Past Papers · SAQ
Epidural Anatomy & Bupivacaine
2015B Q07
Exam questionDraw and label a cross section of the lumbar epidural space (50% of marks). Describe the pharmacology of bupivacaine (50% of marks).
CICMWrecks answer
Master answer
Anatomy:
- Position in sitting or lateral decubitus position
- Level:
- Any of the interspaces between between L2-L5
- L4/5 interspace: Tuffier’s Line: line between iliac crests
- (or) L3/4 interspace: Line joining PSISs (Posterior superior iliac spines)
- Discrepancy between identified and actual intervertebral space in 50% of cases
- Conus medullaris ends at L1 in about 94% of patients
Tissues and target for LP:
- In the subarachnoid space between the arachnoid mater and the pia mater.
- The tissues pierced are (in order):
- skin
- subcutaneous tissue
- supraspinal ligament,
- interspinal ligament,
- ligamentum flavum,
- dura mater,
- the arachnoid mater into the subarachnoid space.
- Lateral/paraspinal approach: Skin – subcutaneous tissue – erector spinae muscles – ligamentum flavum – dura – arachnoid – subarachnoid space
Epidural Space
- Posterolateral Epidural Space
- Posterolateral epidural space extends vertically down the spinal canal and contains arteries, venous plexus, and fat
- Posterolateral epidural space is larger than the anterior epidural space
- Posterolateral epidural space is larger in the sacral region than it is in the cervical region
- Anterior Epidural Space
- Anterior epidural space is a virtual space under normal circumstances (due to adherence of dura to bone of vertebral bodies from the foramen magnum down to L1)
Gladwin / JC 2020
Past papers
Exam appearances
| Exam | Exact exam wording | Candidate success |
|---|---|---|
| 2015B Q07 | Draw and label a cross section of the lumbar epidural space (50% of marks). Describe the pharmacology of bupivacaine (50% of marks). | 35% |