Foot and Ankle Joint Anatomy Quiz

Foot and Ankle Joints

• The foot and ankle are complex structures with numerous joints
• The main joints discussed include subtalar, talocalcaneonavicular, calcaneocuboid, cuneonavicular, intercuneiforms, medial cuneometatarsal, cuboidometatarsal
• Other joints of note include the talocrural (ankle), metatarsophalangeal, interphalangeal.
• The talocrural joint is a hinge type synovial joint, with articulations between the tibia, fibula, and talus. It is the true ankle joint and a part of a complex joint system functioning alongside other joints in the foot.

Aims

• Identify the major joints of the foot and ankle and their cavities.
• Characterise the motions at the joints and their muscular control.
• Detail the neurovascular structures that supply the joints.

Major Foot Joints / Cavities (1 of 3)

• Subtalar: Posterior talocalcaneal joint; Talus, calcaneus
• Anterior talocalcaneal: Talus, calcaneus
• Talonavicular: Talus, navicular
• Calcaneocuboid: Calcaneus, cuboid
• The talonavicular and calcaneocuboid joints form the midtarsal joint, consisting of two distinct joints, each with distinct membranes and cavities.

Major Foot Joints / Cavities (2 of 3)

• Cuneonavicular: Navicular, medial cuneiform
• Intercuneiforms: Cuneiforms
• Cuneocuboid: Lateral cuneiform, cuboid
• Medial cuneometatarsal: 1st cuneiform & metatarsal
• Cuboidometatarsal: 4th & 5th metatarsals, cuboid
• These joints work together in a continuous cavity, connected with other joints in the foot.

Major Foot Joints / Cavities (3 of 3)

• Ankle (talocrural): Tibia, fibula, talus. The ankle joint, is a synovial hinge joint, articulated with the tibia, fibula and talus elements. A hinge-like movement takes place to allow up and down movement only.
• Metatarsophalangeal: Metatarsals and toes.
• Interphalangeal: Phalanges of toes.

Ankle Joint

• The articulation of the tibia and fibula with the talus.
• The lateral and medial malleoli create a mortise-like structure fitting the talus.
• A synovial joint, complete with capsule and synovial membrane.
• A hinge-type classification.
• Also known as the talocrural joint, the true ankle joint.

Ankle Cross-Section

• Diagrams illustrate the neurovascular structures (vessels and nerves) feeding and innervating the ankle. Many muscles can also be recognised.
• The diagram shows many arteries/neurons present.

Bones (Posterior View)

• Tibia
• Fibula
• Tibial plafond
• Trochlear surface of the talus
• Medial malleolus
• Talus
• Sustentaculum tali of the calcaneus

Bones (Diagram of Ankle)

• Tibia
• Fibula
• Mortise of the tibia and fibula (articulations)
• Malleolus (medial and lateral)

Bones (X-Ray View)

• X-ray diagrams illustrate the various bones of the foot

Lateral Ligaments - Ankle

• Anterior talofibular ligament
• Posterior talofibular ligament
• Calcaneofibular ligament
• These ligaments are often injured in sprained ankles, quite common in sports like basketball.
• Ligaments are located on the outside/lateral of the ankle and can be injured in sprained ankles.

Medial Ligaments - Ankle

• Posterior tibiotalar ligament
• Tibiocalcaneal ligament
• Anterior tibiotalar ligament
• Tibionavicular ligament
• Deltoid, medial ligament, stronger than lateral

Posterior View of Foot/Ankle ligaments

• Posterior tibiotalar
• Posterior tibiofibular
• Transverse tibiofibular
• Posterior talofibular
• Calcaneofibular

Anterior(ish) View of Ankle ligaments

• Interosseus membrane
• Anterior tibiotalar
• Calcaneofibular

Ankle Joint Motion

• Primary:
  • Plantarflexion
  • Dorsiflexion
  • More Plantarflexion than Dorsiflexion. More stable in Dorsiflexion than plantarflexion.
• (Some):
  • Inversion
  • Eversion
  • Minimal ADduction
  • Minimal ABduction Also shows the axis of movement

Muscles & Ankle Motion

• Dorsiflexors:
  • Tibialis anterior
  • Extensor digitorum longus
  • Extensor hallucis longus
• Plantarflexors:
  • Gastrocnemius
  • Soleus
  • Plantaris
  • Tibialis posterior
  • Flexor hallucis longus
  • Flexor digitorum longus
  • Peroneus longus
  • Peroneus brevis

Neurovascular Supply - Ankle

• Blood: Malleoli supplied by malleolar anastomosis
  • Talus supplied by branch of dorsalis pedis to head and neck. Talus vulnerable to interruption of blood supply.
• Nerves: Ankle joint supplied by deep peroneal and tibial nerves.

