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194 Cards in this Set
- Front
- Back
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anatomical position
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The body is standing erect, face forward, arms at the sides, palms forward.
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anatomy
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The science which studies the structure of an organism.
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anterior/ventral
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Toward the front of the body.
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cell
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The simplest unit of living matter that can maintain life & reproduce itself.
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coronal/frontal
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A lengthwise plane running from side to side dividing the body or any of its parts into anterior & posterior sections.
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distal
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Away from or furthest from the trunk or the point of origin of a part.
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homeostasis
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A state of equilibrium in which the internal environment of the body remains relatively constant.
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inferior/caudal
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Toward the foot end of the body - away from the head.
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kinesiology
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The science which studies the movement of muscles.
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lateral
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Toward the side of the body - away from the midline.
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medial
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Toward the midline of the body.
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midsaggital
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A lengthwise plane running from front to back dividing the body or any of its parts equally into right & left halves.
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organs
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An organization of several different kinds of tissues so arranged that together they can perform a special function.
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physiology
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The science which studies the function of an organism.
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posterior/dorsal
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Toward the back of the body (in humans).
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proximal
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Toward the nearest the trunk of the body or the point of origin of a particular part.
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sagittal
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A lengthwise plane running from front to back dividing the body or any of its parts into right & left sides.
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superior/cranial
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Toward the head end of the body.
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systems
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An organization of varying numbers & kinds of organs so arranged that together they can perform complex functions for the body.
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tissues
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An organization of a great many similar cells & varying amounts & kinds of non-living intercellular substances between them.
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transverse
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A crosswise plane dividing the body or any of its parts into upper & lower sections.
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dorsal cavity
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Contains the cranial cavity, which houses the brain, and the spinal cavity, which contains the spinal cord. This cavity is bounded by the cranial & spinal bones. (All cavities are bounded by membranes).
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ventral cavity
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Consists of the thoracic chest cavity & the abdominopelvic cavity.
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thoracic or chest cavity
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Contains a right & left pleural cavity & mid-portion called the mediastinum. A fibrous tissue wall around the mediastinum separates it from the right pleural sac, which houses the right lung, & the left pleural sac, which houses the left lung. The only organs not located in the mediastinum are the: heart, trachea, right & left bronchi, esophogus, thymus, & various blood vessels, the thoracic duct, & other lymphatic vessels, various lymph nodes, & nerves. The thoracic cavity is bounded by the sternum, spine, ribs, & diaphragm. The diaphragm separates the thoracic cavity and the abdominal cavity.
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abdominopelvic cavity
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Comprises of an upper abdominal portion & a lower pelvic portion, extending from the diaphragm to the floor of the pelvis. The abdominal cavity contains the liver, gallbladder, stomach, pancreas, intestines, spleen, & uterus. The pelvic cavity, enclosed by the pelvic bones, contains the bladder, certain reproductive organs (uterus, uterine tubes & ovaries in the female; prostate gland, seminal vesicles & par of vas deferens in the male), terminal end of the large intestine (sigmoid colon), and rectum. NOTE: The kidneys are not located within a cavity. They are retoperitoneal - located behind the peritoneum.
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cell
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The smallest structure capable of maintaining life and reproducing. The outermost limit of the cell is the plasma membrane. This protein & lipid structure functions to maintain the wholeness of the cell & serves as a gateway through which chemicals may enter & leave. This membrane is selectively permeable, allowing some substances to pass while excluding others. The cytoplasm is the semi-fluid substance between the surface of the cell & its nucleus. Within the sytoplasm are membranes, which perform specific functions necessary for cell survival, known as organelles.
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endoplasmic reticulum
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Interconnected membranes with spaces between them forming canals; has opening to the outside of the cell & is connected to certain other organelles & to the nuclear membrane.
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ribosomes
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Responsible for the synthesis of protein molecules.
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golgi apparatus
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Responsible for the synthesis of carbohydrate molecules for export from the cell.
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mitochondria
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Energy source of the cell. ATP synthesis. "Powerhouse of the cell." Present in great numbers in muscle tissue.
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lysosomes
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Capable of breaking down & digesting molecules of protein & carbohydrates when their enzymes are released. White blood cells have a great number of them.
