Unit 4 Question Bank
Sourcing: items tagged TMU 2021–22 come from the real final paper. Items tagged
Slide come from the TMU lecture. Items tagged Gray's are built from the textbook to cover
examinable content. Nothing here is invented; answers are verifiable against the cited page — check against
the official marking scheme where one exists.
0 / 20 answered
1The contents of the malleolar canal, from anterior to posterior, are ( ).
Answer: B
Remember Tom, Dick And Very Nervous Harry: Tibialis posterior, flexor Digitorum longus, Artery, Vein, Nerve, flexor Hallucis longus — working backwards from the medial malleolus. Option D lists structures on the front of the ankle, not in the canal.TMU Slide 12 · Gray's 4e p.642
2The malleolar canal is formed by the medial malleolus, the medial surface of the calcaneus and the ( ).
Answer: C
The flexor retinaculum roofs the bony depression to complete the canal. In English-language textbooks the same space is called the tarsal tunnel.TMU Slide 11 · Gray's 4e p.642
3Which nerve supplies the anterior compartment of the leg?
Answer: D
The deep fibular nerve supplies tibialis anterior, extensor hallucis longus and extensor digitorum longus — the dorsiflexors. The superficial fibular nerve supplies the lateral compartment (evertors), and the tibial nerve the posterior compartment (plantarflexors).TMU Slide 20 · Gray's 4e p.624
4The anterior tibial artery reaches the anterior compartment by passing ( ).
Answer: A
It passes forward above the interosseous membrane, close to the neck of the fibula, to enter the anterior compartment. No other vessel takes that route, which is why the anterior compartment has its own dedicated artery.TMU Slide 9
5The dorsalis pedis artery is palpated ( ).
Answer: B
Ask the patient to lift the big toe: the tendon of extensor hallucis longus stands up, and the artery lies immediately lateral to it on the dorsum of the foot. Behind the medial malleolus is where the posterior tibial pulse is felt.Gray's 4e p.654, Fig. 6.125
6The lateral compartment of the leg contains the ( ).
Answer: C
Only two muscles — fibularis (peroneus) longus and brevis — supplied by the superficial fibular nerve and acting as evertors of the foot. Their tendons pass behind the lateral malleolus.TMU Slide 18
7The triceps surae consists of ( ).
Answer: D
Gastrocnemius (two heads) plus soleus (one head) — three heads, hence triceps surae — inserting via the calcaneal (Achilles) tendon. Plantaris is a separate slender muscle of the superficial group, not part of the triceps.TMU Slide 3
8Sensory loss confined to the web space between the first and second toes indicates injury to the ( ).
Answer: A
The deep fibular nerve has a famously small cutaneous territory — only the web between the first and second toes. The rest of the dorsum belongs to the superficial fibular nerve, and the sole to the tibial nerve.Gray's 4e p.654
9The posterior tibial artery terminates by dividing into the ( ).
Answer: B
After passing through the malleolar canal it divides into the medial and lateral plantar arteries, which supply the sole. The dorsalis pedis is the continuation of the anterior tibial artery on the dorsum.TMU Slide 10
10Gastrocnemius is weaker when the knee is flexed because it ( ).
Answer: C
Because it crosses two joints, arising from the femoral condyles, knee flexion slackens the muscle and it cannot generate full force. Soleus, arising below the knee from the tibia and fibula, is unaffected by knee position — which is why plantarflexion with the knee bent tests soleus specifically.TMU Slide 3 · Gray's 4e p.616
11Which muscle is NOT in the deep group of the posterior compartment of the leg?
Answer: D
Plantaris belongs to the superficial group with gastrocnemius and soleus. The deep group is popliteus, flexor digitorum longus, tibialis posterior and flexor hallucis longus.TMU Slide 7
12Tarsal tunnel syndrome produces symptoms in the ( ).
Answer: A
Compression of the tibial nerve beneath the flexor retinaculum causes burning, tingling and numbness in the sole, sparing the dorsum — because the tibial nerve is the sole supply of the plantar surface.Gray's 4e p.642
13The medial-to-lateral order of the deep posterior leg muscles is ( ).
Answer: B
In the leg: flexor digitorum longus is medial, tibialis posterior is in the middle, flexor hallucis longus is lateral. Note this changes at the ankle — behind the medial malleolus tibialis posterior slips in front of flexor digitorum longus, giving the 'Tom, Dick' order in the malleolar canal.TMU Slide 6
14The three muscles of the anterior compartment, from medial to lateral, are ( ).
