Regio cruris - Leg o between knee & ankle joint

o includes most of tibia & fibula Distally, structures pass between the leg & foot mainly through tarsal tunnel on the posteromedial side of the ankle, Except anterior tibial artery & ends of the deep and superficial fibular nerves

Deep fascia of the leg Crural fascia Two intermuscular septa pass, together with the interosseous membrane, divide the leg into 3 compartments Anterior compartment Lateral compartment Posterior compartment

Inferiorly, two band-like thickenings of the fascia form retinacula that bind the tendons of the anterior compartment muscles, preventing them from bowstringing anteriorly during dorsiflexion of the joint: Superior extensor retinaculum Inferior extensor retinaculum

Flexor Retinaculum Between medial malleolus & calcaneus Binds posterior leg’s deep muscles’ tendons to medial malleolus Superior Peroneal Retinaculum Connects the lateral malleolus to calcaneus Binds the tendons of peroneus longus & brevis to lateral malleolus Inferior Peroneal Retinaculum Binds the tendons of the peroneus longus and brevis muscles to calcaneus

Dorsiflexor (extensor) compartment Located anterior to the interosseous membrane between the lateral surface of the shaft of tibia and medial surface of shaft of the fibula anterior to the intermuscular septum that connects them. Bounded anteriorly by the deep fascia of the leg and skin.

Tibialis anterior Extensor hallucis longus Extensor digitorum longus Fibularis tertius

Lateral condyle of tibia

Superior ¾ of medial surface of

fibula and interosseous membrane

Middle and distal phalanges of lateral 4 digits

Extends lateral four digits and dorsiflexes ankle

Lateral condyle of tibia

Superior half of lateral surface of

tibia and interosseous membrane

Medial cuneiform Base of 1st metatarsal

Dorsiflexes ankle

Inverts foot

Middle part of anterior surface of

fibula and interosseous membrane

Dorsal aspect of base of distal phalanx of great toe (hallux)

Tibialis anterior Dorsiflexes the foot at the ankle joint and inverts the foot at the intertarsal joints. During walking, provides dynamic support for the medial arch of the foot. Extensor hallucis longus Extends lateral four digits and dorsiflexes ankle Extensor digitorum longus Extends great toe and dorsiflexes ankle Fibularis tertius Dorsiflexes ankle and aids in eversion of foot

Passes forward into the anterior compartment of leg through an aperture in the interosseous membrane. Begins at the inferior border of the popliteus muscle @ ankle joint midway between the malleoli Name change dorsalis pedis artery (dorsal artery of the foot).

Distally, gives rise to anterior medial malleolar artery anterior lateral malleolar artery pass posteriorly around the distal ends of the tibia and fibula, respectively.

Deep fibular (peroneal nerve)

anterior tibial artery

innervates all muscles in the anterior compartment; [continues into the dorsal aspect of the foot] innervates the extensor digitorum brevis, first two dorsal interossei muscles, and supplies the skin between the great and second toes.

Fibularis longus

Fibularis brevis

Head and superior 2/3 of lateral surface of fibula

Base of 1st metatarsal and medial cuneiform

Inferior 2/3 of lateral surface of fibula

Dorsal surface of tuberosity on lateral side of base of 5th metatarsal

Everts foot and weakly plantarflexes ankle

Neurological Examination

Superficial fibular (peroneal) nerve

Fibularis longus & fibularis brevis Skin on the distal part of the anterior surface of the leg and dorsal areas of the foot and toes except for: the web space between the great and second toes

Gastrocnemius

Soleus

Plantaris

Lateral aspect of lateral condyle of femur

Posterior surface of calcaneus via calcaneal tendon

Popliteal surface of femur superior to medial condyle

Posterior aspect of head and superior ¼ of posterior surface of fibula Soleal line and middle 1/3 of medial border of tibia Tendinous arch extending between the bony attachments

Posterior surface of calcaneus via calcaneal tendon

Inferior end of lateral supracondylar line of femur Oblique popliteal ligament

Posterior surface of calcaneus via calcaneal tendon

Popliteus

Flexor digitorum longus

Flexor hallucis longus

Tibialis posterior

Lateral surface of lateral condyle of femur Lateral meniscus

Posterior surface of tibia Superior to soleal line

Medial part of posterior surface of tibia inferior to soleal line

by a broad tendon to fibula

Bases of distal phalanges of lateral four digits

Inferior 2/3 of posterior surface of fibula Inferior part of interosseous membrane

Base of distal phalanx of great toe (hallux)

Interosseous membrane Posterior surface of tibia inferior to soleal line

Posterior surface of fibula

Tuberosity of navicular Cuneiform, cuboid, and sustentaculum tali of calcaneus Bases of 2nd, 3rd, and 4th metatarsals

Plantarflexes ankle when knee is extended

Plantarflexes ankle independent of position of knee

Plantaris Weakly assists gastrocnemius in plantarflexing ankle Tibialis posterior Plantarflexes ankle Fibularis longus- Fibularis brevis Weakly plantarflexes ankle

Gastrocnemius: Plantarflexes ankle when knee is extended; raises heel during walking; flexes leg at knee joint Soleus: Plantarflexes ankle independent of position of knee; steadies leg on foot

Popliteus acts on the knee joint Unlocking the extended knee @ the initation of flexion Others plantarflex the ankle with two continuing on to flex the toes. Tibialis posterior: Plantarflexes ankle; inverts foot

Popliteal artery Major blood supply to the leg and foot Passes into the posterior compartment of leg between the gastrocnemius and popliteus muscles. under the tendinous arch formed between the fibular and tibial heads of the soleus muscle @ posterior compartment of leg divides into anterior tibial artery & posterior tibial artery

Posterior tibial artery two major branches, the circumflex fibular artery and fibular artery: Nutrient artery of tibia Largest nutrient artery in the body Arises from the origin of the anterior or posterior tibial artery.

Tibial nerve

Passes o under the tendinous arch formed

between fibular and tibial heads of the soleus muscle

o vertically through the deep region of the posterior compartment of leg on the surface of tibialis posterior muscle with the posterior tibial vessels.

Tibial nerve

Leaves the posterior compartment of leg at the ankle via tarsal tunnel behind the medial malleolus. Enters the foot to supply most intrinsic muscles and skin.

Tibial nerve

In the leg, gives rise to: • branches that supply all the muscles in the posterior compartment of leg • 2 cutaneous branches sural nerve & medial calcaneal nerve