Somesthesis Lec14 Flashcards
Tactile mechanoreceptors can be slowly adapting which respond to __ stimuli
enduring
Tactile mechanoreceptors can be rapidly adapting whuch respond to ___ stimuli
the onset of
which receptors have encapsulated endings?
ruffinis and meissners
___ rceptors respond really quickly
pacicinian
describes merkel receptors signals
have an initially strong signal that partially adapts + a weaker signal of slower adaptation
___ and ___ are slow adapting receptors
merkels and ruffinis (sounds like old peoples names.. so slow)
___ and ___ are rapdi adapting receptors
pacianian and meissers
____ have lamina with gelatinous, rapidly dissipating fluid in between the layers
pacinian
Two point discrimination is a good measure of ___-
receptor sensitivity
High tactile sensibility = Fine spatial discrimination = ____ receptor density
High
High receptor density = ____ receptive fields
Small
Areas of greatest sensitivity (highest receptor density) are the (3)
hand, face, and foot
receptor with best spatial resolution?
merkels
receptor with best temporal resolution?
Meissner (RA) & Pacinian (RA)
where do the DML and ALS pathways enter the SC?
via dorsal root ganglion –> lateral margin of the dorsal columns
Medial branch = ____ tract to brain
Dorsal Column
Lateral branch = ____ tract to brain
Anterolateral
Sensory nerves are segregated by ___ and ___ within the dorsal columns of the spinal cord.
receptor type and modality
In addition to segregation by receptor type and modality, there is Somatopic organization in dorsal columns of spinal cord. what is most medial? most lateral?
lower limb – most medial head and neck – most lateral
Dorsal Column Nuclei are the
gracile and cuneate nuclei
Spatial Summation: In the Dorsal Column Nuclei
neurons converge onto 2nd order neurons with____ that have both excitatory and inhibitory regions.
larger receptive fields
in the thalamus
Moving medial-lateral changes ___
place
in the thalamus
moving anterior-posterior changes ___
modality
S1 has 4 cytoarchitectonic regions: ___
3a, 3b, 1, and 2.
Fibers from areas 3a and 3b go to areas ___
1 and 2
Each of the 4 areas of S1 has its own independent, complete, ___
parallel sensory map.
ptimary submodality of 3a
deep tissue input
primary submodality of 3b
cutaneous receptors, SA or RA
primary submodality of 1
cutaneous receptors, ra
primary submodality of 2
deep pressure
in the cortical columns
moving medial-lateral changes ___
place
in the cortical columns
moving anterior-posterior changes ___
modality
____ seizure progressions follow the homunculus:
Jacksonian
Jacksonian seizure progressions follow the homunculus in what order
from finger to arm to shoulder to back to leg
Higher level S1 cells:
____ detect direction of movement
Posterior vertical columns in areas 2 and 1
are Topographic representations are modifiable?
yes, they change with use
___ receptors are located in the deeper layers of the skin, and also in deeper tissues.
ruffinis
Pacinian corpuscles are located ___ and ___
both immediately beneath the skin and also deep in the fascial tissues of the body.
The Pacinian Corpuscle’s ability to respond is based on its unique ____ structure.
lamellar accessory
the Pacinian corpuscle will respond with a single action potential for .
each phase of the stimulus
hair receptors
Slight movement of any hair on the body stimulates another type of receptor that is made up of a___entwining the base of the hair.
nerve fiber
The receptive field is that portion of the skin___
directly innervated by the receptor terminals and the area
limitations fo ALS
poor localizing ability on the body and little capability for fine intensity discrimination
*just crude touch
Sacral axons enter the spinal cord and are packed near the ____
midline
The axons that are added at higher levels are packed at successively more ____
lateral positions.
___ become larger in the dorsal column because they receive convergent input from many primary neurons
Receptive fields
why is the receptive field of second order neurons more complicated?
excitatory and inhbiitory regions
A punctate stimulus activates several touch receptors to varying ____
degree
Punctate stimulus
Each of the primary units influences (2)
- its own secondary unit
- also its nearest neighbors
The fibers of the medial lemniscus synapse on the ___ of the thalamus.
VPL
Sensory information about a particular modality from one part of the body
is processed by collections of neurons that form ___ in the thalamus.
discrete functional units
Axons of the ___that subserve a particular modality from a restricted body part form a bundle as they enter the thalamus
medial lemniscus
The medial division of the VPL projects to the ___ portion of the postcentral gyrus.
lateral
The lateral division of the VPL projects to the ___ portions of the postcentral gyrus.
medial and superior
Most of the thalamic fibers terminate in areas ____ of S1
3a and 3b.
Penfield found that stimulation of the postcentral gyrus produced tactile sensations in particular parts of the ___
opposite side of the body.
The sizes of areas in the SI are directly proportional to the ___ in each respective peripheral area of the body.
number of specialized receptors
3a, 3b, 1, and 2 are adjoining, parallel and they correspond to each other in their ___representation.
medial-to-lateral
