Presentation on theme: "THE MUSCULAR SYSTEM. Characteristics of muscles 1. 1. Muscle cells are elongated (muscle cell = muscle fiber) 2. 2. Contraction of muscles is due to."— Presentation transcript:
THE MUSCULAR SYSTEM
Characteristics of muscles Muscle cells are elongated (muscle cell = muscle fiber) Contraction of muscles is due to the movement of microfilaments All muscles share some terminology Prefix myo refers to muscle Prefix mys refers to muscle Prefix sarco refers to flesh
The Muscular system Muscles are responsible for all types of body movement Three basic muscle types are found in the body 1. 1.Skeletal muscle 2. 2.Cardiac muscle 3. 3.Smooth muscle
Skeletal muscle Most are attached by tendons to bones Cells are multinucleate Striated – have visible banding Voluntary – subject to conscious control Cells are surrounded and bundled by connective tissue Sites of muscle attachment – –Bones – –Cartilages – –Connective tissue coverings
Smooth muscle Has no striations Spindle-shaped cells Single nucleus Involuntary – no conscious control Found mainly in the walls of hollow organs
Cardiac Muscle Has striations Usually has a single nucleus Joined to another muscle cell at an intercalated disc Involuntary Found only in the heart
Functions of muscles Produce movement Maintain posture Stabilize joints Generate heat
Properties of skeletal muscle activity Irritability – ability to receive and respond to a stimulus Contractility – ability to shorten when an adequate stimulus is received Skeletal muscles must be stimulated by a nerve to contract
STOP Gross Anatomy of the Muscular System
Nerve stimulus to muscles Motor unit – –One neuron – –Muscle cells stimulated by that neuron
Nerve stimulus to muscles Neuromuscular junctions – association site of nerve and muscle Synaptic cleft – gap between nerve and muscle Nerve and muscle do not make contact Area between nerve and muscle is filled with interstitial fluid Sodium rushing into the cell generates an action potential Once started, muscle contraction cannot be stopped
Contraction of a skeletal muscle 1. Muscle fiber contraction is “all or none” 2. Within a skeletal muscle, not all fibers may be stimulated during the same interval 3. Different combinations of muscle fiber contractions may give differing responses 4. Graded responses – different degrees of skeletal muscle shortening
Twitch Single, brief contraction Not a normal muscle function Tetanus (summing of contractions) One contraction is immediately followed by another The muscle does not completely return to a resting state The effects are added
Muscle response to strong stimuli 1. Muscle force depends upon the number of fibers stimulated 2. More fibers contracting results in greater muscle tension 3. Muscle can continue to contract unless they run out of energy
STOP Manual Muscle Testing Activity
Energy for muscle contraction 1. Initially, muscles used stored ATP for energy 2. Bonds of ATP are broken to release energy 3. Only 4-6 seconds worth of ATP is stored by muscles 4. After this initial time, other pathways must be utilized to produce ATP
Aerobic Respiration Series of metabolic pathways that occur in the mitochondria Glucose is broken down to carbon dioxide and water, releasing energy This is a slower reaction that requires continuous oxygen
1. Reaction that breaks down glucose without oxygen 2. Glucose is broken down to pyruvic acid to produce some ATP 3. Pyruvic acid is converted to lactic acid 4. This reaction is not as efficient, but is fast 5. Huge amounts of glucose are needed 6. Lactic acid produces muscle fatigue Anaerobic Respiration
Muscle fatigue and oxygen debt 1. When a muscle is fatigued, it is unable to contract 2. The common reason for muscle fatigue is oxygen debt Oxygen must be “repaid” to tissue to remove oxygen debt Oxygen is required to get rid of accumulated lactic acid 3. Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less
Types of muscle contractions 1. Isotonic contractions Myofilaments are able to slide past each other during contractions The muscle shortens 2. Isometric contractions Tension in the muscles increases The muscle is unable to shorten
Muscle tone 1. Some fibers are contracted even in a relaxed muscle 2. Different fibers contract at different times to provide muscle tone 3. The process of stimulating various fibers is under involuntary control
Abnormal Muscle Tone CRAMPSSPASMSSPASTICITYFLACCIDITYPARALYSIS
Cramps and spasms are conditions of the muscles Spasticity, flaccidity and paralysis are conditions of the muscles usually caused by an underlying neurological injury or disease.
CRAMPS Cramps - A cramp is an involuntary and forcibly contracted muscle that does not relax. Cramps can affect any muscle under your voluntary control (skeletal muscle). Muscles that span two joints are most prone to cramping. Cramps can involve part or all of a muscle, or several muscles in a group.
