POSTERIOR
COMPARTMENT
OF LEG
LEARNING OBJECTIVES
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At the end of lecture,students will be able to:
Learn concept of the muscles of posterior compartment of
l eg.
Understand nerve supply of these muscles.
Idea of actions of the muscles of posterior compartment of
l eg.
MUSCLES OF POSTERIOR COMPARTMENT
OF LEG
Superficial layer:
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Gastrocnemius
Soleus
Plantaris
Deep layer:
Popliteus
Flexor digitorum longus
Flexor hallucis longus
Tibialis posterior
Gastrocnemius
Origin:
- medial and lateral condyles of femur.
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Insertion:
- calcaneum via tendo calcaneus
 Action:
- flexes knee joint and plantar flexes foot at ankle joint.
Nerve supply:
- tibial nerve.
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Soleus
Origin:
- soleal line of tibia and upper third of fibula
Insertion:
- calcaneum via tendo calcaneus.
Action:
- flexes knee joint and plantar flexes foot at ankle joint.
Nerve supply:
- tibial nerve.
Plantaris
Origin:
- Lateral supra condylar ridge of femur.
Insertion:
- calcaneum
Action:
- flexes knee joint and plantar flexes foot at ankle joint.
Nerve supply:
- tibial nerve.
POPLITEUS
Origin:
- Lateral surface of lateral condyle of femur.
Insertion:
- Posterior surface of shaft of tibia.
Action:
- Flexes leg at knee joint, unlocks it by lateral rotation of femur.
Nerve supply:
- Tibial nerve.
Flexor digitorum longus
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Origin:
- Posterior surface of shaft of tibia.
Insertion:
- Bases of distal phalenges of lateral four toes.
Action:
-Flexes distal phalenges of lateral four toes.
Nerve supply:
- Tibial nerve.
Flexor hallucis longus
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Origin:
- Posterior surface of shaft of tibia.
Insertion:
- Base of distal phalynx of big toe.
Action:
- Flexes distal phalynx of big toe.
Nerve supply:
- Tibial nerve.
Tibialis posterior
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Origin:
- Posterior surfaces of shaft of tibia and fibula.
Insertion:
- Navicular bone.
Action:
- Plantar flexes foot at ankle joint, inverts foot.
Nerve supply:
- Tibial nerve.
Blood supply of posterior compartment
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Posterior tibial Artery:
- Large terminal branch of popliteal artery.
- Also supplies lateral
foot.
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comptartment of leg & sole of
Course:
- Begins at lower
border of popliteus deep to gastrocnemius.
- Enters back of leg by passing deep to tendinous arch of soleus.
- Terminates deep to flexor retinaculum by dividing into medial &
lateral planter arteries.
Branches of posterior tibial artery:
1.Peroneal artery (largest branch of posterior tibial artery).
2.Muscular branches.
3.Nutrient artery to tibia.
Anastomotic branches:
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Circumflex fibular branch– takes part in anastomsis round the
knee joint.
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Communicating branch- form arch with similar branch from
peroneal artery.
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4.
5.
Malleolar branch- anastomose with arteries over
medial malleolus
Calcaneal branches- anastomose with other arteries in region.
Terminal branches- medial & lateral plantar arteries.
Peroneal Artery
- Largest branch of posterior tibial artery.
- Supplies posterior & lateral compartments of l
Course & relation:
- Starts 2.5cm below the lower border of popliteus.
- Passes behind inferior tibio fibular & ankle joints, medial to peroneal
tendon.
- Terminates by dividing into number of lateral calcanean branches.
Branches of Peroneal artery:
- Muscular branches: posterior & lateral compartments.
- Nutrient artery: fibula.
- Anastomotic branches
- Perforating branch
- Communicating branch
- Calcaneal branch
Tibial Nerve
Course:
- Descends through the popliteal fossa and posterior compartment of
leg.
- Terminates by dividing into medial & lateral plantar nerves.
- Tibial nerve crosses posterior tibial artery from medial to lateral side.
Branches of tibial nerve:
1.Muscular branches:
- Tibialis posterior.
- Flexor digitorum longus.
- Flexor hallucis longus.
- Soleus.
- Popliteus.
- Gastrocnemius.
2.Cutaneous branches:
- Medial calcaneal nerve- supplies skin on back & medial surface of
heel.
- Sural nerve-supplies skin of calf, back of leg, lateral border of foot
and little toe.
3. Articular branches:
Ankle joint
Knee joint
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Medial plantar nerve:
1.Cutaneous branch-supplies medial part of sole, medial three and
half toes, nail beds.
2.Muscular branch- Abductor hallucis
- Flexor digitorum brevis
- Hallucis brevis
- First lumbrical
Lateral plantar nerve:
1.Cutaneous branch: supplies lateral part of sole, lateral one and
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half toes, nail beds.
2.Muscular branch:
- Abductor digiti minimi
- Flexor digiti minimi brevis.
- Adductor hallucis.
- Interosseus.
- Second, Third, Fourth lumbricals.
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