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Muscles Smooth muscle is the muscle of the internal organs and is called involuntary because it is not under voluntary control. The voluntary muscles are of three series: those more or less arranged around the axial skeleton (head, neck, and trunk), and those nonsegmentally arranged around the appendicular skeleton (arms and legs), and those associated with the visceral skeleton (brachiometric muscles). The stimulus for the muscle contraction begins in the cerebral cortex and passes down the spinal cord and the nerve root to the junction between the nerve fiber and the muscle surface. www.american.edu /adonahue/k14muscles.htm   (1491 words)

Muscle - Wikipedia, the free encyclopedia Skeletal muscle or "voluntary muscle" is anchored by tendons to bone and is used to affect skeletal movement such as locomotion and in maintaining posture. Cardiac muscle is the muscle tissue of the heart, and is similar to skeletal muscle in both composition and action, being comprised of myofibrils of sarcomeres. Deep muscles, superficial muscles, muscles of the face and internal muscles all correspond with dedicated regions in the primary motor cortex of the brain, directly anterior to the central sulcus that divides the frontal and parietal lobes. en.wikipedia.org /wiki/Muscle   (3147 words)

Skeletal muscle - Wikipedia, the free encyclopedia Muscles have an elongated, cylindrical shape, and are multinucleated (in vertebrates and flies). The nuclei of these muscles are located in the peripheral aspect of the cell, just under the plasma membrane, which vacates the central part of the muscle fiber for myofibrils. Skeletal muscles usually have one end (the "origin") attached to a relatively stationary bone, (such as the scapula) and the other end (the "insertion") is attached across a joint, to another bone (such as the humerus). en.wikipedia.org /wiki/Voluntary_muscle   (1393 words)

Muscles Striped muscle is the muscle (or meat) on you legs arms etc., you have direct control over these muscles and can make almost any movements which you want to. A pair of muscles, the biceps and triceps, are used to bend and straighten the elbow. This muscle is found in your intestines and in the iris of your eye. www.purchon.com /biology/muscles.htm   (799 words)

[No title]   (Site not responding. Last check: 2007-10-29) Muscle is composed of cells which are specialized to perform mechanical work through contraction. Smooth muscle contracts on an involuntary basis, and the contraction is slow. Muscle fibers are formed during embryogenesis by the fusion of myoblasts. www-personal.umich.edu /~shelden/muscle.html   (1294 words)

Human Physiology - Muscle Some muscles (skeletal muscles) will not contract unless stimulated by neurons; other muscles (smooth and cardiac) will contract without nervous stimulation but their contraction can be influenced by the nervous system. As a result, in a relaxed muscle, there is a very high concentration of calcium in the SR and a very low concentration in the sarcoplasm (and, therefore, among the myofibrils and myofilaments). Because of this arrangement, when skeletal muscle is viewed with a microscope, the ends of a sarcomere (where only thin myofilaments are found) appear lighter than the central section (which is dark because of the presence of the thick myofilaments). www.biology.eku.edu /RITCHISO/301notes3.htm   (2619 words)

Muscle Home Page Voluntary muscle cells are electrically isolated from each other, and respond only to direct instructions from a particular motor neurone via the motor end plate. As in nerves and skeletal muscle, the membrane potential in cardiac muscle is eventually restored to its resting value by a delayed efflux of positive potassium ions from the cells. Smooth muscle contraction speeds are very slow when compared with voluntary muscle, but it can achieve a much greater degree of shortening, and it is very economical to operate. www.bmb.leeds.ac.uk /illingworth/muscle   (3957 words)

Pelvic Floor Muscle Tension   (Site not responding. Last check: 2007-10-29) The coordinated interaction between the smooth muscle and voluntary muscle is essential for normal bladder and bowel function. An important distinction was made between the voluntary control characteristic of pelvic floor muscle, in contrast to the involuntary nature of the muscle of the rectum, colon and bladder. When we evacuate, we relax these muscles quickly and completely which cues the smooth muscle of the colon, rectum and bladder to propel feces or urine through the anal or urethral sphincters (the voluntary muscle which surrounds the urethra or anal canal). www.aboutincontinence.org /PelvicFloor.html   (2237 words)

