Allied Health Sciences I Melissa Lewis, RN Muscular System Allied Health Sciences I Melissa Lewis, RN

Muscles ½ of our body weight comes from our muscles Human body has 656 different muscles Muscles give body form and shape Muscles are also responsible for movement

3 Types of Muscles 1. Skeletal 2. Smooth 3. Cardiac These muscles can be described as striated (striped) , spindle-shaped, and non-striated.

Skeletal Muscles Attach to bones of skeleton Striped or striated Voluntary muscles Each muscle cell is multi-nucleated and known as a muscle fiber The cell membrane of a muscle cell = sarcolemma Cytoplasm of muscle cell = sarcoplasm

Smooth (visceral) Muscle Small and spindle-shaped Only have one nucleus Non-striated They are not attached to bones They act slowly and do not tire easily They remain contracted for a long time Involuntary They are controlled by the autonomic (automatic) nervous system

Smooth (visceral) Muscle cont… They are found in the walls of stomach, intestines, uterus, & blood vessels Their actions = helping food pass along uterine contractions, control of diameter of blood vessels

Cardiac Muscle Found only in the heart Striated Involuntary Cardiac cells are joined in a continuous network So, when one cell receives a signal to contract they all contract together to cause a heart beat Normal heart rate is 72 beats/minute Cardiac cells have to have continuous oxygen to function (no oxygen for 30 seconds = death)

Sphincter/dilator Muscles Special circular muscles in the openings between the esophagus and stomach, and stomach and small intestine Also found in anus, urethra, mouth They open and close to control passage of substances

Principle Skeletal Muscles Skeletal muscles are voluntary Made up of all muscles that attach to and help the skeleton move Make up lining of walls of oral, abdominal, and pelvic cavities Control movement of eyeballs, eyelids, lips, tongue, and skin Muscles are named by their location, size, direction, # of origins, location of origin & insertion, and action

Examples: Location: Frontalis – forehead Size: Gluteous maximus – largest muscle in buttock Number of origins – Biceps – 2-headed muscle on humerus Location of origin/insertion – sternocleidomastoid – originates in sternum

Misc. Muscle Information 656 muscles in human body 327 antagonistic pairs 2 unpaired muscles Orbicularis oris Diaphragm Muscular Regions Head, neck, trunk & extremity

All Muscles have 4 things in common: Contractibility – When a muscle contracts, it shortens causing a decrease in distance b/w parts No other cell can do this Excitability – To respond to certain stimuli by producing impulses Both muscle and nervous cells can do this Extensibility – Ability to be stretched Elasticity – Ability to return to its original length when relaxed

Muscle Attachments & Functions: Muscles have to be attached to bones to cause movement Muscles only pull, they never push

Muscle Attachments & Functions cont… 1. Origin – part of the skeletal muscle that is attached to a fixed structure or bone (it moves the least during contraction) 2. Insertion – the other end of attachment , that is attached to movable part (it moves the most during contraction) 3. Belly – central body of muscle 4. Prime mover – muscles work in pairs, produces movement in a single direction

Muscle Attachments & Functions cont… 5. Antagonist – this is the second muscle that has an opposite pull from the prime mover 6. Synergists – group of muscles, which help steady a movement or stabilize joint activity ***Example of antagonist pair would be the biceps and the triceps (when the biceps is contracted, the triceps is relaxed)***

Sources of Energy and Heat Muscles not only move our bodies, but they also produce heat. Our body temp must be between 98.6 degrees F and 99.8 degrees F. Muscle cells make adenosine triphosphate (ATP) ATP is necessary for muscles to contract and make heat that body needs

Contraction of Skeletal Muscle Two things that cause movement by muscles 1. Myoneural stimulation 2. Contraction of muscle proteins ***A nerve impulse initiates movement 5 steps to muscles movement (look in book 4 this) 1. Nerve Impulse 2. Axon 3. Acetylcholine 4. Synaptic cleft 5. Sarcolemma For cell to return to a resting state, potassium and sodium ions diffuse back to their initial positions outside the cell

Muscle Tone and Fatigue Muscle tone – muscles are always slightly contracted. Gives muscle tone. Muscle tone maintained through adequate nutrition and regular exercise. Atrophy – disuse of muscles thus they shrink or atrophy Hypertrophy – over-exercise, muscles become enlarged or hypertrophied Muscle fatigue – caused by build-up of lactic acid in muscles. Lactic acid is a waste product of muscle cells.

