Sacral plexus

Question 1

What spinal roots make up the sacral plexus

Answer 1

S1-4 and contributions from L4-5

Question 2

Location of sacral plexus

Answer 2

Surface of posterior pelvic wall, anterior to piriformis

Question 3

How are the lumbar and sacral plexi joined

Answer 3

By lumbosacral trunk from combination of roots L4-5

Question 4

What do the spinal roots divide into

Answer 4

Cords

Question 5

What do the cords combine to form and how many

Answer 5

5 branches (major peripheral nerves)

Question 6

What are the branches of the sacral plexus

Answer 6

Superior gluteal nerve,
Inferior gluteal nerve,
Sciatic nerve (covered in separate deck),
Posterior femoral cutaneous nerve/posterior cutaneous nerve of thigh
Pudendal nerve
(Some Irish sailors pester polly)

Question 7

Destination of branches of sacral plexus

Answer 7

1. Leave pelvis via great sciatic foramen

2. Remain in pelvis

Question 8

Roots of superior gluteal nerve

Answer 8

L4-5 and S1

Question 9

Course of superior gluteal nerve

Answer 9

Leaves pelvis via great sciatic foramen, entering gluteal region superior to piriformis

Question 10

Motor Innervation of superior gluteal nerve

Answer 10

Gluteus minimus,
Gluteus medius,
Tensor fascia lata

Question 11

Sensory Innervation of superior gluteal nerve

Answer 11

None (entirely motor)

Question 12

Roots of inferior gluteal nerve

Answer 12

L5 and S1-2

Question 13

Course of inferior gluteal nerve

Answer 13

Leaves pelvis via great sciatic foramen, entering gluteal region inferior to piriformis

Question 14

Motor Innervation of inferior gluteal nerve

Answer 14

Gluteus maximus

Question 15

Sensory Innervation of inferior gluteal nerve

Answer 15

None (entirely motor)

Question 16

Roots of posterior cutaneous nerve of thigh

Answer 16

S1-3

Question 17

Course of posterior cutaneous nerve of thigh

Answer 17

Leaves pelvis via great sciatic foramen, entering gluteal region inferior to piriformis.
It then descends deep to gluteus maximus and runs down back of thigh to knee

Question 18

Motor Innervation of posterior cutaneous nerve of thigh

Answer 18

None

Question 19

Sensory Innervation of posterior cutaneous nerve of thigh

Answer 19

Skin over posterior thigh and leg

Skin over perineum

Question 20

Roots of pudendal nerve

Answer 20

S2-4

Question 21

Course of pudendal nerve

Answer 21

Leaves pelvis via great sciatic foramen then re-enters via lesser sciatic foramen.
It moves anterosuperiorly along lateral wall of ischiorectal fossa and terminates by dividing into several branches

Question 22

Motor Innervation of pudendal nerve

Answer 22

Skeletal muscles in perineum,
External urethral sphincter,
External anal sphincter,
Levator ani

Question 23

Sensory Innervation of pudendal nerve

Answer 23

Penis,
Clitoris,
Most skin over perineum

Question 24

Minor branches of sacral plexus

Answer 24

Nerve to piriformis S2,
Nerve to obturator internus L5 and S1-2,
Nerve to quadrator femoris L4-5 and S1

(Root values may not be correct)

Question 25

Anterior or posterior rami

Answer 25

anterior