Joints of the Ankle and Foot

Tibiofibular joints | Main Anatomy Index | The foot

The Talocrural Joint (ankle joint)

• This is a hinge type of synovial joint.
• It is located between the inferior ends of the tibia and fibula and the superior part of the talus.
• The talocrural joint can be felt between the tendons on the anterior surface of the ankle as a slight depression, about 1 cm proximal to the tip of the medial malleolus.

Articular Surfaces of the Talocrural Joint (p. 488)

• The inferior ends of the tibia and fibula form a deep socket or box-like mortise into which the pulley-shaped trochlea of the talus fits.

• The two malleoli and the inferior end of the tibia form the three-sided mortise.
• The fibula has an articular facet on its lateral malleolus, which faces medially and articulates with the facet on the lateral surface of the talus.

• The tibia articulates with the talus in two places: (1) its inferior surface forms the roof of the mortise, which is wider anteriorly than posteriorly; and (2) the lateral surface of its medial malleolus articulates with the talus.

• The talus has three articular facets, which articulate with the inferior surface of the tibia and malleoli.
• The trochlea of the talus is wider anteriorly than posteriorly and slightly concave side to side.

Movements of the Talocrural Joint (p. 488)

• The talocrural joint is uniaxial; its main movements are dorsiflexion and plantarflexion.

• When the foot is plantarflexed, some rotation, abduction, and adduction of the ankle joint is possible.
• This occurs as in plantarflexion, the trochlea of the talus rocks anteriorly in the three-side mortise. Since the anteriorly it is not as wide, there is considerable room for the ankle to move.

• During dorsiflexion the trochlea of the talus rocks posteriorly in the three-sided mortise, and the malleoli are forced apart because the superior articular surface of the talus is wider anteriorly than posteriorly.
• The separation of the malleoli requires some movement of the proximal tibiofibular joint. Thus, the range of plantarflexion is greater than that of dorsiflexion, but there is considerable variation in these movements.

Articular Capsule of the Talocrural Joint (p. 488)

• The fibrous capsule is thin anteriorly and posteriorly, but it is supported one each side by strong collateral ligaments (medial or deltoid and lateral ligaments).

• It is attached superiorly to the borders of the articular surfaces of the tibia and malleoli.
• It is attached inferiorly to the talus close to the superior articular surface, except anteroinferiorly, where it is attached to the dorsum of the neck of the talus.

The Medial or Deltoid Ligament (p. 488)

• This strong ligament attaches the medial malleolus to the tarsus (tarsal bones).

• The apex of the ligament is attached to the margins and tip of the medial malleolus.
• Its broad base fans out and attaches to three tarsal bones (talus, navicular, and calcaneus).

• The deltoid ligament consists of four parts, which are named according to their bony attachments: (1) tibionavicular, (2) and (3) anterior and posterior tibiotalar, and (4) tibiocalcanean ligaments.
• They strengthen the joint and hold the calcaneus and navicular bones against the talus. In addition, they help to maintain the medial side of the foot against the longitudinal arch.

The Lateral Ligament of the Ankle (pp. 488-9)

• On the lateral side of the ankle there are three ligaments that attach the lateral malleolus to the talus and calcaneus.
• These are not as strong as the medial ligament.

• The three distinct parts of the lateral ligament are the anterior and posterior talofibular ligaments and the calcaneofibular ligaments.

• The anterior talofibular ligament is a flat band that extends anteromedially from the lateral malleolus to the neck of the talus. It is not very strong.
• The posterior talofibular ligament is thick and fairly strong. It runs horizontally medially and slightly posteriorly from the malleolar fossa to the lateral tubercle of the posterior process of the talus.
• The calcaneofibular ligament is a round cord that passes posteroinferiorly from the tip of the lateral malleolus to the lateral surface of the calcaneus. It is crossed superficially by the tendons of the fibularis (peroneus) longus and brevis muscles.

The Synovial Capsule of the Talocrural Joint (p. 489)

• The synovial capsule of the ankle joint lines the fibrous capsule and occasionally projects superiorly for a short distance into the inferior tibiofibular ligament between the tibia and fibula.
• The synovial cavity of the ankle joint is somewhat superficial on each side of the tendo calcaneus. Hence, when the ankle joint is inflamed, the synovial fluid may increase, causing swelling in these locations.

Stability of the Talocrural Joint (pp. 489-90)

• This joint is very strong during dorsiflexion because it is supported by powerful ligaments and it is crossed by several tendons that are tightly bound down by thickenings of the deep fascia called retinacula.
• The stability is also greatest in dorsiflexion because in this position the trochlea of the talus fills the mortise formed by the malleoli. Furthermore, the anterior part of the trochlea forces the malleoli of the leg bones apart slightly.

