Deep Sensibility Flashcards
Functions DCML and spinocerebellar tracts
- vibration
- discriminatory touch (fine touch)
- pressure
- proprioception (position sense & kinesthesia)
Define discriminatory touch
Distance at which 2 stimuli are perceived separately, necessary for stereognosis and grapaesthesia
Deep sensibility ascends through the spinal cord via the…
DCML and spinocerebellar tracts
What is the specific area of skin that a spinal nerve innervates?
Dermatome
Cutaneous & subcutaneous mechanoreceptors (named receptors) have ____ fibers
A-beta or A-alpha
Nociceptors & thermal receptors have _____ fibers
A-delta or C
When do fast adapting somatic cutaneous sensory receptors fire?
Beginning and end of stimulus/signal
When do slow adapting somatic cutaneous sensory receptors fire?
Whole duration of stimulus/signal
A-delta fiber myelination
Least myelin
C fiber myelination
No myelin
A-alpha myelination
Most myelination
A-beta myelination
Second most
A-delta sensory receptors function
Pain & temperature
C fibers sensory receptors function
Temperature, pain, itch
Central axons of dorsal root ganglion in fasciculus gracilis ascend and synapse with ____ in the ____
Nucleus gracilis in medulla
How do Fibers of dorsal columns ascend?
Somatotopically
Most medial fibers = sacral
Central axons of dorsal root ganglion carrying conscious proprioception in fasciculus cuneatus synapse with ____ in the ____
Nucleus cuneatus in medulla
Some fibers of fasciculus cuneatus enter the cerebellum as the ____, and relay…
Cuneocerebellar tract
Unconscious proprioception from T6 up
As fibers of FC and FG enter the spinal cord, they send collaterals to…
Various levels of dorsal & ventral horn bilaterally for reflexes
Collateral fibers of FC and FG travel in the ____
Fasciculus proprius
Central axons of DRG which detect proprioception (conscious & unconscious) from lower limb enter the dorsal horn and synapse with ____
Nucleus dorsalis (Clarke’s column)
Nucleus dorsalis gives rise to the ____
Dorsal spinocerebellar tract
At the medulla, some dorsal spinocerebellar fibers of DSCT (conscious proprioception) synapse with ____
Nucleus Z
Some dorsal spinocerebellar fibers of DSCT (unconscious proprioception) enter the…
Cerebellum - inferior cerebellar peduncle
Central axons of DRG which detect unconscious proprioception from lower extremities enter the ____ and synapse with ____
Dorsal horn
Nucleus proprius
(Becomes VSCT)
Nucleus proprius gives rise to the ____
Contralateral ventral spinocerebellar tract
Fibers of nucleus proprius ascend to the ____, and enter the cerebellum via ____
Midbrain
Superior cerebellar peduncles (after crossing 2nd time)
NG, NC and nucleus Z extend ____ that cross the ____ to form the ____
Internal Arcuate fibers
Great sensory decussation
Medial lemniscus
Somatotopic organization of medial lemniscus in medulla
Cervical, thoracic, lumbar, sacral
= dorsal to ventral
Somatotopic organization of medial lemniscus in pons & midbrain
Cervical, thoracic, lumbar, sacral
= medial to lateral
Medial lemniscus ends in the ____
Thalamus
(Fibers will end in sensory cortex)
Describe variations in receptive field size of mechanoreceptors
Small: each receptor is responsible for a small area of skin; more receptors in an area
Large: receptors are responsible for larger areas; less receptors in a given area
