The Sacral Plexus

Question 0

Origin

Answer 0

Ventral rami of:

• L4, L5
• S1-S4

Question 1

Location

Answer 1

• On post. wall of lesser pelvis

- Closely related to ant. surface of piriformis m.

Question 2

Branches

Answer 2

1. Sciatic nerve (originates from L4, S1-S3)
2. Pudendal nerve (originates from S2-4)
3. Superior gluteal nerve (originates from L4, L5, S1)
4. Inferior gluteal nerve (originates from L5, S1, S2)
5. Nerve to piriformis (originates from S1, S2)
6. Nerve to quadratus femoris & inf. glemellus (originates from L4, L5, S1)
7. Nerve to obturator internus & sup. glemellus (originates from L5, S1, S2)
8. Pelvic splanchnic (originates from S2-S4)

Question 3

Which muscle does sciatic nerve innervate?

Answer 3

• Largest & broadest nerve in body
• Originates from ventral rami of L4, S1-S3 that converge on ant. surface of piriformis
• Exits sacral plexus via greater sciatic foramen
• Enters gluteal region from greater sciatic foramen
• Descends along post. aspect of thigh
• Innervates post. aspect of lower limb

Question 4

Cutaneous branches of the sacral plexus?

Answer 4

1. Post. cutaneous nerve (originates from S1-S4)

2. Perforating cutaneous nerve (originates from S2, S3)