Knee, Leg, Ankle & Foot Anatomy Sean Botham

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. 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.

Foot/digit dorsiflexors & invertors Deep fibular nerve (L4,5,S1) Anterior Compartment Foot/digit dorsiflexors & invertors Deep fibular nerve (L4,5,S1) Anterior tibial artery For each compartment: Action Innervation (with nerve roots) Arterial supply Lateral Compartment Foot evertors Superficial fibular nerve (L5,S1) Fibular artery Deep fibular nerve is at greatest risk of damage from fibula head fracture and/or anterior tibial artery occlusion / aneurysm due to their close association down the anterior leg. Posterior Compartment Foot & digit plantarflexors & invertors Tibial nerve (L4,5, S1,2) Posterior tibial artery

Prevents tibial abduction (valgus) 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 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 Cruciate ligaments sit between the femoral condyles and attach the femur to the tibia. Named according to their origin point on the tibia: remembered using LAMP: Lateral condyle Anterior cruciate Medial condyle Posterior cruciate Valgus (vulgar, to move away) stress test measures MCL, varus stress test measures LCL.

Three roles of the patella? Reduces ligament and tendon wear. Spreads forces passing to femoral condyles = less strain on knee. Increases moment of quadriceps = easier to move around knee joint. Four roles of menisci? Increase contact area = allows even weight distribution over the joint. Weight-bearing. Shock absorbers. Locking mechanism. Medial = attached around its margin to the joint capsule and to MCL = well fixed. As medial meniscus is fused with MCL = damage is more common. Also associated with ACL injuries = the weaker cruciate ligament. Also more likely to be receive a lateral blow to the knee than a medial one! Lateral = unattached to joint capsule, connected to tendon of popliteus muscle, and both connected anteriorly to a transverse ligament = mobile. What is the unhappy triad? Medial meniscus, MCL, ACL   

What’s more stable, dorsiflexion or plantarflexion? 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. 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. Articular surface of talus is much wider anteriorly than posteriorly = bone fits tighter into the socket when dorsiflexed and wider surface of the talus moves into the ankle joint than when plantarflexed and the narrower part of the talus is in the joint. Foot is dorsiflexed during heel strike and swing phases of walking. LoF  foot drop. Compensate = lift leg higher and foot lands first = equine gait, or circumduct the limb so the foot clears the floor. Deep fibular nerve is at greatest risk of damage from fibula head fracture and/or anterior tibial artery occlusion / aneurysm due to their close association down the anterior leg. When is the common fibular nerve at highest risk of damage? As it winds around the fibular head subcutaneously.

Borders of popliteal fossa? Semimembranosus, semitendinosus (medial), biceps femoris (lateral), gastrocnemius (medial and lateral heads). Contents (deep to superficial)? Popliteal artery Popliteal vein Tibial 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).

Surface markings of flexor retinacula? [3] Medial malleolus Talus 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 malleolus Talus Medial surface of calcaneus. Contents of tarsal tunnel? [6] Tibialis Posterior Flexor Digitorum Posterior Tibial Artery Posterior Tibial Vein Tibial Nerve Flexor Hallucis Longus. Flexor retinacula = continuous with deep fascia of the leg superiorly and inferiorly with plantar aponeurosis. Nerve supply to posterior compartment muscles? Tibial branch of sciatic nerve (S1, S2)

Posterior Talofibular Anterior Talofibular Posterior Talofibular Anterior Tibiotalar Posterior Tibiotalar Calcaneofibular Tibionavicular Tibiocalcaneal

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.