look like onions, large receptive field, fast responding, 20-20 layers
Ruffini's endings
large receptive fields, slow adapting
Meissner's corpuscles
small receptive fields, fast responding, rapid adaptation
Merkel's discs
small receptive fields, slow adapting
Axons bringing information from the somatic sensory receptors to the spinal cord or brain stem are the
Primary afferent axons
Different sizes of primary afferent axons from skin
Aalpha
ABeta
Ao
C
Sizes of primary afferent axons from the muscles
Group:
I, II, III, IV
Group I PAA is the largest?
True
Which is the smallest PAA?
IV
The fastest PAA is the one that is the smallest?
False
Why are larger PAA faster?
More mylenated thicker axon = faster conduction
Touch sensation pathway for body
dorsal column medial leminscal
Touch sensation pathway for face
trigeminal touch pathway
what is the first thing stimulated in touch sensation pathways?
mechanoreceptors in the skin
What PAA are in the body pathway?
mostly Abeta-fast conductin
Where does the body pathway enter the spinal cord?
through the dorsal horn, bifurcation at zone of lissar
Where on the body pathway does the axon connect in the spinal cord?
on the reflexive motor pathway within substantia gelatinosa
Body: what happens in the Dorsal Column of Medial lemniscus?
ascent of afferent fibers --> synapse on secondary neurons (NG, NC)--> cross at level of sensory decussation, ascend throuch medial lemniscus to VB of thalamus.
Body: path in thalamus
VB recieves sensory input and relays it to cortex
Body: where is the somatosensory cortex
in the post central gyrus, layer 4 of area 1
Face pathway's sensory receptors are
mechanoreceptors in skin
What kind of PAA is in the face pathway?
Trigeminal nerve- Abeta type- fast conductin from three regions in the face.
What are the three regions in the face that conduct sensory input?
opthalalmic, maxillary, or mandibular branches
Where are the cell bodies for the PAA for the face located?
in the trigeminal ganglion
Face: what happens in the trigeminal nucleus?
primary neurons synapse
What is the trigeminal nucleus' function similar to?
the dorsal nuclei of the spinal cord
Face: T/F- The secondary neurons decussate and synapse on the VB of the thalamus.
TRUE
Face: what happens in the Thalamus?
Recieves info from principle sensory nuclei of V relays info to the lower portion of the post central gyrus.
