Nerves of the lower limb

Question 1

What forms the lumbar plexus?

Answer 1

-Anterior divisions of lumbar spinal nerves L1 to L4 (small contribution from T12)

Question 2

What are the major branches of the lumbar plexus?

Answer 2

• Iliohypogastric nerve
• Ilioinguinal nerve
• Genitofemoral nerve
• Lateral cutaneous nerve of the thigh
• Femoral nerve
• Obturator nerve

Question 3

What is the sensory function of iliohypogasrtic nerve?

Answer 3

-Posteriolateral skin of gluteal region

Question 4

What is the nerve root of ilioinguinal nerve?

Answer 4

-L1

Question 5

What is the sensory function of the ilioinguinal nerve to lower limb?

Answer 5

-Innervates upper medial thigh

Question 6

What is the sensory function of genitofemoral nerve in the lower limb?

Answer 6

-Femoral branch innervates skin on the upper thigh

Question 7

What is the sensory function of lateral cutaneous nerve of the thigh?

Answer 7

-Innervates anterior and lateral thigh down to the knee

Question 8

What nerve roots serve obturator nerve?

Answer 8

-L2, L3 and L4

Question 9

What is the motor function of obturator nerve?

Answer 9

-Gracillis, Adductors, Pectineus and obrurator externus

Question 10

What is the sensory function of obturator nerve?

Answer 10

-Innervates skin over medial thigh

Question 11

What are the nerve roots of the femoral nerve?

Answer 11

-L2, L3 and L4

Question 12

What are the motor functions of femoral nerve?

Answer 12

-Quadratus femoris, sartorius, iliopoas, pectineus

Question 13

What is the sensory function of the femoral nerve?

Answer 13

• Anterior thigh (anterior cutaneous branch)

- Medial leg and foot (Saphenous branch)

Question 14

What is a pneumonic for remembering the branches of lumbar plexus?

Answer 14

-I, I Get Leftovers On Fridays

Question 15

What spinal nerves makes the sacral plexus?

Answer 15

-Anterior divisions of spinal nerve L4-S4

Question 16

What are the 5 main peripheral nerves of the sacral plexus?

Answer 16

• Superior gluteal
• Inferior gluteal
• Sciatic
• Posterior femoral
• Pudendal

Question 17

What are the motor functions of the superior gluteal nerve?

Answer 17

-Gluteus medius, gluteus minimus and tensor facsia latae

Question 18

What are the sensory function of the superior and inferior gluteal nerve?

Answer 18

-None

Question 19

What is a pneumonic for remembering the branches of the sacral plexus?

Answer 19

-Some Irish Sailor Pesters Polly

Question 20

What is the motor function of inferior gluteal nerve?

Answer 20

-Gluteus maximus

Question 21

What are the nerve roots of the sciatic nerve?

Answer 21

-L4, L5, S1,S2, S3

Question 22

What are the motor functions of the sciatic nerve?

Answer 22

• Tibial portion -> hamstrings apart from short head of biceps -> posterior compartment of leg-> sole of foot
• Common fibular portion -> Short head of biceps femoris -> anterior compartment (deep nerve) and lateral (superficial nerve) compartments of leg

Question 23

What is the sensory function of the branches of the common fibular nerve?

Answer 23

• Sural -> Lower posterolateral
• Lateral sural -> upper lateral
• Superficial -> lower anterolateral and dorsum of foot except skin between 1st and 2nd toes
• Deep -> innervates skin between first and second toe

Question 24

What is the sensory function of the posterior femoral cutaneous nerve?

Answer 24

-Innervates skin of posterior thigh and leg

Question 25

What are the smaller nerve branches of the sacral plexus?

Answer 25

- Nerve to piriformis - Nerve to Obturator internus - Nerve to Quadratus femoris

Question 26

What happens to the sciatic nerve?

Answer 26

-Bifurcates into tibial and common fibular nerve at the popliteal fossa

Question 27

What are the branches of the common fibular nerve (coommon peroneal nerve)?

Answer 27

- Superficial fibular (peroneal) nerve - Deep fibular (peroneal) nerve - Lateral sural nerve - Sural nerve (with contribution from tibial)

Question 28

What is the consequence of damage to the common fibula (peroneal) nerve?

Answer 28

-Loss of dorsiflexion, eversion and extension of digits (Loss of anteriolateral compartment)

Question 29

How does damage to common fibular nerve commonly occur?

Answer 29

-Fracture (pedestrian hit by car bumper) or tight plaster cast

Question 30

What causes foot drop?

Answer 30

-Damage to deep fibular nerve or common fibular nerve causing paralysis of muscles in anterior compartment of leg resulting in unopposed plantar flexion

Question 31

What are the sensory functions of the tibial nerve?

Answer 31

- Posterioleteral side of leg (sural) | - Lateral side and sole of foot

Question 32

What is tarsal tunnel syndrome?

Answer 32

- Tibial nerve is compressed within the tarsal tunnel due to: - osteoarthritis - Rheumatoid arthritis - Post-trauma ankle deformities

Question 33

List the major nerves of the lower limb

Answer 33

- Lumbar and Sacral plexus - Femoral nerve - Obturator nerve - Sciatic nerve - Common fibular nerve->Superficial and deep fibular nerves - Tibial nerve