Unit 3 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 superolateral boundary of the popliteal fossa is formed by the ( ).
Answer: C
The diamond is bounded above and laterally by biceps femoris, above and medially by semitendinosus and semimembranosus, and below by the two heads of gastrocnemius.TMU 2021–22 final Section III Q6 · Gray's 4e p.609
2The contents of the popliteal fossa, from superficial to deep, are ( ).
Answer: D
From the surface inwards: the tibial and common fibular nerves, then the popliteal vein, then the popliteal artery lying deepest on the knee joint capsule. The nerves descend just under the deep fascia; the artery arrives from the front through the adductor hiatus.TMU Slide 13 · Gray's 4e p.610
3The popliteal artery begins at the ( ).
Answer: A
The femoral artery becomes the popliteal artery as it passes through the adductor hiatus in adductor magnus. It ends at the lower border of popliteus by dividing into the anterior and posterior tibial arteries.TMU Slide 11 · Gray's 4e p.609
4The sciatic nerve terminates by dividing into its two branches at the ( ).
Answer: B
The sciatic nerve divides into the tibial and common fibular nerves at the superior angle of the popliteal fossa. The neck of the fibula is where the common fibular nerve itself divides into superficial and deep branches.TMU Slide 5
5Which muscle is NOT a true hamstring?
Answer: C
A true hamstring arises from the ischial tuberosity, crosses both hip and knee, and is supplied by the tibial division of the sciatic nerve. The short head of biceps femoris fails all three: it arises from the linea aspera, crosses only the knee, and takes the common fibular division.Gray's 4e p.591
6The small saphenous vein passes ( ) the lateral malleolus and drains into the ( ).
Answer: D
The small saphenous vein arises from the lateral end of the dorsal venous arch, passes behind the lateral malleolus, ascends the back of the calf and drains into the popliteal vein. Compare the great saphenous vein: in front of the medial malleolus, into the femoral vein.TMU Slide 2 · Gray's 4e p.560
7The floor of the popliteal fossa is formed by the ( ).
Answer: A
The floor is the capsule of the knee joint with the adjacent femur and tibia above, and the popliteus muscle below. The deep fascia is the roof, and gastrocnemius and the hamstrings form the borders.Gray's 4e p.609
8The common fibular nerve is most commonly injured at the ( ).
Answer: B
The nerve winds around the neck of the fibula, where it lies almost subcutaneously against bare bone. A fibular neck fracture, tight cast, or prolonged pressure compresses it, producing foot drop.TMU Slide 10 · Gray's 4e p.610
9Foot drop following common fibular nerve injury results from paralysis of ( ).
Answer: C
The common fibular nerve divides into the deep fibular nerve (anterior compartment — dorsiflexors) and the superficial fibular nerve (lateral compartment — evertors). Losing both leaves the foot hanging down and inverted, and the patient lifts the knee high to clear the toes.Gray's 4e p.610
10The popliteal artery ends by dividing into the ( ).
Answer: D
At the lower border of popliteus it divides into the anterior and posterior tibial arteries. The medial and lateral plantar arteries are the terminal branches of the posterior tibial artery in the foot.TMU Slide 11
11Which nerve accompanies the small saphenous vein in the superficial fascia of the back of the thigh?
Answer: A
The posterior femoral cutaneous nerve of the thigh lies centrally in the superficial fascia — the same nerve you traced out of the infrapiriform foramen in Unit 2. The saphenous nerve is on the medial side of the leg and accompanies the great saphenous vein.TMU Slide 3
12The named branches of the popliteal artery are the ( ).
Answer: B
The genicular arteries — superior, middle and inferior — plus muscular branches. They form an anastomotic network around the knee providing collateral flow if the main vessel is gradually occluded.TMU Slide 11
13Which structure is the DEEPEST in the popliteal fossa?
Answer: C
The popliteal artery lies deepest, directly against the knee joint capsule. That depth is precisely why the popliteal pulse is the hardest peripheral pulse to feel and why a popliteal aneurysm can grow large before being noticed.Gray's 4e p.610
14Semitendinosus and semimembranosus are distinguished at dissection because ( ).
Answer: D
The names describe what you feel: semitendinosus has a rope-like tendon for its lower half, while semimembranosus lies deep to it and is a broad flat membrane above. Both lie medially and both take the tibial division.Gray's 4e p.591
15The popliteal vein is formed by the union of the ( ).
Answer: A
It is formed near the lower border of popliteus by the junction of the anterior and posterior tibial veins, mirroring the arterial division at the same level. It receives the small saphenous vein within the fossa.TMU Slide 12
16Which division of the sciatic nerve supplies the long head of biceps femoris?
Answer: B
The tibial division supplies the long head, together with semitendinosus, semimembranosus and the hamstring part of adductor magnus. Only the short head of biceps femoris takes the common fibular division.Gray's 4e p.591
17A knee dislocation mandates urgent assessment of distal pulses because the popliteal artery is ( ).