Subtalar Joint

• Articulation between the posterior, inferior talus and the superior calcaneus.
• A synovial, plane joint, capsule attaches to marginal articular surfaces.
• Exhibits gliding and rotary motions
• Sinus tarsi and canal penetrate through the joint.

Subtalar Joint (Diagram)

• Shows the articulation between the talus and calcaneus.
• Marks the anterior and posterior talocalcaneal articulations between the two bones

Anatomical Variations

• 3 facet
• Transitional 2 facet
• Simple 2 facet
• Special 2 facet.
• More or less stable or mobile of motion according to the number of facets, due to more or less stable motion.

STJ Ligaments

• Interosseous talocalcaneal: Limits inversion/eversion
• Lateral talocalcaneal (cervical): Limits inversion
• Posterior talocalcaneal: Relatively insignificant

STJ Motions

• Pronation / Supination: Two basic motions at the STJ. The determination of movement is whether the foot is on the ground (CKC) or not (OKC).
• Pronation and Supination are tri-planar and take place simultaneously around the axis of movement.

Broadly Speaking (Pronation & Supination)

• Pronation: Part of the shock absorbency mechanism. The foot adapts and becomes mobile for variations in terrain, to aid shock absorbency.
• Supination: Assists propulsion during gait. Helps the foot rigid into a lever to allow movement from A to B in a relatively straight alignment.

OKC & CKC Motion

• OKC: The talus is free to move act as part of the foot.
  • Pronation = Abduction/Evertion/Dorsiflexion
  • Supination = Adduction/version/Plantarflexion
• CKC: The talus is locked between the medial & lateral malleoli/acts as part of the leg. Pronation/supination,

CKC Motion 2

• Pronation / Supination: Table illustrating how the talus and tibia move in a pronated vs. supinated position. Movements of the talus are important for inversion/eversion, plantarflexion/dorsiflexion.
• Table describing movements of the tibia and talus in pronation vs. supination

Muscles & STJ Motion

• Pronators: Peroneus brevis, Peroneus longus, EDL
• Supinators: Tibialis posterior, Tibialis anterior, FHL, Gastrocnemius, Soleus, Plantaris

Neurovascular Supply to STJ

• Blood: Branches of the tibialis posterior and peroneal arteries supply the sinus tarsi and canal. An anterior tibial branch feeds the talus.
• Nerves: Supplied by branches of the deep peroneal nerves, possibly some tibial nerves

Talocalcaneonavicular Joint

• Anterior talcalcaneal + talonavicular joints
• Front part of talus sits on the calcaneal sustentaculum tali. Talus articulates with navicular
• Usually, the talonavicular component is part of the MTJ complex
• Has its own joint capsule
• Spring ligament integral to the joint

The Midtarsal Joint Complex

• Not one anatomical joint, but a pair working functionally together
• The talonavicular and calcaneocuboid joints function as a functional unit
• Joints are continuous with each other.

TCN Joint Ligaments

• Dorsal talonavicular ligament
• Plantar calcaneonavicular (spring) ligament--forms an integral part of the TCN joint, elastic

Calcaneocuboid Joint

• Articulation between the distal calcaneus and the proximal cuboid.
• Synovial, plane joint with capsule.

CC Joint Ligaments

• Bifurcated ligament - Y shaped: calcaneonavicular portion, calcaneocuboid portion
• Dorsal calcaneocuboid ligament
• Long plantar ligament: Calcaneus to cuboid (and metatarsal bases)
• Short plantar ligament: Calcaneus to cuboid

Midtarsal Joint Motions

• MTJ motion is closely related to ankle and STJ. Talus is common to all three joints.
• As STJ pronates, MTJ becomes mobile; as STJ supinates, MTJ locks, to allow foot to act as a rigid lever

MT Joint Motions 2

• Traditional theories suggest two independent axes of motion for the MTJ complex:
  • Longitudinal: mainly inversion/eversion
  • Oblique: mainly dorsiflexion/plantarflexion, with some abduction/adduction
• These combine to result in pronation/supination around the MTJ
• More modern theories challenge the older theories, proposing alternative mechanisms

Muscles & MTJ Motion

• Pronators: Peroneus longus, brevis, tertius, extensor digitorum longus
• Supinators: Tibialis anterior, extensor hallucis longus, tibialis posterior, FHL and FDL (medial fibres of EDL may supinate)

Neurovascular Supply to MTJ

• Blood: Anastomosis from dorsalis pedis, medial, and lateral plantar arteries
• Nerves: Deep peroneal, medial, and lateral plantar nerves

Other Inter-tarsal Joints (Cuneonavicular, Cuboideonavicular, Intercuneiform and Cuneocuboid)

• Describe the anatomical features of these named inter-tarsal joints: articulations, synovial or fibrous classification, ligamentous attachments.