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centrioles
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Help form a spindle that appears during mitosis (cell division).
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cell nucleus
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Directs the activities of the cell; contains relatively large quantities of DNA.
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microvilli
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Tiny hair-like projections of the cytoplasmic membrane located only in the small intestine to facilitate absorption by increasing surface area.
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cilia
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Small hair-like projections of the cytoplasmic membrane located in the respiratory system acting to propel mucous upward.
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flagella
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A single projection, such as found on a sperm cell allowing for propulsion of that cell.
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passive transport systems
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A system in which movement occurs that does not require a direct expenditure of cellular energy.
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diffusion
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Process by which molecules or ions scatter or spread themselves from regions of higher concentration to regions of lower concentration. They move continuously, rapidly, in all directions.
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osmosis
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The diffusion of water (or any fluid) through a selectively permeable membrane. Their concentration on both sides of the membrane eventually becomes equal.
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filtration
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The physical process by which water & solutes pass through a membrane when a hydrostatic pressure is greater on one side of the membrane than the other. (Hydrostatic pressure is the force or weight of a fluid pushing against some surface.)
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dialysis
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The diffusion of solutes through a selectively permeable membrane. It is the process where smaller molecules are separated from larger ones in a liquid.
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active transport system
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Requires the use of ATP (energy). "Uphill" movement through a cell membrane, from an area of lower concentration to an area of higher concentration.
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permease system
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Cell (Ion) Pump. Movement of molecules or ions against a concentration gradient. (i.e. Sodium-Potassium Pump.)
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pinocytosis
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Cell Drinking. Process by which cells engulf tiny droplets of liquid from their surroundings.
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phagocytosis
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Cell Eating. Process by which cells engulf solid particles, such as bacteria & cellular debris.
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epithelial tissues
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Covers the body, organs, & surfaces, which are exposed to the outside as well as lining cavities. Serves as a protective barrier. Cells are packed closely together with very littler intercellular material between them. Avascular - contains no blood vessels. Specializes in moving substances into & out of the blood (absorption & secretion). The cells undergo rapid division (mitosis), a fact of practical importance, so that old or destroyed epithelial cells can be replaced by new ones.
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connective tissue
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Most abundant & widely distributed in the body. Good structural material. Contains relatively few cells & a lot of matrix. Functions to support the body & its parts, to connect & hold them together, to transport substances through the body & to protect it from foreign invaders.
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general characteristics of connective tissue
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Intercellular material predominates in most connective tissues & determine their physical characteristics; consists of fluid, gel, or solid matrix, with or without fibers (collagenous, reticular, & elastic). It connects muscles to muscles, muscles to bones, & bones to bones.
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reticular
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Sheet-like (web-like) network of cells. Associated with the linings of blood vessels in the bone marrow, liver, spleen, & lymph nodes.
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areolar
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(Glue) Widely distributed; composed of fibers in a loose, sticky gel & used to hold adjoining structures together.
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adipose
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Consists of fat tissue to protect, insulate, & cushion internal organs.
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bone
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Most rigid of the connective tissues due to the presence of mineral salts such as calcium phosphate & calcium carbonate; also contains a considerable amount of collagen. Hard & calcified.
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cartilage
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"Gristle". Plastic-like material composed largely of fibers & a protein called chordrin. Functions to support parts, provide frameworks & attachments, & to protect underlying tissues.
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hemopoietic
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Formation of blood & lymphatic cells in the red marrow cavities of bones. Important in the defense against disease.
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blood
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Vascular tissue. Cells are suspended in a liquid intercellular matrix called plasma.
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dense fibrous
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Consists mainly of bundles of fibers arranged in parallel rows in a fluid/gel matrix. It contains relatively few fibroblast cells. This tissue is flexible but very strong. It composes tendons & ligaments. Bundles of collagenous fibers endow tendons with great tensile strength & non-stretchability, desirable characteristics for those structures that anchor our muscles & bones. In ligaments, however, bundles of elastic fibers predominate. Hence, ligaments exhibit some degree of elasticity. Examples of dense fibrous connective tissue include: tendons, ligaments, aponeurosis, deep fascia, scar, and capsule of kidney.