Answer: C
Being fixed at both ends, the artery cannot move out of the way when the joint displaces, so the segment between those points tears. The knee may reduce easily and look normal while the limb is ischaemic — hence mandatory vascular assessment.Gray's 4e p.609 (clinical application)
18The roof of the popliteal fossa is formed by ( ).
Answer: D
The roof is deep fascia, continuous above with the fascia lata of the thigh and below with the deep fascia of the leg. The knee joint capsule is the floor.Gray's 4e p.609
19How does the common fibular nerve leave the popliteal fossa?
Answer: A
It follows the biceps femoris tendon laterally and passes superficial to the lateral head of gastrocnemius before winding round the fibular neck. The tibial nerve, by contrast, runs straight down and passes deep to gastrocnemius, which is why it is far better protected.TMU Slide 10
20Which additional structures are found within the popliteal fossa?
Answer: B
One or two popliteal lymph nodes lie just under the deep fascia close to the popliteal vessels, embedded in fat. They receive lymph from the superficial vessels accompanying the small saphenous vein and from the deep leg and foot.TMU Slide 9 · Gray's 4e p.562
1 Popliteal fossa — TMU 2021–22, Section III Q6 · 6′+
A diamond-shaped space behind the knee joint, between the muscles of the posterior compartments of the thigh and leg.
Superolateral: biceps femoris.
Superomedial: semitendinosus and semimembranosus.
Inferolateral: lateral head of gastrocnemius (with plantaris).
Inferomedial: medial head of gastrocnemius.
Floor: knee joint capsule and adjacent femur and tibia, then popliteus below.
Roof: deep fascia, continuous with the fascia lata above and the deep fascia of the leg below.
Contents (superficial → deep): tibial and common fibular nerves, popliteal vein, popliteal artery; plus popliteal lymph nodes and fat.Gray's 4e p.609–610
Superolateral: biceps femoris.
Superomedial: semitendinosus and semimembranosus.
Inferolateral: lateral head of gastrocnemius (with plantaris).
Inferomedial: medial head of gastrocnemius.
Floor: knee joint capsule and adjacent femur and tibia, then popliteus below.
Roof: deep fascia, continuous with the fascia lata above and the deep fascia of the leg below.
Contents (superficial → deep): tibial and common fibular nerves, popliteal vein, popliteal artery; plus popliteal lymph nodes and fat.Gray's 4e p.609–610
2 Adductor hiatus — 2′+
An opening in the lower attachment of adductor magnus, between its adductor and hamstring portions, transmitting the femoral artery and vein from the adductor canal into the popliteal fossa.
It marks the point at which the femoral vessels are renamed the popliteal vessels.Gray's 4e p.588
It marks the point at which the femoral vessels are renamed the popliteal vessels.Gray's 4e p.588
3 Hamstring muscles — 3′+
The three muscles of the posterior compartment of the thigh — biceps femoris, semitendinosus and semimembranosus — which arise from the ischial tuberosity, cross both the hip and the knee, and are supplied by the tibial division of the sciatic nerve.
They extend the hip and flex the knee. The short head of biceps femoris is excluded: it arises from the linea aspera, crosses only the knee, and is supplied by the common fibular division.Gray's 4e p.591
They extend the hip and flex the knee. The short head of biceps femoris is excluded: it arises from the linea aspera, crosses only the knee, and is supplied by the common fibular division.Gray's 4e p.591
4 Small saphenous vein — 2′+
A superficial vein beginning at the lateral end of the dorsal venous arch of the foot, passing behind the lateral malleolus, ascending the middle of the back of the calf, piercing the deep fascia, and draining into the popliteal vein in the popliteal fossa.TMU Slide 2 · Gray's 4e p.560
5 Popliteal artery — 3′+
The continuation of the femoral artery, beginning at the adductor hiatus and ending at the lower border of popliteus, where it divides into the anterior and posterior tibial arteries.
Branches: superior, middle and inferior genicular arteries and muscular branches. It is the deepest structure in the popliteal fossa, lying on the knee joint capsule.TMU Slide 11 · Gray's 4e p.609
Branches: superior, middle and inferior genicular arteries and muscular branches. It is the deepest structure in the popliteal fossa, lying on the knee joint capsule.TMU Slide 11 · Gray's 4e p.609
6 Common fibular (peroneal) nerve — 3′+
The smaller terminal branch of the sciatic nerve, arising at the superior angle of the popliteal fossa. It follows the tendon of biceps femoris, passes superficial to the lateral head of gastrocnemius, and winds around the neck of the fibula, where it divides into the superficial and deep fibular nerves.
Clinical: the most commonly injured nerve of the lower limb; injury causes foot drop.TMU Slide 10
Clinical: the most commonly injured nerve of the lower limb; injury causes foot drop.TMU Slide 10
1
Describe the boundaries of the popliteal fossa.
6′
Real question — TMU 2021–22 final, Section III Q6.
The popliteal fossa is a diamond-shaped space behind the knee joint, formed between the muscles of the posterior compartments of the thigh and the leg.
