350: Exam 2a (PART 2/5) [Proprioception & Kinesthesis]

Performance significantly depends on

neurological feedback

where are internal receptors located

skin

joints

muscles

tendons

proprioceptors provide positive feedback relative to

• tension (force)

• length (and velocity)

• contraction state of muscles

• position of body and limbs

• movement of joints

proprioception is

subconscious mechanism by which body regulates posture & movement by responding to stimuli from proprioceptors (eg., stepping on an uneven surface — muscles respond to contract and prevent falling)

kinesthesis

• conscious awareness of position and movement of the body in space (eg., when standing on one leg — you are aware of the raised limb’s position) 

Proprioceptors work in combination with other sense organs (i.e. visual, vestibular) 

true

two types of specific proprioceptors (specific to muscles)

muscle spindles

golgi tendon organs (GTO)

muscle spindles consist of

• sensory endings coiled around non-contractile portions of intrafusal muscle fibers

muscle spindles are located

• adjacent to (aligned parallel with) the extrafusal muscle fibers (the primary force-producing fibers) within the muscle belly 

muscle spindles are sensitive to stretch (ie, change in length) and rate of stretch (ie, velocity) 

true

Concentration (density) of spindles varies depending on control precision (ie, greater number of spindles in hand muscles than thigh muscles) 

true

what is the purpose of the golgi tendon organ

relaxation of the agonist

GTOs are located

 in series in musculotendinous junction

GTOs are sensitive to

• muscle tension & active contraction 

GTOs inhibits

• excessive force development 

  • Sensitivity can be impaired through training 

two types of specific proprioceptors (specific to joints and skin)

• meissner’s corpuscles

• ruffini corpuscles

• pacianian corpuscles

• krause’s end-bulbs

type of proprioceptor that is responsible for the activation of the agonist

• myotatic reflex

• stretch reflex

process of myotatic reflex/stretch reflex

1. Rapid muscle stretch occurs

2. Afferent (away from extremities) impulse sent to CNS

3. CNS activates motor neurons of the muscle being stretched, causing activation 

GTO Activation Process

• Tension in tendon increases as muscle contracts

1. GTO stretch threshold is reached

2. Afferent impulse sent to CNS

3. CNS inhibits efferent nerve causing muscle to relax

4. Facilitates activation of antagonist muscle as protective mechanism 

• GTO protects us from an excessive contraction (excessive muscle force) by causing its muscle to relax 

Pacinian Corpuscles are concentrated around

joint capsules, ligaments, tendon sheaths, and beneath skin

in pacinian corpuscles, around the joint capsule

Sense rapid joint angle and pressure changes (but is not effective at detecting constant pressure)

the following proprioceptor provides feedback for location of body part in space following quick movements 

Pacinian Corpuscles 

found in deep layers of skin and joint capsule

• Ruffini’s Corpuscles

• Strong, sudden joint movements and pressure change activate sensors

Ruffini’s Corpuscles

• Reaction to pressure change is slower to develop than Pacinian corpuscles (but if pressure is maintained, activation continues) 

Highly sensitive to minute joint position changes, providing feedback of exact joint angle

• Ruffini’s Corpuscles

Messners’s Corpuscles & Krause’s End-Bulbs are found

• In skin and other subcutaneous tissues

Messners’s Corpuscles & Krause’s End-Bulbs are important in

• receiving stimuli from touch