Ankle & Foot

Definitions

  • Leg: Extends from knee to ankle.

  • Ankle: Joint between leg and foot.

  • Foot: Group of bones that adapt to the ground and transmit forces during weight bearing.

Bones of the Leg & Foot

Leg

  • Tibia

    • Medial & lateral condyles

    • Crest

    • Medial malleolus

  • Fibula

    • Fibular head

    • Lateral malleolus

  • Interosseous membrane

  • Concept Check: What type of joint is this?

Ankle

  • Talo-crural joint

    • Described as a “Mortise & tenon” joint.

  • Talus

    • Tarsal bone.

  • Tibia

    • Found superior and medial.

  • Fibula

    • Found laterally.

Foot

  • Hindfoot (2 bones):

    • Talus

    • Calcaneus

  • Midfoot (5 bones):

    • Navicular

    • Cuboid

    • Cuneiforms (3)

  • Forefoot (19 bones):

    • Metatarsals (5)

    • Phalanges (14)

    • Note: 1st digit only has 2 phalanges, while digits 2-5 have 3 phalanges each.

    • 2 sesamoid bones are embedded in the FHB tendon at the 1st metatarsal head.

Foot - Hindfoot

  • Talus:

    • Dome

    • Neck

    • Head

  • Calcaneus:

    • Sustentaculum Tali (FHL)

    • Peroneal tubercle

    • Medial/lateral tuberosity

    • Calcaneal tuberosity

Foot - Midfoot

  • Navicular:

    • Navicular tuberosity

  • Cuboid:

    • Lateral/inferior groove for the Peroneus longus.

  • Cuneiforms:

    • 1st, 2nd, 3rd (medial, middle, lateral).

Foot - Forefoot

  • Metatarsals:

    • Head

    • Shaft

    • Base

    • Styloid process of 5th metatarsal

  • Phalanges:

    • Head, shaft, base

Articulations - Leg

  • Tibio-Fibular:

    • Superior tibiofibular joint:

    • Synovial joint with a joint capsule.

    • Plane joint allowing some gliding and rotation.

    • Inferior tibiofibular joint:

    • Fibrous joint classified as syndesmosis.

    • Ligaments holding the joint together allow slight movement to accommodate motions of the talus.

Joints of the Leg & Foot

Articulations - Ankle

  • Talo-crural:

    • Described as “tenon & mortise.”

    • Synovial hinge joint.

  • Motions:

    • Plantar flexion (PF) and dorsiflexion (DF).

    • This joint is uniaxial.

  • Concept Check: What plane and around what axis is this joint functioning?

Articulations - Ankle Continued

  • Triplanar:

    • The axis of motion is not on a true plane.

    • Influenced by the lateral malleolus.

Articulations – Foot (Hindfoot)

  • Subtalar joint:

    • Between talus and calcaneus.

    • Synovial plane joint.

    • Movement allows gliding for inversion and eversion of the calcaneus.

Articulations – Foot (Hind → Midfoot)

  • Transverse tarsal joint:

    • Between calcaneus and cuboid; talus and navicular.

    • Classified as synovial plane joints.

    • Movement: Very little active motion; transmission of force between hindfoot and midfoot; moves along with subtalar joint.

Articulations – Foot (Midfoot)

  • Intertarsal joints:

    • Joints between cuboid and navicular, also between cuboid and cuneiforms, and among the cuneiforms.

    • Synovial plane joints with very little movement; primarily for shock absorption.

Articulations – Foot (Mid→Forefoot)

  • Tarsal-Metatarsal joints:

    • Synovial plane joints.

    • Movement is characterized by little active motion with sliding; collapse during weight bearing.

Articulations – Foot (Forefoot)

  • Metatarsal-Phalangeal (MP or MTP) joints:

    • Classified as condyloid synovial joints.

    • Movement includes active flexion/extension, hyperextension, and passive abduction/adduction.

    • Some individuals have more control over their intrinsic muscles.

  • Concept Check: What is a condyloid joint?

Articulations – Foot (Forefoot) Continued

  • Interphalangeal joints:

    • Proximal interphalangeal (PIP) joints, interphalangeal (IP) joints, and distal interphalangeal (DIP) joints.

    • These are hinge synovial joints allowing for active flexion/extension.

