Foot

Pes

Definition

The foot serves as the terminal part of the limb responsible for bearing weight and enabling locomotion. Its skeletal structure comprises three main components: the tarsus, metatarsus, and phalanges.

Tarsus:

  • The tarsus consist of seven bones: the talus (forming the ankle joint superiorly), calcaneum (heel bone), navicular (medial bone), cuboid (lateral bone), and three cuneiform bones (medial, intermediate, and lateral).

  • Intertarsal joints exist between these tarsal bones, including the subtalar, talocalcaneonavicular and calcaneocuboid joints.

  • The subtalar joint, among the intertarsal joints, facilitates foot inversion and eversion movements.

Metatarsus:

  • The metatarsus is composed of five metatarsal bones, one for each digit.

  • Tarsometatarsal joints, found between the metatarsal and tarsal bones, allow limited gliding movements.

  • Metatarsophalangeal joints are connect metatarsal heads with the proximal phalanges, enabling flexion and extension.

Phalanges:

  • Each digit, except the big toe, contains three phalanges. The interphalangeal joints in these digits allow mainly for flexion and extension.

Arches of the foot:

The bones of foot form horizontal and longitudinal arches, supported and maintained by long tendons of leg muscles and ligaments within the foot. The arches absorb the downward force from body weight and serve as weight-bearers.

Muscles of the foot:

Foot muscles can be categorized as extrinsic or intrinsic:

  • Extrinsic muscles originate from the leg bones (tibia, fibula) and insert into the foot. Their long tendons are held in place by deep fascial thickenings called retinacula, maintaining their position relative to the ankle bones.

  • Intrinsic muscles of the foot originate and insert within the foot itself. The extensor digitorum brevis is the only intrinsic muscle located on the dorsum of the foot, while all other intrinsic muscles are situated within the sole of the foot. These muscles modulate the actions of the long tendons of extrinsic muscles and produce intricate toe movements.

Vasculature and innervation:

(A)-Sole of the foot:

  • The neurovasculature of the sole consists of the medial and lateral plantar vessels and nerves. These vessels arise from the posterior tibial vessels, while the nerves are branches of the tibial nerve.

(B)-Dorsum of the foot:

  • The dorsum of the foot is innervated by the superficial and deep peroneal nerves, with contributions from the saphenous and sural nerves on the medial and lateral sides.

  • The dorsalis pedis artery is the continuation of anterior tibial artery on the dorsum of foot.

  • A superficial dorsal venous arch is present, giving rise to the great and small saphenous veins on the medial and lateral sides of the foot, respectively.

Text by Antoine Micheau, MD and reviewed by Muhammad A. Javaid, MD, PhD © 2023 IMAIOS.

  • Drake, R.L., Vogl, A.W. and Mitchell, A.W.M. (2009). ‘Chapter 6: Lower Limb’ in Gray’s anatomy for Students. (2nd ed.) Philadelphia PA 19103-2899: Elsevier, pp.605-616.

  • MacGregor, R. and Byerly, D.W. Anatomy, Bony Pelvis and Lower Limb: Foot Bones. [Updated 2022 May 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557447/


Comparative anatomy in animals

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