1. The tibiofibular joint is a synovial joint between the lateral condyle of the tibia and the head of the fibula. Note this joint.

2. Note that the tibia and fibula are joined by the interosseous membrane. Clean the surfaces of this membrane.

3. Next examine the tibiofibular syndesmosis. Clean the anterior and posterior tibiofibular ligaments, and examine them.

Ankle Joint

Review the tendons in relation to this joint and define the capsule which is thin in front and behind.

1. Note on the medial side the attachment of the medial (deltoid) ligament which fans out from the medial malleolus of the tibia to the navicular bone, plantar calcaneonavicular ligament, neck of talus, sustentaculum tali of the calcaneus and to the body of the talus.

2. Identify on the lateral side the anterior talofibular, calcaneofibular and posterior talofibular ligaments.

3. Cut through the calcaneal tendon, the capsule and ligaments. Separate the foot from the leg and examine the articular surfaces.

4. Observe that the superior (trochlear) articular area of the talus is wider in front. This helps to lock the ankle joint in dorsiflexion.

5. Examine the tibiofibular mortise and also the interosseous ligament of the inferior tibiofibular joint.

Arches of the Foot

1. Identify the medial and lateral longitudinal arches of the foot, bearing in mind that the differences in the heights of the medial and lateral arches are a reflection of their functional differences.

2. Observe that the calcaneus forms the posterior pillar while the heads of the metatarsals form the anterior pillar.

3. The transverse arch is obvious across the bases of the metatarsal bones. This forms only half an arch.

4. Try to understand the part played by the following in the maintenance of the arches:

(a)bony configuration;

(b) ligaments, particularly the plantar ligaments;

(c) long tendons and the intrinsic muscles of the foot; and

(d) plantar aponeurosis (the central part).

Joints of the Foot

1. Clean and define the various dorsal and plantar ligaments by removing the muscles and tendons of the foot. Note that the ligaments on the dorsum of the foot are weak while those on the plantar surface are thick and strong.

2. On the plantar surface, examine the long plantar ligament stretching between the plantar surface of the calcaneus, the tuberosity of the cuboid and the adjacent bases of the lateral three metatarsal bones thus bridging the fibularis longus tendon. Cut this ligament and define the plantar calcaneocuboid ligament which lies deep to the long plantar ligament.

Subtalar Joint

Clean the capsule and the medial and lateral talocalcanean ligaments of the subtalar joint on the medial and lateral sides of the foot respectively. Cut the ligaments.

Talocalcaneonavicular Joint

1. On the plantar surface, clean the important plantar calcaneonavicular (spring) ligament of the talocalcaneonavicular joint. Note that this ligament stretches between the sustentaculum tali of the calcaneus and the plantar surface of the navicular. Cut the ligament and verify that it contains a cartilaginous facet articulating with the head of the talus.

2. Open the joint on the dorsum and medial side and examine the strong interosseous talocalcanean ligament which extends between the neck of the talus and the upper anterior part of the calcaneus. This ligament is important in inversion and eversion of the foot. Cut the ligament in order to free the talus.

Calcaneocuboid Joint

Note the capsule. Open the joint on its dorsum and observe the corresponding articular surfaces. What strong ligaments lie beneath this joint?

Transverse Tarsal Joint

1. Note that the transverse tarsal joint is formed by the talocalcaneonavicular and calcaneocuboid joints which lie in the same transverse plane. What movements are possible at these joints?

2. Note the presence of plantar, dorsal and interosseous ligaments in relation to the other smaller joints of the foot. Metatarsophalangeal and Interphalangeal Joints

1. Examine the capsule and the thickened plantar and collateral ligaments at the metatarsophalangeal and interphalangeal joints. Cut the capsules on the dorsal surface and examine the articular surfaces.

2. Examine the four deep transverse metatarsal ligaments that unite the plantar ligaments of the adjoining metatarsophalangeal joints. These ligaments hold the metatarsal heads together. Dorsal to the ligaments are the interosseous muscles, whereas the lumbricals and digital nerves and vessels are on the plantar surface.

Summary

The ankle joint is a hinge joint in which the range of plantar flexion is greater than dorsiflexion. In addition, there is some degree of side to side movement possible in the plantar flexed position. Since the line of weight falls in front of the ankle joint, there is a tendency for the tibiofibular mortise to slide forwards on the trochlear surface of the talus. This is resisted by the strongest posterior parts of the medial and lateral ligaments which are directed downwards and backwards. During dorsiflexion, the widest anterior part of the trochlea comes in contact with the narrowest, posterior part of the tibiofibular mortise. As a result, no side to side movement is possible. It must be appreciated that the foot serves as a propulsive organ during locomotion and as a supporting pedestal during weight bearing. Consequently, the foot is constructed so as to meet these demands. The foot possesses longitudinal and transverse arches. The medial longitudinal arch is higher and more suited for propulsive efforts, whereas the lateral arch is flattened and suited for weight bearing. The transverse arch runs across the distal parts of the tarsals and bases of the metatarsals. Each foot forms only half of the transverse arch, the other half being completed by the opposite foot. The transverse arch helps in both propulsion and weight transmission. The bones moiety contribute to the formation of the arches of the foot, while the maintenance of these arches depends on:

(a) intersegmental ties, i.e. ligaments extending between adjacent bones, as well as ties between anterior and posterior pillars;

(b) tendons passing under the highest point of the arch and supporting it from below; and

(c) tendons which suspend the arches from above. In addition, the muscles of the sole act as extensile ligaments. Since the foot is also an organ which can adapt itself while walking along uneven surfaces, some degree of mobility must be permitted between the bones of the foot without, however, weakening its main functions of support and propulsion. In this connection the amount of movement, i.e. inversion and eversion, permitted at the subtalar and midtarsal joints must be comprehended. It must also be noted that inversion is maximal during plantar flexion and eversion during dorsiflexion of the foot. The association of eversion with dorsiflexion of the foot is perhaps due to the fact that the evertors were originally a part of the extensor group. This also explains their common nerve supply.