The Ankle and Foot Joints

Function of the foot Provide a stable platform Generate propulsion Absorb shock

Bones Ankle + foot = 28 bones foot = 26 bones Leg: tibia, fibula Foot: –Tarsals (7): talus, calcaneus, navicular, cuboid, and cuneiforms (3) –Metatarsals (5) –Phalanges (14)

Joints Tibiofibular: –articulation between tibia and fibula amphiarthrodial joint Ankle joint –Talocrural articulation between talus and tibia; talus and fibula classified as a ginglymus

Joints Subtalar joint –articulation between talus and calcaneus –classified as arthrodial (gliding) joint Transverse tarsal joint –articulation between talus, navicular, calcaneus and cuboid bones –classified as arthrodial joint

Joints Tarsometatarsal –tarsal bones and metatarsal –classified as arthrodial (gliding) joints Metatarsophalangeal –metatarsals and phalanges –classified as condyloid Interphalangeal joints (proximal and distal) –phalangeal bones –ginglymus

Arches of the foot Medial longitudinal arch –calcaneus, talus, navicular, cuneiforms (3), and medial metatarsals (3). Lateral longitudinal arch –calcanueus, cuboid, lateral metatarsals (4 & 5) Transverse arch –across metatarsals

Classifying Arch Type Pes Planus: Flat foot Pes Cavus: High Arch Normal

Movements Ankle joint –dorsiflexion: “raising the toes” –plantarflexion: “point the toes” Subtalar & Transverse tarsal joints –Calcaneal inversion and eversion Interphalangeal joints –flexion –extension

Movements Supination inversion plantar flexion adduction Pronation eversion dorsiflexion abduction

Summary Bones of the foot: –tarsals, metatarsals, phalanges Joints of the foot and ankle –talocrural (ankle) –subtalar –transverse tarsal –metatarsalphalangeal –interphalangeal Movements –dorsiflexion/plantarflexion (ankle joint) –inversion/eversion (subtalar & transverse tarsal) –flexion and extension of toes about the interphalangeal joints

Muscles Plantar flexors Dorsi flexors Evertors Invertors

Plantar Flexors Gastrocnemius Flexor digitorum longus Peroneus longus Plantaris Soleus Tibialis Posterior

Dorsiflexors Tibialis anterior Peroneus tertius Extensor digitorum longus

Invertors Tibialis anterior Tibialis posterior Flexor hallucis longus

Evertors Peroneus longus Peroneus brevis Peroneus tertius Extensor digitorum longus

Extensor digitorum longus (p44) Origin –lateral condyle of tibia –upper 3/4 of anterior aspect of fibula Insertion –superior aspect of foot, middle and distal phalanges of four lesser toes Action –Extension of four lesser toes –dorsal flexion –eversion

Extensor hallucis longus (p45) Origin –fibula, middle aspect of anterior fibula Insertion –superior aspect of foot, base of distal phalanx of great toe Action –dorsiflexion –extension of great toe

Peroneus tertius (p46) Origin –fibula, anterior-lateral surface of lower 1/3 of fibula Insertion –superior aspect of foot, base of fifth metatarsal Action –Eversion –Dorsal flexion

Tibialis anterior (p47) Origin –Lateral condyle of tibia –Upper two-thirds of anterior-lateral aspect of tibia Insertion –plantar surface of 1st (medial) cuneiform and 1st metatarsal Action –Dorsal flexion –inversion

Peroneus brevis (p48) Origin –fibula, lower two-thirds, lateral aspect Insertion –5th metatarsal tuberosity Action –eversion

Peroneus longus (p49) Origin –lateral surface of tibia –fibula, upper two-thirds of lateral aspect of fibula Insertion –inferior aspect of foot, 1st cuneiform and 1st metatarsal bones Action –Eversion –Plantar flexion

Flexor digitorum longus (p50) Origin –tibia, middle third, posterior aspect Insertion –plantar surface of foot, distal phalanx of each of the four lesser toes (no big toe) Action –‘toe’ flexion –plantar flexion

Flexor hallucis longus (p51) Origin –fibula, lower two-thirds, posterior aspect Insertion –plantar aspect of foot, base of distal phalanx of big toe (‘hallucis’) Action –‘big toe flexion’ –inversion

Gastrocnemius (p52) Origin –medial and lateral epicondyle of the femur Insertion –posterior surface of calcaneus Action –plantar flexion –knee flexion

Soleus (p54) Origin –upper 1/3 posterior shaft of fibula –posterior surface of head of fibula –popliteal line –middle 1/3 of medial border of tibia Insertion –Posterior surface of the calcaneus Action –Plantar flexion

Note Gastrocnemius and Soleus muscles have a common tendon/insertion (calcaneal tendon or Achilles tendon) Some texts refer to the combination of the gastrocnemius and soleus as the triceps surae (three headed muscle).

Plantaris (p53) Origin –posterior surface of lateral epicondyle of femur Insertion –posterior surface of calcaneus Action –plantar flexion

Tibialis Posterior (p55) Origin –middle 1/3 of posterior-lateral surface of tibia –middle 1/3 of posterior-medial surface of fibula Insertion –plantar surface of foot, lower inner surfaces of navicular, cuneiforms, and 2nd & 3rd metatarsals Action –plantar flexion –inversion

Summary of muscles Plantar flexors –gast., sol., flx digitorum long., per longus, tib post, plantaris Dorsi flexors –tib ant, per tertius, ext dig long Evertors –per longus, brevis, tertius, ext dig longus Invertors –tib ant & post, flx hallucis long