l. Anterior Compartment of Leg (Knee Down) – Dorsiflexion (Extension)
1) Tibialis anterior (shin splints muscle)
a. Actions: dorsiflexion, inverts foot (supports medial longitudinal arch)
b. Innervation: Deep peroneal nerve
c. Origin: from lateral condyle and upper tibia
d. Insertion: to medial cuniform bone (tarsal) and 1st metatarsal bone
2) Extensor digitorum longus
a. Actions: dorsiflexion, everts foot, extends toes
b. Innervation: Deep peroneal nerve
c. Origin: from lateral condyle and upper tibia and proximal fibula
d. Insertion: to 2nd and 3rd phalanges of toes 2-5
3) Peroneus tertius
a. Actions: dorsiflexion, everts foot
b. Innervation: Deep peroneal nerve
c. Origin: from distal and anterior fibula passes anterior to lateral malleolus
d. Insertion: on the dorsum of the 5th metatarsal
4) Extensor hallicus longus
a. Actions: extends great toe, dorsiflexion of foot, aids in foot inversion
b. Innervation: Deep peroneal nerve
c. Origin: from anterior, medial fibula
d. Insertion: to distal phalanx of big toe
ll. Muscles of the Lateral Compartment of Leg (Knee Down)
5) Peroneus longus
a. Actions: plantar flexion, everts foot
b. Innervation: Superficial peroneal nerve
c. Origin: from proximal fibula passes under foot
d. Insertion: to 1st metatarsal
6) Peroneus brevis
a. Actions: plantar flexion, everts foot
b. Innervation: Superficial peroneal nerve
c. Origin: from distal fibula passes behind lateral malleolus
d. Insertion: to insert proximally on 5th metatarsal
lll. Superficial Muscles of the Posterior Compartment of Leg (Knee Down)
7) Gastrocnemius
a. Actions: plantar flexion (when knee is extended), weak flexor of knee when foot is dorsifexed
b. Innervation: Tibial nerve
c. Origin: from medal and lateral condyles of femur
d. Insertion: to calcaneous via Achilles tendon (also called Calcaneal tendon)
8) Soleus
a. Actions: plantar flexion (at ankle) – locomotion muscle
b. Innervation: Tibial nerve
c. Origin: from tibia and fibula
d. Insertion: to calcaneous via Achilles tendon (also called Calcaneal tendon)
9) Plantaris
a. Actions: assists in knee flexion, plantar flexion of foot
b. Innervation: Tibial nerve
c. Origin: from posterior femur laterally
d. Insertion: to calcaneous via Achilles tendon (also called Calcaneal tendon)
lV. Deep Muscles of the Posterior Compartment of Leg (Knee Down)
10) Popliteus
a. Actions: flexes knee and rotates leg medially to unlock knee from full extension
b. Innervation: Tibial nerve
c. Origin: from lateral condyles of femur
d. Insertion: to proximal tibia
11) Flexor digitorum longus
a. Actions: plantar flexes foot, inverts foot, flexes toes (helps foot grip ground)
b. Innervation: Tibial nerve
c. Origin: from posterior tibia runs behind medial malleolus
d. Insertion: into 4 tendons to distal phalanges of toes 2-5
12) Flexor hallicus longus
a. Actions: plantar flexes foot, inverts foot, flexes big toe at all joints (pushes off during walking)
b. Innervation: Tibial nerve
c. Origin: from middle fibula runs under foot
d. Insertion: to distal phalanx of big toe
13) Tibialis posterior
a. Actions: inverts foot, plantar flexes foot (supports medial longitudinal arch)
b. Innervation: Tibial nerve
c. Origin: from proximal tibia and fibula it runs behind medial malleolus under arch
d. Insertion: into 4 tendons to tarsals and metatarsals 2-4
Not Muscle:
14) Superior extensor retinaculum
15) Inferior extensor retinaculum
16) Peroneal retinaculum
17) Lateral malleolus or “ankle bone”
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