Bales: spinal cord topography Flashcards
What is hydromyelia and what symptoms can it lead to?
Abnormal enlargement of the central canal is hydromyelia, a subset of spinal cord diseases called syringomyelias (fluid-filled cavity in the cord)
The pressure caused can produce both motor and sensory problems by compression of adjacent tracts (nerves don’t like to be compressed)
Spinal cord itself does not necessarily expand.
What is the dorsal column of the spinal cord’s function? How many columns are in the spinal cord at different levels?
The dorsal column is entirely sensory
From sacral to mid-thoracic level (~T6), the dorsal column is only 1 fasciculus (gracilis)
From mid-thoracic through cervical levels, dorsal column is 2 fasciculi (gracilis (more medial) + cuneatus (lateral))
Where is the fasciculus proprius? and what is its function?
A shell (veneer) of white matter bordering the gray matter in all 3 columns is a specialized tract for conveying fibers between cord levels (“proprio-” = self or within)
What are the laminae components of the dorsal horn of the spinal cord?
I=marginal zone (tip)
II=substantia gelatinosa
III, IV=nucleus proprius
V-VI
ALL are sensory
Which lamina is between dorsal and ventral horns? What is it continuous with? What are some subregions of VII at levels T1-L2?
VII
it is continuous with X (gray commissure)
from T1-L2: VII includes intermediolateral cell column (preganglionic sympathetic fibers) and clarke’s nucleus (proprioceptive relay nucleus)
What laminae are the motor system cell columns?
VIII and IX
Lamina VIII contains interneurons which integrate motor inputs and synapse on motor neurons
The somatic efferent motor neurons (α & γ) are in lamina IX (discontinuous)
What levels of the spinal cord are enlarged and why?
ventral horns of:
C5-T1–> brachial plexus
L4-S4–> lumbosacral plexus
How many anterior spinal arteries does the spinal cord have? What does it supply blood to? What will arise from an anterior spinal A hemorrhage or occlusion?
one (from combining branches of the 2 vertebral arteries)
anterior spinal a. usually supplies bilaterally:
anterior column, ventral horn, commissures, intermediate horn, and adjacent lateral column
A hemorrhage or occlusion will cause paralysis due to the ventral horn’s loss of blood supply
What will be the result of a lesion (hemorrhage/occlusion) of the anterior spinal a. at the level C3-5?
diaphragm paralysis
What will be the result of a lesion of the anterior spinal a. at the level C5-T1
paralysis of upper limb
What will be the result of a lesion of the anterior spinal a. at the level T1-T3?
interrupts sympathetics to the head (Horner’s syndrome)
What will be the result of a lesion of the anterior spinal a. at the level L4-S1?
paralysis of lower limbs
What will be the result of a lesion of the anterior spinal a. at the level S2–S4?
disrupts bladder function, sexual function, and bladder & bowel continence (intermediate horn & Onuf’s nuc.)
What supplies blood to the posterior 1/3 of the spinal cord? What does this posterior 1/3 include?
Posterior spinal aa. (2) supply the posterior 1/3 (branch from PICA)
dorsal columns, dorsal horns, dorsal parts of the lateral columns
What will an upper cervical lesion of the posterior spinal a. lead to?
Because of a the cumulative nature of the dorsal column, an upper cervical lesion will cause loss of senses in lower and upper limbs
