Anatomy of the popliteal fossa, leg and dorsum of the foot

Question 1

Popliteal Fossa

Answer 1

Posterior aspect of the knee. Its boundaries are: semitendinosus, semimembranosus, biceps femoris, gastrocnemius and plantaris. Floor: femur, capsule of knee joint, (popliteus). Roof: Deep fascia.

It conveys vessels and nerves between thigh and leg, posterior to knee (flexor surface). It contains: common fibular (peroneal) n, tibial n, popliteal v, popliteal a (lateral to medial and superficial to deep).

Question 2

Describe the origin of the popliteal artery, and the termination of the popliteal vein.

Answer 2

Adductor hiatus.

Question 3

Anatomical relations of the knee joint

Answer 3

Anteriorly: patella and quadriceps/patellar tendon complex. Posterior: popliteal fossa. Medial: pes anserinus = tendons of sartorius, gracilis, semitendinosus. Lateral: iliotibial tract, tendon of biceps femoris.

Question 4

Organisation of the leg

Answer 4

Three compartments: anterior, lateral, posterior. Posterior further subdivides into superficial and deep.

There are three intermuscular septa: anterior, posterior, transverse dividing the muscle compartments.

There is also an interosseus membrane (fibrous syndesmosis joint) between tibia and fibula. Anteromedially tibia is subcutaneous.

Question 5

What is the deep fascia of the leg called?

Answer 5

Crural fascia.

Question 6

Posterior compartment: superficial group

Answer 6

Muscles: gastrocnemius, soleus (g+s = triceps surae), plantaris. Tendon: calcaneal (Achilles) tendon. Action: plantarflexion at ankle.

Minor actions of these muscles also includes flexion of the leg at the knee.

Test: stand on toes, plantarflex. These muscles are innervated by the tibial nerve. Blood supply: popliteal and posterior tibial vessels.

Question 7

Posterior compartment: deep group

Answer 7

Muscles: flexor digitorum longus (FDL), flexor hallucis longus (FHL, hallux = big toe), tibialis posterior and popliteus. FDL medial, FHL lateral (cross in foot).

These muscles are innervated by the tibial nerve. Blood supply: posterior tibial vessels.

Actions: TP inverts foot; FDL and FHL flex digits 2-5 and 1 respectively. All assist (weak) with plantarflexion.

Question 8

Locking mechanism of the knee joint

Answer 8

At the end of extension the knee joint is locked into position by two mechanisms: 1- change in change and size of articular surfaces of femur and tibia. 2- medial rotation of femur on the tibia during extension.

Question 9

Popliteus muscle

Answer 9

It medially rotates the tibia at knee joint, thereby unlocking knee at beginning of flexion by medial rotation of tibia (equivalently, lateral rotation of femur upon tibia).

Question 10

Tarsal tunnel

Answer 10

Tibial nerve, posterior tibial artery and veins, and tendons of TP, FDL and FHL travel between posterior leg and sole of foot through tarsal tunnel (TDavnH).

Posterior tibial artery pulse point just superior to tunnel.

Roof: flexor retinaculum, between medial malleolus and calcaneus. Nerve entrapment of the ankle is commonly reported at this site.

Question 11

Lateral compartment.

Answer 11

Muscles: fibularis (peroneus) longus, fibularis brevis.
Action: evert foot at ankle, weak plantarflexion. Nerve: superficial fibular (peroneal). Blood: branches from fibular a and anterior tibial a.

Question 12

Anterior compartment

Answer 12

Muscles: tibialis anterior (TA), extensor hallucis longus (EHL), extensor digitorum longus (EDL) and fibularis tertius (FT).

Actions: all dorsiflex foot at ankle, TA inverts, EHL and EDL extend digits. Muscles held into place by the extensor retinacula.

Innervation: Deep fibular nerve; anterior tibial vessels

Question 13

Dorsum of the foot

Answer 13

Tendons from anterior leg compartment muscles travel through it. Deep to them: Extensor digitorum brevis and extensor hallucis brevis muscles.

Deep fibular n – supplies muscles of dorsum of foot

Anterior tibial artery continues as dorsalis pedis artery – palpable lateral to extensor hallucis longus tendon.

Question 14

Inversion of the foot

Answer 14

tibialis anterior, tibialis posterior

Question 15

Eversion of the foot

Answer 15

fibularis longus, brevis, tertius

Question 16

Where does inversion and eversion occur?

Answer 16

These movements occur mainly at subtalar and transverse tarsal joints

Question 17

Arterial supply of the leg

Answer 17

Popliteal artery: Branches to superficial posterior compartment muscles, it terminates by dividing into anterior and posterior tibial arteries. Anterior tibial a – goes through interosseus membrane, supplies anterior and lateral compartments. Posterior tibial a – supplies posterior compartment. Fibular a supplies posterior and lateral compartments. There are also anastomoses around knee and ankle.