The Lumbosacral Plexus

Question 1

Where do the lower limbs receive their nerve supply via?

Answer 1

The lumbosacral plexus

Question 2

What is the lumbar plexus formed from?

Answer 2

Anterior rami of L1-L4 spinal nerves

Question 3

What is the lumbsacral trunk formed from?

Answer 3

L4 + L5 anterior rami

Question 4

What nerves are in the lumbar plexus?
+ their nerve roots

Answer 4

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Iliolunguinal L1
Genitofermoral L1,L2
Lateral femoral cutaneous L2,L3
Obturator L2, L3, L4
Femoral L2,L3,L4

Question 5

Where does the iliolinguinal nerve innervate?

Answer 5

Skin of genitalia + upper medial thigh

Question 6

Iliolinguinal nerve roots

Answer 6

L1

Question 7

Genitofemoral nerve roots

Answer 7

L1, L2

Question 8

What doe the genitofemoral nerve branch into?

Answer 8

Genital branch
Femoral branch

Question 9

Sensory function of lateral femoral cutaneous nerve

Answer 9

To anterolateral thigh to knee

Question 10

Lateral femoral cutaneous nerve roots

Answer 10

L2, L3

Question 11

Obturator nerve roots

Answer 11

L2, L3, L4

Question 12

Sensory innervation of the obturator nerve

Answer 12

Skin over medial thigh

Question 13

What does the femoral nerve branch into?

Answer 13

Anterior femoral cutaneous branch
Saphenous branch

Question 14

Femoral nerve roots

Answer 14

L2, L3, L4

Question 15

Where does the anterior femoral cutaneous branch of the femoral nerve innervate?

Answer 15

Skin of anterior thigh

Question 16

Where does the saphenous branch of the femoral nerve innervate?

Answer 16

Skin of medial leg

Question 17

What is the sacral plexus formed by?

Answer 17

Anterior rami of S1-S5
Receives contribution from L4+L5 via lumbosacral trunk

Question 18

Nerves of the sacral plexus
+ their nerve roots

Answer 18

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Superior gluteal L4 , L5 S1
Inferior gluteal L5, S1, S2
Sciatic L4, L5, S1, S2, S3
Posterior femoral cutaneous S1,S2,S3
Pudendal S2, S3, S4

Question 19

Superior gluteal nerve roots

Answer 19

L4, L5, S1

Question 20

Where does the superior gluteal nerve leave the pelvis?

Answer 20

Greater sciatic foramen above the piriformis

Question 21

What does the superior gluteal nerve innervate?

Answer 21

Gluteus medius
Gluteus minimis
Tensor fascia lata

Question 22

Inferior gluteal nerve roots

Answer 22

L5, S1, S2

Question 23

Where does the inferior gluteal nerve leave the pelvis?

Answer 23

Via the greater sciatic foramen below the piriformis

Question 24

What does the inferior gluteal nerve innervate?

Answer 24

Gluteus maximus

Question 25

Sciatic nerve roots

Answer 25

L4, L5, S1, S2, S3

Question 26

What does the sciatic nerve branch into? Where?

Answer 26

Tibial nerve Common peroneal nerve At popliteal fossa

Question 27

Where does the tibial nerve innervate?

Answer 27

**Posterior thigh** Semitendinosus Semimembranosus Biceps femoris (long head) Ischial part of ADductor mangus

Question 28

What does the common peroneal nerve innervate?

Answer 28

bicep femoris (short head)

Question 29

Tibial nerve roots

Answer 29

L4-S3

Question 30

Common peroneal nerve roots

Answer 30

L4-S3

Question 31

Posterior femoral cutaneous nerve roots

Answer 31

S1, S2, S3

Question 32

Where does the posterior femoral cutaneous nerve innervate?

Answer 32

Skin of posterior thigh + leg

Question 33

Motor innervation of obturator nerve

Answer 33

- obturator externus - pectineus - ADuctor longus, brevis + mangus - gracillis