Spinal Cord Anatomy Lecture Flashcards
How many spinal nerves are there?
31 human pairs:
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 + coccygeal
Where are the sensory neuron cells bodies found? What about its axon?
- cell bodies in dorsal root ganglion
- single axon divides into central and peripheral branches
What does the ventral root contain?
motor neuron axons
Where do spinal nerves originate?
spinal nerves originate from dorsal and ventral roots
What are dermatomes and what do they show?
(dermatome = an area of the skin supplied by nerves from a single spinal root)
–> Each SENSORY area of skin corresponds to a specific spinal nerve
What diseases highlight dermatomes?
Herpes Zoster Infection (shingles)
- Chicken pox virus infects sensory nerve endings
- -> Highlights affected dermatome(s) (with inflammation!)
What is the grey matter of the spinal cord split into?
laminae - numbered from dorsal to ventral in roman numerals (X = 10 in total)
Where in the grey matter are cells larger?
ventral –> big motoneurons
What can parts of the white matter be split into?
Ascending tracts:
- dorsal columns
- spinocerebellar tracts
- spinothalamic tracts
Descending tracts:
- lateral corticospinal tract
(there are more!)
What is decussation?
Axons often cross from right to left or left to right
–> different tracts cross in different places
–> often either in spinal cord (spinal decussation)
or brainstem (brain decussation)
or a mix
What is cordotomy?
- radical intervention for pain relief in terminal cancer patients
- legion of spinothalamic tract at cervical level
- produces pain relief (analgesia) on opposite side
What is arguably the most important descending tract?
- corticospinal
- -> carries information from primary motor cortex
- -> 2 parts: lateral and anterior
What happens to the corticospinal tract in the brainstem?
Pyramidal decussation:
- Most (≈80-90%) of corticospinal tract decussates in medulla to form lateral tract
- Remaining axons form anterior tract and cross in SC
