Locomotor: PBL 3 (Compartment Syndrome)

Question 1

Describe the contents of the anterior compartment of the leg

Answer 1

Anterior tibial artery, common peroneal (fibular) nerve (gives off branches of superficial and deep peroneal nerves)

Question 2

Describe the contents of the lateral compartment of the leg

Answer 2

Fibular artery, common peroneal nerve (superficial and deep peroneal nerves)

Question 3

Describe the contents of the posterior compartment of the leg

Answer 3

Posterior tibial artery and tibial nerve

Question 4

What are the branches of the common peroneal nerve?

Answer 4

Superficial and deep

Question 5

What is the motor role of the deep peroneal nerve?

Answer 5

Supplies tibialis anterior, extensor digitorum longus and extensor hallucis longus involved in dorsiflexion and toe extension

Question 6

What is the motor role of the superficial peroneal nerve?

Answer 6

Supplies fibularis longus and brevis (eversion of the foot)

Question 7

What muscles does the tibial nerve supply?

Answer 7

Flexor digitorum longus, flexor hallucis longus and tibialis posterior (plantarflexion)

Question 8

Describe the branches of the tibial nerve

Answer 8

Sural nerve given off (sensory to calf), in the foot branches into medial and lateral plantar branches:

Question 9

What are the branches of the sciatic nerve?

Answer 9

Common peroneal and tibial

Question 10

What is the sensory role of the superficial peroneal nerve?

Answer 10

Skin of anterior and lateral leg and dorsum of foot (mainly)

Question 11

What is the sensory role of the deep peroneal nerve?

Answer 11

1st interweb space of the toes

Question 12

What is the sensory role of the tibial nerve

Answer 12

Lateral plantar nerve - sensory to lateral 1 1/2 toes on plantar surface
Medial plantar nerve - sensory to medial 3 1/2 toes on plantar surface

Question 13

Which muscles are involved in dorsiflexion (with toe extension)?

Answer 13

Tibialis anterior, extensor digitorum longus and extensor hallucis longus

Question 14

Which muscles are involved in eversion?

Answer 14

Fibularis longus and brevis

Question 15

Which muscles are involved in plantarflexion?

Answer 15

Superficial (attach to calcaneal tendon): gastrocnemius, soleus and plantaris
Deep (attach to foot bones): tibialis posterior, flexor digitorum longus and flexor hallucis longus

Question 16

Describe the superficial veins of the lower limb

Answer 16

Great saphenous vein (starts medial anterior and drains into femoral vein)
Small saphenous vein (drains the posterior calf into the popliteal vein)

Question 17

Describe the path of deep veins in the lower limb

Answer 17

Femoral vein –> lateral circumflex femoral and profunda (lateral bundle) AND continuation of femoral medially –> popliteal vein (as femoral enters fossa) –> posterior tibial, anterior tibial and peroneal/fibular veins

Question 18

Describe the passage and divisions of arteries in the lower limb

Answer 18

Femoral artery –> medial circumflex and profunda.
Profunda femoris –> popliteal as it enters fossa
Popliteal artery –> common tibial –> anterior and posterior tibial arteries
Popliteal artery –> fibular artery also

Question 19

What are the types of compartment syndrome?

Answer 19

Acute and chronic

Question 20

Describe acute compartment syndrome

Answer 20

Occurs after traumatic injury which causes severely high pressure in a compartment leading to insufficient blood supply (ischaemia) and requires emergency surgery otherwise there will be resultant permanent nerve and muscle damage

Question 21

Describe chronic compartment syndrome

Answer 21

Exercise-induced variety whereby pressure in the muscle increases to extremes during exercise causing a decrease in blood flow to the affected area –> ischaemia

Question 22

Describe the symptoms of compartment syndrome

Answer 22

Extreme tightness in affected muscles, painful burning sensation if exercise is continued, foot drop

Question 23

Explain the cause of compartment syndrome

Answer 23

Due to excessive pressure on or within the muscle compartments; if there is any swelling of tissue due to injury or exercise, this can cause the compression of venules and lymphatic vessels, preventing them from draining. Therefore, while arterial inflow is increased, outflow is diminished and this causes further pressure build-up within the compartment eventually leading to the compression of arteries in the area –> ischaemia

Question 24

How may compartment syndrome be treated?

Answer 24

Conservative treatments (chronic) - rest, anti inflammatory drugs, manual decompression (rest affected limb in line of heart)
Surgical (acute) - fasciotomy whereby incisions are made in the affected compartment to allow decompression and relieve pressure on lymphatics and venules to allow increased blood flow through the muscle

Question 25

What complications can arise with compartment syndrome?

Answer 25

Failure to relieve pressure can result in myonecrosis (muscle death) which can have long-lasting effects, especially if there is associated nerve damage, it could even lead to paralysis of the region

Question 26

Why could compartment syndrome cause severe ankle weakness?

Answer 26

Due to loss of nerve supply to the muscles of the ankle

Question 27

Why could compartment syndrome cause bilateral foot drop?

Answer 27

Damage to the deep peroneal nerve as it's involved in producing dorsiflexion, so without there is unopposed plantarflexion (OR relaxed response)

Question 28

Why could compartment syndrome cause oedema?

Answer 28

Due to compression preventing the drainage of lymph and venous blood

Question 29

Why could compartment syndrome cause loss of an Achilles reflex?

Answer 29

Because nervous stimulation to the Achille's tendon is impaired

Question 30

Why could compartment syndrome cause elevated creatine kinase levels?

Answer 30

This molecule is formed in muscle death so is indicative of myonecrosis

Question 31

Why could compartment syndrome cause myoglobin in the urine?

Answer 31

Damage to the muscle cells affects the calcium channel mechanisms, and therefore there are increased levels of free Ca2+ which affects several calcium-dependent enzymes and therefore compromises the integrity of the cell membrane and allows the release of myoglobin --> dark urine indicative of myoglobin

Question 32

Why could compartment syndrome cause myonecrosis?

Answer 32

Ischaemia leads to muscle cell death as cells don't receive enough nutrients to respire

Question 33

Why could compartment syndrome cause impaired sensation over the lateral aspect of the leg?

Answer 33

Due to damage to the superficial peroneal nerve

Question 34

Why could compartment syndrome cause impaired dorsum sensation?

Answer 34

Compression of the superficial peroneal nerve

Question 35

Why could compartment syndrome cause impaired sensation over the sole of the foot (plantar surface)

Answer 35

Due to the tibial nerve being compromised leading to the lateral and medial plantar nerves being diminished

Question 36

What movements are specific for the talocrural (ankle) joints?

Answer 36

Dorsiflexion and plantarflexion

Question 37

What movements are specific for the sub-talar joints?

Answer 37

Inversion and eversion

Question 38

What is the role of myoglobin?

Answer 38

Acts as an oxygen store in muscles

Question 39

What is the role of creatine kinase?

Answer 39

Combines creatine and an inorganic phosphate to form phosphocreatine (PCr) - a source of immediate energy

Question 40

Where would you palpate for the dorsalis pedis pulse?

Answer 40

Lateral to the tendon of extensor hallucis longus on the dorsum of the foot

Question 41

Where would you palpate for the posterior tibial pulse?

Answer 41

Half way between the medial malleolus and the Achilles tendon (calcaneal tendon)

Question 42

What is the definition of a muscular compartment?

Answer 42

A group of muscles that have a common blood and nerve supply and function and are surrounded by a layer of deep fascia

Question 43

Is the tibia medial or lateral in the leg?

Answer 43

Medial