Muscles of the lower leg

Question 1

Answer 1

Tibialis Anterior

• O: anterior proximal tibia, crural fascia (lateral tibial condyle and proximal 2/3 of the anterolateral surface of tibia, interosseous membrane)
• I: medial cuneiform bone, bas of the first metatarsal bone (medial plantar surfaces)
• A: dorsiflexes the ankle joint, and inversion of the ankle
• N: Deep peroneal (fibular) nerve L4-S1

Question 2

Answer 2

Extensor digitorum longus

• O: lateral condyle of tibia, proximal 2/3 of Fibula, interosseous membrane
• I: dorsal surface of digits 2-5 (via dorsal expansion)
• A: extension of digits 2-5 (@ MTP & IP joints); dorsiflexion & eversion of foot at ankle
• N: deep peroneal (fibular) nerve L4, L5, S1

Question 3

Answer 3

Extensor Hallucis Longus

• O: anterior middle 1/3 of fibula, interosseous membrane
• I: base of the distal phalanx of the great toe
• A: extension of big toe @ MTP IP joints, dorsiflexion and eversion of foot
• N: deep peroneal nerve L4, L5, S1

Question 4

Answer 4

Fibularis Terius

• O: distal 1/3 of anterior fibula
• I: base of 5th metatarsal (dorsal surface)
• A: dorsiflexion and eversion of foot
• N: deep peroneal nerve L5, S1

Question 5

Answer 5

Fibularis Longus

• O: head & proximal lateral shaft of fibula
• I: medial cuneiform & base of 1st metatarsal (plantar surface)
• A: eversion and plantar flexion of foot
• N: superficial peroneal nerve L5, S1

Question 6

Answer 6

Fibularis Brevis

• O: distal 1/2 of lateral surface of fibula
• I: base of the 5th metatarsal bone (styloid process)
• A: eversion and plantar flexion of foot
• N: superficial peroneal nerve L5, S1

Question 7

Answer 7

Gastrocnemius

• O: Medial head: medial condyle of femur (posterior surface)
  
  • Lateral head: lateral condyle of femur (posterior surface)
• I: posterior calcaneus via achilles tendon
• A: plantarflexion of foot; knee flexion & inversion of foot
• N: Tibial nerve S1, S2

Question 8

Answer 8

Soleus

• O: soleal line of tibia, head of fibula, posterior proximal fibula
• I: calcaneus via achilles tendon
• A: plantar flexion of the foot, inversion of foot
• N: tibial nerve S1, S2

Question 9

Answer 9

Plantaris

• O: distal posteriolateral femur ( above head of gastroc)
• I: calcaneus via achilles tendon
• A: plantar flexion of foot, very weak flexion of knee
• N: tibial nerve S1, S2

Question 10

Answer 10

Popliteus

• O: distal posterior lateral femur
• I: proximal posterior tibia, medial side above soleal line
• A: unlocks knee from extended position, lateral rotation of femur on tiba or medial rotation of tibia on femur & flexion of the knee
• N: tibial nerve L4, L5, S1

Question 11

Answer 11

Tibialis posterior

• O: posterior proximal 2/3 of tibia, fibula & interosseous membrane
• I: fans out over plantar surface of foot ( navicular, all cuneiforms, 2-4 metatarsals, cuboid & calcaneus)
• A: plantar flexion & inversion of foot
• N: tibial nerve L4, L5, S1

Question 12

Answer 12

flexor digitorum longus

• O: posterior middle 1/3 of tibia
• I: base of distal phalanges 2-5 (plantar surface)
• A: flexion of digits 2-5 (@ MTP & IP joints) plantar flexion & inversion of foot
• N: tibial nerve (L5, S1, S2)

Question 13

Answer 13

Flexor hallucis longus

• O: posterior inferior 2/3 of fibula & interosseous membrane
• I: distal phalanx of big toe (plantar surface)
• A: flexion of big toe, (@MTP & IP joints) plantar flexion & inversion of the foot
• N: Tibial nerve L5, S1,S2