Semiology of sensory disturbances

Semiology of Sensory Disturbances
Somatic Sensation

•The function of each sensorial system is to offer CNS a representation of the exterior
world




•Sensation= stimulus detection and recognition of an event

•Perception= interpretation and appreciation of these event



Sensation =\\ Perception



Classification of Types of Sensation

Elementary Sensation
•Superficial sensation

–Touch

–Temperature  Exteroceptivesensation

–Pain

•Deep sensation

–Kinesthetic Sense ( Proprioceptivesensation)

–Vibratory Sense (“touch-pressure”)

•Interoceptivesensation

–Conscious

–Unconscious




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, The Structure of Sensory Pathways
•Receptors(in the skin, tendons, joint capsules)

-First neuron (dorsal root ganglia, pseudounipolarneuron)

-Second neuron (posterior horn of spinal cord, medulla)

-Third neuron (thalamus)

•Primary sensory area (somatosensoryprojection cortex Broadman’sareas 3,1,2)

•Secondary sensory area (partially Broadmanareas 40, 43)

•Sensory associative areas (general sensory association cortex) (Broadman’sareas 5,
7)




Receptors
•Cerebral and spinal neurons are not activated by direct light, touch, sound stimulation

•Receptors: specialized structures that translate touch, chemical or light stimulation into
a signal that triggers a neuronal response

•Convergence and divergence varies depending on the receptors type, localization and
system’s requests for a certain location




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