A&P Test 3 Flashcards
Sensory information goes what direction in the spinal cord?
up
Motor information goes what direction in the spinal cord?
down
Which pathways are there more of? Sensory or motor
sensory
What kind of sensory sensors do we have?
pressure
temperature
vibration
pain
Where does decision making happen in the spinal cord?
The grey matter
What is the grey matter of the spinal cord made of?
cell bodies and part of neurons that communicate with each other,
lots of synapses.
What does “tract” refer to?
a bundle of axons within the CNS
What is a bundle of axons called in the PNS?
Nerves
The main descending motor pathways are separated into what groups?
pyramidal tract
Extrapyramidal Tract
What does the Pyramidal tract take care of?
The primary motor function we think of: moving an arm or leg around
primarily voluntary
What does the extrapyramidal tract take care of?
accessory motor pathways that help us coordinate complex tasks
primarily involuntary(we don’t have realization or knowledge of these)
-help us find tune our motor commands
What is the ascending sensory pathway called?
dorsal column pathways
Where does the dorsal column pathway sit?
in the back of the cord- dorsal column
What do the does the dorsal column pathway do?
transmit information regarding pressure sensors located in the skin
Perception
helps us figure out if we’re holding onto something or have our hands in the air
Where are the pain signals sent in the spinal cord?
in the anterolateral system
What are the 2 pathways that pain can take in the spinal cord?
the lateral or anterior routes
What is another term that is used to describe pain pathways in the spine besides anterolateral system?
spinalthalamic tracts or pathways
Pain travels through the _____ and then the _______ followed by the ______ which is why it is called spinal thalamic tracts
cord within the spine
thalamus
parietal cortex where it can be sorted out
What are some ways the parietal cortex sorts pain information it receives?
where is the bad pain coming from?
How severe is it?
What is Rexed’s Laminae?
A way to divide up and name the parts of grey matter in the cord
In what direction is Rexed’s Laminae numbered?
back to front
The most dorsal part of the grey matter found in the horn (the tip) is called
Lamina I
What is lamina I known for?
Part of the cord that sends fast pain up to the brain
What kind of neuron is fast pain transmitted through?
Myelinated pain fibers (nociceptors)
These are A-Delta fibers
Fast pain comes in through the dorsal root, through the rootlet, into the cord, and has synapses on
Lamina I
After pain is in Lamina I where does it go?
It crosses over to the other side of the cord and ascends into an anterolateral pathway
Anterior to lamina I in the dorsal horn is
Lamina II and Lamina III
collectively known as Substantia Gelatinosa
What is another name for Lamina I?
Lamina Marginalis
What does the Substantia Gelatinosa send to the brain?
Slow pain
Sometimes with slow pain there is also synaptic connections to _______ in addition to the substantia gelatinosa
Lamina V
Slow pain is typically routed through
non-myelinated nociceptors
C Fibers
Where does slow pain signals go after the Substantia gelatinosa?
The signal hops over to the other side of the cord and goes up towards the brain via the anterolateral or spinal thalamic pathway
What relays information to Lamina I-VI?
mechanoreceptors found in the hands and skin
Where are our motor neuron bodies headquartered?
in the anterior horn
What activates the motor neurons?
The descending motor pathways
How many different Laminae are there in the grey matter of the spinal cord?
IX
Where is lamina X?
around the central canal
What does lamina X allow for?
signals to be routed to the opposite side of the cord
The portion of tissue that can relay information to the other side of the cord that’s made of white matter is called the
anterior white commisur
How many different categories of spinal tracts are there?
5
Spinal cerebellar tracts are ____ tracts that send information from the spinal cord up to the ______
sensory
Cerebellum
What is the major pressure/touch sensory pathway?
the dorsal column Medial Lemniscal system
DCML
Where does the dorsal column medial lemniscal system travel and what does it pass through?
the dorsal column , medial lemniscus
What is another name for the pyramidal tracts? Why?
corticospinal pathway.
The signal originates in the cerebral cortex at the motor cortex and then pass through the spine.
Which direction does information go through the corticospinal pathway?
Descending
What kind of neurons are found in the DCML?
A fibers: alpha, beta, gama, delta
What is the major sensory pathway that takes care of senses other than pain?
Dorsal column medial lemniscus pathway
Are DCML’s fast or slow?
very fast
The left side of the nervous system takes care of the function on the ______ side of the body
right
and vice versa
In the dorsal column pathway, where does the crossover happen?
medulla
What are the two routes that somatosensory information entering from the dorsal rootlets can go?
the grey matter of the cord
one of the ascending pathways in the dorsal columns to the medulla
The somatosensory information that enters from the dorsal rootlet and stays in the grey matter of the cord can do what?
lateral inhibition
modulation of some of the activity in the cord
The higher we go up in the cord, the ______ the dorsal columns are going to be
wider/larger
d/t more information being fed into these from the trunk, arms, neck, etc.
