Exam 3 - Lecture 1 Flashcards
The cord transits sensory information from:
The periphery to the brain stem, cerebellum and brain.
Efferent pathways
Carries motor from spinal cord to skeletal muscles
Cell bodies of motor neurons in the spinal cord are in ________ matter
Grey
What does the grey matter consist of
Cell bodies of motor neurons that communicate with eachother, lots of synapses and connections.
Bundle of axons within CNS? Outside CNS?
Tract, Nerves
Descending pathways are split into two groups:
Pyramidal and extrapyramidal tracts
Pyramidal tracts contain what kind of pathways
Vast majority of motor function such as moving arm or leg around.
Extrapyramidal tracts contain what kind of pathways
Accessory motor pathways that help us do complex tasks
Pyramidal voluntary or involuntary?
Voluntary
Extrapyramidal voluntary or involuntary?
Involuntary, may not be aware but it helps us fine-tune motor commands.
Ascending pathways that sit in back of cord
Dorsal column pathways shaped like a broccoli
Dorsal column pathways
Transmit information regarding pressure sensors in skin, touch/perception (if we are holding onto something)
Anterolateral system is split into ____ pathways
2 pathways. Anterior and lateral component.
Another term to call pain pathways (anterolateral tracts)
Spinothalamic tract
Spinothalamic terminology corresponds to:
Pain signals go into cord, cord is within the SPINE, and our pain information is relayed through THALAMUS, to parietal cortex.
Spino-Thalamic
2 names for pain pathways
Anterolateral tracts and Spinothalamic tracts
Grey matter in cord is split into parts called? How is it numbered?
Rexed’s laminae, numbered back to front (dorsal to ventral)
Lamina I: what signal does it send and what kind of fibers?
Fast pain/sharp pain
myelinated pain fibers/nociceptors, also called A delta fibers
Whats the pathway for lamina I to get to the brain
Crosses over to the bottom right side of the cord and ascends through anterolateral/spinothalamic tract
First thing fast pain comes into contact with in spinal cord
Cell bodies in Lamina I
Laminae II and III are called ______ and what do they do? What kind of fibers?
Substantia Gelatinosa, important place for cell body synapses in slow pain conduction system.
C-fibers, nociceptors, non-myelinated
Sometimes with slow pain, there can also be synaptic connection with:
Lamina V
why is slow pain sent slower?
sent through non-myelinated pathways
Whats the pathway for slow pain to get to the brain?
Crosses over to the bottom right side of the cord and ascends through anterolateral/spinothalamic tract
Lamina I -> VI also have
mechanoreceptors that relay infrormation through grey matter in cord
Typically, we have mechanoreceptors or ________ in the hand or skin, and they feed information into the ______ of the cord. They are located in laminas ________.
Pressure sensors; grey matter; I -> VI
What is the route to brain for mechanoreceptors?
Through the dorsal column pathways
Alt name for Lamina I
Lamina marginalis because its on the tip of dorsal horn
Motor neuron cell bodies in ventral horn can be excited by
Stimulus from brain or reflex arcs
Lamina X
Middle of the grey matter, allows cross over of signals through itself or anterior white commissure on the outside of it.
Laminae VIII
Lots of large motor neurons, receive stimulus from brain or reflex arcs to excite motor movement.
5 spinal tracts
-Extrapyramidal tracts (accessory motor pathways)
-Spinocerebellar tracts
-Dorsal column pathway
-Corticospinal tracts (Pyramidal tracts)
-Spinothalamic tracts (anterolateral tracts/pain pathways)
spinocerebellar tracts
sensory tracts that send information from spinal cord to cerebellum
What does the ‘medial lemniscal’ part of the name for the Dorsal column pathway mean?
Refers to structure it passes through as information goes through brain stem, called the medial lemniscus.
Abbreviation for Dorsal-column medial lemniscal system?
DCML
Corticospinal tracts
AKA pyramidal tracts.
-Descending tracts that originate in the cerebral cortex (motor cortex), pass through spine to talk to skeletal muscles.
Characteristics of DCML
-Very fast signal propagation (A-fibers)
-Fine vibrations/pressure
What kind of A fibers are in DCML?
A alpha, A beta, A delta, A gamma
All myelinated
Where does DCML crossover?
At the medulla
Usually, the left side of the central nervous system takes care of
right side of the body and vice versa
Touch information comes in through back of cord and goes where?
Part of it ascends through DCML to the brain and the other part goes into grey matter of the cord (usually stays there)
Higher we go up in the cord, the ______ the dorsal columns will be
Larger
Due to more information, e.g. lower part of the cord only sends up lower extremity information, but higher up includes the legs plus everything above them.
Lower extremity sensory information in the DCML is sent through
Fasciculus Gracilis,
where is the fasciculus gracilis on the DCML?
immediately lateral to the right and left of the midline.
Where does upper extremity sensory information in the DCML get sent through?
Fasciculus Cuneatus
Where is the fasciculus cuneatus on the DCML?
Lateral parts of DCML.
What would the signal path be for a feather tickling your left foot?
Into the left side of dorsal horn in the back, part of it sent to the Fasciculus Gracilis, up the spinal cord where it crosses over at the LOWER PART of the medulla oblongata, then to the right side of the medial lemniscus in pons, to right side of midbrain, then to thalamus at the VENTROBASAL COMPLEX, then to internal capsule, then to the right parietal lobe.
Ventrobasal complex
Part of thalamus in charge of sensory information to send to parietal lobe in brain.
Internal capsule
Sits just outside thalamus, a route/path that signal takes to get to parietal.
Where is the lower extremity information processed in parietal lobe?
Top part
Where is the trunk information processed in parietal lobe?
just posterior to lower extremity
Where is the upper extremity information processed in parietal lobe?
just posterior to trunk
Where is the face information processed in parietal lobe?
Posterior to upper extremity, very back of parietal lobe
Creepy drawing that lays out map of where NON-PAIN sensory information is processed in parietal lobe
Homunculus
Which body part has a ton of pressure sensors that take up a large part of parietal lobe?
Hands, extra sensors in there. Also face.
Why is it difficult to figure out where someone is poking you in the back?
Low density of pressure sensors located in trunk.
Main motor tracts are:
pyramidal tracts; descending pathways
What are the pyramidal motor tracts called?
Primary and secondary (1 each per side)
Primary pyramidal tract pathway order from brain to spinal cord?
Cortex -> internal capsule -> Pyramids of medulla -> X-over -> Lateral corticospinal tracts ->activation of motor neurons in anterior horn
What % of motor function is the primary pyramidal tract?
80%
Pyramids of brainstem are found in:
Anterior part of brainstem on the medulla, and this is where crossover occurs for the primary pyramidal tract.
Where specifically does crossover occur in primary pyramidal tract?
Pyramidal decussation in pyramids of medulla
What does pyramidal decussation look like
Cross-hatched pattern on the midline of pyramids of medulla, for x-over
Ridges in anterior inferior part of medulla
Pyramids
Secondary pyramidal tract is found in
anterior part of cord, just lateral to anterior median fissure
Secondary pyramidal tract is also known as the
Anterior corticospinal tract
What % of motor information goes through secondary pyramidal tract
17%
where does x-over of motor information occur in secondary pyramidal tract?
at the level of where motor neurons communicate in anterior horn where its being sent out
What % of motor information does not cross over to other side at any point?
2-3%
Why doesn’t some motor info ever cross over?
it takes a 3rd pathway known as uncrossed lateral corticospinal tract, and its most lateral tract in the pictures
Pain is relayed through which pathway
Spinothalamic/anterolateral pathway