Answer: C
Tibialis anterior (medial) → extensor hallucis longus (middle) → extensor digitorum longus (lateral). Their tendons cross the ankle in the same order, which is how you identify them clinically.TMU Slide 17
15The earliest reliable sign of anterior compartment syndrome is ( ).
Answer: D
Venous outflow fails first and arterial inflow last, so the pulse may still be present while muscle is dying. Waiting for pulselessness means waiting too long. The compartment must be released by fasciotomy on the basis of pain and passive-stretch pain.Gray's 4e p.624 (clinical application)
16The tendon of fibularis longus is unusual because it ( ).
Answer: A
It passes behind the lateral malleolus, then turns under the foot and crosses the sole from lateral to medial to insert on the medial cuneiform and base of the first metatarsal. With tibialis anterior it forms a sling that supports the transverse arch.Gray's 4e p.622, Fig. 6.91
17The superficial fibular nerve becomes cutaneous ( ).
Answer: B
It descends between fibularis longus and brevis, supplies them both, and pierces the deep fascia in the distal one-third of the leg to supply most of the skin of the dorsum of the foot.TMU Slide 16
18Which artery supplies the lateral compartment of the leg?
Answer: C
The lateral compartment has no artery of its own. It is supplied by branches of the fibular (peroneal) artery that perforate the posterior intermuscular septum — an exception to the otherwise tidy one-compartment-one-artery rule.Gray's 4e p.620–622
19Soleus is clinically important in venous thrombosis because ( ).
Answer: D
Soleus is riddled with venous sinuses. Contraction during walking pumps blood up the deep veins against gravity — the 'peripheral heart'. Immobility stops the pump, blood stagnates, and deep vein thrombosis begins. This is why early mobilisation is standard after surgery.Gray's 4e p.616 (clinical application)
20Which pulse is felt midway between the medial malleolus and the heel?
Answer: A
The posterior tibial pulse is felt where the artery runs through the malleolar canal, midway between the medial malleolus and the calcaneus, palpated through the flexor retinaculum. With dorsalis pedis it forms the standard two-point assessment of foot perfusion.Gray's 4e p.642
1 Malleolar canal (tarsal tunnel) — drawing homework · 3′+
An osteofibrous canal on the posteromedial side of the ankle.
Formed by: the medial surface of the calcaneus, the medial malleolus, and the overlying flexor retinaculum.
Contents (anterior → posterior): tendon of tibialis posterior · tendon of flexor digitorum longus · posterior tibial artery and veins · tibial nerve · tendon of flexor hallucis longus.
Mnemonic: Tom, Dick And Very Nervous Harry.
Clinical: compression of the tibial nerve here causes tarsal tunnel syndrome — burning and numbness in the sole.TMU Slides 11–12 · Gray's 4e p.642
Formed by: the medial surface of the calcaneus, the medial malleolus, and the overlying flexor retinaculum.
Contents (anterior → posterior): tendon of tibialis posterior · tendon of flexor digitorum longus · posterior tibial artery and veins · tibial nerve · tendon of flexor hallucis longus.
Mnemonic: Tom, Dick And Very Nervous Harry.
Clinical: compression of the tibial nerve here causes tarsal tunnel syndrome — burning and numbness in the sole.TMU Slides 11–12 · Gray's 4e p.642
2 Triceps surae — 3′+
The combined muscle mass of gastrocnemius (two heads, from the femoral condyles) and soleus (one head, from the tibia and fibula), inserting together via the calcaneal (Achilles) tendon on the calcaneus.
Nerve: tibial nerve. Action: plantarflexes the foot at the ankle; gastrocnemius also flexes the knee. It steadies the leg on the foot during standing.TMU Slide 3
Nerve: tibial nerve. Action: plantarflexes the foot at the ankle; gastrocnemius also flexes the knee. It steadies the leg on the foot during standing.TMU Slide 3
3 Dorsalis pedis artery — 2′+
The continuation of the anterior tibial artery on the dorsum of the foot, beginning as the vessel crosses the ankle joint.