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muscle tissue
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Specializes in movement & has the ability to contract. Moves the body & its parts. There are three types of muscle tissue: skeletal, cardiac, & visceral. On the basis of nervous control, muscle is considered either voluntary or involuntary.
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skeletal muscle
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Attached to bones. It is under voluntary control & its fibers are striated (alternating light & dark cross-markings producing visible lines or striae).
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cardiac muscle
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Composes the walls of the heart. It is involuntary & striated. At the end of the cell, where it touches another cell, is a band called an intercalated disc, which only occurs in cardiac tissue.
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visceral muscle
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In the walls of hollow internal structures such as blood vessels, intestines, uterus, stomach, urinary bladder, & many others. It is involuntary & smooth. It does not contain striations.
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nervous tissue
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Specializes in rapid communication between various parts of the body & in integration of their activities. It is found in the brain, spinal cord, & associated nerves. The basic cells of this tissue are called neurons, which transmit impulses along cytoplasmic extensions to other neurons, muscles, or glands. In addition to neurons, nerve tissue contains neuroglia, which function to support, insulate, bind, and protect the neuron.
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membranes
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Constitute a special class of organs in that they are thin sheets of tissues covering or lining various parts of the body. Of the numerous membranes in the body, five kinds are discussed: mucous, serous, synovial, fascial, and cutaneous (skin).
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mucous membranes
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Contain epithelial cells which line cavities or passageways of the body that open to the exterior, such as the lining of the mouth & entire digestive tract, the respiratory passages, and the genitourinary tracts. It consists, as do serous and cutaneous membranes, of a surface layer of epithelial tissue over a deeper layer of connective tissue. Mucous membranes perform the functions of protection (against microbial invasion), secretion (of mucous), and absorption of water, salts, and other solutes.
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serous membranes
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Contain epithelial cells that line the closed cavities of the body, those that do not open to the exterior. The serous membrane which lines the thoracic cavity is called pleura, that which lines the abdominal cavity is called peritoneum, and that which lines the sac in which the heart lies is called the pericardium. It also covers the organs lying in these spaces. The term visceral layer is applied to the part of the membrane that covers the organs, whereas that which lines the cavity is called the parietal layer. Between the two layers, there is a potential space kept moist by a small amount of serous fluid. When an organ moves against the body wall, (as the lungs do in respiration or when the heart beats in its serous sac), friction between the moving parts is reduced. The mechanical principle that moving parts must have lubricated surfaces is thereby carried out in the body.
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synovial membranes
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Contain connective tissue cells that line joint capsules, tendon sheaths, and bursa. Its smooth, moist surfaces also protect against friction.
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fascial membranes
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Contain connective tissue cells and a semi-liquid, gel-like ground substance. Fascia covers, supports, and separates muscles and may be superficial, subcutaneous or deep.
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cutaneous (skin) membranes
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Contain epithelial cells and are composed of two main layers, the superficial and thinner layer known as the epidermis, and the deeper and thicker layer known as the dermis. The epidermis contains melanocytes which produce melanin (basic determinant of skin color), and keratinocytes, which produce keratin (fibrous waterproof protein). The dermis is composed largely of fibrous connective tissue, which includes tough white collagenous fibers & yellow elastin fibers. This gives the dermis its strength and elasticity. The dermis also contains structures like: hair, nails, glands, sebaceous glands, sweat glands, and ceruminous glands.
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hair
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The part of the hair that is visible is the shaft, whereas that which is embedded in the dermis is the root. The root, together with its coverings (an outer connective tissue sheath & an inner epithelial coating that is a continuation of the stratum germinativum), forms the hair follicle. At the bottom of the follicle is a loop of capillaries enclosed in a connective tissue covering called the hair papilla.
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nails
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Produced by layers of specialized epithelial cells that are continuous with the epithelium of the skin. The keratin they contain is harder than that formed in the epidermis and hair follicles.
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glands
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Consist of epithelial cells specialized for synthesizing compounds which they secrete into either ducts or blood. Endocrine glands secret into blood capillaries, and exocrine glands secrete into ducts that open on the surface of the epithelium.
