Sciatic Nerve Flashcards

Explore sciatic nerve anatomy, including its sacral plexus roots, gluteal and thigh course, terminal branches, motor supply, and clinical injuries.

Card 1 of 30Question

From which nerve plexus does the sciatic nerve arise?

The sacral plexus.

In This Section

1. From which nerve plexus does the sciatic nerve arise?

The sacral plexus.

2. Which spinal nerve roots contribute to the sciatic nerve?

L4, L5, S1, S2, and S3.

3. What is the largest nerve in the human body?

The sciatic nerve.

4. Which two major nerve components form the sciatic nerve?

The tibial and common fibular nerve components.

5. Which divisions of the sacral plexus form the tibial component of the sciatic nerve?

The anterior divisions of L4 to S3.

6. Which divisions of the sacral plexus form the common fibular component?

The posterior divisions of L4 to S2.

7. Through which opening does the sciatic nerve normally leave the pelvis?

The greater sciatic foramen.

8. What is the usual relationship between the sciatic nerve and piriformis?

The sciatic nerve passes inferior to piriformis.

9. Between which two bony landmarks does the sciatic nerve pass in the gluteal region?

The greater trochanter and ischial tuberosity.

10. Which large gluteal muscle covers the sciatic nerve posteriorly?

Gluteus maximus.

11. Which short lateral rotator muscles lie deep to the sciatic nerve in the gluteal region?

Superior gemellus, obturator internus, inferior gemellus, and quadratus femoris.

12. Which major muscle lies anterior to the sciatic nerve in the posterior thigh?

Adductor magnus.

13. Which hamstring muscle commonly covers the sciatic nerve posteriorly in the thigh?

The long head of biceps femoris.

14. Where does the sciatic nerve usually divide into its terminal branches?

Near the superior angle of the popliteal fossa, although the division level varies.

15. Which terminal branch of the sciatic nerve continues through the popliteal fossa into the posterior leg?

The tibial nerve.

16. Which terminal branch of the sciatic nerve travels laterally toward the fibular neck?

The common fibular nerve, also called the common peroneal nerve.

17. Which hamstring muscles receive motor branches from the tibial component of the sciatic nerve?

Semitendinosus, semimembranosus, and the long head of biceps femoris.

18. Which hamstring muscle is supplied by the common fibular component of the sciatic nerve?

The short head of biceps femoris.

19. Which portion of adductor magnus receives innervation from the sciatic nerve?

The hamstring part, supplied by the tibial component.

20. Does the sciatic nerve directly provide cutaneous branches to the thigh?

No, it does not directly supply the skin of the thigh.

21. How does the sciatic nerve contribute to cutaneous sensation below the knee?

Through branches of its tibial and common fibular terminal nerves.

22. Which arteries contribute to the blood supply of the sciatic nerve in the gluteal region?

Branches of the inferior gluteal artery.

23. Which arterial system contributes to the blood supply of the sciatic nerve in the posterior thigh?

Perforating branches of the profunda femoris artery.

24. What anatomical variation may occur in the relationship between the sciatic nerve and piriformis?

The common fibular component may pass through or above piriformis while the tibial component passes below.

25. Which gluteal injection placement helps reduce the risk of sciatic nerve injury?

The superolateral gluteal region, with the ventrogluteal site generally preferred.

26. What is sciatica?

Pain radiating along the sciatic nerve distribution, commonly caused by irritation of lumbosacral nerve roots.

27. Which lumbar intervertebral disc level commonly produces irritation of the L5 nerve root?

The L4-L5 intervertebral disc, particularly with a posterolateral herniation.

28. What motor deficits may occur following a complete sciatic nerve injury in the thigh?

Weak knee flexion and severe impairment of ankle and foot movements.

29. Which clinical sign tests irritation of lumbosacral nerve roots associated with sciatic pain?

The straight leg raise test.

30. Which imaging modality is commonly used to evaluate structural compression of lumbosacral nerve roots causing sciatica?

Magnetic resonance imaging (MRI) of the lumbar spine.