Posterior Leg Anatomy Quiz

Posterior Leg

• The lecture focused on the posterior leg, including a review quiz up to the current content and a review of nerves and vessels of the lower extremity.
• Images of the posterior leg, highlighting bones, muscles, and nerves, were presented.
• The posterior compartment is divided into superficial and deep sub-compartments.
• Superficial compartment muscles include gastrocnemius, soleus, and plantaris.
• Gastrocnemius (two heads) and soleus comprise the triceps surae.
• Deep compartment muscles include popliteus, flexor hallucis longus (FHL), flexor digitorum longus (FDL), and tibialis posterior (TP).

Gastrocnemius

• Originates from the medial and lateral femoral condyles (above the knee joint).
• The two heads merge at the mid-leg.
• Inserts into the tendo Achilles (tendo calcaneus).
• Innervated by the tibial nerve.
• Action involves foot plantar flexion and knee flexion.

Soleus

• Lies deep to the gastrocnemius.
• Originates from the head and upper one-third of the fibula and the soleal line.
• Inserts into the tendo Achilles.
• Innervated by the tibial nerve.
• Action is plantarflexion of the foot; active in gait during loading to toe-off.

Plantaris

• A small muscle of little functional importance.
• Originates from the lateral supracondylar line (above the knee joint).
• Inserts into the Achilles tendon.
• Action is a very weak knee flexor and plantarflexor.

Deep Posterior Compartment

• Muscles: popliteus, flexor hallucis longus (FHL), flexor digitorum longus (FDL), tibialis posterior (TP).
• Popliteus forms the floor of the popliteal fossa.
• Origin/insertion: lateral condyle of the femur/lateral meniscus -> soleal line of the posterior tibia.
• Innervation: tibial nerve.
• Action: medial/lateral rotation of the knee joint.

Flexor Hallucis Longus

• Origin/insertion: lower two-thirds of the fibula/intermuscular septum--> wraps around the medial malleolus--> passes between the sesamoids (under the 1st MTPJ) --> inserts into the distal hallux phalanx.
• Innervation: tibial nerve.
• Action: 1st MTPJ/IPJ flexion and ankle joint flexion.

Flexor Digitorum Longus

• Origin/insertion: posterior tibia --> wraps around the medial malleolus under flexor retinaculum --> divides into four tendons --> insert into the distal phalanx of the lesser four toes.
• Innervation: tibial nerve.
• Action: plantarflexes the lesser four phalanges and foot; stabilises toes on ground during gait.

Tibialis Posterior

• Origin/insertion: interosseous membrane and tibia/fibula --> flexor retinaculum --> navicular tuberosity and all tarsal bones except talus.
• Nerve supply: tibial nerve.
• Action: foot inversion and plantarflexion.
• Pathology: weakness/rupture --> progressively pronated foot.

Structures under Flexor Retinaculum

• Tom, Dick and very naughty Harry: TP, FDL, Art, Vein, Nerve, and FHL (anterior-to-posterior order)

Nerve Supply: Tibial Nerve

• Larger terminal branch of the sciatic nerve.
• Passes deep to the triceps surae, wraps behind the medial malleolus.
• Divides into medial and lateral plantar nerves; muscular, cutaneous, and articular branches.

Nerve Supply: Common Peroneal Nerve

• Wraps around the lateral neck of the fibula.
• Supplies the knee joint (articular) and skin on posterior and postero-lateral aspects of the leg.
• Divides into superficial and deep peroneal nerves.
• Superficial peroneal n.: lateral compartment of leg; anterior ankle and dorsum of foot (except 1st webspace).
• Deep peroneal n.: enters anterior compartment, moves under extensor retinaculae; supplies skin (1st webspace).

Nerve Supply: Sural Nerve

• . Formed by branches of tibial and common peroneal nerves.
• Runs down the posterior calf with the short saphenous vein.
• Supplies skin on the posterior calf, heel, and lateral foot.

Femoral & Obturator Nerves

• Femoral nerve enters the inguinal ligament, sartorius, and the adductor canal.
• Motor branches supply anterior compartment muscles.
• Sensory branches supply skin over anterior and medial thigh; saphenous nerve supplies a strip of skin medially to the 1st MTPJ
• Obturator nerve passes through the obturator foramen.
• Supplies muscles of the thigh adductor compartment, and overlying skin (HJ & KJ).

Blood Supply to the Lower Limb

• External iliac --> femoral artery (enters femoral triangle) --> profunda femoris (medial & lateral circumflex and perforating a.) --> (adductor canal & adductor hiatus) --> popliteal artery --> anterior and posterior tibial arteries --> medial/lateral malleolar branches --> (AJ) dorsalis pedis --> posterior tibial --> medial and lateral plantar arteries.
• Abdominal aorta --> common iliac a. --> External iliac a. --> superior and inferior gluteal a.

Venous Drainage of the Lower Limb

• Superficial: dorsal venous arch --> short saphenous vein --> popliteal fossa —> long saphenous vein --> femoral vein —> external iliac vein—>inferior vena cava
• Deep: two venae comitantes accompanying smaller arteries --> form popliteal vein—> adductor hiatus—> femoral vein
• Connecting these two sets by fascia lata = communicating veins.

Lymphatic Drainage of the Lower Limb

• Follows the general pattern of superficial and deep venous drainage
• Little communication between superficial and deep lymphatics
• Superficial lymph glands are near the inguinal ligament and popliteal fossa.

Summary

• Students have learned about most of the lower extremity, emphasizing the importance of connecting anatomy.
• Practical exercises on family members/friends are recommended to understand anatomical variations.