What do the lower extremities feed information into?
fasciculus gracilis
How can you remember that the lower extremities feed into the fasciculus gracilis?
There is a leg muscle called the gracilis muscle
As we go higher in the spinal cord, we add to the _______ of the dorsal column
lateral sides
What is the portion of the DCML pathway that sits to the lateral sides of the fasciculus gracilis?
The Fasciculus cuneatus
What is fed into the fasciculus cuneatus?
The sensory information coming from the upper extremities
What is a very, very sensitive pathway and is able to pick up very small changes in the pressure?
the DCLM pathways both fasciculus gracilis and fasciculus cuneatus
If someone tickles your foot with a feather, what is the pathway that information is going to take?
through the dorsal root
dorsal root ganglia
dorsal rootlets
into the dorsal column -Fasciculus gracilis
Sensory is added in the fasciculus cuneatus
Lower part of the medulla is where it crosses over
goes through the medial lemniscus
ventrobasal complex of thalamus
Internal capsule
parietal lobe
What is the ventrobasal complex of the thalamus in charge of?
running sensory information up towards the parietal lobe of the brain
Where is the internal capsule?
between the thalamus and parietal lobe of the brain
What is another name for the parietal lobe section that somatosensory information gets sent to?
Post central gyrus
Where is the post central gyrus?
immediately behind the central sulcus
Different parts of the body’s sensory information are taken care of by different parts of the ________
parietal lobe/ sensory cortex
Which part of the parietal lobe takes care of the lower extremities?
The top part
The area of the parietal lobe that is more in the middle of the brain takes care of what part of the body?
trunk
The area of the parietal lobe that is below the middle portion of the brain takes care of what part of the body?
upper extremities
What does the lateral borders of the parietal lobe get information from?
face
If we have a stroke in the top part of the parietal lobe, we would expect to see what part of the body effected?
lower extremities
What is the homunculus?
a picture that shows which part of the body is going to be taken care of by which part of the parietal lobe
on the homunculus, the face is taken care of by which portion of the parietal lobe?
bottom lateral portion of the parietal lobe
on the homunculus, the lower extremities are taken care of by which portion of the parietal lobe?
the area more midline
the amount of area that you have processing all this information in the brain is proportional to the number of
sensory receptors we have in that part of the body.
How many pressure sensors do we have in the hands and face?
tons and tons and tons
in order to have really detailed information processed in the parietal lobe, we have to have
a lot of different pressure sensors in a large quantity
The amount of tissue in the parietal lobe that processes sensory information is proportional to the ______________
number of sensory receptors that feeds that specific area
What is one of the lower density areas (has few sensory connections) that take up a smaller portion of the parietal lobe?
Trunk
Why are the pyramidal tracts called that?
they pass through the pyramids in the brainstem
What are the 2 portions of the pyramidal tract?
primary descending motor pathway
secondary descending motor pathway
Primary motor pathway:
signals originates in the motor cortex which is part of the frontal lobe and on the way down it passes through the
internal capsule right outside of the thalamus
Part of the brainstem: medulla at a specific part called the pyramids. this is where it crosses over
down the cord via lateral corticospinal tracts
activation of our motor neurons that are in the anterior horn or the spinal cord at the level it is associated with
What percent of our motor functions get passed through the primary motor descending pathway?
80% or 4/5
Where are the pyramids of the brainstem located?
anterior part of the medulla
What is another name for the pyramids?
medullary pyramids
What is the place in the medullary pyramids called where cross over happens?
pyramidal decussation
Where do signals originate that travel through the lateral corticospinal tract?
From the motor cortex
What does the decussation look like?
crosshatch pattern found in the anterior portion of the brainstem
what are the ridges called on the medulla?
pyramids
secondary motor pathway is sent down which area of the spinal cord?
anterior motor pathways, a lot smaller than the lateral tracts.
What percent of motor function goes through the secondary motor pathway?
17%
What is the main difference between the primary and secondary motor pathways?
Where they cross over
Where does the secondary motor pathways cross over?
In the spinal cord in the level where the tract talks to the motor neuron in the anterior horn
secondary motor pathway:
signals originates in the motor cortex which is part of the frontal lobe
travels down the anterior part of the spinal cord
crosses over in the cord at the level it needs to work
activation of our motor neurons that are in the anterior horn or the spinal cord at the level it is associated with
What percent of our motor information does not cross to the other side of the body at all?
2-3%
What is an example of a motor function that does not cross to the other side of the body?
Smidt doesn’t know!!
The pain system transmits pain sensations via what 2 routes
fast pain signal
slow pain signal
both types of pain routes travel through the
spinal thalamic/ anterolateral tracts
what determines which specific pathway pain takes?
if it’s a fast or slow pain
What is one way that the body modulates pain?
a descending pain inhibitory complex
What do we use as targets for our analgesia drugs?
