3 Proprioception Flashcards
At what end of the DRG do we find generator potential?
dorsal end of the DRG
Describe the process of the knee jerk reflex
When the DRG is stimulated by excitation of cells responding to sudden pressure on the knee joint, it stimulates motor neuron that triggers quad, as well as a local interneuron that inhibits the hamstring from kicking back
What is an intrafusal muscle fiber and what does it do?
important for telling the brain about the elongation position of the muscles
What is an extrafusal muscle fiber and what does it do?
important for telling the brain about the work of the muscle
How do the intrafusal muscle fibers operate to trigger DRG?
DRG/muscle spindle afferent wraps around the the non contracile portion, of intrafusal mf is the muscle spindle afferent. when the contraclie region contracted, the noncontracile portion is stretched which causes deformation of the unmylenated portion of the DRG and causes generator and action potentials depending on the degree of elongation (yellow part is the unmylenated DRG)
Muscle spindle afferents carry [transient/sustained] information about muscle elongation
transient
There is a particlar type of motor fiber that synapses on the contractile regions which cause them to reset to their original state, which can then reset or restretch the noncontracile portion. This allows the muscle spindle afferent to
trasmit only transient information rather than be stretched the entire time the muscle is elongated
which organ encodes sustained information about muscle contraction?
The golgi tendon
(is activated the entire time the fibers are deformed)
which component of the somatosensory system is parallel to the golgi tendon organ in the proprioceptive system?
(hint: sustained information)
Merkel cells
what are five of the functions of the proprioceptive system?
joint protecting reflexes (e.g. knee jerk)
adjustment of muscle contraction and relaxation
kinesthesia (detection of body position and movement)
coordination of motor commands
sense of self?
where is the integration of proprioceptive and tactile of information performed?
the somatosensory cortex
where is the first synapse of the DRG cell?
medulla
pinocchio effect
proprioceptive sensory illusion where contraction of the bicep muscle while touching the nose results in the feeling that your nose is growing
[touch receptors on nose and finger are being stimulated, and muscle spindle afferent are telling the brain the bicep is being elongated, producing the perceptual illusion that the nose is growing)
What are three of the functions of the vestibular system?
postural reflexes
gaze adjustment (detect head motion and adjust gaze)
assessment of self-motion
what is the hair cell receptor and what system does it belong to?
transduction of both head motion (vestibular system) and sound waves (auditory system) into neural signals
