Part 3: The lower limb
The lower limb consists of four major parts: a girdle formed by the hip bones, the thigh, the leg, and the foot. It is specialized for the support of weight, adaptation to gravity, and locomotion. In descriptions of the lower limb, it is customary to include regions that are transitional between the limb and the trunk, especially the gluteal and inguinal regions.
The following Latin words (given with their English equivalents) are the basis of many anatomical terms, e.g., femoral artery, sural nerve, calcaneus, and extensor hallucis: Membrum (limb), inguen (groin), natis or clunis (buttock; gloutos is a corresponding Greek word), coxa (hip; ischion is a corresponding Greek word), femur (thigh), genu (knee), crus (leg), sura (calf), talus (ankle), pes or pedis (foot), calx (heel), planta (sole), digiti pedis (toes), and hallux or hallucis (big toe).
The limb buds appear in the embryo at four weeks, the upper about two days before the lower. At first the limbs show a similar arrangement, with pre-axial and postaxial borders at seven weeks (see figs. 8-10 and 15-11). During fetal life, changes (generally termed the "rotation of the limbs") occur so that walking on the soles (plantigrade) will become possible later on. The big toes are then medial. Each limb possesses a girdle and a subsequent skeletal segment (humerus in the upper limb, femur in the lower limb). More distally are several pre-axial elements: radius (tibia); lunate and scaphoid (talus and navicular); trapezium, trapezoid, and capitate (cuneiforms); and metacarpals (metatarsals) 1 to 3. Postaxial components include the ulna (fibula), triquetrum (calcaneus), hamate (cuboid), and metacarpals (metatarsals) 4 and 5.
Additional reading
Castaing, J., and Soutoul, J. H., Atlas de coupes anatomiques. I. Membre superieur. II. Membre inferieur, Maloine, Paris, 1967. Interesting didactic drawings of cross sections.
Frazer's Anatomy of the Human Skeleton, 6th ed., rev. by A. S. Breathnach, Churchill, London, 1965. A detailed synthesis of skeletal and muscular anatomy arranged regionally. A classic.
Haymaker, W., and Woodhall, B., Peripheral Nerve Injuries: Principles of Diagnosis, 2nd ed., W. B. Saunders Company, Philadelphia, 1953. Detailed, illustrated account, including tests of muscular actions. Important reference.
Henry, A. K., Extensile Exposure, 2nd ed., Livingstone, Edinburgh, 1957. Excellent account of applied anatomy.
Lockhart, R. D., Living Anatomy, 6th ed., Faber & Faber, London, 1963. Photographs showing muscles in action.
Medical Research Council, Aids to the Examination of the Peripheral Nervous System, H.M.S.O., London, 1976. Brief and valuable, including tests of muscular actions.
Royce, J., Surface Anatomy, Davis, Philadelphia, 1965. Photographs and key drawings of the living body.