Kin P2 Class 11 - sensory feedback control of movement

Whats a sensory input in movement control?

Proprioception: your sense of body position and movement. Comes from sensory receptors within our skeletal muscles.

what sensory receptors help contribute to proprioceptive sense? and what are they examples of?

sensory receptors in our skin (e.g skin stretching when flexing or extending joint)

sensory receptors in our joints (but not main proprioceptors)

examples of mechanoreceptors.

what are Muscle Spindles and Golgi Tendon Organs and where are they located?

Muscle spindles senses changes in muscle length. located in parallel with regular muscle fibers

Golgi Tendon organs sense the force the muscle exerts. located in the tendon of the muscle. become stretched when muscle contracts.

[Reflex pathways in the spinal cord] what does that mean and whats a withdrawal reflex? whats the inputs and outputs?

its an automatic response your body makes without waiting for the brain.

Withdrawal reflex has the input/sensory stimulus of pain (via pain receptors/nociceptors. has the motor output/response of coordinated skeletal muscle contraction.

e.g. pulls the limb away (flexion on pain side) and the other side extends to support you (extention on other side)

whats the stretch reflex? (knee jerk response)

sensory stimulus and receptor the input is a stretch detected by the muscle spindle

motor output/response is the skeletal muscle contraction of the same muscle.

What are rhythmically generated movements?

many rhythmic movement circuitry reside in the brainstem or spinal cord.

what alternating coordination patterns are in walking (locomotion - moving frm place to place)?

left to right and swing (flexion) to stance (extention) without u thinking abt it.

do infants automatically have the stepping response even when they dont voluntarily walk yet?

yes. they have an automatic stepping response bfr voluntary walking.

pathways from brain -> spinal cord not fully developed -> supports idea of spinal cord circuitry supporting walking in humans.

whats the stumbling corrective response?

If tap the top of the foot in swing (foot off the ground moving forward), the leg lifts higher (avoids a trip). same tap in stance (on the ground) -> no lift

what happens to our sensory feedback from our muscle receptors during regular locomotion (no tripping)

intiates reflex responses to help control muscle activation during walking.

Whats the two common rules acrosss species for sensory feedback control of walking?

stretch of hip flexor muscles -> muscle spindles activated, senses length and speed of stretch -> signals that we switch from stance to swing phase.

Loading of postural muscles (calf muscles) -> Golgi tendon organs sense tension/force and inc muscle activity in extensor muscle to ensure we maintain upright stance.

what advances the onset of swing phase? and what delays the onset?

the rapid pulling of hip into extension (i.e stretch hip flexors)

preventing hip from going into extension (keeping it flexed) delays the onset.

whats involved when accuracy is required? and why

the motor cortex since you need to focus on e.g. hitting a small target, control push-off so you dont slip etc. so instead of spinal cord its motor cortex