Anatomy for Neuraxial Anesthesia Flashcards
How many bones make up the vertebral column?
33 bones that are sequentially interconnected
-separated by fibrocartilaginous disks
The vertebral column provides
a bony reference for various procedures
The vertebral column extends from
the base of the skull to the tip of the coccyx
Describe the natural curves of the spinal column.
anterior curvatures (cervical & lumbar) posterior curvatures (thoracic & sacral)
Describe the pertinent anatomic landmarks
vertebra promins- C7
Inferior angle of scapula- T7
Tuffier’s line- L4-L5- line drawn at iliac crest
Just using the anatomic or landmark technique,
finds that the accuracy is variable; providers are generally off by at least 1 level
Describe the sacrum.
fused into one bone
can perform caudal anesthesia by going through the sacral hiatus
Describe what lumbarization is.
when L5 & S1 are fused
Describe what sacralization is.
when S1 & S2 are fused together
Describe the three posterior ligaments.
supraspinous, interspinous, ligamentum flavum
Describe the ligamentum flavum.
yellow, strongest, most posterior ligament
thickest in the midline
Describe the interspinous ligament.
connects various spinous processes, thinner in the lumbar region
Describe the supraspinous ligament.
it is thick, major ligament in the cervical & upper thoracic
Describe the structures traversed from outward to inward when performing a spinal.
- skin
- subcutaneous tissue and fat
- supraspinous ligament
- interspinous ligament
- ligamentum flavum
- epidural space (potential space)
- dura
- subarachnoid space
Describe the layers of the meninges.
dura
arachnoid
pia
The spinal cord extends to what level in adults?
L1
The spinal cord extends to what level in children?
L3
Describe the conus medularis
cone shaped tip of the spinal cord
Describe the filum terminae.
continues from the conus medularis
inserts into 1st sacral vertebral soma
Describe the cauda equina.
“Horse’s tail”- nerve roots hang freely within thecal sac
less likely to pierce anything in this area
Describe the dura mater.
outermost, tough fibrous layer
extends from foramen magnum to S2-S3
Describe the arachnoid mater.
Delicate middle layer
non-vascular
ends at S2
Describe the subarachnoid space.
Between pia & arachnoid
CSF found here
Describe the pia mater.
highly vascular
covers spinal cord
Describe the epidural space.
continuous space within vertebral canal
The epidural space contains:
fat, arteries, veins, lymphatics, & nerve roots
The average distance from the skin to the lumbar epidural space is
5 cm.
can reach it as quickly as 3 cm. depending on intervertebral space & body habitus
Dermatomes help us to define
area of cutaneous sensation
used them as a “sensation” map
method for determining level of block
Describe the significance of the T4 dermatome.
the nipple line
Describe the significance of the T10 dermatome.
the umbilicus
Describe the arterial distribution of the spinal cord.
segmental arteries
longitudinal arteries- 1 anterior w/ artery of Adamkiewicz & 2 posterior
Radicular
Describe the blood supply of the veins of the spinal cord.
epidural veins- valve-less & engorged in pregnant & obese patients
most prominent lateral
Describe the subarachnoid space.
space between the arachnoid & pia mater–> CSF found here
site of spinal anesthesia- subarachnoid, intrathecal
Describe the appearance of CSF.
clear colorless fluid- selective filtrate of the blood
Describe the function of CSF.
mechanical buffer to protect the brain and spinal cord
What is the specific gravity of the CSF?
1.003-1.009
The total CSF volume in an adult is
150 mL
produce 21 mL/hour
spinal SAH space holds 20-35 mL