Planes of Motion

  • Sagittal plane:

    • Associated with plantar/dorsiflexion.

  • Frontal plane:

    • Changes in calcaneal inversion (varus) and eversion (valgus).

  • Transverse plane:

    • Associated with abduction and adduction.

  • Combined plane motions:

    • Supination: Plantar flexion/inversion/adduction.

    • Pronation: Dorsiflexion/eversion/abduction.

Stabilizing Structures of the Ankle & Foot

Ligaments

  • Tibia to Fibula Ligaments:

    • Anterior superior tibio-fibular.

    • Posterior superior tibio-fibular.

    • Anterior inferior tibio-fibular.

    • Posterior inferior tibio-fibular.

    • NOTE: Ligaments are named for the bones that they span.

Ligaments - Lateral Ankle

  • **Lateral ligament: **

    • Anterior talo-fibular (ATFL).

    • Calcaneo-fibular (CFL).

    • Posterior talo-fibular (PTFL).

    • Common site of injury.

  • Concept Check: What type of force (movement of the calcaneus) would cause the most damage to the lateral ankle ligaments?

Ligaments - Medial Ankle

  • Deltoid ligament:

    • Posterior tibio-talar.

    • Tibiocalcaneal.

    • Tibionavicular.

    • Anterior tibio-talar.

    • This is a deep structure.

Additional Fibrous Structures

  • Ligaments on the plantar surface:

    • Spring ligament.

    • Short plantar ligament.

    • Long plantar ligament.

  • Retinaculum:

    • Holds tendons in place at ankle; influences line of pull of muscles.

  • Plantar fascia:

    • Contributes to the support and stability of the foot's structure.

Arches of the Foot

Medial longitudinal arch contains the calcaneus, talus, navicular, three cuneiforms, and the first three metatarsals, providing critical alignment and weight distribution during walking and running.

Lateral longitudinal arch includes the calcaneus, cuboid, and the fourth and fifth metatarsals, which aids in maintaining balance and accommodating various terrains.

Transverse arch runs across the foot and is formed by the navicular, cuneiforms, and the bases of the metatarsals, playing a vital role in the overall stability and flexibility of the foot.

Arch Structures

  • Arches maintained by:

    • Shape of the bones and their relationships to one another.

    • Plantar fascia and ligaments.

    • Muscles providing 15-20% of total support.

    • Talus:

    • Acts as the keystone of the arches, receiving the weight of the body.

Weight-Bearing Surfaces

  • Calcaneus and metatarsal heads:

    • 1st and 5th metatarsal heads contribute to weight-bearing.

  • Observation of callous formation on the plantar surface of the foot can show wear patterns.

    • This can be observed in a laboratory setting.

Muscles

General Organization

  • Muscle components:

  • Origin & Insertion:

    • Both located in the foot, distal to the ankle.

    • Actions occur in the foot at the toes.

    • Muscles are found on the plantar surface.

    • Categorized into 4 layers:

    • Extrinsic Muscles:

    • Originate on the leg, insert distal to the ankle, actions occur at the ankle or in the foot at toes.

    • Organized into four compartments in the leg:

      • Superficial posterior

      • Deep posterior

      • Anterior

      • Lateral

    • Intrinsic Muscles:

    • Muscles located within the foot itself, are subdivided into layers.

Extrinsic Muscles – Superficial Posterior

  • Gastrocnemius:

    • Most superficial muscle; a two-joint muscle that crosses knee and ankle joints.

  • Plantaris:

  • Soleus:

    • A one-joint muscle, together they form the Achilles tendon.

  • Common action:

    • Plantarflexion of the ankle.

Extrinsic Muscles – Deep Posterior

  • Tibialis posterior:

  • Flexor digitorum longus:

    • Flexes the lesser toes.

  • Flexor hallucis longus:

    • Flexes the great toe.

  • Common action:

    • Plantarflexion and inversion of the ankle.

Extrinsic Muscles – Anterior Group

  • Tibialis anterior:

    • Responsible for inversion.

  • Extensor digitorum longus:

    • Extends the lesser toes.

  • Extensor hallucis longus:

    • Extends the great toe.

  • Common action:

    • Dorsiflexion.

Extrinsic Muscles – Lateral Group

  • Peroneus longus:

    • Responsible for plantarflexion.