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sebaceous glands
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Secrete oil for the hair. Wherever hairs grow from the skin, there are at least two sebaceous glands for each hair. The oil or sebum secreted by these tiny glands has value not only because it keeps the hair supple, but it also keeps the skin soft & pliant. Moreover, it prevents excessive water evaporation from the skin and water absorption through the skin. Because fat is a poor conductor of hear, the sebum lessens the amount of heat lost from this large surface.
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sweat glands
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Although very small structures, they are very important and very numerous, especially on the palms, soles, forehead, and axillae (armpits). Histologists estimate, for example, that a single square inch of skin on the palms of the hands contains about 3,000 sweat glands. Sweat secretion helps maintain homeostasis of fluid & electrolytes & body temperature. In as much as sweat contains some nitrogenous wastes, they also function as excretory organs. Apocrine glands are numerous in the armpits & groin, whereas eccrine glands are common on the forehead, neck, and back where they produce profuse sweating on hot days and during physical exercise.
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ceruminous glands
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Thought to be modified sweat glands. They are located in the external ear canal. Instead of watery sweat, they secrete a waxy, pigmented substance called cerumen.
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skeletal system
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Bones are the organs of the skeletal system. These organs, which are composed of several kinds of tissues, are classified according to their shapes & the ways they develop. Since they are rigid structures, bones provide support & protection for softer tissues, & they act together with skeletal muscles to make body movements possible. They also serve to manufacture blood cells & to store inorganic salts. The shapes of individual bones are closely related to their functions. Projections provide places for the attachments of muscles, tendons, and ligaments; openings serve as passageways for bloods vessels, and nerves and the ends of bones, are modified to articulate with other bones at joints.
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axial skeleton
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Consists of the skull, hyoid bones, vertebral column & thoracic cage.
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appendicular skeleton
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Consists of the pectoral girdle, arms, pelvic girdle & legs.
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long bones
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Bones of the upper and lower arm (humerus, ulna), of the thigh and leg (femur, tibia, & fibula), & of the fingers & tows (phalanges). Consists of the following structures: diaphysis, epiphysis, articular cartilage, periosteum, medullary (marrow) cavity, & endosteum.
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diaphysis
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The main shaft-like portion. Its hollow, cylindrical shape & thick compact bone, which composes it, adapts the diaphysis well to its function of providing strong support without cumbersome weight. Contains the medullary cavity, which is filled with marrow.
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epiphysis
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Expanded portion at the end of each long bone, which articulates or forms a joint with another bone. Their shape is somewhat bulbous. This provides generous space for muscle attachments near joints & gives joints greater stability. Like a sponge, it is permeated by innumerable small spaces, hence its name spongy or concellous bone. Because of the porous nature of this bone, & because the epiphyses have only a thin outer layer of dense, compact bone, they are lightweight structures for their size. Marrow fills the spaces of cancellous bone (yellow marrow in most adult epiphyses, but red marrow in the proximal epiphyses of the humerus & femur).
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articular cartilage
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The thin layer of hyaline cartilage that covers the articular or joint surfaces of the epiphysis. The resiliency of this material cushions jars & blows.
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periosteum
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A tough covering of dense, white fibrous tissue that covers the bone except at joint surfaces, (where articular cartilage forms the covering). The periosteum is vascular and well innervated. Many of its fibers penetrate the underlying bone, welding these two structures to each other. (The penetrating fibers are called Sharpey's fibers.) Muscle tendon fibers interlace with periosteal fibers anchoring muscles firmly to bone. The periosteum contains many small blood vessels and numerous osteoblasts (bone-forming cells), in the inner layer of growing bones. Because its blood vessels send branches into the bone, the periosteum is essential for the nutrition of bone cells and therefore for their survival. Because of its osteoblasts, it is essential for both growth and repair of bones.
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short bones
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Wrist & ankle bones (carpals & tarsals).
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flat bones
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Certain bones of the cranium (frontals, occipital, & parietals), sternum, ribs, scapula, & pelvis.
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irregular bones
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Bones of the spinal column (vertebrae, sacrum, coccyx), and certain bones of the skull (sphenoid, ethmoid, & mandible).
