Popliteal fossa and leg

• Patella


  Large sesamoid bone formed in the tendon of the quadriceps femoris after birth, located anterior to the mid-condylar region of the femur, articulates with the patellar surface of the femur

  
• Patella


  • Apex (non-articular tip pointing distally)
  • Base (non-articular proximal end)
  • Articular surface (posterior smooth surface covered with articular cartilage, divided into medial and lateral articular facets by a vertical ridge)
  • Lateral articular facet (larger part of the articular surface)
  • Medial articular facet (smaller than the lateral articular facet)
  • Vertical ridge and balanced pull of vastus muscles keep patella centred in intercondylar groove of femur

  
• Tibia


  Articulates with condyles of femur superiorly and talus inferiorly, connected to fibula by dense interosseous membrane, located on anteromedial side of leg nearly parallel to fibula

  
• Tibia


  • Superior articular surface (tibial plateau, divided into 2 articular sections for each femoral condyle)
  • Medial condyle
  • Lateral condyle (smaller and rounder than medial)
  • Intercondylar eminence (raised area between articular facets)
  • Medial and lateral intercondylar tubercles (form intercondylar eminence)
  • Anterior and posterior intercondylar areas (non-articular)
  • Superior fibular articular facet
  • Tibial tuberosity (rugose area, patellar ligament and quadriceps femoris insert here)
  • Soleal (popliteal) line
  • Medial malleolus (projection on medial side, forms subcutaneous medial knob at ankle)
  • Fibular notch (triangular non-articular area for tibiofibular ligament)
  • Distal fibular articular surface

  
• Fibula


  Lies lateral to tibia, articulates twice with tibia and once with talus, functions as attachment for muscles and stabilises ankle joint

  
• Fibula


  • Fibular head (swollen proximal end)
  • Apex (most proximal projection)
  • Neck (extends from shaft and flares proximally to meet head)
  • Proximal fibular articular surface (round, flat, medial surface corresponding to tibia)
  • Shaft (long, thin segment divided into 3 surfaces by 3 borders)
  • Lateral malleolus (inferiormost projection, lateral surface is subcutaneous and forms lateral knob of ankle)

  
• Tarsal bones


  • Talus
  • Calcaneus
  • Cuboid
  • Navicular
  • 3 Cuneiforms (medial, intermediate, lateral)

  
• Talus


  • Head (rounded, convex surface that articulates with navicular)
  • Neck (connects head to body)
  • Body (squarish bulk posterior to neck)
  • Trochlea (saddle-shaped articular surface of body, sides are lateral and medial malleolar surfaces)

  
• Calcaneus


  • Anterior 2/3 of superior surface articulates with talus
  • Anterior surface articulates with cuboid
  • Calcaneal tuberosity (large, blunt, non-articular posterior process, insertion point of Achilles tendon)
  • Fibular trochlea (oblique ridge on lateral surface)
  • Sustentaculum tali (shelf on medial side that supports talar head)

  
• Metatarsus


  • Consists of 5 metatarsals numbered from medial side
  • 1st metatarsal is shorter and stouter than others
  • 2nd is the longest
  • Each has base, shaft, and head
  • Bases are larger and articulate with cuneiform and cuboid bones
  • Heads articulate with proximal phalanges
  • Medial and lateral sesamoid bones on plantar surface of 1st metatarsal head

  
• Phalanges


  • 14 in total
  • 1st digit (great toe) has 2 phalanges (proximal and distal)
  • Other 4 digits have 3 phalanges each (proximal, middle, distal)
  • Each phalanx has base, shaft, and head
  • Phalanges of 1st digit are short, broad, and strong
• Popliteal fossa


  Space behind the knee joint

  
• Popliteal fossa boundaries


  • Superficial: superolateral (biceps femoris), superomedial (semimembranosus, semitendinosus), inferior (lateral and medial heads of gastrocnemius), posterior (skin and popliteal fascia)
  • Deep: superior (diverging medial and lateral supracondylar lines of femur), inferior (soleal line of tibia), anterior (popliteal surface of femur, posterior aspect of knee joint capsule, popliteus muscle and fascia)

