Somatosensory disorders - Garner Flashcards
What are Tactile (innocuous) sensations?
Tactile sensation is the feeling produced by pressure receptors in the skin. “Tactile sensations are mediated by low threshold mechanoreceptors such as Merkel, Ruffini, Meissner and Pacinian”
What are the different types of mechanoreceptors that provide tactile sensation?
Merkel
Ruffini
Meissner
Pacinian
What type of receptors provide proprioception input?
Muscle spindle
Golgi tendon
What receptors provide thermal sensations
thermoreceptors
What receptors mediate nociceptive (painful) sensations?
Mechanical, thermal and polymodal nociceptors
What are nociceptors?
free nerve endings that penetrate epithelial cells
What determines 2 point discrimination touch?
Sensitivity is correlated with density of sensory innervation.
Areas of high sensitivity are fingertips and face,
Areas of low sensitivity are torso and limbs
True or false :
“conduction velocity is positively correlated with axon diameter?”
TRUE
As axon diameter increases, conduction speed also increases.
Where is the primary, secondary and associated somatosensory areas?
Primary somatosensory area:
Postcentral gyrus
Secondary area:
lies adjacent to postcentral gyrus next to lateral sulcus.
Association areas:
posterior parietal cortex.
What is astereoagnosia?
the inability to identify objects based on touch alone due to damage of posterior parietal cortex.
what is neglect syndrome?
a body part or visual field is neglected to to damage to posterior parietal cortex.
