L03: Overview Of Ascending And Descending Tracts Flashcards
What type of information does ascending tracts carry
Sensory information
What are the 2 regions that ascending tracts are separated to
Head and neck region
Rest of the body
Which specific nerve is involves in the ascending tract of the head and neck region
Trigeminal nerve (CN5)
What are the 2 main sensory organs in the body
Skin
Muscles
What is a dermatome
A slice of skin whose sensation is conducted by a SINGLE spinal nerve
What does muscles senses
Position in 3D i.e propioception
What does general sensory afferent sense
Pain and temperature
What does propioceptive afferents detect
Propioception
What is the sense organs for propioception
Muscle spindles
Golgi tendon organs
Joint receptors
What is a sensory homonculus
Represents the emphasises of sensation in the body
Which parts in the sensory homonculus emphasis sensation
Hands and head
What does it mean to have a big hand in the sensory homonculus
Sensation of the fingers is significant
What are the 3 types of ascending tracts that take sensory information to the brain
Dorsal columns
Spinothalamic tract
Dorsal and ventral spinocerebellar tract
What is the 2 tracts that the dorsal column is spit into
Fascilus gracilis
Fasiculus cuneatus
Which part of the body does the fasiculus cuneatus carry the sensation of
Upper part of the body (above T4)
What part of the body does the fasiculus gracilis carry the sensation of
Lower part of the body (below t4)
What are the 2 tracts that the spinothalamic tract split into
Anterolateral
Lateral
What is the spinocerebellar tract split into
Dorsal spinocerebellar tract
Ventral spinocerebellar tract
What type of sensory information does the lateral/anterolateral spinothalamic tract carry
Pain
Temperature
Crude touch (non-discriminative touch i.e you cannot localise where you have been touched)
What type of sensory information does the dorsal column carry
Tactile sensation
Propioceptive
What is tactile sensation
Very light sensation
What type of sensory information does the dorsal/ventral spinocerebellar tract carry
Propioception only
Which 2 ascending tracts take the signal to the brain (primary sensory cortex)
Spinothalamic tract
Dorsal column
Which ascending tracts take the signal to the cerebellum
Dorsal/ventral spinocerebellar tract
Therefore which ascending tract is involves in conscious sensation
Dorsal columns
Spinothalamic tract
Which ascending tract is involved in non-conscious sensation
Spinocerebellar Tract
What is the arrangement of neurones in the dorsal columns and spinothalamic tract
1st order neurone
2nd order neurone
3rd order neurone
What is similar in the dorsal columns and spinothalamic tract
They have 3 neurones involved
What is the difference in the tracts of the dorsal column and spinothalamic tract
The way they get to the brain
Where is the cell body of the 1st order neurone/primary neurone found
Dorsal root ganglion
Where does the axon of the primary neurone terminate in the spinothalamic tract
Dorsal horn of the spinal cord
Where does the axon of the primary neurone split
Posterolateral tract of lissauer
How does the axon of the primary neurone split
Same spinal level
One spinal level above
One spinal level below
If the tract is a anterolateral spinothalamic tract which happens to the second neurone from the dorsal horn
Is passes/decusates under the central canal to cros the controlateral side (opposite side)
Where does the second order neurone of the anterolateral spinothalamic tract terminate
Ventral posterior lateral nucleus at thalamus
Which part of the white matter does the spinothalamic tract ascend in
Lateral funiculus
If the ascending tract is the dorsal column what happens to the 1st order neurone from the dorsal horn of the spinal cord
It ascending on the same side of the spinal cord until the medulla where it terminates to become the second order neurone
Where does the second order neurone of the dorsal column begin
In the medulla
What happens to the second order neurone at the medulla
The second order neurone decussates at the medulla to the controlateral side
Where does the second order neurone terminate for both the dorsal column and spinothalamic tract
Thalamus to become the third order neurone
What is syringomyelia
Scared tissue in the spinal cord that forms fibrosis and cuts off fibres of the spinothalamic tract
What is the brown sequard syndrome
Pain of controlateral side if lost
Which 2 lobes does the central sulcus separate
Frontal lobe
Parietal lobe
Which lobe is the sensory cortex in
Parietal lobe
Which lobe is the motor cortex in
Frontal lobe
What is the gyrus of the primary motor cortex known as
Pre-central gyrus
What sit eh gyrus of the sensory cortex known as
Post -central gyrus
After the ascending tract has fed into the brain how does the brain trigger movement
By the descending tract
What is the motor homonculus
Representation of the muscles where it is big in the head and hands
What does the brain command the muscles to do
Contact
Or
Rest
Which muscle does the right motor cortex control
Left muscles of the body
Which muscles does the left motor cortex control
Right muscles of the body
Why does the right motor cortex control the left muscles and vice versa
Due to decassation
What are the 2 classes of descending tracts
1) tracts that have cell body at primary motor cortex
2) tract that starts at the brain stem
What are the effector organs of the descending tract
Skeletal muscle
What are the neurones that innervate the skeletal muscle called
Moto neurones
What are the 2 categories of motor neurones
Motor neurone that has cell body in brain = upper motor neurone
Motor neurone that has cell body in the spinal cord= lower motor neurone
What does the axon to the upper motorneurones travel as
Descending tracts
What does the axon of the lower motor neurone travel as
Motor efferent
What is the location of the descending tracts in the spinal cord
Lateral funicilus
Anterior