CRAMPS The most commonly affected muscle groups are: –Back of lower leg/calf (gastrocnemius). –Back of thigh (hamstrings). –Front of thigh (quadriceps). The exact cause of muscle cramps is unknown (idiopathic) Factors may be exercising or working in intense heat, dehydration and depletion of salt and minerals (electrolytes).
CRAMPS Treatment and prevention Cramps usually go away on their own without seeing a doctor. Self-care: Stop doing whatever activity triggered the cramp. Gently stretch and massage the cramping muscle, holding it in stretched position until the cramp stops. Apply heat to tense/tight muscles, or cold to sore/tender muscles.
SPASMS A charley horse is the common name for a muscle spasm, particularly in the leg. Muscle spasms can occur in any muscle in the body. When a muscle is in spasm, it contracts involuntarily and does not relax. Muscle spasms commonly occur when a muscle is over-used or injured. The muscle may keep firing small contractions. It may be that nerves working with the muscle become irritated.
SPASMS At the first sign of a muscle spasm, stop your activity and try stretching and massaging the affected muscle. Heat will relax the muscle at first, although ice may be helpful after the initial spasm and pain has improved.
SPASTICITY Spasticity: A state of increased tone of a muscle (and an increase in the deep tendon reflexes). For example, with spasticity of the legs (spastic paraplegia) there is an increase in tone of the leg muscles so they feel tight and rigid and the knee jerk reflex is exaggerated. It may interfere with gait, movement and speech. Spasticity is caused by neurological injuries and diseases.
FLACCIDITY Muscle Flaccidity: Weak and soft muscles with decreased resistance to movement, increased mobility and greater than normal range of movements. Flaccidity is caused by neurological injuries and diseases.
PARALYSIS Paralysis is the complete loss of muscle function for one or more muscle groups. Paralysis often includes loss of feeling in the affected area. Paralysis is caused by neurological injuries and diseases.
SPRAINS A sprain is an injury to a ligament The ligaments can be injured by being stretched too far from their normal position. The most common symptoms of a sprain are: pain, swelling, and bruising of the affected joint. Symptoms will vary with the intensity of the sprain or strain.
STRAINS A strain is an injury to a muscle or tendon. Strains are caused by pulling too far on a muscle, or by pulling a muscle in one direction while it is contracting in the other. Strains can also be caused by chronic activities that develop an overstretching of the muscle fibers.
Can Strains and Sprains be prevented? Unfortunately, not all sprains and strain can be prevented. Some helpful hints on how to avoid strains and sprains are listed below. StretchStretch before you exercise or workout. exercise Stretchexercise Wear proper shoes for the activity. Warm up properly before activities. Do not run on icy or uneven surfaces.
RUPTURED TENDONS A tendon is the fibrous tissue that attaches muscle to bone in the human body. The forces applied to a tendon may be more than 5 times your body weight. In some rare instances, tendons can snap or rupture. Ruptured tendons can be treated either surgically or medically depending on the severity of the rupture.
RUPTURED TENDONS The 4 most common areas of tendon rupture are as follows: QuadricepsAchilles Rotator cuff Biceps
Ruptured Tendon Symptoms A snap or pop you hear or feel Severe pain Rapid or immediate bruising Marked weakness Inability to use the affected arm or leg Inability to move the area involved Inability to bear weight Deformity of the area
Ruptured Achilles Tendon
WARNING! THE NEXT SLIDE CONTAINS A PHOTO OF A SURGICAL REPAIR
Repair of the Ruptured Achilles Tendon
Ruptured Extensor Tendon
Ruptured Quadriceps Tendon
RUPTURED PATELLA TENDON
PatellarTendon Disorders Patellar Tendonitis (jumper’s knee) –Inflammation of the patellar tendon Patella-Femoral Syndrome –Irritation on the underside of the patella –Can lead to softening or loss of the underside cartilage lining Osgood-Schlatter Disease –Irritation where the patella tendon inserts on the tibia –Mostly occurs in boys during a growth spurt
Muscles and body movement Movement is attained due to a muscle moving an attached bone Muscles are attached to at least two points –Origin: attachment to an immoveable bone –Insertion: attachment to a movable bone
How to describe how muscles are used in motion 1. Prime mover: muscle with the major responsibility for a certain movement 2. Antagonist: muscle that opposes or reverses a prime mover 3. Synergist: muscle that aids a prime mover in a movement and helps prevent rotation 4. Fixator: stabilizes the origin of a prime mover