Somatosensory Pathway

Question 1

What’s the trigeminal system?

Answer 1

Pathway of sensation from the face.
Mechanoreceptors in the face take stimulus through trigeminal ganglion, crosses to other side of the brain and ascends up the trigeminothalamic tract up into ventral posterior medial nucleus of thalamus and into primary somatic sensory cortex

Question 2

What’s the somatosensory system?

Answer 2

Mechanosensory receptors from upper and lower body go into the spinal cord, to the caudal medulla where they cross over, go up through mid-pons and midbrain and into ventral posterior lateral nucleus of the thalamus and into primary somatic sensory cortex

Question 3

Pain and temperature pathways

Answer 3

Pain comes into body, crosses over in the spinal cord, ascends up medulla, mid-pons and midbrain into ventral posterior lateral nucleus of the thalamus into the primary somatosensory cortex

Question 4

How is the pain pathway different to somatosensation?

Answer 4

The stimulation crosses over in the spinal cord in pain pathways but crosses in the medulla in somatosensation

Question 5

What about pain and temperature sensation from the face?

Answer 5

Come in, goes to spinal nucleus of trigeminal complex and crosses over in caudal medulla, up the middle medulla, mid-pone and midbrain and into the ventral posterior medial nucleus of the thalamus

Question 6

Pattern of dissociated sensory loss following spinal cord hemisection

Answer 6

Looking at the pain sensation and somatosensory sensations you might have allows you to see the damage that might be accrued to spinal cord

Question 7

Dorsal column pathway for visceral pain? How is it studied?

Answer 7

There’s particular parts of spinal cord associated with particular types of visceral pain. E.g. gastrointestinal pain ascends in dorsal column via dorsal root ganglion cells into the spinal cord, crossing over in the medulla and ascending to the ventral posterior nuclear complex of the thalamus. Showed in animal studies where administered visceral pain and imaged pathways in the brain. Showed if lesioned the dorsal column of spinal cord then can stop visceral pain getting to the brain

Question 8

Descending systems that modulate the transmission of ascending pain signals

Answer 8

Descending pathways come down to inhibitory neurons in spinal cord so can turn things off. Some drugs ie opioids have receptors on GABAergic interneurons.

Question 9

Ventral posterior lateral nucleus receives projections from

Answer 9

The body - via mechanoreceptors

Question 10

Ventral posterior medial nucleus receives projections from …

Answer 10

Trigeminal system carrying somatosensory info from the gace

Question 11

Descending pathways for pain

Answer 11

Anterolateral system