Motor (1) Flashcards
What are the different proprioceptive receptors?
muscle spindle, Golgi tendon organ in muscles, pacinian corpuscles in joints, ruffini endings in joints, and Golgi organs in joints
What are the characteristics of the muscle spindle receptors?
senses muscle stretch, signals muscle length and velocity, adapts rapid initial transient and slow sustained
What are the characteristics of the golgi tendon organ in muscles?
sense muscle tension, signals muscle contraction, adaption is slow
What are the characteristics of the Pacinian corpuscles in joints?
senses joint movement at beginning and end of movement, signals direction and velocity, adapts rapidly, low threshold, sense quick mechanical deformation or vibration
What are the characteristics of the Ruffini endings in joints?
senses joint pressures at rest and moving (stretch), signals pressure and angle, adapts slowly, low threshold, innervated by group II fibers,
What are the characteristics of the Golgi organ in joints?
senses joint torque, signals twisting force, adaption is slow, axon endings are tightly intertwined with collagen of ligament, physically deforming axon causes firing, active at end of joint range,
In general proprioceptors sense what?
detect where our body is in space, whether it is moving, in what direction and how fast
What are the skeletal muscle proprioceptors?
mechanosensitive proprioceptors, muscle spindle receptors, and Golgi tendon organs
What do the synovial junction proprioceptors do?
in between bones, detect mechanical deformation, within capsule and ligaments; purpose- to protect joint from potentially injurious flexion and extension, 4 types- free nerve ending (pain), Golgi (torque), Ruffini endings (pressure), and paciniform (movement)
What are the characteristics of the free nerve endings in joints?
activated only by extreme mechanical or chemical irritation, have a high threshold, slow adapting, most numerous of joint receptors
What are the structural features of the muscle spindle?
intrafusal fibers (static and dynamic bag and nuclear chain) innervated by Ia and II, fusimotor ending innervated by gamma fiber; unit in parallel with extrafusal muscle fibers; particularly concentrated in fine motor muscles
What is the relation between the Golgi tendon organ and muscle fibers?
in series at junction of muscle and tendon, weaved between collagen, when tendon stretches it deforms the axons opening cation channels, innervated by goup Ib afferent, myelinated, slightly smaller in diameter than Ia
What activity takes place in the muscle spindle?
afferent Ia activity increases during stretch, less activity during contraction- have to contract spindle to get continued information from muscle
What are the characteristics of group Ia fibers?
fiber from primary endings on both nuclear bag and chain fibers, respond partly to muscle length (static) but more powerfully to changes in length; extension of muscle and spindle causes a reflex contraction
What are the characteristics of group II fibers?
afferent intermediate size, from secondary endings on chain fibers or static bag fibers, sense the static muscle length and are less sensitive to rate of change in length