Boundaries
- Superolateral: biceps femoris
- Superomedial: semitendinosus and semimembranosus
- Inferolateral: lateral head of gastrocnemius, with plantaris
- Inferomedial: medial head of gastrocnemius
Floor
The capsule of the knee joint and adjacent surfaces of the femur and tibia above; the popliteus muscle below.
Roof
Deep fascia, continuous above with the fascia lata of the thigh and below with the deep fascia of the leg.
Contents (add these — they are usually worth marks even when only boundaries are asked)
From superficial to deep: tibial and common fibular nerves → popliteal vein → popliteal artery, together with popliteal lymph nodes and fat.
Marking guide: diamond shape stated 1 · four borders 2 (½ each) · floor 1 · roof 1 · contents 1.
2
Describe the posterior muscle group of the thigh — names, actions, nerve and blood supply.
8′
The three muscles
- Biceps femoris — long head from the ischial tuberosity, short head from the linea aspera; inserts on the head of the fibula
- Semitendinosus — ischial tuberosity to the medial surface of the upper tibia (pes anserinus)
- Semimembranosus — ischial tuberosity to the medial condyle of the tibia
Actions
Extend the thigh at the hip and flex the leg at the knee. Biceps femoris also laterally rotates the flexed knee; semitendinosus and semimembranosus medially rotate it.
Nerve supply
- Tibial division of the sciatic nerve — long head of biceps femoris, semitendinosus, semimembranosus
- Common fibular division of the sciatic nerve — short head of biceps femoris (the exception)
Blood supply
Perforating branches of the deep femoral artery (profunda femoris), with contributions from the inferior gluteal artery proximally and the popliteal artery distally.
Marking guide: three muscles named 2 · attachments 1 · actions 2 · nerve supply including the exception 2 · blood supply 1.
3
A patient sustains a fracture of the neck of the fibula. Explain the anatomical basis of the resulting deficit.
6′
The nerve at risk
The common fibular (peroneal) nerve. After arising from the sciatic nerve at the superior angle of the popliteal fossa, it follows the tendon of biceps femoris, passes superficial to the lateral head of gastrocnemius, and winds around the neck of the fibula — where it lies almost subcutaneously against bare bone with no muscular padding.
What is lost
The nerve divides at that point into two branches, so both are affected:
- Deep fibular nerve — anterior compartment: tibialis anterior, extensor hallucis longus, extensor digitorum longus → loss of dorsiflexion; sensory loss in the web space between the first and second toes
- Superficial fibular nerve — lateral compartment: fibularis longus and brevis → loss of eversion; sensory loss over most of the dorsum of the foot
Clinical picture
Foot drop. The foot hangs plantarflexed and inverted because the unopposed posterior compartment (tibial nerve) is intact. The patient develops a high-stepping gait, lifting the knee excessively to clear the toes.
Marking guide: nerve identified 1 · reason for vulnerability at the fibular neck 2 · the two branches and their losses 2 · gait description 1.
4
Compare the great and small saphenous veins.
6′
| Great saphenous vein | Small saphenous vein | |
|---|---|---|
| Origin | Medial end of the dorsal venous arch | Lateral end of the dorsal venous arch |
| Malleolus | Passes in front of the medial malleolus | Passes behind the lateral malleolus |
| Course | Up the medial side of the leg and thigh | Up the middle of the back of the calf |
| Termination | Femoral vein, 3–4 cm below the inguinal ligament, through the saphenous opening | Popliteal vein, within the popliteal fossa |
| Accompanying nerve | Saphenous nerve (medial leg) | Sural nerve (posterolateral leg) |
Clinical relevance
- The great saphenous vein is harvested for coronary and peripheral arterial bypass grafting
- It is the site of emergency venous cutdown anterior to the medial malleolus
- Both are affected in varicose veins; a duplex scan must assess both the saphenofemoral junction in the groin and the saphenopopliteal junction behind the knee
Marking guide: origins 1 · malleolar relations 2 · terminations 2 · one clinical point 1.
5
Describe the contents of the popliteal fossa and explain why the popliteal pulse is difficult to palpate.
6′
Contents, superficial to deep
- Tibial nerve and common fibular nerve — the terminal branches of the sciatic nerve, lying just deep to the roof
- Popliteal vein — formed by the union of the anterior and posterior tibial veins; receives the small saphenous vein
- Popliteal artery — deepest, lying directly on the capsule of the knee joint
Also present: popliteal lymph nodes (one or two, close to the vessels) and fat.
Why the arrangement is as it is
The nerves descend from above in the plane just beneath the deep fascia; the artery enters from in front through the adductor hiatus, on the bone side of the limb. The vein lies between them. The layering therefore records where each structure came from.
Why the pulse is hard to feel
The artery is the deepest structure, with the vein and both nerves piled on top of it and a tough fascial roof over all of them. To palpate it the knee must be flexed to relax the roof, and firm pressure applied with the fingers of both hands against the back of the tibia.
The same depth explains why a popliteal aneurysm often presents late — by compressing the tibial nerve or by thrombosing — rather than as a visible swelling.
Marking guide: three contents in correct depth order 3 · lymph nodes 1 · explanation of depth 1 · palpation technique 1.