Nerves and vessels of the lower limb

Question 1

How many sacral and coccygeal nerves are there?

Answer 1

Sacral: 5
Coccygeal: 1

Question 2

Which spinal nerves supply each of the following:
Neck 
Upper Limb
Trunk
Lower Limb
Perineum

Answer 2

Neck: C1-C4
Upper Limb: C5-T1
Trunk: T2-L1
Lower Limb: L2-S3
Perineum: S2-C1

Question 3

Which muscles does the superior gluteal nerve innervate?

Answer 3

Gluteus medius
Gluteus minimus
Tensor fasciae latae

Question 4

The femoral nerve innervates all the muscles in the anterior compartment of the thigh. Which extra spinal root contributes to the innervation of iliopsoas?

Answer 4

L1

Question 5

Which nerve roots are responsible for:
Inversion
Eversion
Toe Extension
Toe Flexion

Answer 5

Inversion: L4
Eversion: L5, S1
Toe Extension: L5, S1
Toe Flexion: S1, 2

Question 6

What nerve supplies sensory innervation to most of the posterior of the thigh?

Answer 6

Posterior cutaneous nerve of the thigh

Question 7

Which two spinal nerve roots are responsible for sensory innervation of most of the posterior side of the lower limb?

Answer 7

S1 + S2

Question 8

What are autonomous sensory zones?

Answer 8

Regions where you can be confident of the spinal root affected if there is any abnormal sensation in those regions

Question 9

Which part of the lower limb does the obturator nerve supply sensory innervation to?

Answer 9

Medial compartment of thigh

Question 10

Which part of the leg does the saphenous nerve provide sensory innervation to?

Answer 10

Medial part of the leg

Question 11

Which nerve provides sensory innervation to most of the dorsum of the foot?

Answer 11

Superficial peroneal nerve

Question 12

Where can the common peroneal nerve be damaged easily?

Answer 12

At the neck of the fibula

Question 13

Describe the position of the posterior tibial artery relative to the medial malleolus.

Answer 13

It is posterior to the medial malleolus

Question 14

Where can the dorsalis pedis pulse be felt?

Answer 14

Just lateral to the extensor hallucis longus tendon

Question 15

Where can the posterior tibial artery pulse be felt?

Answer 15

Just posterior to the medial malleolus

Question 16

What is cut-down and when it is performed?

Where is the incision made in cut-down?

Answer 16

An emergency procedure to gain access to the veins of a patient in shock
2 cm lateral + proximal to the medial malleolus

Question 17

What is intermittent claudication?

Answer 17

Muscle pain induced by exercise + relieved by rest

Caused by inadequate blood supply to the affected muscles (associated with arterial disease)

Question 18

What is compartment syndrome?

Answer 18

Ischaemia caused by trauma-induced increased pressure in a confined limb compartment

Question 19

What is the normal pressure in muscle compartments?

Answer 19

25 mm Hg

Question 20

What pressure is required to collapse vessels?

Answer 20

50-60 mm Hg

so pulse is still present despite tissue becoming ischaemic

Question 21

What are the causes of acute and chronic compartment syndrome?

Answer 21

Acute: trauma-associated
Chronic: exercise-induced

Question 22

What is the treatment of acute compartment syndrome?

Answer 22

Emergency fasciotomy

Question 23

How do varicose veins form?

Answer 23

Valve dysfunction in the superficial, deep + perforating veins
Results in deep venous return being pushed superficially
Saphenofemoral junction valve is the most important
Can cause lipodermatosclerosis + ulcers

Question 24

What is a nerve plexus?

Answer 24

A nerve plexus forms when peripheral spinal nerve roots merge + split to produce a network of nerves from which new multi-segmental peripheral nerves emerge.

Question 25

Describe the path of the common peroneal nerve

Answer 25

Leaves popliteal fossa Wraps laterally round neck of fibula (susceptible to damage here) Divides to give superficial + deep peroneal nerves

Question 26

What is the saphenous nerve the main terminal branch of? What does it supply?

Answer 26

Femoral nerve | Sensory supply to skin on medial leg + foot

Question 27

What forms the sural nerve?

Answer 27

Communicating branches of tibial + common peroneal nerves | Form cutaneous nerve of lateral leg + foot

Question 28

Where does the tibial nerve divide?

Answer 28

At ankle | Forms lateral + medial plantar nerves supplying muscles in sole of foot

Question 29

``` Describe the composition of the: Femoral nerve Obturator nerve Sciatic nerve Superior Gluteal nerve Inferior Gluteal nerve ```

Answer 29

``` F: L2-4 (posterior fibres) O: L2-4 (anterior fibres) S: L4-S3 (anterior + posterior fibres) SGN: L4-S1 IGN: L5-S2 ```

Question 30

Generally if a muscle is more distal in limb

Answer 30

Its nerve supply is more caudal in spine

Question 31

Which pairs of spinal nerves are involved in hip flexion and extension?

