BACK OF LEG (FLEXOR COMPARTMENT)
Skin and Superficial fascia
It contains fat, fibrous tissue, cutaneous nerves, small saphenous vein and lymphatics.
Cutaneous nerves :
1) Posterior femoral cutaneous nerve (S1, S2, S3)
Terminal part of posterior femoral cutaneous nerve pierce deep fascia of in middle part of popliteal fossa. It runs downward along with small saphenous vein and supply skin of upper part of back of leg.
2) Saphenous nerve ( L3, L4)
It pierce deep fascia of medial side of knee. It runs along with great saphenous vein. Medial side of back of leg upto great toe supplied by branches of saphenous nerve.
3) Lateral cutaneous nerve of calf ( L4, L5, S1)
It is a branch of common peroneal nerve. It pierce deep fascia of lateral side of leg. Supply skin of lateral side of leg of upper part.
4) Sural nerve (L5, S1, S2)
It is a branch of tibial nerve. It pierce deep fascia of back of leg in middle part. Then runs along with small saphenous vein. Sural communicating nerve joins with it in middle of leg. Supply skin of lower lateral part of back of leg, lateral aspect of dorsum of foot, lateral margin of little toe.
5) Medial calcaneal branch of tibial nerve (S1, S2)
After piercing flexor retinaculum medial calcaneal branch of tibial nerve supply heel (weight bearing area) medial side of sole of foot.
Small saphenous vein
After forming on lateral margin of dorsum of foot it goes up after passing posterior to lateral malleolus. On posterior aspect of popliteal fossa in mid-line pierce deep fascia present over popliteal fossa joins with popliteal vein. Finally it is get connected with great saphenous vein.
Skin and Superficial fascia
It contains fat, fibrous tissue, cutaneous nerves, small saphenous vein and lymphatics.
Cutaneous nerves :
1) Posterior femoral cutaneous nerve (S1, S2, S3)
Terminal part of posterior femoral cutaneous nerve pierce deep fascia of in middle part of popliteal fossa. It runs downward along with small saphenous vein and supply skin of upper part of back of leg.
2) Saphenous nerve ( L3, L4)
It pierce deep fascia of medial side of knee. It runs along with great saphenous vein. Medial side of back of leg upto great toe supplied by branches of saphenous nerve.
3) Lateral cutaneous nerve of calf ( L4, L5, S1)
It is a branch of common peroneal nerve. It pierce deep fascia of lateral side of leg. Supply skin of lateral side of leg of upper part.
4) Sural nerve (L5, S1, S2)
It is a branch of tibial nerve. It pierce deep fascia of back of leg in middle part. Then runs along with small saphenous vein. Sural communicating nerve joins with it in middle of leg. Supply skin of lower lateral part of back of leg, lateral aspect of dorsum of foot, lateral margin of little toe.
5) Medial calcaneal branch of tibial nerve (S1, S2)
After piercing flexor retinaculum medial calcaneal branch of tibial nerve supply heel (weight bearing area) medial side of sole of foot.
Small saphenous vein
After forming on lateral margin of dorsum of foot it goes up after passing posterior to lateral malleolus. On posterior aspect of popliteal fossa in mid-line pierce deep fascia present over popliteal fossa joins with popliteal vein. Finally it is get connected with great saphenous vein.
Deep fascia of leg
Deep shows attachment on anterior margin of tibia up to medial malleolus. Near lower part of leg on posterior to medial malleolus get modified into flexor retinaculum. Shows attachment on medial malleolus and calcaneus.
Posterior compartment of leg again divided into superficial and deep parts by superficial and deep transverse fascial septum. Deep transverse fascial septum shows attachment on medial margin of tibia and posterior margin of fibula. Forming superficial and deep compartment.
Deep shows attachment on anterior margin of tibia up to medial malleolus. Near lower part of leg on posterior to medial malleolus get modified into flexor retinaculum. Shows attachment on medial malleolus and calcaneus.
Posterior compartment of leg again divided into superficial and deep parts by superficial and deep transverse fascial septum. Deep transverse fascial septum shows attachment on medial margin of tibia and posterior margin of fibula. Forming superficial and deep compartment.