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sesamoid/round bones
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They are usually small & occur within tendons adjacent to joints. (patella; distal end, inferior surface of 1st metatarsal).
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bony landmarks
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Projections of bone that are sites for muscle attachments & help to form joints. Depressions & openings in bone allowing blood vessels & nerves to pass.
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tuberosity
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Large, rounded projection may be roughened.
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tubercle
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Small, rounded knob-like process (supraglenoid tubercle of the scapula).
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trochanter
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Very large, blunt, irregular process only on femur.
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crest
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Narrow ridge of bone, usually prominent (iliac crest of ilium).
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line
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Narrow ridge of bone, less prominent than a crest (linea aspera of the posterior femur).
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epicondyle
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Raised area on or above a condyle.
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spine
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Sharp, slender, often pointed projection.
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malleolus
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Medial & lateral projections at the distal ends of the tibia & fibula (i.e. anklebones).
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process
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A prominent projection on a bone (i.e. mastoid process of the temporal bone).
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head
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bony expansion carried on a narrow neck; an enlargement on the end of a bone that usually articulates with another bone (i.e. head of the humerus).
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facet
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Smooth, nearly flat articular surface (i.e. costal facet of a thoracic vertebra).
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condyle
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Rounded process that usually articulates with another bone (i.e.) occipital condyle).
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ramus
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Arm-like bar of bone (i.e.ramus of the mandible).
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suture
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A line of union between bones (i.e. lambdoidal suture between the occipital & parietal bones).
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meatus
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A tube like passageway within a bone (i.e. auditory meatus).
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sinus
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Cavity within a bone, filled with air & lined with mucous membrane.
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fossa
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Shallow, basin-like depression in a bone, often serving as an articular surface.
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groove
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Furrow in bone (i.e. bicipital groove).
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fissure
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Narrow, slit-like opening.
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foramen
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Round or oval opening through a bone that usually serves as a passageway for blood vessels, nerves, or ligaments (i.e. foramen magnum of the occipital bone).
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five functions of bones
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Support, protection, movement, reservoir (storage), & hemopoiesis.
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support
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Bone serve as the supporting framework of the body much as steel girders function as the supporting framework of buildings.
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protection
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Hard, bony "boxes" protect delicate structures enclosed by them. (i.e. the skull protects the brain, and the rib cage protects the lungs & heart.)
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movement
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Bones with their joints constitute levers. Muscles are anchored firmly to bones. As muscles contract & shorten, force is applied to the bony levers and movement results.
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reservoir (storage)
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Bones serve as the major reservoir into which calcium is deposited, or from which it is withdrawn as needed to maintain the homeostasis of blood calcium, a vitally important condition.
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hemopoiesis
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The process of blood cell formation. Tissues that carry on this process are specialized connective tissues of two kinds, myeloid tissue and lymphatic tissue. (Red bone marrow is another name for myeloid tissue.) In the adult, it is only found in a few bones in the sternum and ribs, in the bodies of the vertebrae, in the diploe of the cranial, bones, and in the proximal epiphyses of the femur and humerus. Red marrow occurs in many more bones in newborn infants and children. Because it forms blood cells, red bone marrow is one of the most important tissues of the body. Its very location, hidden in the bones like valuables in a safety deposit box, suggests its vital importance.
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skeletal system articulations
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Articulations or joints are junctions between bones. They are classified according to the amount of movement they make possible.
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synarthroses
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Occur between bones that come into close contact with one another. A thin layer of fibrous tissue separates the bones at these joints. No active (very slight) movement takes place. (i.e. the suture between a pair of flat bones of the cranium.)
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amphiarthroses
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Slightly movable joints. They are connected by discs of cartilage. (i.e. between the ribs & sternum, the vertebrae in the vertebral column, and the symphysis pubis.)
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diarthroses
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Freely movable joints. The ends of bones are held together by a joint capsule composed of an outer layer of ligaments and an inner layer of synovial membrane, which secretes synovial fluid to act as a joint lubricant. For this reason, freely movable joints are also called synovial joints. This is our most numerous type of joint.