Answer 31

Flexion: L2 + 3 Extension: L4 + 5

Question 32

Which pairs of spinal nerves are involved in knee flexion and extension?

Answer 32

Flexion: L5 + S1 Extension: L3 + 4

Question 33

Which pairs of spinal nerves are involved in ankle flexion and extension?

Answer 33

Dorsiflexion (extension): L4 + 5 | Plantarflexion (flexion): S1 + 2

Question 34

What is the general rule of segmental supply of opposing muscles?

Answer 34

Opposing muscles are innervated by 2 adjacent segments above or below

Question 35

Describe the segmental and peripheral supply of the posterior thigh

Answer 35

Segmental: S1 + 2 supply most of posterior thigh Peripheral: Posterior cutaneous nerve supplies posterior thigh (mixed nerves)

Question 36

What should you remember when considering segmental and peripheral supply?

Answer 36

Peripheral nerves have fibres from more than 1 spinal root | Not all fibres from a spinal root go via a particular peripheral nerve

Question 37

What would you observe in assessment of a prolapsed intervertebral disc at L5/S1 (a root injury)?

Answer 37

Motor: Loss of eversion Sensory: Loss of sensation outer border of foot Reflex: Loss of ankle jerk (S1) Autonomic: Minimal

Question 38

What would you observe in assessment of a lesion of common peroneal nerve at fibular neck?

Answer 38

Motor: Foot drop Sensory: Loss of sensation of dorsum of foot Reflex: No changes Autonomic: Minimal

Question 39

Describe arterial supply of the lower limb

Answer 39

Aorta (splits into internal + external iliac) External iliac Femoral (gives off circumflex + deep arteries, passes from anterior to posterior through hiatus of adductor magnus) Popliteal- trifurcates into: 1 Anterior tibial (becomes dorsalis pedis artery) 2 Posterior tibial (becomes plantar arteries) 3 Common peroneal artery (divides into superficial + deep)

Question 40

Which artery of the lower limb branches off the internal iliac?

Answer 40

Obturator artery

Question 41

List the 4 key pulses that can be palpated in the lower limb

Answer 41

Femoral Popliteal Posterior tibial Dorsalis Pedis

Question 42

Describe the borders of the femoral triangle

Answer 42

``` Inguinal ligament (superior border) Lateral border of adductor longus Medial border of sartorius ```

Question 43

Where are the arteries in relation to the veins in the popliteal fossa?

Answer 43

Arteries are deeper than veins

Question 44

Where can the femoral artery be palpated?

Answer 44

Midinguinal point (between ASIS + pubic symphysis)

Question 45

Describe the pathway of the great saphenous vein

Answer 45

Formed from branches of dorsal venous arch of foot which merge anterior + superior to medial malleolus Travels up medial leg Skirts slightly behind knee Up medial thigh, becoming more anterior Passes through saphenous opening to drain into femoral vein

Question 46

Describe the pathway of the short saphenous vein

Answer 46

``` Forms from dorsal venous arch Goes behind lateral malleolus Runs up posterior of leg Pierces fascia over popliteal fossa Drains into popliteal vein ```

Question 47

How are deep veins arranged in the lower limb? What is the advantage of this?

Answer 47

Run alongside arteries as venae comitantes- multiple veins with connections between them form networks of smaller veins which accompany arteries Pulsations of arteries squeeze veins, increasing venous return Allows blood cooled at extremities to warm on its return to the heart

Question 48

What has cutdown been superseded by?

Answer 48

Intraosseous administration of fluids | Needle inserted into bone marrow space to infuse fluid

Question 49

What connects superficial and deep veins in the lower limb? Describe their structure

Answer 49

Perforating veins | Have a valve orientated to only allow flow from superficial to deep

Question 50

What is DVT?

Answer 50

Deep vein thrombosis= clot lodging in deep veins Associated with inactivity If becomes dislodged may result in PE

Question 51

What is the result of deep veins being sandwiched between calf muscles?

Answer 51

Activity causes contraction of muscles, squeezing the veins + pushing the blood back to the heart = calf pump

Question 52

How do elastic surgical socks promote vigorous venous return?

Answer 52

Compress superficial veins, forcing blood back via deep return

Question 53

What can venous grafts be used for? What must be ensured?

Answer 53

Coronary artery bypass grafts | Ensure valves in the vein are orientated in correct direction