Foot and Ankle Anatomy, Articulations, Malalignments, Ligaments, and Muscles

Comprehensive vocabulary flashcards covering the structural osteology, joint classifications, structural arches, postural malalignments, ligamentous stabilizers, functional kinesiology, and extrinsic/intrinsic musculature of the leg, ankle, and foot.

Tibia

The medial bone of the lower leg; it is the primary weight-bearing bone.

Fibula

The lateral bone of the lower leg.

Malleoli

Large bumps located at the distal ends of the shafts of both the tibia and the fibula.

Lateral Malleolus

The bony prominence located at the distal end of the fibula.

Medial Malleolus

The bony prominence located at the distal end of the tibia.

Forefoot

The anterior segment of the foot composed of $19$ bones: $14$ phalanges and $5$ metatarsal bones.

Hallux

The medical term for the big toe (or great toe), which contains only $2$ phalanges and bears most of the body's weight when weight-bearing.

Metatarsal Bones

The $5$ long bones of the foot, numbered $1$ to $5$ from medial to lateral.

Midfoot

The central segment of the foot composed of $5$ tarsal bones: the cuboid, navicular, and three cuneiforms.

Navicular

A midfoot tarsal bone located proximal to the three cuneiform bones; also known as the scaphoid.

Cuboid

The most lateral of the $5$ midfoot tarsal bones.

Cuneiform Bones

Three midfoot tarsal bones (medial, intermediate, and lateral) situated proximal to the medial metatarsal bones.

Rearfoot

The posterior segment of the foot composed of $2$ tarsal bones: the talus and calcaneus.

Calcaneus

The heel bone, which is the largest tarsal bone of the foot.

Talus

The rearfoot tarsal bone that sits on top of (proximal to) the calcaneus.

Sustentaculum Tali

A bony prominence extending medially from the superior surface of the calcaneus that serves as a platform for part of the talus to sit on.

Subtalar Joint (Talocalcaneal Joint)

The articulation between the talus and the calcaneus that provides movement for inversion and eversion of the ankle.

Talocrural Joint

The articulation between the tibia, fibula, and talus; also referred to as the ankle mortise.

Tuberosity of the 5th Metatarsal

A rough eminence on the lateral side of the base of the $5^{\text{th}}$ metatarsal bone that serves as a site for muscle attachment and is commonly injured.

Sesamoid Bones of the Foot

Two bones located on the plantar surface of the head of the first metatarsal bone; they are not counted within the standard $26$ bones of the foot.

Tarsometatarsal Joints

Articulations between the tarsal bones and the bases of the metatarsal bones, clinically associated with Lisfranc injuries.

Intermetatarsal Joints

The articulations located between the bases of the five metatarsal bones.

Metatarsophalangeal (MTP) Joints

The articulations between the heads of the metatarsals and the proximal phalanges.

Interphalangeal (IP) Joints

Articulations between the phalanges of the foot, which include the single IP joint of the hallux as well as the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints of the lesser toes.

Arches of the Foot

Three functional structures (transverse, medial longitudinal, and lateral longitudinal) that absorb shock, increase foot flexibility, and provide a protected space for blood vessels, nerves, and muscles.

Medial Longitudinal Arch

The longitudinal arch of the foot that is most commonly injured.

Lateral Longitudinal Arch

The longitudinal arch of the foot that is rarely injured.

Squared Foot

A foot alignment characterized by the $1^{\text{st}}$ and $2^{\text{nd}}$ toes being equal in length, occurring in approximately $9\%$ of the population.

Morton's Foot

A foot alignment where the $2^{\text{nd}}$ toe is longer than the $1^{\text{st}}$ toe, occurring in approximately $22\%$ of the population.

Egyptian Foot

A foot alignment where the $1^{\text{st}}$ toe is the longest, representing the most common presentation at approximately $69\%$.

Pes Planus

The clinical condition commonly known as flat foot.

Pes Cavus

The clinical condition characterized by an abnormally high arch of the foot.

Hammer Toes

A toe malalignment characterized by proximal interphalangeal (PIP) joint flexion.

Claw Toes

A toe malalignment characterized by metatarsophalangeal (MTP) joint hyperextension, proximal interphalangeal (PIP) joint flexion, and distal interphalangeal (DIP) joint flexion.

Mallet Toes

A toe malalignment characterized specifically by distal interphalangeal (DIP) joint flexion.

Interosseous Ligament of the Lower Leg

A ligament located between the medial border of the fibular shaft and the lateral border of the tibial shaft, running from proximal to distal ends.

Tibiofibular Ligaments

The anterior and posterior ligaments found on the lateral aspect of the distal lower leg connecting the tibia and fibula.

Deltoid Ligament

A major ligament complex of the medial ankle composed of three superficial bands and one deep band.

Anterior Talofibular (ATF) Ligament

The shortest lateral ankle ligament and the most commonly sprained ligament in the ankle joint; extends from the anterior aspect of the distal lateral malleolus to the talus.

Sinus Tarsi

A soft anatomical depression situated just anterior and distal to the end of the fibula, crossed by the anterior talofibular ligament.

