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Flashcards in Exam 2 Deck (30)
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1

How many neurons does the spinal cord have?

long and thin and can contain up to 100 million neurons

2

how long is the spinal cord?

40-45 cm or 16-18 inches (most 18 inches)

3

what is the diameter of the spinal cord?

1.3cm maximum diameter (in cervical enlargement)

4

At what area does the cord occupy 75% of the vertebral canal

C5-C6

5

How much does the spinal cord weigh

27-35 grams in weight only 2% of the total CNS weight

6

what is the superior boundary of the spinal cord
(both convenient and precise)

foramen magnum for convenience: the superior most ventral rootlet of the first cervical spinal nerve when being precise. C1 nerve rootlet/superior most anterior C1 rootlet

7

what is the inferior boundary of the spinal cord (adult)

the disc between vertebral levels L1-L2 (90%) (leaves almost one third of vertebral canal and sacral canal below) Conus Medularis disc level between L1-L2

8

How many spinal nerve pairs exist

31 pairs

9

Each spinal nerve will have what kind of rootlets within the vertebral canal

dorsal and ventral roots

10

states that dorsal roots contain sensory (afferent) fibers and ventral roots are motor (efferent) fibers. exceptions when a few afferent fibers come through the ventral roots

Bell-Magendi Law

11

Roots (rootlets) spinal nerves and their rami are PNS or CNS structures

PNS
The only CNS structure in the vertebral canal is the spinal cord itself

12

C1 exits between what

occiput and atlas (occasionally missing dorsal rootlets)

13

C4 exits at IVF between what

C3 and C4 vertebrae (always one above and the one below)

14

C8 exits at the IVF between what

C7 and T1 vertebrae

15

What are the cervical nerves

C1-C8 vertebrae

16

What are the thoracic nerves

T1-T12 vertebrae

17

T1 exits at IVF between what

T1 and T2 vertebrae (same level then one below)

18

T6 exits at IVF between what

T6 and T7 vertebrae

19

T12 exits at IVF between what

T12 and L1 vertebrae

20

The rami consist of what kinds of nerves

mixed: motor and sensory

21

The rootlets consist of what kinds of nerves

Motor or Sensory

22

What are the Lumbar Nerves

L1-L5

23

L1 exits at IVF between what

L1 and L2 Vertebrae (like thoracic)

24

L5 exits IVF between what

L5 and S1 vertebrae

25

how many bones fuse together to form the sacrum

5 bones

26

what are the sacral nerves

S1-S5

27

S1-S4 nerves exit where

The dorsal and ventral sacral foramina

28

S5 exits where

The sacral hiatus

29

What is the coccygeal nerve abbreviated as

Co1

30

Where does the Co1 exit at

the sacral hiatus (this nerve may be missing)