rate of stretch

   2. Golgi Tendon Organs:

   3. Joint, tendon, ligament, & skin receptors: detect joint angles, mechanical pressure, and skin contact

2. Vestibular System: Sense organs in the inner ear that detects head position, movement, and balance (tells your brain where ur head is)

3. Visual systems: provides sensory feedback regarding the body’s orientation relative to the surrounding environment (tells your brains where you are and what’s around you)