Ch. 9 & Ch. 10 Muscles and Muscle Tissues

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Anatomy & Physiology

tendon

a band of fibrous tissue that connects muscle to bone

aponeurosis

fibrous or membranous sheet connecting a muscle and the part it moves

Sarcolemma

plasma membrane of a muscle fiber

Sarcoplasm

cytoplasm of a muscle cell

myoglobin

a red pigment that stores oxygen; similar to hemoglobin (transports oxygen in blood)

sarcoplasmic reticulum

The smooth ER of a muscle cell, enlarged and specialized to act as a Ca2+ reservoir. The SR winds around each myofibril in the muscle cell.

neuromuscular junction or end plate

the junction between a nerve fiber and the muscle it supplies

synapse

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or cleft.

endomysium

fine areolar connective tissue surrounding each muscle fiber

epimysium

Sheath of fibrous connective tissue surrounding a muscle

perimysium

fibrous connective tissue that surrounds groups of muscle fibers called fascicles

origin

less moveable of the two bones is considered to be the starting point of the muscle

insertion

the end that moves when the muscle contracts

refractory period

(neurology) the time after a neuron fires or a muscle fiber contracts during which a stimulus will not evoke a response

rigor mortis

Cross bridge detachment requires ATP. 3-4 hours after death muscles begin to stiffen with weak rigidity at 12 hours post mortem. Dying cells take in calcium (the cross bridge fromation). BUT no ATP generated to BREAK CROSS BRIDGE

isometric contraction

contraction that results in development of muscular tension but results in no movement ( you push the car but car doesn't move) (muscle doesn't shorten or lengthen)

isotonic contraction

muscle length changes and moves a load

motor unit

A motor neuron and all the muscle fibers it stimulates

myogram

a graphical recording of muscle activity

(unfused) incomplete tetanus

further increase in stimulus...leads to a state of sustained fluttering contraction

(wave) temporal summation

Increased stimulus frequency (muscle does not completely relax btwn stimuli)...produces second contraction of greater force

complete tetanus

If stimuli are given quickly enough,muscle reaches maximal tension. One smooth sustained contraction. No relaxation. (like when someone has superhuman strength)

maximal stimulus

strongest stimulus that increases contractile force

threshold stimulus

stimulus strength causing first observable muscle contraction

Concentric contractions

Muscle shortens and does work

Eccentric Contractions

Muscle generates force as it lengthens

Muscle Tone

The state of partial contraction in a muscle, even when the muscle is not being used. Muscle tone does not produce active movements, but it keeps muscles firm, healthy and ready to respond to any situation

Aerobic endurance

The length of time a muscle can continue to contract using aerobic pathways

Anaerobic threshold

The point at which muscle metabolism converts to anaerobic glycolysis

Muscle Fatigue

is a state of physiological inability to contract even though the muscle still may be receiving stimuli

Oxygen debt or excess postexercise oxygen consumption (EPOC)

The extra amount of oxygen that the body must take in for a restorative process

contractures

lack in ATP; states of continuous contraction because the cross bridges are unable to detach. It's a permanent and often painful stiffening of a joint and muscle.

hypertrophy

increase in the size of tissue, such as muscle

atrophy

any weakening or degeneration (especially through lack of use)

calmodulin

calcium binding protein that regulates calcium in smooth muscle tissue

hyperplasia

abnormal increase in number of cells

aponeurosis

strong sheet of tissue that acts as a tendon to attach muscles to bone

myasthenia gravis

a chronic progressive disease characterized by chronic fatigue and muscular weakness (especially in the face and neck)

Fibromyositis

Also known as fibromyalgia. A group of conditions involving chronic inflammation of a muscle, its connective tissue coverings and tendon, and capsules of nearby joints. Symptoms are nonspecific and involve varying degrees of tenderness, as well as fatigue and sleeplessness.

Hernia

Protrusion of an organ through its body cavity wall. May be congenital (owing to failure of muscle fusion during development), but most often is caused by heavy lifting or obesity and subsequent muscle weakening.

Myalgia

Muscle pain resulting from any muscle disorder

Myofascial pain syndrome

Pain caused by a tightened bad of muscle fibers, which twitch when the skin over them is touched. Mostly associated with overused and strained postural muscles.

Myopathy

any disease of the muscle

Myostonic Dystrophy

A form of muscular dystrophy that is less common than DMD; in the US it affects about 14 of 100K ppl. Symptoms include a gradual reduction in muscle mass and control of the skeletal muscles, abnormal heart rhythm, and diabetes mellitus. May appear at any time; not sex-linked. Underlying genetic defect is multiple repeats of a gene on chromosome 19. Repeats increase each generation. Subsequent generations develop more severe symptoms. No effective treatment.

