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AAAD01 21/5/05 10:59 AM Page 166
Nerve supply: Sciatic nerve (tibial component).
properties.
• Semimembranosus
• Popliteus
Origin: From the ischial tuberosity.
Origin: From the back of the tibia above the soleal line.
Insertion: To a groove on the tibial medial condyle. A detached piece of the lateral head of gastrocnemius with similar
Actions: Extension of the hip and flexion of the knee. Insertion: To the lateral condyle of the femur.
Nerve supply: Sciatic nerve (tibial component). Actions: Flexion and medial rotation of the leg (thus ‘unlocking’ the
• Tibialis anterior extended knee joint).
Origin: From the lateral surface of the tibia. Nerve supply: Tibial nerve.
Insertion: To the base of the 1st metatarsal and the medial cuneiform. • Tibialis posterior
Actions: Dorsiflexion and inversion of the foot. Origin: From the back of the tibia and fibula.
Nerve supply: Deep peroneal nerve. Insertion: To the tuberosity of the navicular and other tarsal bones.
• Extensor hallucis longus Actions: Plantar flexion and inversion of the foot.
Origin: From the middle third of the shaft of the fibula. Nerve supply: Tibial nerve.
Insertion: To the base of the distal phalanx of the big toe. • Flexor hallucis longus
Actions: Extension of the big toe and dorsiflexion of the foot. Origin: From the back of the fibula.
Nerve supply: Deep peroneal nerve. Insertion: To the base of the distal phalanx of the big toe.
• Extensor digitorum longus Action: Flexion of the big toe.
Origin: From the shaft of the fibula. Nerve supply: Tibial nerve.
Insertion: To the bases of the middle and distal phalanges of the four • Flexor digitorum longus
lateral toes via the dorsal extensor expansions. Origin: From the back of the tibia.
Actions: Extension of the toes and dorsiflexion of the foot. Insertion: To the bases of the distal phalanges of the four lateral toes via
Nerve supply: Deep peroneal nerve. the openings in the tendons of flexor digitorum brevis.
• Peroneus tertius Action: Flexion of the toes.
Origin: Formed by the lower part of extensor digitorum longus. Nerve supply: Tibial nerve.
Insertion: Into the base of the 5th metatarsal. • Abductor hallucis
Action: Dorsiflexion of the foot. Origin: From the calcaneal tuberosity.
Nerve supply: Deep peroneal nerve. Insertion: To the medial side of the proximal phalanx of the big toe.
• Extensor digitorum brevis Action: Abduction of the big toe.
Origin: From the upper surface of the calcaneus. Nerve supply: Medial plantar nerve.
Insertion: To the proximal phalanx of the big toe and to the extensor • Flexor digitorum brevis
digitorum longus tendons of the next three toes. Origin: From the calcaneal tuberosity.
Actions: Dorsiflexion of the foot and extension of the toes. Insertion: To the sides of the middle phalanges of the lateral four toes,
Nerve supply: Deep peroneal nerve. its tendons being perforated by those of flexor digitorum longus.
• Peroneus longus Action: Flexion of the toes.
Origin: From the upper two-thirds of the lateral surface of the shaft of Nerve supply: Medial plantar nerve.
the fibula. • Abductor digiti minimi
Insertion: To the base of the 1st metatarsal and the medial cuneiform, Origin: From the calcaneal tuberosity.
via the groove on the cuboid. Insertion: To the proximal phalanx of the little toe.
Action: Eversion of the foot. Actions: Flexion and abduction of the little toe.
Nerve supply: Superficial peroneal nerve. Nerve supply: Lateral plantar nerve.
• Peroneus brevis • Lumbricals
Origin: From the lower two-thirds of the shaft of the fibula. Origin: From the tendons of flexor digitorum longus.
Insertion: To the base of the 5th metatarsal. Insertion: To the dorsal extensor expansions.
Action: Eversion of the foot. Actions: Assist the actions of the interossei.
Nerve supply: Superficial peroneal nerve. Nerve supply: First lumbrical by the medial and the others by the lateral
• Gastrocnemius plantar nerves.
Origin: From the femur just above both femoral condyles. • Flexor digitorum accessorius
Insertion: To the middle third of the back of the calcaneus via the tendo Origin: From the undersurface of the calcaneus.
calcaneus. Insertion: Into the side of the tendon of flexor digitorum longus.
Actions: Plantar flexion of the foot; weak flexion of the knee. Action: Tenses the tendon of this muscle.
Nerve supply: Tibial nerve. Nerve supply: Lateral plantar nerve.
• Soleus • Flexor hallucis brevis
Origin: From the soleal line of the tibia and the upper part of the back of Origin: From the underside of the cuboid.
the fibula. Insertion: To the sides of the proximal phalanx of the big toe with a
Insertion: To the middle third of the back of the calcaneus via the tendo sesamoid bone in each tendon.
calcaneus in common with the gastrocnemius. Action: Flexion of the proximal phalanx of the big toe.
Actions:Plantar flexion of the foot. Is the main factor in the ‘muscle pump’. Nerve supply: Medial plantar nerve.
Nerve supply: Tibial nerve. • Adductor hallucis
• Plantaris Origin: From the heads and from the bases of the metatarsals.
166 Muscle index