Spinal Cord + Meninges

Question 1

Spinal Cord

Answer 1

• part of CNS, occupies VC
• in infants, SC extends into sacrum
• in adults, from foramen magnum to L2 (more superior in flexion)
• cervical enlargement (for arms) at C5 -> T1
• lumbar enlargement (for legs) at L1 -> S3
• enlargements have higher density of nerves

Question 2

external surface of SC

Answer 2

of fissures + sulci

anterior media fissure - extends length of anterior surface
posterior median sulcus - extends along posterior surface
posterolateral sulcus - on each side of posterior surface - where posterior rootlets of SNs enter cord

Question 3

internal surface of SC

Answer 3

CSF, white matter (SC tracts, info to/from brain), gray matter (synapses + cell bodies)

Question 4

Spinal nerves

Answer 4

31 pairs of spinal nerves

8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
C1-C7 on top of vert, C8 and below are inferior to vert
if herniation btwn C7 + T1, compressing C8

Question 5

Spinal cord ending

Answer 5

ends at L2
conus medullaris = end of SC
cauda equina = nerve roots
filum terminale = anchors SC in place

Question 6

Dura mater

Answer 6

• outermost, thick/dense inelastic mem
• attached around foramen magnum and bodies of C2+C3
• tubular extensions enclose roots of SNs
• end of dural sac at S2, extends to coccyx as filum terminale externum

Question 7

Arachnoid mater

Answer 7

• middle, delicate spiderweb-like mem
• not attached to dura
• ends at S2
• avascular

Question 8

Pia mater

Answer 8

• vascular membrane, adheres to SC, prevents excessive movement
• denticulate ligaments - extend laterally to arachnoid/dura mater (btwn post/ant roots), attached to SC medially -> position SC in center of subarachnoid space
• filum terminale internum (anchors SC)

Question 9

subarachnoid space

Answer 9

• separates arachnoid + pia mater, contains CSF, BVs, CT
• extends inferiorly past SC to S2 = lumbar cistern -> has CSF
• surrounds cauda equina

Question 10

Lumbar tap

Answer 10

put needle thru skin -> fat -> fascia -> supraspinous ligament -> interspinous lig -> ligamentum flavum -> dura + arachnoid -> subarachnoid space to get CSF

Question 11

Epidural space

Answer 11

btwn vert + dura, has epidural fat + IV venous plexus

Question 12

subdural space

Answer 12

btwn dura + arachnoid, contains only serious fluid, potential space, ends at S2

if damage, blood accumulates here, compresses SC

Question 13

Epidural

Answer 13

• for labor -> at S2-S3 or sacral hiatus (below coccyx)

- inject anesthesia into epidural space (btwn ligament flavum + dura mater - outside of SC, affects SN roots)

Question 14

Vertebral Arteries

Answer 14

1 anterior + 2 posterior spinal arts -> longitudinal, along entire length of SC, main supply, supplemented by segmental/feeder arteries

Question 15

segmental arteries

Answer 15

• anterior + posterior radicular, segmental medullay arts
• largest = arteria radicularis magna or artery of Adamkiewicz
• reinforce art supply to lower SC, esp lumbar enlargement

Question 16

Veins

Answer 16

ant/post spinal veins -> intervertebral vein -> internal venous plexus (in epidural space) -> basivertebral veins (drain VBs) -> external venous plexus -> systemic/azygos veins

venous drainage of VC anastomoses w/veins of SC