RICE

Acronym for Rest, Ice, Compression, and Elevation. The standard treatment for a pulled muscle, or excessively stretched tendons or ligaments.

Spasm

A sudden, involuntary twitch in smooth or skeletal muscle ranging from merely irritating to very painful. May be due to chemical imbalances. In spasms of eyelid or facial muscles, called ticks, psychological factors may be involved. Stretching and massaging may help. A cramp is a prolonged spasm, usually occurs at night or after exercise.

Strain

Commonly called a "pulled muscle." A strain is excessive stretching and possible tearing of a muscle due to muscle overuse or abuse. The injured muscle becomes painfully inflamed (myositis) and adjacent joints are usually immobilized.

Tetanus

(1) A state of strained contraction of a muscle that is a normal aspect of skeletal muscle functioning. (2) An acute infectious disease caused by the anaerobic bacterium Clostridium tetani and resulting in painful spasms of some skeletal muscles. Progresses to fixed rigidity of the jaws (lockjaw) and spasms of trunk and limb muscles. Usually fatal due to respiratory failure.

prime mover or agonist

muscle that has the principal responsibility for a given movement

antagonists

muscles that oppose or reverse a movement. Usually helps regulate action of prime mover. Resistance.

synergist

Muscle that aids the prime mover by adding a little extra force or reducing undesirable movements that might occur as the Prime mover contracts.

fixator

muscle that immobilizes one or more bones, gives prime mover stable base on which to act.

Sphincters

circular muscle that surrounds a tube such as the urethra and constricts the tube when it contracts

fusiform muscles

spindle-shaped with a central belly that tapers to tendons on each end; allos them to focus their power onto small, bony targets; ex. bracialis, biceps brachii

pennate muscle

A muscle with fibers that align obliquely with the tendon, creating a featherlike arrangement.

Charley horse

a muscle contusion. ie. tearing of muscle followed by bleeding into the tissue (hematoma) and severe, prolonged pain. A common contact sport injury; football players frequently suffer a charley horse of the quadriceps (muscle of the thigh)

Electromyography

Recording and interpretation of graphic records of the electrical activity of contracting muscles. Electrodes inserted into the muscles record the impulses that pass over muscle-cell membranes to stimulate contraction.

Hernia

An abnormal protrusion of abdominal contents (typically coils of the small intestine) through a weak point in the muscles of the abdominal wall. Most often caused by increased intraabdominal pressure during lifting or straining. The hernia penetrates the muscle wall, but not the skin and so appears as a visible bulge in the body surface. Common abdominal hernias include the inguinal and umbilical hernias.

Quadriceps and hamstring strains

Also called quad and hamstring pulls, these conditions involve tearing these muscles or their tendons; happen mainly in athletes who do not warm up properly and then fully extend their hip (qad pulls) or knee (hamstring pull) quickly or forcefully (e.g., sprinters, tennis players). Not painful at first, but pain intensifies within three to six hours (30 minutes if the tearing is severe). After a week of rest, stretching is the best therapy

Ruptured calcaneal tendon

Although the calcaneal (achilles) tendon is the largest, strongest tendon in the body, its rupture is surprisingly common, particularly in older people as a result of stumbling and in young sprinters when the tendon is traumatized during takeoff. The rupture is followed by abrupt pain; a gap is seen just above the heel, and the calf bulges as the triceps surae are released from their insertion. Plantar flexion is weak or impossible, but dorsiflexion is exaggerated. Usually repaired surgically.

Shin splints

Common term for pain in the anterior compartment of the leg caused by irritation of the tibialis anterior muscle as might follow extreme or unusual exercise without adequate prior conditioning. Because it is tightly wrapped by fascia, the inflamed tibialis anterior cuts off its own circulation as it swells and presses painfully on its own nerves.

Tennis elbow

Tenderness due to trauma or overuse of the tendon of origin or the forearm extensor muscles at the lateral epicondyle of the humerus. Caused and aggravated when these muscles contract forcefully to extend the and at the wrist--as in executing a tennis backhand or lifting a loaded snow shovel. Despite its name, tennis elbow does not involve the elbow joint; most cases caused by work activities.

Torticollis

A twisting of the neck in which there is a chronic rotation and tilting of the head to one side, due to injury of the sternocleidomastoid muscle on one side; also called wryneck. Sometimes present at birth when muscle fibers are torn during difficult delivery. Exercise that stretches the affected muscle is the usual treatment.

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