Somatosensory Flashcards
Where does sensory info come from? (somatosensory system)
Skin and Muscles
What kind of receptors are at the distal ends of peripheral neurons?
Mechanoreceptors
Chemoreceptors
Thermoreceptors
(Nociceptors)
Dermatome vs Peripheral Nerve
Dermatome: skin innervated by axons from a single dorsal root
Peripheral N: axons from dorsal root innervating specific parts of the limbs groups to form nerve
Meissner’s Corpuscles stimulated by?
Touch, vibration
Merkel’s Disc stimulated by?
Pressure
Why do we have receptors that lie superficially AND deeper?
It allows our body to sense the levels of stimuli
What’s a muscle spindle?
Sensory organ in skeletal muscle (Extrafusal)
What does a muscle spindle consist of?
Muscle fibers, motor endings, sensory endings
Quick and tonic stretch of spindle is registered by which fibers?
Ia afferents
Slow tonic stretch is monitored by which fibers?
II afferents
Role of gamma motor neurons?
adjusts spindle fiber length thru special musc. fibers (Intrafusal)
keeps spindle fiber stretched at sensitive length
Are gamma motor neurons Efferent or Afferent
Efferent
What do the GTOs do?
Sends info about tension in tendon
Active contraction + Passive stretch
Information to GTOs are transmitted by what fibers?
Ib afferents
Where are cell bodies of most peripheral sensory neurons located?
OUTSIDE of Spinal Cord
in DRG or Cranial Nerve Ganglia
What are the two axons of peripheral sensory neurons?
Distal Axons: receptor to cell body
Proximal Axons: cell body to SC or Brainstem
What happens at the somatosensory cortex: Primary
Registers receptor activation
What happens at the somatosensory cortex: Secondary
Processes info from sensory system
Patterns of activity and anticipation
What happens at the somatosensory cortex: Sensory association cortex
integrates related activity of different sensory systems
