Exam 2

Question 1

How many neurons does the spinal cord have?

Answer 1

long and thin and can contain up to 100 million neurons

Question 2

how long is the spinal cord?

Answer 2

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

Question 3

what is the diameter of the spinal cord?

Answer 3

1.3cm maximum diameter (in cervical enlargement)

Question 4

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

Answer 4

C5-C6

Question 5

How much does the spinal cord weigh

Answer 5

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

Question 6

what is the superior boundary of the spinal cord

both convenient and precise

Answer 6

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

Question 7

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

Answer 7

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

Question 8

How many spinal nerve pairs exist

Answer 8

31 pairs

Question 9

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

Answer 9

dorsal and ventral roots

Question 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

Answer 10

Bell-Magendi Law

Question 11

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

Answer 11

PNS

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

Question 12

C1 exits between what

Answer 12

occiput and atlas (occasionally missing dorsal rootlets)

Question 13

C4 exits at IVF between what

Answer 13

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

Question 14

C8 exits at the IVF between what

Answer 14

C7 and T1 vertebrae

Question 15

What are the cervical nerves

Answer 15

C1-C8 vertebrae

Question 16

What are the thoracic nerves

Answer 16

T1-T12 vertebrae

Question 17

T1 exits at IVF between what

Answer 17

T1 and T2 vertebrae (same level then one below)

Question 18

T6 exits at IVF between what

Answer 18

T6 and T7 vertebrae

Question 19

T12 exits at IVF between what

Answer 19

T12 and L1 vertebrae

Question 20

The rami consist of what kinds of nerves

Answer 20

mixed: motor and sensory

Question 21

The rootlets consist of what kinds of nerves

Answer 21

Motor or Sensory

Question 22

What are the Lumbar Nerves

Answer 22

L1-L5

Question 23

L1 exits at IVF between what

Answer 23

L1 and L2 Vertebrae (like thoracic)

Question 24

L5 exits IVF between what

Answer 24

L5 and S1 vertebrae

Question 25

how many bones fuse together to form the sacrum

Answer 25

5 bones

Question 26

what are the sacral nerves

Answer 26

S1-S5

Question 27

S1-S4 nerves exit where

Answer 27

The dorsal and ventral sacral foramina

Question 28

S5 exits where

Answer 28

The sacral hiatus

Question 29

What is the coccygeal nerve abbreviated as

Answer 29

Co1

Question 30

Where does the Co1 exit at

Answer 30

the sacral hiatus (this nerve may be missing)