1. Sensory pathways Dr. Gallatz Katalin

2. 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

3. PROTOPATHIC SENSIBILITY: TEMPERATURE, TOUCH, PAIN
ANTEROLATERAL SYSTEM – spinothalamic tract
EPICRITIC SENSIBILITY: FINE AND DISCRIMINITIVE TOUCH
DORSAL COLUMN SYSTEM– medial lemniscus
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4. PRIMARY AFFERENTS
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5. 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

6. 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

7. 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 somato- sensory cortex

8. MEDIAL LEMNISCUS – EPICRITIC SENSIBILITY

9. SOMATOTOPY IN THE SPINAL CORD
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10. PROTOPATHIC SENSYBILITY
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

11. SPINOTHALAMIC TRACT
Dr. Kozsurek Márk anyagából

13. epicritic sensibility 2. neuron and crossing in the medulla
MEDIAL LEMNISCUS
epicritic sensibility
2. neuron and crossing
in the medulla
SPINOTHALAMIC TRACT
protopathic sensibility
2. neuron and crossing
in the spinal cord
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14. SZOMATOSENSORY PATHWAYS CONNECTING WITH THE
PAIN SENSATION
functional activity
localization and
discrimination
pathways
Spinothalamic tract
Ventral trigeminothalamic tract (ventral trigeminal lemniscus)
termination
thalamus (VPL),
VPM
primary and secondary
sensory cortex (SI, SII)
Spinoreticulothalamic tract reticular formaton (RF)
Pain-feeling intralaminar nuclei of th.
It has function in emotional, limbic cortical areas
affective and behavioural
answers for pain sensation
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15. NUCLEI OF THE TRIGEMINAL NERVE
MESENCEPHALIC NUCLEUS
PRINCIPAL SENSORY NUCLEUS
SPINAL TRIGEMINAL NUCLEUS

16. TRIGEMINAL SENSORY PATHWAYS
DORSAL TRIGEMINAL
LEMNISCUS
TRIGEMINAL LEMNISCUS

17. VENTRAL TRIGEMINOTHALAMIC TRACT. TRIGEMINAL LEMNISCUS
TRIGEMINAL GANGLION
SPINAL TRIGEMINAL TRACT
SPINAL TRIGEMINAL NUCL. X
Contralateral VPM
POSTCENTRAL GYRUS

18. TRIGEMINAL SENSORY PATHWAYS

19. TRIGEMINAL SENSORY PATHWAYS
DORSAL TRIGEMINOTHALAMIC TRACT
DORSAL TRIGEMINAL LEMNISCUS
epicritic sensibility
trigeminal ganglion
principal sensory nucleus of V.
VPM
postcentral gyrus

20. SOMATOTOPY

22. SOMATOSENSORY CORTEX
THALAMUS

23. PAIN Receptors - nociceptors
- 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

24. 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)

25. Melzack és Wall gate control theory
The stimulation of thick (touch,
pressure, vibration) sensory fibers
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.
Inhibitory neuron
Projection neuron
stimulation of thin fibers
inhibition of the inhibitory neurons
Gate opens toward the ascending pathway-neurons

26. 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

27. PAIN-CONDUCTING PATHWAYS
activity
localization and
discrimination of the pain
pain motivation, affective
and behavioral responses
pathways
spinothalamic tract
trigeminal lemniscus
spinoreticulothalamic tract
trigemino-reticulothalamic
tract
terminals
thalamus (VPL) -
sensory cortex
midline thalamic nuclei -
limbic cortex

28. PAIN SENSATION – spinoreticulo- thalamic 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
intralaminar nuclei
frontal cortex
limbic cortical areas: cingular, insular cortex

29. Thank you for your attention!