Flexor retinaculum
It is modification of deep fascia of leg in relation with medial malleolus.
Attachments: It shows attachment anteriorly and above to posterior margin of medial malleolus up to its tip, below and posteriorly to medial surface of calcaneus near calcaneal tuberosity.
Structures passing deep to it are (medial to lateral side) tibialis posterior tendon, flexor digitorum longus tendon, posterior tibial artery, posterior tibial nerve, flexor hallucis longus tendon.
It is modification of deep fascia of leg in relation with medial malleolus.
Attachments: It shows attachment anteriorly and above to posterior margin of medial malleolus up to its tip, below and posteriorly to medial surface of calcaneus near calcaneal tuberosity.
Structures passing deep to it are (medial to lateral side) tibialis posterior tendon, flexor digitorum longus tendon, posterior tibial artery, posterior tibial nerve, flexor hallucis longus tendon.
Superficial lymphatics
Lymphatics from lateral aspect of foot and lower part of leg on lateral side drains into popliteal group of lymph nodes. Lymphatics runs along with small saphenous vein.
Boundaries
Posterior compartment of leg is bounded by
Anteriorly : Posterior surface of tibia and fibula with interosseous membrane in between.
Posteriorly : Deep fascia of leg between medial margin of tibia and posterior intermuscular septum.
Laterally : Posterior intermuscular septum
Contents
Muscles
Superficial part : gastrocnemius, soleus, plantaris
Deep part : popliteus, flexor digitorum longus, flexor hallucis longus, tibialis posterior
Vessels : posterior tibial and peroneal vessels
Nerve : tibial nerve
Muscles
Gastrocnemius
Origin : It shows origin from two heads medial and lateral. Medial head shows origin from upper part of posterior surface of medial condyle of femur by a flat tendon and from inferomedial part of popliteal of surface of femur. Lateral head shows origin from lateral surface of lateral condyle just above lateral epicondyle of femur and lower part of lateral supracondylar line. Also some fibres shows origin from capsule of knee joint.
Insertion : Below in middle part of leg these two bellies unite to form a aponeurosis. Tendon of soleus muscle joins with it from on deep surface to form tendo-calcaneus (triceps surae). Tendo-calcaneus shows insertion on middle one third part of posterior surface of calcaneus.
Nerve supply : It receives nerve supply from tibial nerve.
Action : Plantar flexion of foot at ankle joint. Flexion of knee joint. Helps in fast movement acts as top gear during running and jumping.
Lymphatics from lateral aspect of foot and lower part of leg on lateral side drains into popliteal group of lymph nodes. Lymphatics runs along with small saphenous vein.
Boundaries
Posterior compartment of leg is bounded by
Anteriorly : Posterior surface of tibia and fibula with interosseous membrane in between.
Posteriorly : Deep fascia of leg between medial margin of tibia and posterior intermuscular septum.
Laterally : Posterior intermuscular septum
Contents
Muscles
Superficial part : gastrocnemius, soleus, plantaris
Deep part : popliteus, flexor digitorum longus, flexor hallucis longus, tibialis posterior
Vessels : posterior tibial and peroneal vessels
Nerve : tibial nerve
Muscles
Gastrocnemius
Origin : It shows origin from two heads medial and lateral. Medial head shows origin from upper part of posterior surface of medial condyle of femur by a flat tendon and from inferomedial part of popliteal of surface of femur. Lateral head shows origin from lateral surface of lateral condyle just above lateral epicondyle of femur and lower part of lateral supracondylar line. Also some fibres shows origin from capsule of knee joint.
Insertion : Below in middle part of leg these two bellies unite to form a aponeurosis. Tendon of soleus muscle joins with it from on deep surface to form tendo-calcaneus (triceps surae). Tendo-calcaneus shows insertion on middle one third part of posterior surface of calcaneus.
Nerve supply : It receives nerve supply from tibial nerve.
Action : Plantar flexion of foot at ankle joint. Flexion of knee joint. Helps in fast movement acts as top gear during running and jumping.
Soleus
It is a multipennate muscle and sole shaped deep to gastrocnemius.
Origin : It shows origin from posterior surface of head of fibula and upper one fourth part of posterior surface of shaft of fibula, soleal line and middle one third part of medial border of tibia and fibrous band present between tibia and fibula.
