Sensory pathways Dr Gallatz Katalin SENSORY PATHWAYS Spinothalamic
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Sensory pathways Dr. Gallatz Katalin
SENSORY PATHWAYS Spinothalamic system is for the pain temperature and light touch protopathic sensibility Medial lemniscus is for fine and discrimitive touch, vibration and propriocepcion epicritic sensibility In contrast of the spinothalamic system, in which fibers cross at the spinal level, the fibers that costitute the medial lemniscus system ascend ipsilaterally in the dorsal funiculus and cross in the caudal medulla
PROTOPATHIC SENSIBILITY: SENSIBILITY TEMPERATURE, TOUCH, PAIN ANTEROLATERAL SYSTEM – spinothalamic tract EPICRITIC SENSIBILITY: SENSIBILITY FINE AND DISCRIMINITIVE TOUCH DORSAL COLUMN SYSTEM– medial lemniscus
PRIMARY AFFERENTS
EPICRITIC SENSYBILITY Receptors: of the touch - Meissner corpuscles of vibration – Paccinian corpuscles of proprioception – muscle spindles, tendon spindles, Golgi tendon organs nerve endings in and near to the capsules and ligaments of the joints
MEDIAL LEMNISCUS – EPICRITIC SENSIBILITY FINE AND DISCRIMINITIVE TOUCH I. neuron: spinal ggl/trigeminal ggl gracile és cuneate fascicle II. neuron: gracile and cuneate nucleus internal arcuate fibers X MEDIAL LEMNISCUS III. neuron: VPL (contralateral) SOMATOSENSORY CORTEX
MEDIAL LEMNISCUS – EPICRITIC SENSIBILITY 1. neuron: spinal ( dorsal root) ganglion the central processes of the ganglion cells enter the spinal cord through the spinal root and ascend in the gracile and cuneate fascicles to the caudal medulla 2. neuron: gracile and cuneate nucleus the axons of these neurons - the internal arcuate fibers cross in the midline - lemniscal deccusation, and ascend as medial lemniscus to the thalamus 3. neuron: ventral posterolateral (VPL) nucleus of the thalamus the axons of these neurons ascend through the internal capsule to the postcentral gyrus - primary somatosensory cortex
MEDIAL LEMNISCUS – EPICRITIC SENSIBILITY
SOMATOTOPY IN THE SPINAL CORD
SPINOTHALAMIC TRACT – PROTOPATHIC SENSYBILITY - pain, touch, temperature - receptors in the skin: mechano, - termo, and nociceptors 1. neuron: spinal ganglion or trigeminal ganglion 2. neuron: in the dorsal horn of the spinal cord or in the spinal trigeminal nucleus. (in pain sensation also the 3. neuron) 3. neuron: thalamus VPL or VPM somatosensy cortex – postcentral gyrus
SPINOTHALAMIC TRACT Dr. Kozsurek Márk anyagából
MEDIAL LEMNISCUS epicritic sensibility 2. neuron and crossing in the medulla SPINOTHALAMIC TRACT protopathic sensibility 2. neuron and crossing in the spinal cord
SZOMATOSENSORY PATHWAYS CONNECTING WITH THE PAIN SENSATION functional activity ------------localization and pathways -------------Spinothalamic tract termination ---------thalamus (VPL), discrimination Ventral trigeminothalamic tract (ventral trigeminal lemniscus) VPM primary and secondary sensory cortex (SI, SII) Spinoreticulothalamic tract reticular formaton (RF) Pain-feeling intralaminar nuclei of th. It has function in emotional, affective and behavioural answers for pain sensation limbic cortical areas
NUCLEI OF THE TRIGEMINAL NERVE MESENCEPHALIC NUCLEUS PRINCIPAL SENSORY NUCLEUS SPINAL TRIGEMINAL NUCLEUS
TRIGEMINAL SENSORY PATHWAYS DORSAL TRIGEMINAL LEMNISCUS
VENTRAL TRIGEMINOTHALAMIC TRACT. TRIGEMINAL LEMNISCUS TRIGEMINAL GANGLION SPINAL TRIGEMINAL TRACT SPINAL TRIGEMINAL NUCL. X Contralateral VPM POSTCENTRAL GYRUS
TRIGEMINAL SENSORY PATHWAYS
TRIGEMINAL SENSORY PATHWAYS DORSAL TRIGEMINOTHALAMIC TRACT DORSAL TRIGEMINAL LEMNISCUS epicritic sensibility trigeminal ganglion principal sensory nucleus of V. VPM postcentral gyrus
SOMATOTOPY
SOMATOSENSORY CORTEX THALAMUS
PAIN - The pain is an unpleasant sensation, but it is life-important in our connection with the outside-world. - The brain can recognize and localize the pain, and activates a lot of mechanizms. - The organism gives different and complex answers for the pain. In the pain sensation participate: - sensory receptors, - sensory fibers, - ascending pathway- neurons. Receptors - nociceptors
Nociceptors - are activated by any process that either causes damage or has the capacity to cause damage if continued or intensified, - most nociceptors respond to a variety of noxious stimuli: - extreme hot or cold temperatures, - intense mechanical manipulations (pinching, pinpricks, cutting), - increased tissue acidity, and other causes of injury, - a variety of chemical agents released from cells that are damaged or responding to a foreign body such as an infectious agent (for example, a bacterium)
Melzack és Wall gate control theory - The stimulation of thick (touch, pressure, vibration) sensory fibers Inhibitory neuron Projection neuron excite, - while the stimulation of the thin (pain) sensory fibers inhibit the activity of inhibitory interneurons regulating the activity of funicular neurons of ascending pathways. stimulation of thin fibers inhibition of the inhibitory neurons Gate opens toward the ascending pathway-neurons
The answers for the pain-producing stimuli - protective reflex – spinal cord, brainstem - vegetative reflex – spinal cord, brainstem - a recognition and localization of the pain - primer és secunder sensory cortex - emotional reactions - limbic cortex - hormonal changes - hypothalamus
PAIN-CONDUCTING PATHWAYS activity pathways terminals localization and discrimination of the pain spinothalamic tract trigeminal lemniscus thalamus (VPL) sensory cortex pain motivation, affective spinoreticulothalamic tract and behavioral responses midline thalamic nuclei trigemino-reticulothalamic tract limbic cortex
PAIN SENSATION – spinoreticulothalamic tract Pain-feeling. It has function in emotional, affective and behavioural answers for pain sensation. - receptors are in the skin - nociceptors - I. neuron: spinal ganglion or trigeminal ganglion - II-III. neuron: spinal cord or spinal trigeminal nucleus - further neurons : reticular formation, thalamus CM and - frontal cortex intralaminar nuclei - limbic cortical areas: cingular, insular cortex
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