Posterior Talofibular (PTF) Ligament

The strongest of the lateral ankle ligaments; runs from the posterior aspect of the lateral malleolus to the talus.

Calcaneofibular (CF) Ligament

The longest lateral ankle ligament; spans from the lateral malleolus of the fibula to the lateral surface of the calcaneus.

Retinaculum

A band or band-like structure that holds an organ or anatomical part in place; there are $5$ primary retinacula stabilizing tendons around the foot and ankle.

Extensor Retinacula

Superior and inferior fibrous bands that hold the extensor muscle tendons in place on the anterior ankle and foot.

Flexor Retinaculum

A fibrous band that secures the flexor tendons in place along the medial aspect of the ankle and foot.

Peroneal Retinacula

Superior and inferior fibrous bands that hold the peroneal muscle tendons in place as they travel posterior to the lateral malleolus during dorsiflexion and plantar flexion.

Dorsiflexion

The upward movement of the foot toward the anterior lower leg.

Plantar Flexion

The downward movement of the foot.

Eversion

The lateral (outward) movement of the foot occurring at the subtalar joint.

Inversion

The medial (inward) movement of the foot occurring at the subtalar joint.

Supination (Foot)

A composite triplanar foot motion consisting of ankle inversion in the frontal plane, foot adduction in the horizontal plane, and plantarflexion in the sagittal plane.

Pronation (Foot)

A composite movement of the foot consisting of ankle eversion and foot abduction.

Extrinsic Muscles of the Lower Leg and Foot

Muscles that originate outside of the foot (in the lower leg or femur) and insert within the foot.

Intrinsic Muscles of the Foot

Muscles that have both their origin and insertion entirely within the foot, arranged primarily into $4$ layers on the plantar aspect.

Tibialis Anterior

An anterior compartment muscle originating on the upper $\frac{2}{3}$ of the lateral tibia and inserting on the medial cuneiform and base of the first metatarsal; produces dorsiflexion and inversion of the ankle.

Extensor Digitorum Longus

An anterior compartment muscle originating from the lateral tibial condyle, proximal $\frac{3}{4}$ of the fibula, and interosseous membrane; inserts onto the middle and distal phalanges of the lateral four toes to produce ankle dorsiflexion and MP, PIP, and DIP joint extension.

Extensor Hallucis Longus

An anterior compartment muscle originating from the middle half of the medial fibula and interosseous membrane, inserting onto the distal phalanx of the great toe; produces ankle dorsiflexion, ankle inversion, and great toe MP/IP extension.

Peroneus Tertius

An anterior compartment muscle originating on the lower $\frac{1}{3}$ of the fibula and interosseous membrane, inserting on the dorsal surface of the base of the fifth metatarsal; produces ankle dorsiflexion and eversion.

Peroneus Longus

A lateral compartment muscle originating on the head and proximal $\frac{2}{3}$ of the lateral fibula and lateral tibial condyle, inserting on the medial cuneiform and first metatarsal; produces plantar flexion and eversion.

Peroneus Brevis

A lateral compartment muscle originating on the lower half of the lateral fibula, inserting on the tuberosity at the base of the fifth metatarsal; produces plantar flexion and eversion.

Gastrocnemius

A two-headed superficial posterior compartment muscle originating on the popliteal surface of the femur (medial and lateral condyles) that crosses both the knee and ankle joints, inserting onto the calcaneus via the Achilles tendon to perform plantar flexion.

Soleus

A superficial posterior muscle originating from the proximal third of the posterior fibula and middle third of the posterior tibia, inserting on the calcaneus via the Achilles tendon to produce plantar flexion.

Plantaris

A superficial posterior compartment muscle that possesses the longest tendon in the human body, inserting on the posterior calcaneus separately from the Achilles tendon to produce plantar flexion.

Achilles Tendon

The thick conjoint tendon formed by the union of both heads of the gastrocnemius with the soleus muscle, inserting onto the calcaneus.

Tibialis Posterior

A deep posterior compartment muscle that inserts onto the navicular, medial cuneiform, and the bases of the $2^{\text{nd}}$ through $5^{\text{th}}$ metatarsals; produces ankle plantar flexion and inversion.

Flexor Digitorum Longus

A deep posterior muscle originating on the lower $\frac{2}{3}$ of the posterior tibia and inserting onto the bases of the distal phalanges of the four lateral toes; produces plantar flexion, ankle inversion, and flexion of the lateral toes.

Flexor Hallucis Longus

A deep posterior muscle originating on the lower $\frac{2}{3}$ of the posterior fibula and inserting on the base of the distal phalanx of the great toe; produces plantar flexion, ankle inversion, and hallux flexion.

Plantar Fascia

A dense fibrous band situated superficial to all muscles on the plantar surface of the foot that protects underlying nerves, vessels, and muscles.

Quadratus Plantae

A second-layer intrinsic foot muscle that arises by two heads from the medial and lateral surfaces of the calcaneus and attaches to the flexor digitorum longus tendons to assist with toe flexion.

Lumbricales of the Foot

A group of four second-layer intrinsic muscles originating from the tendons of the flexor digitorum longus and inserting on the extensor digitorum longus tendons, notable for having no direct bony attachments.