Insertion : Large belly of muscle below in lower part of leg forms a tendon. Tendon of soleus muscle joins with it on deep surface to form tendo-calcaneus (triceps surae). Tendo-calcaneus shows insertion on middle one third part of posterior surface of calcaneus.
Nerve supply : It receives nerve supply from tibial nerve.
Action : Plantar flexion of foot at ankle joint. It helps to start movement to overcome initial inertia. It acts as bottom gear for strolling.
Plantaris
It is a small muscle between gastrocnemius and soleus.
Origin : It shows origin from lower one third part of lateral supracondylar ridge of femur and oblique popliteal ligament.
Insertion : Belly of muscle lies in relation with lateral head of gastrocnemius. After forming a long tendon it goes downward between gastrocnemius and soleus. Shows insertion on calcaneus medial to insertion of tendo-calcaneus. Sometime may join with medial margin of tendo-calcaneus for insertion on middle one third part of posterior surface of calcaneus.
Nerve supply : It receives nerve supply from tibial nerve.
Action : Plantar flexion of foot at ankle joint. Help in action of gastrocnemius.
It is a multipennate muscle and sole shaped deep to gastrocnemius.
Origin : It shows origin from posterior surface of head of fibula and upper one fourth part of posterior surface of shaft of fibula, soleal line and middle one third part of medial border of tibia and fibrous band present between tibia and fibula.
Insertion : Large belly of muscle below in lower part of leg forms a tendon. Tendon of soleus muscle joins with it on deep surface to form tendo-calcaneus (triceps surae). Tendo-calcaneus shows insertion on middle one third part of posterior surface of calcaneus.
Nerve supply : It receives nerve supply from tibial nerve.
Action : Plantar flexion of foot at ankle joint. It helps to start movement to overcome initial inertia. It acts as bottom gear for strolling.
Plantaris
It is a small muscle between gastrocnemius and soleus.
Origin : It shows origin from lower one third part of lateral supracondylar ridge of femur and oblique popliteal ligament.
Insertion : Belly of muscle lies in relation with lateral head of gastrocnemius. After forming a long tendon it goes downward between gastrocnemius and soleus. Shows insertion on calcaneus medial to insertion of tendo-calcaneus. Sometime may join with medial margin of tendo-calcaneus for insertion on middle one third part of posterior surface of calcaneus.
Nerve supply : It receives nerve supply from tibial nerve.
Action : Plantar flexion of foot at ankle joint. Help in action of gastrocnemius.
Popliteus
It is triangular in shape and present in the floor of popliteal fossa.
Origin : It shows origin inside capsule of knee joint from a groove present on lateral surface of lateral femoral condyle from its anterior part as a tendon. Some fibres from arcuate popliteal ligament and outer margin of lateral meniscus.
Insertion : Below in lower part goes medially and downward after piercing capsule of knee joint forms fleshy part showing its insertion on a triangular area on posterior surface of tibia just above soleal line and popliteal fascia.
Nerve supply : It receives nerve supply from tibial nerve.
Action : It initiates flexion of knee joint and help in unlocking of knee joint. It prevents trapping of lateral meniscus between condyles of femur and tibia by pulling it backward.
It is triangular in shape and present in the floor of popliteal fossa.
Origin : It shows origin inside capsule of knee joint from a groove present on lateral surface of lateral femoral condyle from its anterior part as a tendon. Some fibres from arcuate popliteal ligament and outer margin of lateral meniscus.
Insertion : Below in lower part goes medially and downward after piercing capsule of knee joint forms fleshy part showing its insertion on a triangular area on posterior surface of tibia just above soleal line and popliteal fascia.
Nerve supply : It receives nerve supply from tibial nerve.
Action : It initiates flexion of knee joint and help in unlocking of knee joint. It prevents trapping of lateral meniscus between condyles of femur and tibia by pulling it backward.
Flexor digitorum longus
It is a bipennate muscle.
Origin : It shows origin from upper two third part of posterior surface of tibia below soleal line and from fascia covering tibialis posterior muscle.