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joint capsule
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Sleeve-like extension of the periosteum of each of the articulating bones. The capsule completely encases the ends of the bones and binds them to each other.
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synovial membrane
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Moise, slippery membrane that lines the inner surface of the joint capsule. It attaches to the margins of the articular cartilage and secretes synovial fluid, which lubricates the inner joint surfaces.
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articular cartilage
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Hyaline cartilage that covers and cushions the articulating ends of the bones.
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joint cavity
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Small space between the articulating surfaces of the two bones of a joint. Because of this cavity with no tissue growing between the articulating surfaces of the bones, the bones are free to move against one another.
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ligaments
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Strong cords of dense, white, fibrous tissue at most synovial joints. These grow between the bones, lashing them even more firmly together than possible with the joint capsule alone.
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ball & socket joints (multiaxial)
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Those in which a ball-shaped head of one bone fits into a concave socket of another bone (i.e. the shoulder and hip joints). Of all the joints in our bodies, the ball & socket joints permit the widest range of movements, namely flexion, extension, abduction, adduction, rotation, & circumduction.
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ellipsoidal joints (multiaxial)
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Those in which an oval-shaped condyle fits into an elliptical socket. The radius joins the carpal bones (scaphoidlunate and triquetrum) by means of an ellipsoidal joint, which permits the movements of flexion & extension of the hand in one axis and movement of abduction and adduction in another axis. This is known as biaxial movement. Note: Next to the ball & socket joints, ellipsoidal joints allows the widest range of movements. (also known as condyloid joints)
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saddle joints (biaxial)
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Like ellipsoidal joints, permit biaxial movements, The shapes of the articulating ends of the bones, however, differ in the two types of joints. In the saddle join, a saddle-shaped surface of one bones fits into a saddle-shaped surface of another bone. Only one pair of saddle joints exists in the body, one in each hand between the metacarpal and carpal bones of the thumb called the trapezium. These are deservedly famous joints, at least to anatomists. They make possible the great mobility of the human thumbs. We can flex, extend, abduct, and adduct them. But most importantly of all, we can oppose them (i.e. move out thumbs to touch the tip of any one of our fingers). If we did not have a saddle joint at the base of each thumb, we could not oppose the thumb and would be unable to do such simple things as picking up a pin or grasping a pencil between the thumb and forefinger.
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hinge joints (uniaxial)
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Permit only flexion and extension movements, which might be called hinged-door movements (i.e. bending the elbow).
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pivot joints (uniaxial)
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Those in which a small projection of one bone pivots in an arch of another bone, causing the first bone to rotate on its axis. There are two pivot joints in the body, one between the first two cervical vertebrae (atlas & axis), & the other between the proximal ends of the radius & ulna.
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gliding joints (uniaxial)
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Allow only the simplest type of motion, specifically, a little gliding back and forth or sideways. These include most of the joints between both the carpal and tarsal bones, and also all of the joints between the articular processes of the vertebrae (includes: facet type joints).
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flexion
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Decreases the size of the angle between the anterior surfaces of articulating bones. (Exception: flexion of the knee and the joints decrease the angle between the posterior surfaces of the articulated bones.) Flexing movements are bending or folding movements (i.e. bending the head forward is flexion of the joint between the occipital bone and the atlas; bending the elbow is flexion of the elbow joint or of the lower arm). Flexing movements of the arms and legs may be thought of as "withdrawing" movements.
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lateral flexion
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Decreasing the size of the angle between the lateral surfaces of the body (i.e. lateral flexion of the trunk brings the trunk closer to the hip).
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extension
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The return from flexion. Increases the size of the angle between articulating bones. Extension restores a part to its anatomical position form the flexed position. Examples of extension would include: returning the head to its upright anatomical position from its flexed, bent forward position; unbending the elbow thus returning the forearm to tis anatomical position. Continuation of extension beyond anatomical position is called hyperextension. Hyperextension of the head would be stretching it backward from the upright position; of the arm, bringing the humerus straight back behind the body.
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abduction
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Moves a bone away from the midline of the body (i.e. moving the arms straight out to the sides).
