Knee, Leg, Ankle & Foot AnatomySean Botham

What is this and what attaches to it?

Tibial tuberosity.

Quadriceps.

What passes anteriorly to this?

Long saphenous vein.

What passes posteriorly to this?

Short saphenous vein.

What is the significance of the poor vascularisation of the medial border of the tibial shaft?

Common area for skin conditions to present e.g. erythema nodosum.

Anterior Compartment

Foot/digit dorsiflexors & invertors

Deep fibular nerve (L4,5,S1)

Anterior tibial artery

Lateral Compartment

Foot evertors

Superficial fibular nerve (L5,S1)

Fibular artery

Posterior Compartment

Foot & digit plantarflexors & invertors

Tibial nerve (L4,5, S1,2)

Posterior tibial artery

For each compartment:

• Action• Innervation (with

nerve roots)• Arterial supply

What does ACL do?

How is it damaged?

Prevents anterior tibial movement on femur

Force to back of flexed knee

What does PCL do?

How is it damaged?

Prevents posterior tibial movement on femur

Force to front of load-bearing knee

What does MCL do?

How is it damaged?

Prevents tibial abduction (valgus)

Lateral blow to the knee

What does LCL do?

How is it damaged?

Prevents tibial adduction (varus)

Medial blow to the knee

Three roles of the patella?

1. Reduces ligament and tendon wear.

2. Spreads forces passing to femoral condyles = less strain on knee.

3. Increases moment of quadriceps = easier to move around knee joint.

Four roles of menisci?

1. Increase contact area = allows even weight distribution over the joint.

2. Weight-bearing.

3. Shock absorbers.

4. Locking mechanism.

What is the unhappy triad?

Medial meniscus, MCL, ACL

What’s more stable, dorsiflexion or plantarflexion?

Dorsiflexion.

What muscle is primarily responsible for dorsiflexion?

Tibialis anterior

(also extensor hallucis longus & extensor digitorum longus).

What is the clinical sign seen in compression of the deep fibular nerve?

Foot drop / equine gait.

When is the common fibular nerve at highest risk of damage?

As it winds around the fibular head subcutaneously.

Structures in anterior leg compartment (medial to lateral)

THESE HOSPITALS ARE NOT DIRTY PLACES!

Tibialis anterior.Extensor Hallucis longus.Anterior tibial artery.Deep fibular Nerve.Extensor Digitorum longus.Peroneus / fibularis tertius.

Borders of popliteal fossa?

Semimembranosus, semitendinosus (medial), biceps femoris (lateral), gastrocnemius (medial and lateral heads).

Contents (deep to superficial)?

Popliteal arteryPopliteal veinTibial nerve

Common fibular nerve passes close to long head of biceps femoris.

Three differentials for popliteal swellings?

Popliteal artery aneurysm (pulsatile).Popliteal cyst (above knee joint line).Baker cyst (below knee joint line).

Tendons of posterior compartment pass behind medial malleolus to access the foot. Covered in flexor retinacula to prevent them from bowstringing.

Surface markings of flexor retinacula? [3]

Medial malleolusTalusMedial surface of calcaneus.

Contents of tarsal tunnel? [6]

Tibialis PosteriorFlexor DigitorumPosterior Tibial ArteryPosterior Tibial VeinTibial NerveFlexor Hallucis Longus.

Nerve supply to posterior compartment muscles?

Tibial branch of sciatic nerve (S1, S2)

Anterior Tibiotalar

Posterior Tibiotalar

Tibionavicular

Tibiocalcaneal

Posterior Talofibular

Anterior Talofibular

Calcaneofibular

Roles of medial and lateral collateral ligaments (ankle)?

Medial – prevent excess foot eversion.

Lateral – prevent excess foot inversion.

Lateral collateral ligament damage is more common. Why?

Number of ligaments (4 medially, 3 laterally).

Fibularis muscles on lateral side strengthen eversion movement.

Lateral malleolus overhands over calcaneus = eversion is limited.

What is the result of excess tension of the ligaments during inversion / eversion?

Sprains

Malleolar avulsion fracture.