It runs lateral to the tendon of extensor hallucis longus, where its pulse is palpated, and gives arcuate, dorsal metatarsal and deep plantar branches — the last passing into the sole to complete the plantar arch.Gray's 4e p.654
It runs lateral to the tendon of extensor hallucis longus, where its pulse is palpated, and gives arcuate, dorsal metatarsal and deep plantar branches — the last passing into the sole to complete the plantar arch.Gray's 4e p.654
4 Compartments of the leg — 3′+
The leg is divided by the interosseous membrane and the anterior and posterior intermuscular septa into three compartments:
Anterior — deep fibular nerve, anterior tibial artery, dorsiflexion.
Lateral — superficial fibular nerve, branches of the fibular artery, eversion.
Posterior — tibial nerve, posterior tibial artery, plantarflexion (superficial and deep layers).Gray's 4e p.612
Anterior — deep fibular nerve, anterior tibial artery, dorsiflexion.
Lateral — superficial fibular nerve, branches of the fibular artery, eversion.
Posterior — tibial nerve, posterior tibial artery, plantarflexion (superficial and deep layers).Gray's 4e p.612
5 Flexor retinaculum of the ankle — 2′+
A strap-like band of connective tissue spanning the bony depression between the medial malleolus and the calcaneus, converting it into the malleolar canal.
Septa from its deep surface create separate tunnels for the flexor tendons, each lined by a synovial sheath. It is continuous above with the deep fascia of the leg and below with the plantar aponeurosis.Gray's 4e p.642
Septa from its deep surface create separate tunnels for the flexor tendons, each lined by a synovial sheath. It is continuous above with the deep fascia of the leg and below with the plantar aponeurosis.Gray's 4e p.642
6 Foot drop — 3′+
Loss of dorsiflexion and eversion of the foot following injury to the common fibular nerve, most often where it winds around the neck of the fibula.
Both terminal branches are affected — the deep fibular nerve (anterior compartment, dorsiflexors) and the superficial fibular nerve (lateral compartment, evertors). The foot hangs plantarflexed and inverted, and the patient adopts a high-stepping gait to clear the toes.Gray's 4e p.610, 624
Both terminal branches are affected — the deep fibular nerve (anterior compartment, dorsiflexors) and the superficial fibular nerve (lateral compartment, evertors). The foot hangs plantarflexed and inverted, and the patient adopts a high-stepping gait to clear the toes.Gray's 4e p.610, 624
1
Draw and describe the malleolar canal and its contents.
8′
Set as homework in TMU Lecture 4 — expect it as a drawing question.
Position
An osteofibrous canal on the posteromedial side of the ankle, the gateway through which structures pass from the posterior compartment of the leg into the sole of the foot.
Formation
- Anteriorly / above: the medial malleolus of the tibia
- Laterally / floor: the medial surface of the calcaneus (and the talus)
- Roof: the flexor retinaculum, which sends septa inwards to create separate tunnels for each tendon, lined by synovial sheaths
Contents — anterior to posterior
- Tendon of tibialis posterior
- Tendon of flexor digitorum longus
- Posterior tibial artery and its venae comitantes
- Tibial nerve
- Tendon of flexor hallucis longus
Mnemonic: Tom, Dick And Very Nervous Harry.
Clinical importance
- The posterior tibial pulse is palpated here, midway between the medial malleolus and the heel
- Compression of the tibial nerve causes tarsal tunnel syndrome: burning pain and numbness in the sole, sparing the dorsum
- Beyond the canal the artery and nerve divide into medial and lateral plantar branches for the sole
Marking guide: position 1 · three boundaries 2 · five contents in correct order 3 (½ each, rounded) · one clinical point 2.
2
Describe the three compartments of the leg, giving the muscles, nerve, artery and action of each.
10′
How the compartments are formed
The tibia and fibula are united by the interosseous membrane; the anterior and posterior intermuscular septa run from the fibula to the deep fascia. Together these divide the leg into three compartments.
Anterior compartment
- Muscles: tibialis anterior, extensor hallucis longus, extensor digitorum longus (± fibularis tertius)
- Nerve: deep fibular nerve · Artery: anterior tibial artery
- Action: dorsiflexion of the foot; extension of the toes
Lateral compartment
- Muscles: fibularis longus, fibularis brevis
- Nerve: superficial fibular nerve · Artery: perforating branches of the fibular artery (no artery of its own)
- Action: eversion of the foot
Posterior compartment
- Superficial: gastrocnemius, soleus, plantaris
- Deep: popliteus, flexor digitorum longus, tibialis posterior, flexor hallucis longus
- Nerve: tibial nerve · Artery: posterior tibial artery (with the fibular artery)
- Action: plantarflexion; inversion; flexion of the toes
Clinical link worth stating
Because the common fibular nerve divides at the fibular neck into the deep and superficial fibular nerves, a single injury there paralyses two compartments at once — producing foot drop.
