Somatic Senses General Sensory System Sensation l l

Somatic Senses General Sensory System

Sensation l l Define Stimulus Type Sensory Organ Sensory Receptors l l l l Exteroceptors Interoceptors Proprioceptors Receptor Potential Transduction Pathway Response Adaptation

Somatosensory Receptors Nocireceptors l Thermoreceptors l Mechanoreceptors l l l Tactile Baroreceptors Proprioceptors Chemoreceptors

Somatosensory Exteroceptors

Somatic Sensory Modalities l Discriminative Touch l Pressure, Vibration, Texture l Rapidly Adapting l l l Slowly Adapting l l Merkel Disks Pain and Temperature l Free nerve endings l l l Meissners Corpuscles Pacinian Corpuscles Fast Pain : A Fibers Slow Pain: C Fibers Ruffini corpuscle: heat Krause corpuscle: cold Proprioception l l Muscle Spindle Golgi Tendon Organ

Pseudounipolar Neuron

Ascending Sensory Tracts

Crossing Over

General Somatosensory Pathway

Ascending Sensory Spinal Cord Tract Information l Touch and Pressure l Discriminative l l Crude l l Anterior Spinal Thalamic Pain and Temperature l l Dorsal Columns: Fasciculus Group Lateral Spinal Thalamic Proprioception l l Length : Posterior Spinocerebellar Force: Anterior Spinocerebellar

Sensory Cortex

Sensory Homunculus

Association Areas

Touch and Pressure

Meissners Corpuscles

Pacinian Corpuscles

Merkel Disks

Posterior [Dorsal] Columns

Sensory Receptors: Pain

Sensory Receptors: Temperature

Proprioception

Histology of Proprioceptors Golgi Tendon Organ Muscle Spindle Fibers

Experiments l Discrimination l Location l Density l Threshold l Adaptation tests

Testing Fields for Pressure

Depth and Threshold

Receptor Potentials

Receptor Testing Variations

Temperature

Somatosensory Responds to: l Contact with foreign objects Warning l Feedback l Development l l Changes in temperature Warning l Heat regulation l l Avoid Damage

Dermatomes Skin region monitored l Sensory receptors l Spinal Nerve pair maps the body l CN V supplies face l

Cranial Nerves with Somatosensory l CN V l l Ophthalmic Br. Maxillary Br. Mandibular Br. CN X l ANS parasympathetic for pain

Reflex Response

Pain and Temperature Reflex

Reflex Testing

Motor Response from Higher Centers

Descending Motor Tracts l Corticospinal l Lateral Anterior Corticobulbar Vestibulospinal l Tectospinal l Recticulospinal l Rubrospinal l