Regional Anaesthesia

Question 1

Within which space is a spinal anaesthetic administered?

Answer 1

Subarachnoid space

Question 2

Describe the layers transversed in spinal anaesthesia (superficial to deep)

Answer 2

Skin
Subcutaneous tissue
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space
Dura mater
Arachnoid mater
Subarachnoid space

Question 3

Which vertebral level is a spinal anaesthetic usually administered?

Answer 3

L3-L4, L4-L5

Question 4

What spinal level is the conus medullaris at?

Answer 4

L1-L2

Question 5

Where does the spinal cord end?

Answer 5

L1-L2 (conus medullaris

Question 6

Which structures are blocked in a spinal anaesthetic?

Answer 6

Dorsal (posterior) roots - (sensory loss, loss of pain, temperature, touch below block level)

Ventral (anterior) roots - loss of motor function below level of block

Autonomic (SNS) - preganglionic sympathetic fibres (T1–L2)

Question 7

What is the effect of blockage of pre-ganglionic sympathetic fibres in a spinal anaesthetic?

Answer 7

Vasodilation, ↓ SVR, hypotension, bradycardia (if high block)

Question 8

Which nerves are involved in hip innervation?

Answer 8

Femoral nerve (L2–L4) Anterior thigh, hip joint

Obturator nerve (L2–L4)
Medial thigh, hip joint

Lateral femoral cutaneous (L2–L3) Lateral thigh (skin)

Sciatic nerve (posterior capsule) (L4–S3)
Posterior hip, lower limb

Superior gluteal nerve (L4–S1)
Gluteal region, hip abductors