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

The End!!!

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