Marking guide: septa and membrane 1 · anterior compartment 3 · lateral compartment 2 · posterior compartment 3 · clinical link 1.
3
Trace the arterial supply of the leg and foot from the popliteal artery to the toes.
8′
1 · Popliteal artery
Begins at the adductor hiatus; ends at the lower border of popliteus by dividing into the anterior and posterior tibial arteries.
2 · Anterior tibial artery
- Passes forward through the aperture in the upper interosseous membrane, close to the neck of the fibula
- Descends in the anterior compartment with the deep fibular nerve
- Becomes the dorsalis pedis artery at the ankle
- Dorsalis pedis gives the arcuate artery → dorsal metatarsal → dorsal digital arteries, and the deep plantar artery which dives between the first and second metatarsals to complete the plantar arch
3 · Posterior tibial artery
- Gives off the fibular (peroneal) artery proximally, which supplies the posterior and — by perforating branches — the lateral compartment
- Runs between the superficial and deep muscles of the calf
- Passes through the malleolar canal behind the medial malleolus
- Divides into the medial and lateral plantar arteries; the lateral plantar artery forms the plantar arch, giving plantar metatarsal and digital arteries
Palpation points
Popliteal (behind the flexed knee) · posterior tibial (midway between medial malleolus and heel) · dorsalis pedis (lateral to the extensor hallucis longus tendon).
Marking guide: popliteal division 1 · anterior tibial course and renaming 2 · dorsalis pedis branches 1 · fibular artery 1 · posterior tibial course 1 · plantar division and arch 1 · palpation points 1.
4
A patient has a foot that hangs down and inverted, and cannot evert it. Analyse the lesion.
6′
Diagnosis
Foot drop from a common fibular (peroneal) nerve lesion, most probably at the neck of the fibula.
Why both movements are lost
The common fibular nerve divides at the fibular neck into two branches, and a lesion at that point takes out both:
| Branch | Compartment | Movement lost | Sensory loss |
|---|---|---|---|
| Deep fibular n. | Anterior | Dorsiflexion | Web space between toes 1 and 2 |
| Superficial fibular n. | Lateral | Eversion | Most of the dorsum of the foot |
Why the foot is inverted as well as dropped
The posterior compartment (tibial nerve) is intact and now unopposed. Tibialis posterior inverts, and the plantarflexors pull the foot down — so the foot rests plantarflexed and inverted.
Gait
A high-stepping (steppage) gait: the knee is lifted excessively so the toes clear the ground, and the foot slaps down because dorsiflexors cannot control descent.
Common causes
Fracture of the fibular neck, a tight below-knee cast, prolonged leg-crossing, or pressure on the lateral leg during anaesthesia.
Marking guide: nerve and site identified 2 · the two branches with movements 2 · explanation of inversion 1 · gait 1.
5
Compare the superficial and deep muscle groups of the posterior compartment of the leg.
7′
Superficial group
- Gastrocnemius — two heads from the femoral condyles; crosses knee and ankle
- Soleus — from the soleal line of the tibia and the head and upper fibula; crosses the ankle only
- Plantaris — small, with a very long slender tendon
Gastrocnemius and soleus form the triceps surae and insert by the calcaneal (Achilles) tendon. Because gastrocnemius crosses the knee, it is weakened by knee flexion; soleus is not — which is how the two are tested separately.
Deep group
- Popliteus — unlocks the fully extended knee to allow flexion to begin
- Flexor digitorum longus (medial), tibialis posterior (middle), flexor hallucis longus (lateral)
The three long tendons pass through the malleolar canal into the sole. Note the order changes at the ankle: behind the medial malleolus tibialis posterior lies anterior to flexor digitorum longus.
Common features
Both groups are supplied by the tibial nerve and the posterior tibial artery, and both act mainly as plantarflexors.
Clinical note
The venous sinuses within soleus are the origin of most calf deep vein thromboses; the muscular pump fails during immobility.
Marking guide: superficial group named 2 · triceps surae and tendon 1 · deep group named 2 · nerve and artery 1 · one clinical or functional point 1.