Lumbar Plexus Flashcards

Study the lumbar plexus, its spinal roots, major branches, anatomical relationships, motor supply, and sensory distribution.

Card 1 of 28Question

Which spinal nerve roots primarily form the lumbar plexus?

The anterior rami of L1 to L4, often with a contribution from T12.

In This Section

1. Which spinal nerve roots primarily form the lumbar plexus?

The anterior rami of L1 to L4, often with a contribution from T12.

2. Where is the lumbar plexus formed?

Within the posterior part of the psoas major muscle, anterior to the lumbar transverse processes.

3. Which nerve roots contribute to the iliohypogastric nerve?

Primarily L1, sometimes with a contribution from T12.

4. Which spinal nerve root primarily forms the ilioinguinal nerve?

L1.

5. Which nerve roots form the genitofemoral nerve?

L1 and L2.

6. Which nerve roots form the lateral femoral cutaneous nerve?

L2 and L3.

7. Which nerve roots form the femoral nerve?

The posterior divisions of the anterior rami of L2, L3, and L4.

8. Which nerve roots form the obturator nerve?

The anterior divisions of the anterior rami of L2, L3, and L4.

9. Which nerve roots typically form the accessory obturator nerve when present?

L3 and L4.

10. Which lumbar plexus branches emerge from the lateral border of psoas major?

The iliohypogastric, ilioinguinal, lateral femoral cutaneous, and femoral nerves.

11. Which lumbar plexus nerve emerges through the anterior surface of psoas major?

The genitofemoral nerve.

12. Which major lumbar plexus nerve emerges from the medial border of psoas major?

The obturator nerve.

13. What is the primary motor function of the femoral nerve?

Innervation of the anterior thigh muscles, particularly the quadriceps femoris for knee extension.

14. Through which space does the femoral nerve enter the thigh?

Deep to the inguinal ligament, lateral to the femoral artery.

15. Which terminal branch of the femoral nerve provides cutaneous sensation to the medial leg and foot?

The saphenous nerve.

16. What is the principal motor function of the obturator nerve?

Innervation of most muscles in the medial thigh compartment responsible for hip adduction.

17. Through which opening does the obturator nerve enter the medial thigh?

The obturator canal.

18. Which region receives cutaneous innervation from the lateral femoral cutaneous nerve?

The anterolateral thigh.

19. What are the two terminal branches of the genitofemoral nerve?

The genital branch and femoral branch.

20. Which muscle receives motor innervation from the genital branch of the genitofemoral nerve in males?

The cremaster muscle.

21. Which skin regions are supplied by the iliohypogastric nerve?

The suprapubic region and part of the posterolateral gluteal region.

22. Which regions receive cutaneous innervation from the ilioinguinal nerve?

The upper medial thigh and anterior external genital region.

23. Which spinal nerve roots form the lumbosacral trunk?

Part of the anterior ramus of L4 and the anterior ramus of L5.

24. What is the relationship between the lumbosacral trunk and the sacral plexus?

The lumbosacral trunk descends into the pelvis and contributes to the formation of the sacral plexus.

25. What condition results from compression of the lateral femoral cutaneous nerve?

Meralgia paresthetica, characterized by sensory disturbance over the anterolateral thigh.

26. Which deep tendon reflex may be reduced or absent after significant femoral nerve injury?

The patellar reflex, primarily mediated by L3 and L4.

27. Which movement is typically weakened by an obturator nerve injury?

Hip adduction.

28. Why can a psoas compartment hematoma cause multiple neurological deficits?

The lumbar plexus lies within psoas major and may be compressed by expanding blood collections.