Insertion : Below in lower part of leg this muscle forms a tendon. Tendon crosses tendon of tibialis posterior superficial to it from medial to lateral side. Then it goes to sole after passing deep to flexor retinaculum. In sole it passes superficial to tendon of flexor hallucis longus medial to lateral side. Finally it divides into four tendons for lateral four toes. Digital tendons of second, third and forth toes receives attachment of flexor digitorum accessories on its lateral side. It gives attachment to four lumbricals. Finally tendon passes through flexor digitorum brevis and shows insertion on plantar aspect of base of distal phalanx of lateral four toes.
Nerve supply : It receives nerve supply from tibial nerve L5, S1, S2.
Action : Plantar flexion of lateral four toes. Plantar flexion of ankle. It maintains longitudinal arch of foot.
Flexor hallucis longus
It is a bipennate muscle.
Origin : It shows origin from lower two third part of posterior surface shaft of fibula, adjacent part of interosseous membrane, fascia covering tibialis posterior muscle and posterior intermuscular septum.
Insertion : Below in lower part of leg this muscle forms a tendon. Tendon passes deep to flexor retinaculum and between medial and posterior tubercle of talus. Passes below sustentaculum tali. Finally shows attachment on base of distal phalanx of great toe on plantar aspect.
Nerve supply : It receives nerve supply from tibial nerve L5, S1, S2.
Action : Plantar flexion of great toe. Plantar flexion of ankle. It maintains medial longitudinal arch of foot.
It is a bipennate muscle.
Origin : It shows origin from upper two third part of posterior surface of tibia below soleal line and from fascia covering tibialis posterior muscle.
Insertion : Below in lower part of leg this muscle forms a tendon. Tendon crosses tendon of tibialis posterior superficial to it from medial to lateral side. Then it goes to sole after passing deep to flexor retinaculum. In sole it passes superficial to tendon of flexor hallucis longus medial to lateral side. Finally it divides into four tendons for lateral four toes. Digital tendons of second, third and forth toes receives attachment of flexor digitorum accessories on its lateral side. It gives attachment to four lumbricals. Finally tendon passes through flexor digitorum brevis and shows insertion on plantar aspect of base of distal phalanx of lateral four toes.
Nerve supply : It receives nerve supply from tibial nerve L5, S1, S2.
Action : Plantar flexion of lateral four toes. Plantar flexion of ankle. It maintains longitudinal arch of foot.
Flexor hallucis longus
It is a bipennate muscle.
Origin : It shows origin from lower two third part of posterior surface shaft of fibula, adjacent part of interosseous membrane, fascia covering tibialis posterior muscle and posterior intermuscular septum.
Insertion : Below in lower part of leg this muscle forms a tendon. Tendon passes deep to flexor retinaculum and between medial and posterior tubercle of talus. Passes below sustentaculum tali. Finally shows attachment on base of distal phalanx of great toe on plantar aspect.
Nerve supply : It receives nerve supply from tibial nerve L5, S1, S2.
Action : Plantar flexion of great toe. Plantar flexion of ankle. It maintains medial longitudinal arch of foot.
Tibialis posterior
It is a bipennate muscle.
Origin : It shows origin between origin of flexor hallucis longus and flexor digitorum longus deep to these from upper two third part of interosseous membrane, posterior surface of tibia on its lateral part below soleal line, adjacent part of posterior surface of shaft of fibula.
Insertion : Below in lower part of leg this muscle forms a tendon. Tendon passes downward and medially superficial to flexor digitorum longus. Passes below medial malleolus deep to flexor retinaculum. It shows insertion on tuberosity of navicular bone also shows insertion on all tarsal bones and base of second to fourth metatarsal bones by slips except talus, base of first and fifth metatarsal bones.
Nerve supply : It receives nerve supply from tibial nerve L4, L5.
Action : Inversion of foot. Adduction of foot. Plantar flexion of foot. Support medial longitudinal arch.
It is a bipennate muscle.
Origin : It shows origin between origin of flexor hallucis longus and flexor digitorum longus deep to these from upper two third part of interosseous membrane, posterior surface of tibia on its lateral part below soleal line, adjacent part of posterior surface of shaft of fibula.
