Anatomy for Neuraxial Anesthesia

Question 1

How many bones make up the vertebral column?

Answer 1

33 bones that are sequentially interconnected

-separated by fibrocartilaginous disks

Question 2

The vertebral column provides

Answer 2

a bony reference for various procedures

Question 3

The vertebral column extends from

Answer 3

the base of the skull to the tip of the coccyx

Question 4

Describe the natural curves of the spinal column.

Answer 4

anterior curvatures (cervical & lumbar)
posterior curvatures (thoracic & sacral)

Question 5

Describe the pertinent anatomic landmarks

Answer 5

vertebra promins- C7
Inferior angle of scapula- T7
Tuffier’s line- L4-L5- line drawn at iliac crest

Question 6

Just using the anatomic or landmark technique,

Answer 6

finds that the accuracy is variable; providers are generally off by at least 1 level

Question 7

Describe the sacrum.

Answer 7

fused into one bone

can perform caudal anesthesia by going through the sacral hiatus

Question 8

Describe what lumbarization is.

Answer 8

when L5 & S1 are fused

Question 9

Describe what sacralization is.

Answer 9

when S1 & S2 are fused together

Question 10

Describe the three posterior ligaments.

Answer 10

supraspinous, interspinous, ligamentum flavum

Question 11

Describe the ligamentum flavum.

Answer 11

yellow, strongest, most posterior ligament

thickest in the midline

Question 12

Describe the interspinous ligament.

Answer 12

connects various spinous processes, thinner in the lumbar region

Question 13

Describe the supraspinous ligament.

Answer 13

it is thick, major ligament in the cervical & upper thoracic

Question 14

Describe the structures traversed from outward to inward when performing a spinal.

Answer 14

1. skin
2. subcutaneous tissue and fat
3. supraspinous ligament
4. interspinous ligament
5. ligamentum flavum
6. epidural space (potential space)
7. dura
8. subarachnoid space

Question 15

Describe the layers of the meninges.

Answer 15

dura
arachnoid
pia

Question 16

The spinal cord extends to what level in adults?

Answer 16

L1

Question 17

The spinal cord extends to what level in children?

Answer 17

L3

Question 18

Describe the conus medularis

Answer 18

cone shaped tip of the spinal cord

Question 19

Describe the filum terminae.

Answer 19

continues from the conus medularis

inserts into 1st sacral vertebral soma

Question 20

Describe the cauda equina.

Answer 20

“Horse’s tail”- nerve roots hang freely within thecal sac

less likely to pierce anything in this area

Question 21

Describe the dura mater.

Answer 21

outermost, tough fibrous layer

extends from foramen magnum to S2-S3

Question 22

Describe the arachnoid mater.

Answer 22

Delicate middle layer
non-vascular
ends at S2

Question 23

Describe the subarachnoid space.

Answer 23

Between pia & arachnoid

CSF found here

Question 24

Describe the pia mater.

Answer 24

highly vascular

covers spinal cord

Question 25

Describe the epidural space.

Answer 25

continuous space within vertebral canal

Question 26

The epidural space contains:

Answer 26

fat, arteries, veins, lymphatics, & nerve roots

Question 27

The average distance from the skin to the lumbar epidural space is

Answer 27

5 cm.

can reach it as quickly as 3 cm. depending on intervertebral space & body habitus

Question 28

Dermatomes help us to define

Answer 28

area of cutaneous sensation
used them as a “sensation” map
method for determining level of block

Question 29

Describe the significance of the T4 dermatome.

Answer 29

the nipple line

Question 30

Describe the significance of the T10 dermatome.

Answer 30

the umbilicus

Question 31

Describe the arterial distribution of the spinal cord.

Answer 31

segmental arteries
longitudinal arteries- 1 anterior w/ artery of Adamkiewicz & 2 posterior
Radicular

Question 32

Describe the blood supply of the veins of the spinal cord.

Answer 32

epidural veins- valve-less & engorged in pregnant & obese patients
most prominent lateral

Question 33

Describe the subarachnoid space.

Answer 33

space between the arachnoid & pia mater–> CSF found here

site of spinal anesthesia- subarachnoid, intrathecal

Question 34

Describe the appearance of CSF.

Answer 34

clear colorless fluid- selective filtrate of the blood

Question 35

Describe the function of CSF.

Answer 35

mechanical buffer to protect the brain and spinal cord

Question 36

What is the specific gravity of the CSF?

Answer 36

1.003-1.009

Question 37

The total CSF volume in an adult is

Answer 37

150 mL
produce 21 mL/hour
spinal SAH space holds 20-35 mL