Anatomy Foot/Ankle Complex

functions of foot/ankle

• supports body weight

• shock absorption

• balance

  • senses perceive the location and movements of our body parts

tibia

main weight bearing bone of lower leg; connects to fibula via interosseus membrane

interosseus membrane

thick, dense fibrous sheet of connective tissue that spans between the space of 2 bones

fibula

bone parallel & lateral to tibia; considerably smaller than tibia

tarsal bones (7)

talus, calcaneus, navicular, cuboid, 3 cuneiforms (medial, intermediate, lateral)

metatarsals (5)

miniature long bones in the feet; numbered great toe 1st through pinky toe 5th

phalanges (14)

toe bones; proximal, middle, distal of 4 lesser toes (great toe lacks middle bone)

sesamoids (2)

accessory bones located on the plantar aspect of 1st metatarsal head

sections of the foot

• rearfoot

• midfoot

• forefoot

tibiofibular joint

• proximal = gliding joint, medial = syndesmosis

• fibrous structure connecting 2 adjacent bones

• contributes to ankle stability

• no obvious motion

talocrural joint (TCJ)

• “ankle joint”

• formed by distal ends of tibia/fibula with dome of talus

• hinge joint → dorsiflexion/plantarflexion

subtalar joint

• joint between the inferior talus & superior calcaneus

• condyloid joint → inversion/eversion, abduction/adduction, circumduction

transverse tarsal joints

• joints that divide the rearfoot and midfoot

• gliding joints → inversion/eversion, abduction/adduction, plantarflexion/dorsiflexion

lisfranc joint complex

• joints that connect the midfoot and forefoot

• made up of a complex system of bones and ligaments

• very little motion

• crucial in stabilizing foot for pushing off during walking

metatarsal phalangeal joints (MPJs)

• joint that connects each metatarsal head to their corresponding proximal phalange

• condyloid joints

1st MPJ

joint with 90 degrees of extension; required for demi-pointe

interphalangeal (IP) joints

joints between each phalange bone

lateral ankle ligaments

• anterior talofibular ligament

• calcaneofibular ligament

• posterior talofibular ligament

• function:

  • lateral stability

  • restricts inversion

deltoid ligament

triangular shaped ligament located on the medial aspect of the ankle; function is medial ankle stability and restricting eversion

medial longitudinal arch

• arch of the foot on medial aspect

• keystone at navicular

• function

  • accommodation

  • shock absorption

lateral longitudinal arch

• arch of the foot on lateral aspect

• keystone at anterior aspect of calcaneus

• function = stability

transverse arch

• arch of foot on dorsal aspect

• keystones at intermediate cuneiform & 2nd metatarsal

• function = accommodation

plantar fascia

• connective tissue that runs from the Achilles to each phalange

• functions

  • providing stability to a loaded foot

  • providing support to medial longitudinal arch

  • shock absorption

bursae

fluid filled sacs that reduce friction

heel fat pad

thick pad of fat located between the plantar surface of the calcaneus and the skin; essential in shock absorption

tibial torsion

• external rotation of the distal tibia relative to the proximal tibia

• appearance of increased turnout in the foot

• decreases ankle stability

pes planus

• “flat foot”

• diminished or absent medial longitudinal arch (MLA)

• center of pressure shifts medially

• flexible = MLA present when not weight bearing

• rigid = MLA absent no matter weight bearing status

pes cavus

• abnormally high medial longitudinal arch

• center of pressure shifts laterally

• tends to be more rigid

claw toes

• lesser toes are excessively flexed

• hyperextension at MTP joint

• flexion at proximal and distal IP joints

• commonly associated with pes cavus

hallux valgus/bunions

• mal-alignment of the 1st MTP joint

• stress on medial aspect of joint → bony/soft tissue inflammation and enlargement

• more common in femal ballet dancers