Muscular System Allied Health Sciences I Melissa Lewis, RN.
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Transcript of 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. CardiacThese 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 –
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 armVastus Lateralis (anterior thigh)Gluteus medius (buttocks)
Major Muscles of BodyMUSCLE 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 BodyMUSCLE LOCATION FUNCTION
Biceps brachii Upper arm Flexes lower arm
Triceps brachii Upper arm Extends lower arm
Pectoralis major Upper chest Adducts upper arm
Major Muscles of BodyMUSCLE 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 BodyMUSCLE LOCATION FUNCTION
Gluteus maximus
Buttocks Extends thigh
Sartorius Front of thigh Abducts
Quadriceps femoris
Front of thigh Extends leg
Major Muscles of BodyMUSCLE 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 BodyMUSCLE LOCATION FUNCTION
Hamstring Posterior thigh Extends hip and flexes knee
Hamstring is actually the 3 muscles below1. Semitendinosus
2. Semimembranosus
3. Bicepts femoris
Posterior thigh Extends hip and flexes knee