Lower leg (519-533)

Question 1

Name the compartments of the lower leg;

Answer 1

Lateral compartment, Anterior compartment, Deep posterior compartment, Superficial posterior compartment.

Question 2

Name the muscles of the anterior compartment of lower leg. What is their origin and insertion?;

Answer 2

x3/4 muscles (dorsiflexion).
- Tibialis anterior (origin- lateral surface of tibia. Inserts- medial cuneform and base metatarsal I). [goes under foot to base of metatarsa - does inversion as well as dorsiflexion]
- Extensor digitorum longus [deep to tibialis anterior] (origin- lateral condyle of tibia & medial fibula. Inserts- tendon splits into four and inserts onto a toe).
- Extensor hallucis longus [deep to tibilasis anterior and extensor digitroum longus] (Origin- medial surface fibula shaft. Inserts base of great toe (distal phalanx)).
- Fibularis Tertius (not present in all individuals).

Question 3

Which artery supplies the anterior compartment of lower leg?;

Answer 3

Anterior tibial artery (Branch of popliteal artery at distal end of popliteal fossa- popliteal artery then continues as tibial-fibular trunk)

Question 4

What is the innervation of the anterior compartment of lower leg?;

Answer 4

Deep fibular (peroneal) nerve [L4-S2] - (terminal branch of common fibular nerve (bifurcation of sciatic nerve))

Question 5

What is the main action of the muscles in the anterior compartment of lower leg? What is the clinical relevance?;

Answer 5

All muscles - Dorsiflexion of the foot. Tibialis anterior- also inversion of foot. Extensor digitorum longus- also extension of lateral 4 toes. Extensor hallucis longus- also extension of big toe. Clinical relevant- foot drop (inability to dorsiflex foot at ankle joint - indicates paralysis or weakness of muscles in anterior compartment. Typically occurs as consequence of damage to common fibular nerve (from which deep fibular nerve arises).

Question 6

Name the muscles of the lateral (peroneal) compartment of lower leg. Origjn and Inserts?;

Answer 6

Fibularis Longus (origin- lateral surface of fibula. Travels posterior to lateral malleolus then cross under the foot. Inserts- medial cuneform and base of metatarsal I).

Fibularis Brevis (origin- inferolateral surface of fibular shaft. Travels posterior to lateral malleolus. Inserts- tubercle on 5th metatarsal).

Question 7

Describe the action of the muscles of the lateral compartment of lower leg. Innervated by what nerve?;

Answer 7

Eversion and plantarflexion (fibularis longus) of foot. Innervation- superfical fibular (peroneal) nerve.

Question 8

Name the muscles of the posterior compartment of the leg;

Answer 8

Superfical compartment- Gastrocnemius, soleus, plantaris.
Deep compartment- popliteus, flexor digitorum longus, flexor hallucis longus, tibialis posterior.

Question 9

What is the arterial and nerve supply of the flexor compartment of the lower leg?;

Answer 9

Posterior tibial artery (bifurcation of tibial-fibular trunk [continuation of popliteal artery once anterior tibial artery branches off]).
Tibial nerve (Branch of sciatic nerve)

Question 10

Define compartment syndrome;

Answer 10

Critical pressure increase within a closed osteofascial compartment, resulting in impaired local circulation. Can result in necrosis of tissues.

Question 11

What are the key signs and symptoms of compartment syndrome?;

Answer 11

6 P’s- Pain (very severe [out of proportion to injury]), Paresthesia, Pulselessness, Paralysis, Pallor, Perishinly cold. Pain on passive stretch of affected muscles.

Question 12

Name four important causes of compartment syndrome;

Answer 12

Trauma (particularly tibia fractures), Crush injury, Severe burns (particularly electrical), Revascularisation injuries.

Question 13

At what compartment pressure in the lower leg would you consider a fasciotomy?;

Answer 13

State compatment syndrome is a clinical diagnosis however can use intra-compartmental pressure monitor if clinical uncertainty (atypical presentation or patient unconscious). Greater than 40 mmHg (normal compartmental pressures are 0-8mmHg) requires fasciotomy.

Question 14

What is the significance of the blood pressure in compartment syndrome;

Answer 14

If hypotensive need to work out delta pressure (Delta P - difference between patient’s diastolic pressure and compartment pressure). If Delta P less than 30 mmHg, it strongly suggests acute compartment syndrome.

Question 15

Where would you place the incisions in the lower leg for fasciotomies?;

Answer 15

Two incisions.
2cm lateral from anterior border of tibia [outside calf] (anterior and lateral compartment). 2
cm medial to medial border of tibia [inside calf] (deep and superficial posterior compartments).
If clinically suspects compartment syndrome needs to be operated within 60 minutes.