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adduction
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Moves a bone toward the midline of the body (i.e. bringing the arms back to the sides).
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horizontal adduction
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Moves a bone toward the midline of the body at a horizontal level (i.e. raising the humerus and bringing it across the chest).
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rotation
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The pivoting of a bone on its own axis somewhat as a top turns on its axis (i.e. holding the head in an upright position and turning it from one side to the other).
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inversion
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Turns the sole of the foot inward.
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eversion
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Turns the sole of the foot outward.
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circumduction
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Causes the bone to describe the surface of a cone as it moves. The distal end of the bone describes a circle. It combines flexion, abduction, extension, and adduction in succession (i.e. describing a circle with the arms outstretched).
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supination
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Movement of the forearm that turns the palm forward, as it is in anatomical position (adduction + inversion = supination of the foot).
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pronation
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Turning the forearm so as to bring the back of the hand forward, palms down (abduction + eversion = pronation of the foot).
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elevation
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Raising a part (i.e. shrugging the shoulders).
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depression
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Lowering a part (i.e. drooping the shoulders).
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protraction
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Moving a part forward (i.e. thrusting the chin forward).
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retraction
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Moving a part backward (i.e. pulling the chin backward).
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muscular system
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Muscles, the organs of the muscular system, account for nearly half of the body weight. They consist largely of muscle cells, which have become differentiated into contractile units and can be stimulated by the actions of certain nerve cells to contract. There are three types of muscle tissue: skeletal, cardiac, and visceral.
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anatomy of skeletal muscle
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Skeletal muscle is usually fastened to bones. Its fibers are striated and under voluntary control.
Composed of nerve, vascular, and various connective tissues as well as striated muscle tissue. Each fiber represents a single muscle cell, which is the unit of contraction. Muscle fibers are cylindrical cells with numerous nuclei and are grouped into bundles by fascia. The protein myofilaments (actin & myosin) within a muscle cell contract towards each other causing movement. Calcium and ATP are necessary for this action. Striations cross-bands, are produced by the arrangement of the actin & myosin filaments. Muscle fibers are stimulated to contract by motor neurons. The area of contact between a muscle fiber and nerve is known as the motor end-plate or neuro-muscular junction. ATP supplies the energy for muscle fiber contraction. Muscle cells contain a great many mitochondria. |
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three general functions of skeletal muscle
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Movement, heat production, & posture.
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movement
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Skeletal muscle contractions produce movement either of the body as a whole or of its parts (i.e. walking, talking, breathing, shallowing, facial expressions).
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heat production
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Muscle cells, like all cells, produce heat by the process known as catabolism (the break down of larger molecules into smaller ones). Because skeletal muscle cells are both highly active and numerous, they produce a major share of total body heat. Skeletal muscle contractions, therefore, constitute one of the most important parts of the mechanism for maintaining homeostasis of temperature.
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posture
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The continued partial contraction of many skeletal muscles makes possible standing, sitting, & other maintained positions of the body.
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types of muscular contractions
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Tonic, isotonic, isometric, fibrillation, twitch, & tetanic.
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tonic (tone)
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A continual, partial contraction. At any one moment a small number of the total fibers in a muscle contract, producing tautness of the muscle rather than a recognizable contraction & movement.
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isotonic
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(iso = same; tonic = tone, pressure, or tension) A contraction in which the tone or tension within a muscle remains the same, but the length of the muscle changes, producing movement and doing work.
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concentric
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Muscle contraction in which the muscle fibers shorten (i.e. flexion of the elbow in lifting a weight).
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eccentric
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Muscle contraction in which the muscle fibers lengthen with resistance (resistance of flexors in extension of elbow when lowering a weight).
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isometric
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(iso = same; metric = measurement) A contraction in which muscle length remains the same, but in which muscle tension increases. The muscle will tighten, but will not produce movement or do work (i.e. pushing your arm against a wall and feeling the tension increase in your arm muscle).
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fibrillation
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An abnormal type of contraction in which individual fibers contract asynchronously, producing a flutter of the muscle but no effective movement (i.e. fibrillation of the heart occurs fairly often).
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twitch
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A single quick, jerky muscular contraction from a single nerve impulse followed by relaxation.
