SOMATIC SENSORY SYSTEM D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM

FUNCTIONS OF THE SOMATIC SENSORY SYSTEM zTACTILE RECEPTORS zTHERMAL RECEPTORS zNOCIOCEPTORS zPROPRIOCEPTORS

TACTILE RECEPTORS zSENSE MECHANICAL STIMULATION ON BODY’S SURFACE zTOUCH, PRESSURE, AND VIBRATION zRAPIDLY ADAPTING (PACINIAN CORPUSCLE, HAIR RECEPTOR) OR SLOWLY ADAPTING (RUFFINI ENDING)

TYPES OF SENSORY RECEPTORS IN THE SKIN EPIDERMIS DERMIS RUFFINI ENDING FREE NERVE ENDING HAIR RECEPTOR PACINIAN CORPUSCLE

STATIC PROPRIOCEPTORS LIMB POSITION I LIMB POSITION I I LIMB POSITION II I

DYNAMIC PROPRIOCEPTORS CHANGE IN LIMB POSITION CHANGE IN LIMB POSITION CHANGE IN LIMB POSITION

THERMAL RECEPTORS zSENSE CHANGES IN TEMPERATURE ON THE BODY’S SURFACE zCOLD RECEPTORS: BELOW 30° C zWARM RECEPTORS: ABOVE 30° C

NOCIOCEPTORS zPAIN RECEPTORS ACTIVATED BY HARMFUL STIMULI zMECHANICAL zHEAT

PROPRIOCEPTORS zREPORT POSITION AND MOVEMENTS zSTATIONARY OR STATIC (TONIC-JOINT CAPSULE AND CUTANEOUS MECHANORECEPTORS, MUSCLE SPINDLE RECEPTOR) zDYNAMIC: ACTIVATED BY LIMB MOVEMENTS

ORGANIZATION OF SOMATIC SENSORY SYSTEM zGENERAL PRINCIPLES zANATOMICAL CONSIDERATIONS

GENERAL PRINCIPLES OF SOMATIC SENSORY ORGANIZATION zLABELED LINE zMOST PATHWAYS CROSS zRELATIVE POSITIONS IN BODY ARE PRESERVED ALL THE WAY UP

ANATOMICAL CONSIDERATIONS

FURTHER ANATOMICAL CONSIDERATIONS zCELL BODIES OF SOMATIC SENSORY NERVES ARE IN THE DORSAL ROOT GANGLION zTWO MAJOR PATHWAYS: DORSAL COLUMN AND ANTEROLATERAL

ANATOMICAL CONSIDERATIONS: TERMINOLOGY zROSTRAL-CAUDAL: NOSE TO TAIL zDORSO-VENTRAL: BACK TO BELLY zMEDIAL: TOWARDS THE MIDLINE zLATERAL: TOWARDS THE SIDE zANTERIOR: TOWARDS THE FRONT zPOSTERIOR: TOWARDS THE BACK

TERMINOLOGY ILLUSTRATED ROSTRAL (SUPERIOR) VENTRAL CAUDAL (INFERIOR) DORSAL

THE SPINAL CORD IN SOMATIC SENSORY FUNCTION zWHITE AND GREY MATTER zSEGMENTAL ORGANIZATION

SEGMENTAL STRUCTURE OF SPINAL NERVES DERMATOMES

SPINAL CORD DORSAL HORN GREY MATTER DORSAL VENTRAL SPINAL NERVE DORSAL ROOT GANGLION VENTRAL HORN WHITE MATTER LATERAL

TOUCH AND PRESSURE DORSAL COLUMN PATHWAY INCOMONG SENSORY NERVE TRAVELS UPWARD IN THE DORSAL COLUMN AND SYNAPSES IN THE DORSAL COLUMN NUCLEUS

PAIN AND TEMPERATURE ANTEROLATERAL PATHWAY

LESION ON RIGHT HALF OF SPINAL CORD zLOSS OF PAIN SENSATION ON LEFT SIDE BELOW LESION zLOSS OF TOUCH AND VIBRATION ON RIGHT SIDE BELOW LESION zLOSS OF BOTH ON RIGHT SIDE AT SAME LEVEL zNO LOSS ABOVE LESION

THE CRANIAL NERVES zTRIGEMINAL zGLOSSOPHARYNGEAL zPLAY SAME ROLE AS SPINAL NERVES

THE THALAMUS IN SOMATIC SENSATION zMAJOR SITE FOR RECEIVING SENSORY INFORMATION zVENTRAL POSTERIOR LATERAL NUCLEUS (VPL) zSENDS SENSORY INFORMATION TO THE CORTEX

THE THALAMUS IN SOMATIC SENSATION DORSAL COLUMN MEDULLA MEDIAL LEMNISCUS SENSORY NEOCORTEX DORSAL COLUMN NUCLEI

SOMATOSENSORY CORTEX zNEOCORTEX: REGION OF CORTEX WHICH EVOLVED MOST RECENTLY zPRIMARY: POST CENTRAL GYRUS zSOMATOTOPIC ORGANIZATION

THE SOMATOSENSORY CORTEX

SOMATOTOPIC ORGANIZATION OF THE SENSORY CORTEX GENETALS TOES FOOT LEG HIP. LIPS TONGUE

SOMATOTOPIC ORGANIZATION OF THE SENSORY CORTEX