Nerves and vessels of the lower limb

Question 1

Where do nerves to the lower limb emerge from?

Answer 1

Lumbosacral plexus

L2-S3

Question 2

What does the femoral nerve supply?

Answer 2

Anterior compartment of thigh

Question 3

What does the obturator nerve supply?

Answer 3

Medial (adductor) compartment of thigh

Question 4

What does the sciatic nerve supply?

Answer 4

Posterior thigh
Anterior and posterior leg
Foot

Question 5

Which muscle is an important landmark in relation to the nerves and vessels of the gluteal region?

Answer 5

Piriformis muscle- one of the lateral rotator group of gluteal muscles

Question 6

What does the sciatic nerve divide into?

Answer 6

Tibial nerve

Common peroneal nerve

Question 7

What does the tibial nerve supply?

Answer 7

Posterior compartment of the leg- superficial and deep calf muscles

Question 8

What does the tibial nerve divide into?

Answer 8

Medial and lateral plantar nerves at the sole of the foot

Question 9

What do the medial and lateral plantar nerves supply?

Answer 9

Muscles of the foot and regions of sensation in the foot

Question 10

What does the common peroneal nerve divide into?

Answer 10

Deep and superficial peroneal nerves

Question 11

What are the roots of the femoral nerve?

Answer 11

L2-4, posterior fibres

Question 12

What are the roots of the obturator nerve?

Answer 12

L2-4, anterior fibres

Question 13

What are the roots of the sciatic nerve?

Answer 13

L3-S3, anterior and posterior fibres

Question 14

What are the roots of the superior gluteal nerve?

Answer 14

L4-S1

Question 15

What are the roots of the inferior gluteal nerve?

Answer 15

L5-S2

Question 16

What does the superior gluteal nerve supply?

Answer 16

Gluteus medius and minimus, tensor fascia lata

Question 17

What does the inferior gluteal nerve supply?

Answer 17

Gluteus maximus

Question 18

What is the segmental motor supply to hip flexors?

Answer 18

L2-3

Question 19

What is the segmental motor supply to hip extensors?

Answer 19

L4-5

Question 20

What is the segmental motor supply to knee extensors?

Answer 20

L3-4

Question 21

What is the segmental motor supply to knee flexors?

Answer 21

L5-S1

Question 22

What is the segmental motor supply to ankle dorsiflexors (extensors)?

Answer 22

L4-5

Question 23

What is the segmental motor supply to ankle plantarflexors (flexors)?

Answer 23

S1-2

Question 24

When assessing nerve function, what is seen in a root injury such as prolapsed intervertebral disc at L5/S1?

Answer 24

Motor- loss of eversion
Sensory- loss of sensation outer border of foot
Reflex- loss of ankle jerk (S1)
Autonomic- minimal

Question 25

When assessing nerve function, what is seen in a lesion of common peroneal nerve at fibular neck?

Answer 25

Motor- foot drop
Sensory- dorm of foot at least
Reflex- none
Autonomic- minimal

Question 26

What arteries supply the lower limb?

Answer 26

Abdominal aorta
Common iliac arteries (internal and external)
Femoral artery (deep femoral artery is main supply to thigh)
Popliteal artery
-Posterior tibial artery
-Anterior tibial artery
-Peroneal artery
-Dorsalis pedis

Question 27

What do the femoral artery and vein pass through from the anterior compartment to the popliteal fossa?

Answer 27

Hiatus of adductor magnus muscle

Question 28

What are the superficial veins of the lower limb?

Answer 28

Dorsal venous arch
Long saphenous vein
Short saphenous vein
Perforating veins
Sapheno-femoral junction
Blood flow is from superficial to deep.

Question 29

What are the deep veins of the lower limb?

Answer 29

Run alongside arteries, venae comitantes
'Muscle pump' in the calf.
Anterior and posterior tibial veins
Popliteal vein (receives SSV)
Profunda femoris vein
Femoral vein (receives LSV)
External iliac vein

Question 30

When may cut-down of the LSV at medial malleolus be required?

Answer 30

To administer fluids in a shocked patient, ATLS

2cm lateral and proximal to medial malleolus

Question 31

What happens in arterial embolism?

Answer 31

Sudden occlusion
Acute ischaemia
Intermittent claudication (muscle pain commonly in calf during activity, associated with arterial disease)

Question 32

What is compartment syndrome?

Answer 32

The neuromuscular compartments of the limbs are enclosed in fibrous sheaths which confines them
Ischaemia caused by trauma-induced increased pressure in a confined limb compartment
Commonly the anterior, posterior and lateral compartments of the leg

Question 33

What is required in acute compartment syndrome (trauma-associated)?

Answer 33

Emergency fasciotomy to prevent death of muscles in the affected compartment

Question 34

How do varicose veins occur?

Answer 34

Perforating veins connecting superficial and deep veins contain a valve that allows flow only from superficial to deep.
If the valve is compromised, blood is pushed from deep to superficial veins, leading to varicose veins.

Question 35

Why is the muscle pump in the calf important?

Answer 35

In the leg, deep vessels are sandwiched between layers of calf muscles.
During walking and running, contractions of these muscles squeeze the thin-walled veins and push blood up them.
Immobility means less efficient venous return from the foot and leg
Sluggish deep venous return can lead to deep vein thrombosis.

Question 36

What is the purpose of elastic surgical socks?

Answer 36

Compress superficial veins, promoting more vigorous deep venous return to prevent DVT.