Somatosensory 2 Flashcards
What is the fibre class of the dorsal column medial lemniscus pathway?
Aa/Ab
What modalities does the dorsal column medial lemniscus pathway carry?
fine touch, pressure, vibration and conscious proprioception
What modalities does the spinothalamic tract carry?
pain; thermosensation; crude touch, itch and tickel
What are hte fibre classes of spinothalamic tract?
Ad/C
What levels of the spinal cord travel in the fasciculus gracilis?
T6 and below
How are the areas of the spinal cord arranged in the dorsal column?
upper is lateral to lower medial
What do second order neurones of the DCML cross in?
the great sensory decussation
What nucleus do the second order neurones synapse within?
ventral posteriolateral nucleus of the thalamuc
How do the thrid order neuones of the DCML travel to S1?
posterior internal capsule
What is sterognosis?
ability to recognise an object by feeling it
What is contrast enhancement?
the amplification in the differences in the activity of adjacent neurones at synapses
How is contrast enhancement acheived?
lateral inhibition by inhibitory interneurones
Where are the soma of trigeminal sensory neurones located?
in the trigeminal sensory ganglion
What modality synapses in the chief trigeminal sensory nucleus
general tactile stimuli
What modalities synapse in the spinal nucleus?
pain, temperature
How do second order neurones of the trigeminothalamic pathway reach the thalamus?
via the trigeminal lemniscus
What nucleus do the second order neurones of hte trigeminothalamic pathway synapse within?
ventroposteriormedial nucleus of thalamuc
How do thrid order neurones of the trigeminothalamic pathway relay info to the cortex?
via the thalamocortical neurones
What is the input to Brodmann’s area 3a?
proprioception
What is the input to Brodmann’s area 3b?
cutaneous SA and RA receptors; BA 3a
What is the input to Brodmann’s area 1?
cutaneous RA mechanoreceptors, BA 3a
What is the input to BA2?
joint afferents; golgi tendon organs, deep tissues, BA3a and BA 3b
What is the modality to BA3b?
touch- texture, shape and stimulus size
What is the modlaity to BA1?
texture discrimination
what is the modality to BA2?
object perception- stereognosis
What are the Brodmanns areas from anterior to posterior?
3a–3b–1–2
What separates the head from the face in the priamry somatosensory cortex?
the hand
How many cell layers are there in the somatosensory cortex?
6
What cell layer do thalamic inputs to S1 terminate?
layer IV
How are the multiple somatotopic maps in the S1 arranged?
in parralel and mirror image