  
• Contents of popliteal fossa

  • Termination of small saphenous vein
  • Popliteal arteries and branches, popliteal veins and tributaries
  • Tibial and common fibular nerves
  • Posterior cutaneous nerve of thigh
  • Popliteal lymph nodes and lymphatic vessels

  
• Popliteal fascia


  • Strong sheet of deep fascia, continuous superiorly with fascia lata and inferiorly with deep fascia of leg, serves as a retinaculum for hamstring muscles
• Neurovascular structures in popliteal fossa

  • Nerves are more superficial than veins, arteries are deepest
  • Arteries lie directly on floor of fossa

  
• Nerves in popliteal fossa

  • Tibial nerve (medial, larger terminal branch of sciatic nerve, most superficial of 3 main components)
  • Common fibular nerve (lateral, smaller terminal branch of sciatic nerve, begins at superior angle, follows medial border of biceps femoris and tendon, leaves fossa passing superficial to lateral head of gastrocnemius)
  • Posterior cutaneous nerve of thigh (most inferior branches supply skin over fossa)

  
• Arteries in popliteal fossa

  • Popliteal artery (continuation of femoral artery, begins at adductor hiatus, ends at inferior border of popliteus)
  • 5 genicular branches of popliteal artery supply capsule and ligaments of knee joint, participate in genicular anastomosis

  
• Veins in popliteal fossa

  • Popliteal vein (continuation of posterior tibial vein, begins at distal border of popliteus, becomes femoral vein at adductor hiatus)
  • Small saphenous vein (passes from posterior aspect of lateral malleolus to popliteal fossa, pierces deep popliteal fascia to enter popliteal vein)

  
• Lymph nodes in popliteal fossa

  • Superficial popliteal nodes in subcutaneous tissue
  • Deep popliteal nodes surrounding vessels, receive lymph from knee joint capsule and leg lymph vessels, drain to deep inguinal nodes

  
• Nerves of the leg

  • Femoral nerve (descends with femoral vessels, saphenous nerve branch supplies skin on medial ankle and foot)
  • Sciatic nerve (sural nerve branch descends between heads of gastrocnemius, becomes superficial at middle of leg, supplies skin on posterior and lateral leg, lateral foot)
  • Tibial nerve (forms as sciatic bifurcates, descends through popliteal fossa and on popliteus, runs inferiorly)
  • Common fibular nerve (forms as sciatic bifurcates, begins at superior angle of popliteal fossa, follows medial border of biceps femoris, leaves fossa passing superficial to lateral head of gastrocnemius, winds around neck of fibula and divides into terminal branches)

  
• Lymph nodes


  • Superficial popliteal nodes are in the subcutaneous tissue
  • Deep popliteal nodes surround the vessels
  • Receive lymph from the joint capsule of the knee and the lymph vessels of the leg
  • Drain to deep inguinal nodes

  
• Nerves of the Leg

  1. Femoral nerve descends with femoral vessels through femoral triangle & adductor canal, then descends with great saphenous vein

  2. Sciatic nerve arises from branches of both tibial and common fibular nerves, descends between heads of gastrocnemius, becomes superficial at middle of leg, descends with small saphenous vein

  3. Tibial nerve forms as sciatic bifurcates at apex of popliteal fossa, descends through popliteal fossa and lies on popliteus, runs inferiorly on tibialis posterior with posterior tibial vessels, divides beneath flexor retinaculum into medial and lateral plantar nerves

  4. Common fibular nerve forms as sciatic bifurcates at apex of popliteal fossa, follows medial border of biceps femoris and its tendon, passes over posterior aspect of head of fibula, winds around neck of fibula deep to fibularis longus, divides into deep and superficial fibular nerves

  
• Nerves of the Leg

  • Femoral
  • Sciatic
  • Tibial
  • Common fibular
  • Superficial fibular
  • Deep fibular

  
• Arteries of the Leg

  1. Popliteal artery passes through popliteal fossa to leg, ends at lower border of popliteus muscle, divides into anterior and posterior tibial arteries

  2. Anterior tibial artery passes between tibia and fibula into anterior compartment through gap in superior part of interosseous membrane, descends between tibialis anterior and extensor digitorum longus

