Human Anatomy - Kotsan I. Ya. 2009

Skeleton of the Lower Limb
Joints of the Bones of the Leg

The BONES OF THE leg are connected to each other by interrupted joints (synovial joints or articulations) and continuous joints (syndesmoses, such as ligaments and interosseous membranes) (Fig. 82).

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Fig. 82. Connections of the leg bones: tibiofibular joint, interosseous membrane, tibiofibular syndesmosis (right, anterior view)

1 — Tibia, 2 — anterior tibiofibular ligament, 3 — Fibula, 4 — interosseous membrane, 5 — anterior ligament of the fibular HEAD

The proximal ends of the leg bones are connected to each other by the tibiofibular joint.

The tibiofibular joint (articulatio tibiofibularis) is formed by the articular surface of the head of the fibula and the fibular articular surface of the tibia. The Joint Capsule is tightly stretched and attached to the margins of the articular surfaces. The joint cavity sometimes communicates with the cavity of the knee joint. Anteriorly, the capsule is reinforced by the anterior ligament of the fibular head (lig. capitis fibulae anterius), and posteriorly by the posterior ligament of the fibular head (lig. capitis fibulae posterius). The joint is simple, plane, and has limited mobility (small gliding movements are possible).

The shafts of the leg bones are connected by the interosseous membrane of the leg (membrana interossea cruris), which attaches to the interosseous borders of the tibia and fibula. In its upper and lower parts, the membrane has apertures for Blood Vessels and nerves.

The distal ends of the leg bones are connected by the tibiofibular syndesmosis (syndesmosis tibiofibularis), which is formed by numerous short Connective Tissue fibers. Anteriorly, the syndesmosis is reinforced by the anterior tibiofibular ligament (lig. tibiofibulare anterius), and posteriorly by the posterior tibiofibular ligament (lig. tibiofibulare posterius), both located between the lateral malleolus and the tibia. Occasionally, the synovial membrane of the ankle joint protrudes into the tibiofibular syndesmosis, in which case an inferior tibiofibular joint is formed.

The leg is connected to the FOOT by means of the ankle joint (Fig. 83).

Fig. 83. Joints and ligaments of the right foot (section through the ankle joint)

1 — ankle joint, 2 — talocalcaneonavicular joint, 3 — calcaneocuboid joint, 4 — transverse tarsal joint, 5 — bifurcated ligament, 6 — cuneonavicular joint, 7 — tarsometatarsal joints, 8 — dorsal tarsometatarsal ligament, 9 — metatarsophalangeal joints, 10 — interphalangeal JOINTS OF THE foot, 11 — subtalar joint

The ankle joint (articulatio talocruralis) is formed by the inferior articular surface of the tibia, the articular surfaces of the medial and lateral malleoli, and the articular surfaces of the trochlea of the talus. Together, the tibia and fibula form a mortise that grips the trochlea of the talus. The joint capsule of the ankle joint is attached almost everywhere to the margins of the articular surfaces, except anteriorly, where it extends slightly away from them. On the sides, the joint capsule is strong and thick, whereas anteriorly and posteriorly it is thin and loose, forming folds.

Fig. 84. Medial (deltoid) ligament of the ankle joint (right)

1 — joint capsule, 2 — medial (deltoid) ligament

Fig. 85. Ligaments and joints of the right foot (dorsal surface)

1 — medial malleolus, 2 — ankle joint, 3 — medial (deltoid) ligament (tibionavicular part), 4 — talonavicular ligament, 5 — bifurcated ligament, 6 — dorsal cuneonavicular ligaments, 7 — joint capsule of the first metatarsophalangeal joint, 8 — joint capsule of the interphalangeal joint of the great toe, 9 — collateral ligaments, 10 — metatarsophalangeal joint of the fourth digit, 11 — dorsal metatarsal ligaments, 12 — dorsal tarsometatarsal ligaments, 13 — dorsal cuneocuboid ligament, 14 — interosseous talocalcaneal ligament, 15 — lateral talocalcaneal ligament, 16 — calcaneofibular ligament, 17 — lateral malleolus, 18 — anterior talofibular ligament, 19 — anterior tibiofibular ligament, 20 — interosseous membrane of the leg

The joint is reinforced by ligaments located on its medial and lateral sides. On the medial side of the joint lies the medial (deltoid) ligament (lig. mediale (deltoideum)), which is triangular in shape and extends from the medial malleolus to the navicular, talus, and calcaneus bones (Fig. 84). It comprises four parts: the tibionavicular part (pars tibionavicularis), the tibiocalcaneal part (pars tibiocalcanea), the anterior tibiotalar part (pars tibiotalaris anterior), and the posterior tibiotalar part (pars tibiotalaris posterior). On the lateral side, the ankle joint is reinforced by three ligaments: the anterior talofibular ligament (lig. talofibulare anterius), which connects the lateral malleolus to the neck of the talus; the posterior talofibular ligament (lig. talofibulare posterius), which extends from the lateral malleolar fossa to the lateral tubercle of the talus; and the calcaneofibular ligament (lig. calcaneofibulare), which runs downward and backward from the lateral malleolus to the lateral surface of the calcaneus (Fig. 85).

The ankle joint is a compound, hinge (ginglymus), uniaxial joint. Movements around the frontal axis are possible in the joint: plantarflexion (bending the foot toward the sole) and dorsiflexion (bending the foot toward the dorsum). In addition, when the foot is flexed, slight side-to-side movements are possible because the narrower posterior part of the trochlea of the talus enters the crural mortise during flexion.

One of the Characteristic Features of the ankle joint is that in adults it possesses greater mobility toward the plantar surface, whereas in children, especially newborns, it is more mobile toward the dorsum of the foot, which is associated with the specifics of its development.