Flashcards in Module D-02 Deck (63)
What are the 5 somatosensory modalities?
Touch, vibration,proprioception(muscular),pain and temperature
What type of neurons are the somatosensory receptor neurons?
Where are sensory endings of the somatosensory receptor neurons found?
In skin or in (close to) muscle
Where are cell bodies of the somatosensory receptor neurons found?
Dorsal root and Cranial nerve Ganglia
What are the 2 Cutaneous touch receptors?
What type of specific touch is transduced by Merkel's disks?
What type of specific touch is transduced by Ruffini’s endings?
What are the 2 Cutaneous receptor specific for Vibration?
1) Meissner's corpuscles
2) Pacinian corpuscles
What type of vibration do Meissner's corpuscles have highest sensitivity?
highest sensitivity / lowest threshold for lower frequencies of about 50 Hz
What type of vibration do Pacinian corpuscles have highest sensitivity?
highest sensitivity / lowest threshold for higher frequencies of about 300 Hz
What type of receptors transduce the signal for pain and temperature?
Free nerve endings
What type of free nerve endings for prickling pain and burning pain?
- pricking pain by rapidly adapting mechano-sensitive or thermo-sensitive receptors,
- burning pain by slowly adapting polymodal receptors
What type of free nerve endings for Temperature?
Cold and warm receptors
What type of receptors transduce proprioception (position sense)?
Muscle spindles and Golgi tendon organs
Where are muscle spindles found?
Embedded in extrafusal fibers of working musculature
What type of receptor are the primary receptor of muscle spindle ?
Rapidly adapting receptor with a 1a afferent fiber
Which receptor for deep tendon reflex(myotatic reflex)?
Ia afferent fiber
What type of receptor is the secondary receptor of a muscle spindle?
slowly adapting receptor class II afferent fiber
What type of info does the primary muscle spindle fiber (1a)transduce?
What type of info does the secondary muscle spindle fiber (class II) transduce?
Where are golgi tendon organs located?
border between muscle and tendon
What type of receptor is the golgi afferent fiber?
What do the 1b fiber form?
afferent limb of inverse myotatic reflex
Afferent fibers from proprioceptors form which important pathways to the cerebellum ?
dorsal and ventral spinocerebellar tracts (don't reach consciousness)
Somatosensory receptors use four different fiber types:
1)Large myelinated fibers (muscle 1 and cutaneous A alpha)
2)medium myelinated fibers (muscle II and cutaneous A beta)
3) small myelinated fibers (muscle III and cutaneous A delta)
4) unmyelinated fibers (muscle IV and cutaneous C)
Size and conduction velocity of Large and medium myelinated fibers
diameters : up to 20 μm
conduction velocities : up to 120 m/sec
What type of receptors use Large and medium myelinated fibers?
cutaneous mechanoreceptors and proprioceptors
What type of sensory info do Large and medium myelinated fibers carry?
touch, vibration and proprioception
Size and conduction velocity of small myelinated fibers
diameters: about 1 μm
conduction velocities : 5 m/sec