Structure and Functions (Magill’s Medical Guide, Sixth Edition)
The lower extremities consist of the thighs, lower legs, and feet. Each extremity attaches to the pelvis (innominate bone) at the hip joint. The lower extremity is made mostly of bones and muscles, but it also contains blood vessels, lymphatics, nerves, skin, toenails, and other structures. Important directional terms for the lower extremity include proximal (closer to the base or attached end), distal (further from the base or attached end), medial (on the same side as the tibia and big toe), and lateral(on the same side as the fibula and little toe). Along the foot, the lower surface is called plantar; the upper surface is called dorsal. The lower extremity is clothed in skin (or integument). The sole or plantar surface of the foot is unusual, along with the palm of the hand, in being completely hairless; it also contains the thickest outer skin layer (the stratum corneum) of any part of the body. Each toe has a hardened toenail on its dorsal surface.
The pelvic girdle that supports the lower extremity develops as three separate bones: the ilium, ischium, and pubis. All three help form the acetabulum, a socket into which the femur fits. Below the acetabulum, the ischium and pubis surround a large opening called the obturator foramen. The right and left pubis meet to form a pubic symphysis. The bones of the lower extremity include the femur, tibia, fibula, tarsals, metatarsals, and phalanges. The femur (thigh bone)...
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Disorders and Diseases (Magill’s Medical Guide, Sixth Edition)
Many medical conditions and disorders affect the lower extremity; these include animal bites (including snakebites), injuries, fungus infections such as athlete’s foot, contact dermatitis (including poison ivy), and an assortment of neuromuscular disorders, including nerve paralyses, muscular atrophies, and muscular dystrophies. Nerve paralyses of the lower extremities usually arise from traumatic injury.
Muscular atrophies are diseases in which muscle tissues become progressively weaker and smaller, usually beginning after the age of forty. Spastic movements sometimes occur. The small muscles of the hands and feet are usually affected sooner and more severely in comparison to the larger muscles of the legs and thighs. Amyotrophic lateral sclerosis (ALS), commonly known as Lou Gehrig’s disease, is one such disease that usually begins with weakness and deterioration of the distal muscles. The disease proceeds to affect the rest of the extremities, then other parts of the body; it is usually fatal within three to five years after onset. A more rare type of atrophy, myelopathic muscular atrophy (or Aran-Duchenne atrophy), affects both upper and lower extremities and eventually spreads to the trunk. A degenerative lesion of the gray matter in the cervical region of the spinal cord is usually responsible.
Muscular dystrophy is a series of inherited diseases that begin in early childhood, affecting males more...
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Perspective and Prospects (Magill’s Medical Guide, Sixth Edition)
The major muscles and bones of the lower extremities were studied in ancient societies by such individuals as Galen (or Caius Galenus), the physician to the Roman army in the second century. Ironically, the science of anatomy took many great strides because of the efforts of artists, who studied the human body in order to create realistic sculptures and paintings. During the Renaissance, Leonardo da Vinci (1452-1519) and Michelangelo (1475-1564) dissected human corpses illegally in their quest for this knowledge. Andreas Vesalius (1514-1564) produced the first well-illustrated anatomical texts, containing information that corrected many of the errors made by Galen.
Injuries to the leg are generally treated surgically. Whenever possible, broken bones are set in place, immobilized in a cast, and then allowed to heal. Muscles (or their tendons) must be sewn together. Nerve endings must be matched with their former locations if they are to grow back correctly. Gangrene, or tissue death from lack of circulation, occurs more often in the lower extremities than in the upper extremities. When the lower extremity is gangrenous or is injured beyond repair, an amputation is often performed. Artificial legs or partial legs are sometimes attached to the lower extremity.
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For Further Information: (Magill’s Medical Guide, Sixth Edition)
Agur, Anne M. R., and Arthur F. Dalley. Grant’s Atlas of Anatomy. 12th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2009. Excellent, detailed illustrations can be found in this standard reference work.
Crouch, James E. Functional Human Anatomy. 4th ed. Philadelphia: Lea & Febiger, 1985. A good beginning reference for an introduction to anatomy. This easy-to-read book provides clear explanations.
Currey, John D. Bones: Structures and Mechanics. 2d ed. Princeton, N.J.: Princeton University Press, 2006. Very accessible overview of a range of information related to whole bones, bone tissue, and dentin and enamel. Topics include stiffness, strength, viscoelasticity, fatigue, fracture mechanics properties, buckling, impact fracture, and properties of cancellous bone.
Marieb, Elaine N. Essentials of Human Anatomy and Physiology. 9th ed. San Francisco: Pearson/Benjamin Cummings, 2009. This text discusses the functional significance of various anatomical structures, including the foot. Readers will enjoy the excellent pictures and diagrams of the foot and associated body parts.
Rosse, Cornelius, and Penelope Gaddum-Rosse. Hollinshead’s Textbook of Anatomy. 5th ed. Philadelphia: Lippincott-Raven, 1997. Helpful descriptions and illustrations mark this thorough, detailed reference source.
Standring, Susan, et al., eds....
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