Name the layers of the spinal cord distal to proximal.
Epidural space, dura mater, subdural space, arachnoid matter, subarachnoid space, and pia
What is the pia mater?
Vascular membrane investing the spinal cord & forms the filum terminal distally.
What is the arachnoid mater and where is it located?
Nonvascular membrane closely attached to the dura.
What is the dura mater and where is it located?
Outer most membrane. It is a direct extension of the cranial dura & extends from foramen magnum to S2.
Where is the epidural space located?
right before the dura matter
Extends from the foramen magnum to sacral hiatus.
Where is the ligamentum flavum located?
Forms the posterior boundary of the epidural space. Extends from foramen magnum to sacral hiatu
What are the contents of the epidural space?
Nerve roots, lymphatics, blood vessels.
Where is a spinal placed?
In the subarachnoid space
What is posterior to the ligamentum flavum
Lamina, spinous processes, interspinous ligament, supraspinous ligament.
What is the sacral hiatus?
Results from the failure of the laminae of S4-S5 to fuse.
What is the most commonly used technique in obstetric patients, especially for labor?
Review for exam from Mrs. Harmon on Regional Anesthesia (what do I need to know for this exam!) Follow the study.
2 main kinds of block
The principle site of action for spinal & epidual is the __ ___
Where is a spinal placed?
in the subarachnoid space (or intrathecal space)
Where is an epidural placed?
in the epidural space
What is the difference between epidural and spinal?
- inject LA (local anesthetic) into the epidural space.
- can perform at various level along the neuraaxis
- use higher volume of LA then spinal (20-30 ml)
- use epidural catheter
- can extend the use - such as for post-op pain control
-- epidural catheter can migrate (get pull out/pull -in, kink up)
- epidural LA works by difusion
- slower onset than spinal
- inject LA into the subarachnoid space (intrathecal) - which contains CSF
- use smaller volume of LA (2-3 ml)
- last 90-120 minutes
What are the layers of structure that you poke through when performing a spinal block?
typically 16-18 gauge (bigger than Spinal needle - 25 G)
Shown here are 2 types of epidural needles
- First 2 on the left - are the Crawford with a straight needle allowing slightly easier insertion of catheter but with a greater risk of dural puncture
- Last 2- on the right - are Tuohy needle. Use commonly. The needle curves at the end and pushes the dura away after penetrating the ligamentum flavum
- used for intra-op or post-op
- designed to pass through the lumen of the needle
- generally 25 gauge
- have either a single end-hole or a number of side holes at the distal end
- after advancing the catheter through the needle to the desired depth, the needle is removed leaving the catheter in place
- The catheter is then secured along the back with tape