  • Peroneus brevis:

    • Also involved in plantarflexion.

  • Peroneus tertius:

    • Contributes to dorsiflexion.

  • Common action:

    • Eversion.

Intrinsic Muscles

  • 1st Layer:

    • Abductor hallucis

    • Flexor digitorum brevis

    • Abductor digiti minimi

  • 2nd Layer:

    • Lumbricals

    • Quadratus plantae

  • 3rd Layer:

    • Flexor hallucis brevis

    • Adductor hallucis

    • Flexor digiti minimi brevis

  • 4th Layer:

    • 3 Plantar interossei

    • 4 Dorsal interossei

  • Dorsal Surface:

    • Extensor hallucis brevis

    • Extensor digitorum brevis

Organization of Muscles

Grouping by Muscle Action - Dorsiflexion

  • Muscles include:

    • Anterior tibialis

    • Extensor hallucis longus

    • Extensor digitorum longus

    • (Peroneus tertius)

Grouping by Muscle Action - Plantarflexion

  • Muscles include:

    • Gastrocnemius

    • Soleus

    • Peroneus brevis

    • Peroneus longus

    • Flexor hallucis longus

    • Flexor digitorum longus

    • Tibialis posterior

Grouping by Muscle Action - Inversion

  • Muscles include:

    • Tibialis anterior

    • Tibialis posterior

    • Flexor hallucis longus

    • Flexor digitorum longus

    • Extensor hallucis longus

Grouping by Muscle Action - Eversion

  • Muscles include:

    • Peroneus tertius

    • Peroneus longus

    • Peroneus brevis

Nervous System of Leg & Foot

Dermatomes

  • Regions covered by sensory innervation:

    • Innervation segments: L4-S2

    • Anterior aspects: L2-L5

  • Map of dermatomes:

    • L4, L5, S1, S2

Myotomes

  • Muscle control regions:

  • Nerves derived from lumbo-sacral plexus.

  • Myotome innervation includes:

  • Control via L4-S2

    • Eversion and inversion capabilities.

Innervation of Muscles of the Leg

  • Nerve branches from L4-S2 exit the spine to form the sciatic nerve.

    • Sciatic nerve branches at the knee into:

    • Tibial nerve:

      • Origin: L4-S3; located along the posterior leg.

      • Motor signal to posterior leg muscles including:

      • Gastrocnemius

      • Soleus

      • Plantaris

      • Tibialis posterior

      • Flexor digitorum longus

      • Flexor hallucis longus

    • Common peroneal nerve:

      • Origin: L4-S2; wraps around fibular head and branches into:

      • Superficial peroneal nerve:

        • Runs laterally along fibula; motor innervation to peroneus longus and peroneus brevis.

      • Deep peroneal nerve:

        • Runs anteriorly along tibia; motor innervation to tibialis anterior, extensor digitorum longus, extensor hallucis longus, peroneus tertius, and dorsal intrinsics.

Effects of Nerve Injury

  • Tibial nerve injury:

    • Loss of ankle plantarflexion

    • Loss of toe flexion

    • Weakening of ankle inversion

  • Common peroneal nerve injury:

    • Loss of ankle dorsiflexion, prone to “drop foot.”

    • Loss of toe extension

    • Loss of ankle eversion.

Leg & Foot Postures

Posture and Abnormalities

  • Many variables leading to abnormalities in foot posture, such as:

    • Calcaneal alignment

    • Height of arches

    • Mobility of foot

    • Alignment of metatarsals & phalanges

Abnormal Conditions

  • Pes planus:

    • Flat foot condition.

  • Pes cavus:

    • High arch condition.

  • Pes equinus:

    • Severely high arch with flexed toes and elevated heel.

  • Hallux valgus:

    • Condition involving the great toe adduction

Common Injuries

  • Ankle sprain:

    • 1st degree: Slight stretching, some ligament damage.

    • 2nd degree: Partial tearing of ligament; muscles provide stability.

    • 3rd degree: Complete tearing of ligament; joint instability present.

  • Shin splints:

    • Generalized classification of injury; often periosteal inflammation.

  • Morton’s neuroma:

    • Occurs between metatarsal heads.

  • Plantar fasciitis:

    • A common overuse injury; pain often at the attachment site of the fascia to the calcaneus.

Questions?