Insertion : Below in lower part of leg this muscle forms a tendon. Tendon passes downward and medially superficial to flexor digitorum longus. Passes below medial malleolus deep to flexor retinaculum. It shows insertion on tuberosity of navicular bone also shows insertion on all tarsal bones and base of second to fourth metatarsal bones by slips except talus, base of first and fifth metatarsal bones.
Nerve supply : It receives nerve supply from tibial nerve L4, L5.
Action : Inversion of foot. Adduction of foot. Plantar flexion of foot. Support medial longitudinal arch.
Vessels
Posterior tibial artery
It is a branch of popliteal artery arises near lower border of popliteus muscle in back of leg. Artery goes to posterior compartment by passing deep to gastrocnemius enters and passing deep to tendinous arch of soleus. It goes downward and slightly medially between medial malleolus and medial tubercle of calcaneus then goes deep to reach flexor retinaculum. Deep to flexor retinaculum divides into medial and lateral plantar artery. It is accompanied by two venae comitantes.
Artery runs over the surface of tibialis anterior, flexor digitorum longus, tibia, ankle joint anteriorly from above downwards. Covered by gastrocnemius, soleus, deep transverse fascia, skin and fascia posteriorly from above downwards.
Branches
1) Circumflex fibular : It encircles the neck of fibula. It anastomose with anterior tibial recurrent artery, inferior lateral genicular artery and medial genicular artery.
2) Nutrient : It is largest nutrient artery for tibia.
3) Muscular : To adjacent muscles in flexor compartment of leg.
4) Communicating : Communicating branch of posterior tibial artery joins with communicating branch of peroneal artery just five centimetre above ankle.
5) Medial malleolar : It goes medially towards medial malleolus to join with medial malleolar network.
7) Calcaneal : It pierce flexor retinaculum and supply skin and fatty tissue of heel. It also gives small branches to medial malleolar network and calcaneal branches to peroneal artery.
8) Medial plantar : It is smaller terminal branch of posterior tibial artery.
9) Lateral plantar : It is larger terminal branch of posterior tibial artery.
10) Peroneal artery : It arises 2.5 centimetre distal to popliteus. It goes downward in relation with medial crest of fibula between tibialis posterior and flexor hallucis longus muscle. In relation with inferior tibiofibular joint gives calcaneal branch.
Branches of peroneal artery :
1) Nutrient artery : It gives a nutrient artery to fibula.
2) Muscular artery : Muscular branch supply muscles of posterior and lateral compartment of leg.
3) Communicating branch : Communicating branch joins with communicating branch from posterior tibial artery five centimetre above ankle joint.
4) Perforating branch : Perforating branch pierce interosseous membrane in lower part of leg in front of inferior tibiofibular joint goes to extensor compartment and joins with anterior lateral malleolar artery and lateral tarsal branch of dorsalis pedis artery forming lateral malleolar network.
5) Calcaneal artery : Lateral calcaneal branch anastomose with anterior lateral malleolar and calcaneal branches of posterior tibial artery forming lateral malleolar network.
Nerve :
Tibial nerve (l4, L5, S1, S2, S3)
It is larger branch of sciatic nerve. It is derived from ventral branches of fourth, fifth lumbar and first to third sacral ventral rami. Tibial nerve arises as a branch of sciatic nerve on the back of thigh at the junction of upper two third part and lower one third part. It goes down on back of thigh to reach lower margin of popliteus muscle. Then goes to posterior compartment of leg by passing deep to gastrocnemius enters and passing deep to tendinous arch of soleus with popliteal artery. It lies medial to posterior tibial artery in upper part then it crosses posterior tibial superficial to it and lies lateral to it in lower part of leg. Deep to flexor retinaculum divides into medial and lateral plantar nerves.
Branches :
1) Muscular : Supply gastrocnemius, soleus, plantaris and popliteus by its proximal branch. Muscular branches in leg supply soleus, tibialis posterior, flexor digitorum longus and flexor hallucis longus.
2) Articular : Articular branch supply knee joint along with superior and inferior medial genicular arteries and middle genicular artery. In lower part it gives an articular branch to ankle joint.
3) Cutaneous : Medial calcaneal branch pierce flexor retinaculum and supply skin of back and lower part of heel.
4) Sural nerve : It goes downward between two heads of gastrocnemius. After piercing deep fascia of leg joins with sural communicating nerve a branch of common peroneal nerve.