Muscle in on Muscles Activity - Text Version - Virtual Astronaut Voluntary and Involuntary are the two types of muscles in your body. Skeletal muscle is typically attached to bones by tendons, a string-like tissue. Smooth muscle is found in the iris of the eye and in your intestines, among other places. virtualastronaut.jsc.nasa.gov /textonly/act21/text-muscleactivity.html   (404 words)

Voluntary Muscle, Muscle Tone and Posture Voluntary muscles allow us to throw the javelin, kick a football, swim, sprint and any other action where the joint angles change and the skeleton moves. Voluntary muscles also contract to maintain good posture when sitting, standing or moving. The muscles are always in a state of slight tension. www.teachpe.com /cloze/voluntary_muscle_muscle_tone_posture.htm   (452 words)

Spinal and Supraspinal Factors in Human Muscle Fatigue -- Gandevia 81 (4): 1725 -- Physiological Reviews Muscle fatigue is an exercise-induced reduction in maximal voluntary muscle force. Voluntary activation was measured in MVCs of thumb adduction on the left and right sides using twitch interpolation with supramaximal stimulation of the ulnar nerve at the wrist. Reduction in voluntary force and the increase in nerve- and cortically evoked twitches during a sustained MVC of elbow flexor muscles. physrev.physiology.org /cgi/content/full/81/4/1725   (10079 words)

Cardiac and skeletal muscle adaptations to voluntary wheel running in the mouse -- Allen et al. 90 (5): 1900 -- Journal ... Voluntary exercise resulted in a significant increase in IIa + IId/x MHC protein at 2 wk for the gastrocnemius muscle and at 2 and 4 wk for TA. Fiber percents for the gastrocnemius (A) and TA (B) muscles from exercised and nonexercised mice. Voluntary exercise decreases the progression of muscular dystrophy in diaphragm of mdx mice. jap.physiology.org /cgi/content/full/90/5/1900   (6214 words)

What is skeletal muscle?   (Site not responding. Last check: 2007-10-29) Skeletal muscle is usually attached to two bones, and thus a muscle contraction will move one bone relative to the other bone. At the neuromuscular junction between a motor neuron of the somatic nervous system and a skeletal muscle cell, a chemical known as a neurotransmitter is released when electrical events known as action potentials arrive in the motor neuron. The trigger for the inhibition of the inhibition of muscle contraction is the release of calcium ions into the cytoplasm of muscle fibers (cells). www.bergen.org /ACADEMY/Bio/molbio/MUSCLE/molbio5musclepic.html   (1173 words)

Voluntary muscle activation varies with age and muscle group -- Jakobi and Rice 93 (2): 457 -- Journal of Applied ... voluntary activation was an average of the attempts at MVC. There was a significant interaction (*P < 0.05) for muscle activation between age and muscle group (A) that resulted from a lower mean voluntary activation score in the old men compared with the young men in both muscle groups and from a difference between elbow flexion and extension activation in the old men. Muscle force, perceived effort, and voluntary activation of the elbow flexors assessed with sensitive twitch interpolation in fibromyalgia. jap.physiology.org /cgi/content/full/93/2/457   (4394 words)

Circulatory Responses to Voluntary and Electrically Induced Muscle Contractions in Humans -- Miller et al. 80 (1): 53 ... The effects of voluntary and electrically evoked muscle contractions on calf blood flow and vascular resistance. longus muscle (a plantar flexor muscle not innervated by the Skeletal muscle blood flow capacity: role of muscle pump in exercise hyperemia. www.ptjournal.org /cgi/content/full/80/1/53   (3597 words)

Voluntary muscle movments After close examination i have discoverd i can verticaly move my scrotum slightly by contracting a muscle which seems to be inbetween the muscles i use to stop mid-way through urinating and the muscle i use to contract my anal sphincter. I don't think muscle movements is totaly an evolutionary trait, i think they can be learned. i have no idea how it is possible, but i can flex some muscles somewhere around my head and i feel my middle ear vibrating and it sounds like im in the middle of an avalanche. www.physicsforums.com /showthread.php?p=252736   (500 words)

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