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tetanic
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A continuous, forceful muscular contraction arising from a series of at least 30 nerve impulses per second. (also known as a spasm or cramp)
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threshold stimulus
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Minimal stimulus needed to elicit a muscular contraction.
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all-or-none response
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If a muscle fiber (cell) contracts at all, it will contract completely (all the way).
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prime mover
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The muscle or muscles whose contraction is mainly responsible for a particular body movement.
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antagonist
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The muscle or muscles that relax while the prime mover is contracting to produce the movement (exception: contraction of the antagonist at the same time as the prime mover when some part of the body needs to be held rigid, such as the knee joint when standing.)
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synergist
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Muscle or muscles that contract at the same time as the prime mover. They may help the prime mover produce its movement or stabilize a part, hold it steady, so that the prime mover produces a move effective movement.
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fixator (stabilizer)
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The muscle or muscles responsible for stabilizing the non-movable part of a joint so other muscles can contract to produce a certain movement (i.e. the shoulder joint being held immobile while the biceps are contracting to flex the forearm).
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neutralizer
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Counteracts the action of another muscle to prevent undesirable movements.
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tendon
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A strong, tough cord of white fibrous connective tissue that connects a muscle to a bone. It is continuous with the fibrous covering of bone, (periosteum) and fascia of muscle. The fibrous wrapping of a muscle may extend as a broad, flat sheet of connective tissue known as an aponeurosis, to attach it to adjacent structures, usually the fibrous wrappings of another muscle.
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bursae
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Small connective tissue sacs lined with synovial membrane and containing synovial fluid. Bursae are located wherever pressure is exerted over moving parts (i.e. between skin and bone, between tendons and bone, between muscles and bones, or ligaments and bone). They act as cushions, relieving pressure between moving parts. Some bursae that fairly frequently become inflamed (bursitis) are as follows: subacromial bursa, between the head of the humerus and the acromion process and the deltoid muscle; olecranon bursa, between the olecranon process of the ulna and the skin; prepatellar bursa, between the patella and the skin. Inflammation of the pre-patellar bursa is known as housemaid's knee, whereas olecranon bursitis is called student's elbow.
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trapezius origin
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Occipital bone C7-T12 (spinous processes)
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trapezius inertion
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Clavicle & scapula
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trapezius action
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Elevation, upward rotation & retraction of scapula. Extends head when occipital acts as insertion.
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serratus anterior origin
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Outer surface of upper 8 ribs
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serratus anterior insertion
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Scapula
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serratus anterior action
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Pulls shoulder forward; protracts & rotates it upward. Stabilizes scapula against chest wall.
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pectoralis major origin
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Clavicle, sternum, & costal cartilage of upper 6 ribs
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pectoralis major insertion
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Humerus (bicipital groove)
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pectoralis major action
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Flexes upper arm; adducts upper arm anteriorly; draws it across chest. (Horizontal adduction.) Medial rotation of humerus.
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pectoralis minor origin
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Anterior 3, 4, & 5 ribs
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pectoralis minor insertion
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Scapula (coracoid)
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pectoralis minor action
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Pulls shoulder down and forward. Abducts scapula.
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latissimus dorsi origin
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Aponeurosis from T7 to iliac crest, lower 3 or 4 ribs, inferior angle of the scapula
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latissimus dorsi insertion
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Humerus (bicipital groove)
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latissimus dorsi action
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Extends upper arm; adducts upper arm posteriorly; medial rotation of arm.
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teres major origin
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Scapula
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teres major insertion
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Humerus (bicipital groove)
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teres major action
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Assists latissimus dorsi in extension, adduction, and medial rotation of arm.
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deltoid origin
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Clavicle & scapula
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deltoid insertion
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Humerus (bicipital groove)
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deltoid action
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Abducts upper arm; assists flexion & medial rotation of humerus.
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levator scapula origin
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C1-C4
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levator scapula insertion
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Scapula
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levator scapula action
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Elevation & downward rotation of scapula.
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rhomboids origin
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C7-T5
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rhomboids insertion
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Scapula
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rhomboids action
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Retraction & downward rotation of scapula.
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