Blood Supply of the Talocrural Joint (p. 490)

• The articular arteries are derived from the malleolar branches of the fibular (peroneal) and anterior and posterior tibial arteries.

Nerve Supply of the Ankle Joint (p. 490)

• The articular nerves are derived from the tibial nerve and the deep fibular (peroneal) nerve, a division of the common fibular (peroneal nerve).

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The Subtalar (talocalcanean) Joint (p. 490-1)

• The subtalar (talocalcanean) joint is distal to the ankle joint where the talus rests on and articulates with the calcaneus.
• The subtalar joint is a synovial joint between the inferior surface of the body of the talus and the superior surface of the calcaneus.

• It is surrounded by an articular capsule, which is attached near the margins of the articular facets.
• The fibrous capsule is weak but it is supported by medial, lateral and posterior talocalcanean ligaments.
• In addition, it is supported anteriorly by the interosseous talocalcanean ligament.

Movements of the Subtalar (talocalcanean) Joint (p. 491)

• Inversion and eversion are the main movements that occur at this joint.
• The joint also permits slight gliding and rotation that assist with inversion and eversion of the posterior part of the foot.

• Movements of the subtalar (talocalcanean) joint are closely associated with those at the talocalcaneonavicular and calcaneocuboid joints (parts of the transverse tarsal joint).

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The Talocalcaneonavicular Joint (p. 491)

• This joint is located where the head of the talus articulates with the socket formed by the posterior surface of the navicular bone, the superior surface of the plantar calcaneonavicular ligament ("spring ligament"), the sustentaculum tali, and the articular surface of the calcaneus.

• The talocalcaneonavicular articulation is a synovial joint of the ball and socket type.
• The ball is the head of the talus and the socket comprises two bones and two ligaments.
• The head of the talus has three facets, one for the navicular and two for the calcaneus.

• All these articular surfaces are surrounded by a single articular capsule that blends with the interosseous talocalcanean ligament posteriorly.
• The talocalcaneonavicular joint is reinforced dorsally by the dorsal talonavicular ligament, a broad band connecting the neck of the talus and the dorsal surface of the navicular bone.

• The plantar calcaneonavicular ligament ("spring ligament") is a triangular band that extends from the sustentaculum tali to the posteroinferior surface of the navicular bone.
• This ligament blends with the deltoid ligament medially and forms part of the socket for the head of the talus.
• It also plays an important role in maintaining the longitudinal arch of the foot.

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The Calcaneocuboid Joint (p. 491)

• This is a synovial joint between the anterior surface of the calcaneus and the posterior surface of the cuboid.
• It is part of the transverse tarsal joint.

• The dorsal calcaneocuboid ligament and plantar calcaneocuboid ligament (short plantar ligament) strengthen the capsule of the calcaneocuboid joint.

• The long plantar ligament covers the plantar surface of the calcaneus. It passes from the plantar surface of the calcaneus, including its anterior and posterior tubercles, to both lips of the groove on the cuboid bone.
• Some of its fibres extend to the bases of the second, third, and fourth metatarsal bones, thereby forming a tunnel for the tendon of the fibularis (peroneus) longus muscle.
• This muscle passes though the groove in the cuboid bone to insert into the bases of the first metatarsal and the adjoining part of the medial cuneiform bone.
• The long plantar ligament is important in maintaining the arches of the foot.

• The plantar calcaneocuboid ligament (short plantar ligament) is deep to the long plantar ligament. It extends from the anterior aspect of the inferior surface of the calcaneus to the inferior surface of the cuboid.

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The Transverse Tarsal Joint (p. 491-2)

• This joint is the talonavicular joint and the calcaneocuboid joint.
• These are separate joints but together they constitute the transverse tarsal joint or mid-tarsal joint.
• They extend across the tarsus in almost the same transverse plane.

Movements of the Transverse Tarsal Joint

• Movements occurring at this joint produce inversion and eversion of the foot.

• During inversion, the foot is adducted and directed so that its medial border is raised and its lateral border is depressed, i.e., the sole of the foot is directed towards the medial plane.
• In eversion, the foot is abducted and directed so that the lateral border is raised and the medial border is depressed, i.e., the sole of the foot is directed away from the median plane.

• The strong medial (deltoid) ligament tends to prevent overeversion of the foot; the weaker lateral ligaments (with the assistance of the fibularis (peroneus) longus and brevis muscles) tend to prevent overinversion of the foot.

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