Supply posterior and lateral part of skin in lower one third of leg. Then it goes to distal to lateral malleolus and supply lateral side of foot and little toe.
Posterior tibial artery
It is a branch of popliteal artery arises near lower border of popliteus muscle in back of leg. Artery goes to posterior compartment by passing deep to gastrocnemius enters and passing deep to tendinous arch of soleus. It goes downward and slightly medially between medial malleolus and medial tubercle of calcaneus then goes deep to reach flexor retinaculum. Deep to flexor retinaculum divides into medial and lateral plantar artery. It is accompanied by two venae comitantes.
Artery runs over the surface of tibialis anterior, flexor digitorum longus, tibia, ankle joint anteriorly from above downwards. Covered by gastrocnemius, soleus, deep transverse fascia, skin and fascia posteriorly from above downwards.
Branches
1) Circumflex fibular : It encircles the neck of fibula. It anastomose with anterior tibial recurrent artery, inferior lateral genicular artery and medial genicular artery.
2) Nutrient : It is largest nutrient artery for tibia.
3) Muscular : To adjacent muscles in flexor compartment of leg.
4) Communicating : Communicating branch of posterior tibial artery joins with communicating branch of peroneal artery just five centimetre above ankle.
5) Medial malleolar : It goes medially towards medial malleolus to join with medial malleolar network.
7) Calcaneal : It pierce flexor retinaculum and supply skin and fatty tissue of heel. It also gives small branches to medial malleolar network and calcaneal branches to peroneal artery.
8) Medial plantar : It is smaller terminal branch of posterior tibial artery.
9) Lateral plantar : It is larger terminal branch of posterior tibial artery.
10) Peroneal artery : It arises 2.5 centimetre distal to popliteus. It goes downward in relation with medial crest of fibula between tibialis posterior and flexor hallucis longus muscle. In relation with inferior tibiofibular joint gives calcaneal branch.
Branches of peroneal artery :
1) Nutrient artery : It gives a nutrient artery to fibula.
2) Muscular artery : Muscular branch supply muscles of posterior and lateral compartment of leg.
3) Communicating branch : Communicating branch joins with communicating branch from posterior tibial artery five centimetre above ankle joint.
4) Perforating branch : Perforating branch pierce interosseous membrane in lower part of leg in front of inferior tibiofibular joint goes to extensor compartment and joins with anterior lateral malleolar artery and lateral tarsal branch of dorsalis pedis artery forming lateral malleolar network.
5) Calcaneal artery : Lateral calcaneal branch anastomose with anterior lateral malleolar and calcaneal branches of posterior tibial artery forming lateral malleolar network.
Nerve :
Tibial nerve (l4, L5, S1, S2, S3)
It is larger branch of sciatic nerve. It is derived from ventral branches of fourth, fifth lumbar and first to third sacral ventral rami. Tibial nerve arises as a branch of sciatic nerve on the back of thigh at the junction of upper two third part and lower one third part. It goes down on back of thigh to reach lower margin of popliteus muscle. Then goes to posterior compartment of leg by passing deep to gastrocnemius enters and passing deep to tendinous arch of soleus with popliteal artery. It lies medial to posterior tibial artery in upper part then it crosses posterior tibial superficial to it and lies lateral to it in lower part of leg. Deep to flexor retinaculum divides into medial and lateral plantar nerves.
Branches :
1) Muscular : Supply gastrocnemius, soleus, plantaris and popliteus by its proximal branch. Muscular branches in leg supply soleus, tibialis posterior, flexor digitorum longus and flexor hallucis longus.
2) Articular : Articular branch supply knee joint along with superior and inferior medial genicular arteries and middle genicular artery. In lower part it gives an articular branch to ankle joint.
3) Cutaneous : Medial calcaneal branch pierce flexor retinaculum and supply skin of back and lower part of heel.
4) Sural nerve : It goes downward between two heads of gastrocnemius. After piercing deep fascia of leg joins with sural communicating nerve a branch of common peroneal nerve.
Supply posterior and lateral part of skin in lower one third of leg. Then it goes to distal to lateral malleolus and supply lateral side of foot and little toe.