Intermetatarsal Joints

• Articulations between metatarsal bases
• Synovial, plane joints
• Connected by dorsal, plantar and interosseous ligaments

Tarsometatarsal Joints

• Articulations between tarsal and metatarsals (AKA Lisfranc's joint)
• Synovial, plane joints
• First joint has its own cavity (recessed 2nd joint).
• Connected by dorsal, plantar, and interosseous ligaments

Rays of the Forefoot

• 1st ray: Medial cuneiform and 1st metatarsal
• 2nd ray: Intermediate cuneiform and 2nd metatarsal
• 3rd ray: Lateral cuneiform and 3rd metatarsal
• 4th ray: 4th metatarsal only
• 5th ray: 5th metatarsal only

What are Rays?

• One or more bones acting together as a functional unit
• Example: 1st ray plantarflexes as one to assist in turning the foot into a rigid lever for propulsion
• 1st and 5th rays typically act independently.
• 2nd-4th rays often work together

Effects of Pronation

• STJ pronation results in MTJ unlocking (making the foot wibbly wobbly)
• Ground reaction forces push the 1st ray up (dorsiflexion) reducing 1st metatarsophalangeal joint ROM..
• Tibia internally rotates, unlocking the knee to allow quadriceps to absorb impact as knee flexes

Effects of Supination

• STJ supination locks the MTJ
• 1st ray plantarflexes, increasing ROM at 1st metatarsophalangeal joint
• 1st metatarsophalangeal joint extends to facilitate ‘normal’ gait
• Tibia externally rotates and knee locks

Metatarsophalangeal (MTP) Joints

• All MTP joints are similar
• 1st MTPJ slightly different

Metatarsophalangeal Joints 2

• Large, convex articular surface on metatarsal heads to allow extension/flexion.
• Articular surface of the proximal phalanx, smaller and concave.
• 1st MTPJ also articulates with sesamoids
• Synovial, condyloid joints
• Primarily flexion/extension; some abduction/adduction

Muscles that cross the MTPJs

• Hallux: EHL, EHB, EDB, FHB, FHL, ADH, ABH
• Lesser toes: EDL, EDB, FDL, FDB, PADs, DABs, Lumbricals, ABDM, FDMB in the 5th toe

Motions at MTPJs

• Muscles determine action at the joints
• Primarily extension/flexion
• Some abduction/adduction
• Negligible frontal plane rotation in normal foot

Ligaments of the MTPJs

• Tough fibrous capsule surrounds the joints
• Thickened sides for collateral ligaments
• Thickened plantar surface for plantar plates
• Hallux has intersesamoid, plantar sesamoid, and deep transverse metatarsal ligaments

Plantar Plates

• Lesser toes have plantar plates, which form part of fibrocartilagenous joint encapsulation.
• 1st toe also has a sesamoid apparatus within the flexor hallucis brevis tendon
• Provides attachment for plantar aponeurosis, flexor sheath, DTML and collateral ligaments as well as expansion for extensor expansion

Plantar MTPJs

• (Diagram) shows a fibrous capsule surrounding the joints. The plantar plate, the first plantar ligament, FHL, FHB and OADH are shown.

Neurovascular Supply - MTPJs

• Blood: Dorsal digital and plantar metatarsal & digital arteries feed the joints.
• Nerves: Dorsal digital, common, and proper plantar digital nerves supply the area.

Interphalangeal (IP) Joints

• Only 1 IPJ in 1st toe, 2 in other lesser toes
• Synovial, hinge joints
• Motion primarily flexion/extension; flexion typically more than extension
• Proximal interphalangeal joint (PIPJ) typically moves more than distal interphalangeal joint (DIPJ)

Muscles / Tendons that cross the IPJs

• Cross PIPJ: FDL, EDL, FDB, and EDB, and lumbricals (via the extensor expansion)
• Cross DIPJ: FDL, EDL, and lumbricals (via the extensor expansion)
• Cross hallux IPJ: EHL and FDL

Extensor Expansion

• Extensor tendons broaden and flatten in the foot.
• These tendons are thickened and form a fascial sheet surrounding the toes
• Central insertion into the intermediate phalanx, lateral insertion into the distal phalanx.

Flexor Sheaths

• Inferior surface of each toe covered in fascial thickening.
• Proximal end of the flexor tendons within synovial sheaths.
• Sheaths are thick over the phalanges, but thinner and more lax over the IPJs.

Flexor Tendons

• Flexor digitorum brevis splits, allowing the FDL to pass through to the distal phalanx.

Neurovascular Supply - IPJs

• Blood: Supplied by plantar and dorsal digital arteries
• Nerves: Proper plantar digital and dorsal digital nerves, with the nail supplied mainly by plantar nerves due to embryo development.