Along its course, the anterior tibial artery supplies numerous branches to adjacent muscles and is joined by the perforating branch of the fibular artery, which passes forward through the lower aspect of the interosseous membrane from the posterior compartment of the leg.
Distally, the anterior tibial artery gives rise to an anterior medial malleolar artery and an anterior lateral malleolar artery, which pass posteriorly around the distal ends of the tibia and fibula, respectively, and connect with vessels from the posterior tibial and fibular arteries to form an anastomotic network around the ankle.
Deep veins follow the arteries and have similar names.
The nerve associated with the anterior compartment of the leg is the deep fibular nerve (Fig. 6.94). This nerve originates in the lateral compartment of the leg as one of the two divisions of the common fibular nerve.
The deep fibular nerve passes anteromedially through the intermuscular septum that separates the lateral from the anterior compartments of the leg and then passes deep to the extensor digitorum longus. It reaches the anterior interosseous membrane where it meets and descends with the anterior tibial artery.
The deep fibular nerve: innervates all muscles in the anterior compartment; then continues into the dorsal aspect of the foot where it innervates the extensor digitorum brevis, contributes to the innervation of the first two dorsal interossei muscles, and supplies the skin between the great and second toes.
The foot is the region of the lower limb distal to the ankle joint. It is subdivided into the ankle, the metatarsus, and the digits.
There are five digits consisting of the medially placed digits, ending laterally with the little toe (digit V) (Fig. 6.95).
The foot has a superior surface (dorsum of foot) and an inferior surface (sole; Fig. 6.95).
Abduction and adduction of the toes are defined with respect to the long axis of the second digit. Unlike in the hand, where the thumb is oriented 90° to the other fingers, the great toe is oriented in the same position as the other toes. The foot is the body’s point of contact with the ground and provides a stable platform for upright stance. It also levers the body forward during walking.
There are three groups of bones in the foot (Fig. 6.96): the seven tarsal bones, which form the skeletal framework for the ankle; metatarsals (I to V), which are the bones of the metatarsus; and the phalanges, which are the bones of the toes—each toe has three phalanges, except for the great toe, which has two.
The tarsal bones are arranged in a proximal group and a distal group with an intermediate bone between the two groups on the medial side of the foot (Fig. 6.96A).
The proximal group consists of two large bones, the talus (Latin for “ankle”) and the calcaneus (Latin for “heel”):
The talus is the most superior bone of the foot and sits on top of and is supported by the calcaneus (Fig. 6.96B)—it articulates above with the tibia and fibula to form the ankle joint and also projects forward to articulate with the intermediate tarsal bone (navicular) on the medial side of the foot.
The calcaneus is the largest of the tarsal bones—posteriorly it forms the bony framework of the heel and anteriorly it projects forward to articulate with one of the distal group of tarsal bones (cuboid) on the lateral side of the foot.
The talus, when viewed from the medial or lateral sides, is snail-shaped (Fig. 6.97A,B). It has a rounded head, which is projected forward and medially at the end of a short broad neck, which is connected posteriorly to an expanded body.
Anteriorly, the head of the talus is domed for articulation with a corresponding circular depression on the posterior surface of the navicular bone. Inferiorly, this domed articular surface is continuous with an additional three articular facets separated by smooth ridges: