Spinal Cord and Somatic PNS

Question 1

spinal cord ending in adults

Answer 1

usually between L1 and L2 (conus medullus can be as high as T12 or as low as L3)

Question 2

what are the spinal cord enlargements?

Answer 2

cervical enlargement and lumbosacral (lumbar) enlargement

Question 3

cervical enlargement

Answer 3

C4-T1 most of the anterior rami from it form the brachial plexus (innervate the upper limbs)

Question 4

lumbosacral enlargement

Answer 4

L1 - S3, ant rami form the lumbar and sacral plexus (innervate lower limbs)

Question 5

cauda equina

Answer 5

bundle of spinal nerve roots running inferior to spin cord through lumbar cistern

Question 6

how many spinal nerves?

Answer 6

31 (8 cerv, 12 thor, 5 lum, 5 sac, 1 coc)

Question 7

what arteries supply the spinal cord?

Answer 7

(3 longitudinal arteries)

1. ) anterior spinal artery
2. ) paired posterior spinal arteries

Question 8

where are the anterior and posterior segmental medullary arteries located?

Answer 8

the cervical and lumbosacral enlargements because the need for a good blood supply to the spinal cord is here

Question 9

great anterior segmental medullary artery

Answer 9

• much larger than other segmental As
• reinforces 2/3s of the spinal cord circulation (inc: lumbosac enlarge)
• arise on left side at low thoracic and upper lumbar levels

Question 10

Posterior and ant radicular arteries

Answer 10

• run along nerve roots

- supply post and ant roots of spinal nerves and their coverings

Question 11

what drains the 3 ant and 3 post spinal veins?

Answer 11

-up to 12 ant and post medullary and radicular veins

Question 12

veins draining the spinal cord join the _____________ in the epidural space

Answer 12

internal vertebral venous plexus