Exercise and Training Exercise and training changes the size, structure and strength of a muscle. Atrophy – muscles goes away Hypertrophy – muscles get bigger Proper training can improve: Coordination Respiratory and circulatory system Rids excess fat Joint movement Strength can improve Muscle size Muscle coordination Functioning of cortical brain region

Injury and overuse Sprain – Strain – Bursitis – Ligaments either torn from attachments to bones or torn across. Rapid swelling and acute pain Treatment = anti-inflammatory drugs Strain – Tear in muscle result of excessive use (tx = ice) Bursitis – these bursa sacs contain synovial fluid that serves as lube to prevent friction b/w tendon and bone. If sac is injured it can cause bursitis.

Injury and overuse cont… Muscle spasm – a cramp (sustained contraction of the muscle) Myalgia – muscle pain Muscular dystrophy – group of diseases in which the muscle cells deteriorate Myasthenia gravis – leads to progressive muscular weakness and paralysis, sometimes death (unknown cause)

Tendons Cords of connective tissue that attach the muscles to bone Sometimes they are excessively stretched through exercise They become unable to contract & return to their original place Therefore, they are more susceptible to straining and tearing

Recreational Injuries Tennis Elbow – also called lateral epicondylitis Inflammed tendon that connects arm muscle to elbow Treatment = pain relief, ice packs, surgery last resort

Recreational Injuries cont… Shin splints – occur when there is injury to muscle tendon in front of shin Usually occurs during jogging One should wear supportive shoes Rotator cuff disease – inflammation of group of tendons that fuse together and surround shoulder joint Treatment = rest & physical therapy

Treatment Massage – occasionally a HC professional may need to give a total body massage or a massage to specific body area One must know which skeletal muscles are involved and proper way to massage area Physiotherapy – treatment of disease/injury by physical means using light, heat, cold, water, electricity, massage, & exercise

Intramuscular Injections Injections (shots) given directly into the muscle Most common sites for intramuscular injections: Deltoid muscle of upper arm Vastus Lateralis (anterior thigh) Gluteus medius (buttocks)

Major Muscles of Body MUSCLE LOCATION FUNCTION Sternocleid-omastoid Side of neck Turns & flexes head Trapezius Upper back & neck Turns head, moves shoulder Deltoid Shoulder Abducts arm

Major Muscles of Body MUSCLE LOCATION FUNCTION Biceps brachii Upper arm Flexes lower arm Triceps brachii Extends lower arm Pectoralis major Upper chest Adducts upper arm

Major Muscles of Body MUSCLE LOCATION FUNCTION Intercostals Between ribs Moves ribs for breathing Rectus abdominus Ribs to pubis Compresses abdomen Latissimus dorsi Spine around to chest Extends & adducts upper arm

Major Muscles of Body MUSCLE LOCATION FUNCTION Gluteus maximus Buttocks Extends thigh Sartorius Front of thigh Abducts Quadriceps femoris Extends leg

Major Muscles of Body MUSCLE LOCATION FUNCTION Tibialis anterior Front of lower leg Flexes & inverts foot Gastrocnemius Back of lower leg Flexes sole of foot Diaphragm Dome-shaped muscle separating thoracic & abdominal cavities Helps control breathing

Major Muscles of Body MUSCLE LOCATION FUNCTION Hamstring Posterior thigh Extends hip and flexes knee Hamstring is actually the 3 muscles below 1. Semitendinosus 2. Semimembranosus 3. Bicepts femoris

Next unit is ___________System The End!!! Next unit is ___________System