A 13 Spinal Cord Pathways Flashcards
Where do you find internal arcuate fibers?
In the DCML system. Once the primary fibers have synapsed in the cuneate or gracile nuclei, the tracts cross over and they are called internal arcuate fibers. This now becomes medial lemniscus as it ascends.
where does the DCML synapse in the thalmus?
the VPL (ventral posterolateral nucleus)
visceral pain is sensed through which system?
DCML
What does the Romberg test test for?
DCML dysfunction
where does the spinothalmic system run in the spinal cord?
it runs anteriorly and laterally
where do spinothalmic afferent neurons cross?
after synapsing in the dorsal horn, they pass through the ventral white commisure of the same spinal level.
If you have a loss of pain, temperature, tickle and itch on the left side of the body, what would this most likely be?
A right side lesion of the spinothalmic tract
Why do you get anesthesia 1-2 levels below the level of the lesion with the spinothalmic tract lesion?
This occurs because frequently the spinothalmic afferents (A delta and C fibers) ascend up in lissauers tract before synapsing and crossing over.
Afferent spinothalmic fibers for pain and temperature are most commonly found where? what about crude touch?
1) laminae 1 and 2
2) laminae 1 and 5
spinothalmic 2nd order neurons are most likely found in which dorsal horn layers?
1,4,5,6
What is the function of C fibers in the spinothalmic system? where do they usually synapse?
1) C fibers carry pain sensory of aching and burning because they are non-myelinated and slow.
2) they usually synapse in laminae 2 of the dorsal horn which is called substantia gelatinosa.
What does it mean to be sacral sparring?
It just means that the sacral levels of the spinal cord are unaffected. This is because they lie on the outside of the spinal cord.
where do secondary fibers in the spinothalmic tract end?
In the VPL of the thalamus. This is the same as as the DCML pathway.
which lamina of the dorsal horn are found at all levels?
1-5
what are the (1-10) lamina called of the grey horns called?
(1) posteromarginal nucleus
(2) substantia gelatinosa
(3-5) nucleus proprius
(5-6) basal nucleus/ base of dorsal horn
(7) intermediate zone
(8) reticular core of ventral horn
(9) LMN group
(10) central grey area
What is the function of the dorsal spinocerabellar tract? What types of primary neurons does it use?
relay information from individual muscles from the trunk and lower limbs only. It uses 1a and 1b neuronal fibers.
where do the primary neurons synapse in the dorsal spinocerabellar tract? When does it cross over?
In clarkes nucleus which is in the dorsal horn. It never does!
In what levels do you find clarkes nucleus?
Thoracic and upper lumbar regions.
What is the function of the cuneocerebellar tract?
to relay information from the upper limbs to the cerebellum.
Where does the cuneocerebellar tract synapse?
In the accessory cuneate nucleus but by traveling through the fasciculus cuneatus (same as DCML)
where is the accessory cuneate nucleus located?
When does the cuneocerebellar tract cross over?
In the medulla? It does not cross over.
What is the function of the ventral spinocerebellar tract? Which type of primary neurons does it use?
to convey information about the whole lower limb and not just specific muscles. It uses type 1b neurons only.
Where do the ventral spinalcerebellar fibers synapse?
In the dorsal horn in non-named nuclei in the lumbosacral levels. They immediately cross, and once they reach the level of the cerebellum they cross again and enter.
What is the main function of lateral corticospinal pathway?
To supply the skeletal muscles concerned with skilled movements in the distal extremities.
Where do UMN’s of the corticospinal system originate? What is the pathway?
They come from the motor cortex, parietal, temporal, and frontal lobes.
They then pass through the internal capsule (diencephalon), through the midbrain (cereberal peduncle), through the pons, then medulla which divide into lateral and anterior corticospinal tracts.
What is tract of barnes?
the small percentage of anterior corticospinal nerves that never cross over and innervate axial muscles.
A lesion of the lateral corticospinal tract would result in what?
Loss of voluntary movement below that level to the distal extremities. This is referred to as an UMN lesion.
What is the function of the hypothalmospinal pathway?
mainly autonomics but also thermoregulation, pain modulation, secretion of epinephrine by supra-renal gland.
What is horners syndrome?
damage to the hypothalmospinal pathway above the level of T1.
The bulbospinal pathway (raphespinal tract) does what? Where does it originate?
It functions in pain transmission by blocking many unwanted pain signals.
1) PAG or peraquaductal gray
2) Locus ceruleus
3) nucleus raphe magnus
Of the ventral horn of spinal cord, dorsal and ventral correspond to what functions?
- Flexors
- Extensors
Where do the spinothalmic neurons ascend the spinal cord? Where is the first synapse?
In the anterolateral column
Synapses in dorsal horn laminae 1,2 or 1,5
At which level is the cervical enlargement?
C3-T2
What is the function of onufs nucleus?
Somatomoter to pudendal nerve mainly. Located S1-S4
Where do you find the ascending fibers for lissaurs tracts?
In the dorsal lateral tract.
