I'm demonstrating that the pain pathway moves up the spinal cord on a different side to the touch pathway & Temperature pathway.

1. MECHANISM OF TOUCH
TEMPERATURE & PAIN
FATIMA WAHID MANGRIO
fatimawahid1234@gmail.com

3. Posterior Column–Medial Lemniscus Pathway to
the Cortex
 Nerve impulses for touch, pressure, vibration, and
conscious proprioception from the limbs, trunk, neck, and
posterior head ascend to the cerebral cortex along the
posterior column–medial lemniscus pathway. The name of
the pathway comes from the names of two white-matter
tracts that convey the impulses: the posterior column of
the spinal cord and the medial lemniscus of the brain
stem.

4.  First-order neurons in the posterior column–medial
lemniscus pathway extend from sensory receptors in the
limbs, trunk, neck, and posterior head into the spinal
cord and ascend to the medulla oblongata on the same
side of the body.
 The cell bodies of these first-order neurons are in the
posterior (dorsal) root ganglia of spinal nerves. In the
spinal cord, their axons form the posterior (dorsal)
columns, which consist of two parts: the gracile
fasciculus and the cuneate fasciculus .

5.  The axons synapse with the dendrites of second-order
neurons whose cell bodies are located in the gracile
nucleus or cuneate nucleus of the medulla. Nerve
impulses for touch, pressure, vibration, and conscious
proprioception from the upper limbs, upper trunk, neck,
and posterior head propagate along axons in the cuneate
fasciculus and arrive at the cuneate nucleus. Nerve
impulses for touch, pressure, and vibration from the
lower limbs and lower trunk propagate along axons in
the gracile fasciculus and arrive at the gracile nucleus.

6.  The axons of the second-order neurons
cross to the opposite side of the medulla
and enter the medial lemniscus, a thin
ribbon like projection tract that extends
from the medulla to the ventral posterior
nucleus of the thalamus. In the thalamus,
the axon terminals of second-order
neurons synapse with third-order neurons,
which project their axons to the primary
somatosensory area of the cerebral
cortex.

8. Anterolateral Pathway to the Cortex
 Nerve impulses for pain, temperature,
itch, and tickle from the limbs, trunk,
neck, and posterior head ascend to the
cerebral cortex along the anterolateral
(spinothalamic) pathway. Like the
posterior column–medial lemniscus
pathway, the anterolateral pathway is
composed of three-neuron sets.

9.  The first-order neurons connect a
receptor of the limbs, trunk, neck, or
posterior head with the spinal cord. The
cell bodies of the first order neurons are
in the posterior root ganglion.
 The axon terminals of the first-order
neurons synapse with second-order
neurons, whose cell bodies are located in
the posterior gray horn of the spinal
cord.

10.  The axons of the second-order neurons
cross to the opposite side of the spinal
cord. Then, they pass upward to the brain
stem as the spinothalamic tract.
 The axons of the second-order neurons end
in the ventral posterior nucleus of the
thalamus, where they synapse with the
third-order neurons. The axons of the third
order neurons project to the primary
somatosensory area on the same side of the
cerebral cortex as the thalamus.

12. Trigeminothalamic Pathway to the Cortex
 Nerve impulses for most somatic sensations
(tactile, thermal, and pain) from the face, nasal
cavity, oral cavity, and teeth ascend to the
cerebral cortex along the trigeminothalamic
pathway.
 Like the other somatosensory pathways just
described, the trigeminothalamic pathway
consists of three neuron sets
 First-order neurons extend from somatic
sensory receptors in the face, nasal cavity, oral
cavity, and teeth into the pons through the
trigeminal (V) nerves.

13.  The cell bodies of these first-order
neurons are in the trigeminal ganglion.
 The axon terminals of some first-order
neurons synapse with second-order
neurons in the pons. The axons of other
first order neurons descend into the
medulla to synapse with second order
neurons.

14.  The axons of the second-order neurons
cross to the opposite side of the pons
and medulla and then ascend as the
trigeminothalamic tract to the ventral
posterior nucleus of the thalamus.
 In the thalamus, the axon terminals of
the second order neurons synapse with
third-order neurons, which project their
axons to the primary somatosensory area
on the same side of the cerebral cortex
as the thalamus.