  3. Dorsalis pedis artery is continuation of anterior tibial artery distal to inferior extensor retinaculum, descends anteromedially to first interosseous space, divides into plantar and arcuate arteries

  4. Posterior tibial artery passes through posterior compartment of leg, divides distal to flexor retinaculum into medial and lateral plantar arteries

  5. Fibular artery descends in posterior compartment adjacent to post. intermuscular septum

  
• Arteries of the Leg

  • Popliteal
  • Anterior tibial
  • Dorsalis pedis
  • Posterior tibial
  • Fibular

  
• Posterior Compartment of the Leg

  • Plantarflexor compartment and the largest of the 3 leg compartments
  • Muscles in this compartment are divided into superficial and deep sub-compartments by a transverse intermuscular septum that ends at the tip of the medial malleolus and the calcaneus to form the flexor retinaculum

  
• Superficial Muscles of Posterior Compartment

  • Gastrocnemius
  • Soleus
  • Plantaris
• Deep Muscles of Posterior Compartment

  • Popliteus
  • Flexor hallucis longus
  • Flexor digitorum longus
  • Tibialis posterior
• Gastrocnemius and soleus


  • Form the triceps surae and share a common tendon- calcaneal tendon
  • Thickest and strongest tendon in the body
  • Gastrocnemius and soleus can act alone: "you stroll with the soleus but win the long jump with the gastrocnemius"
• Bursa of Posterior Compartment


  • Subcutaneous calcaneal bursa is between the skin and calcaneal tendon
  • Deep bursa of calcaneal tendon is between the tendon and calcaneus
  • Popliteus bursa lies deep to the popliteus tendon

  
• Soleus


  • Tendinous arch between the bony attachments

  
• Tibial Nerve


  • Nerve of the posterior leg compartment
  • Larger of the 2 terminal branches of the sciatic nerve
  • Runs vertically through the popliteal fossa passing between the heads of gastrocnemius
  • Exits the fossa by passing deep to the tendinous arch of soleus
  • At the ankle lies between the tendons of flexor hallucis longus and flexor digitorum longus, posteroinferior to medial malleolus, divides into medial and lateral plantar nerves
  • The sural nerve is formed by medial sural cutaneous nerve of tibial n. and sural communicating branch of the common fibular n.

  
• Posterior Tibial Artery


  • Larger terminal branch of popliteal a.
  • Gives rise to fibular a. which runs parallel to it
  • Deep to the flexor retinaculum, it divides into medial and lateral plantar aa.

  
• Circumflex Fibular Artery


  • Arises from the anterior or posterior tibial a. at the knee
  • Passes laterally over the neck of the fibula to the anastomoses around the knee

  
• Anterior Compartment of the Leg

  • Dorsiflexor/extensor compartment located anterior to the interosseous membrane
  • Between the lateral surface of tibia and medial surface of the fibula
  • Bound anteriorly by the deep fascia of the leg and skin

  
• Fascia of Anterior Compartment


  • The deep fascia overlying the anterior compartment is dense superiorly
  • Inferiorly, 2 retinacula bind the tendons of the anterior compartment muscles before and after they cross the ankle joint - superior extensor retinaculum and inferior extensor retinaculum

  
• Muscles of Anterior Compartment

  • Tibialis anterior
  • Extensor digitorum longus
  • Extensor hallucis longus
  • Fibularis tertius
• Deep Fibular Nerve


  • Nerve of the anterior leg compartment
  • One of the 2 terminal branches of the common fibular n.
  • Arises between fibularis longus and the neck of the fibula
  • Accompanies the anterior tibial artery proximally between tibialis anterior and extensor digitorum longus, and distally between tibialis anterior and extensor hallucis longus
  • Exits the compartment across the ankle joint into the foot
  • Lesion results in inability to dorsiflex the ankle- foot drop

  
• Lateral Compartment of the Leg

  • Evertor compartment and smallest compartment in the leg
  • Bound by the lateral surface of the fibula, anterior and posterior intermuscular septa, and deep fascia of the leg
  • Ends inferiorly at the superior fibular retinaculum