Muscular System

Muscle Facts

• There are over 600 different muscles in the human body

• Body contains three muscle types: skeletal, cardiac, and smooth

• Skeletal muscles are voluntary muscles• Cardiac and smooth muscles are involuntary

Functions of Muscles

• Work with bones to create movement• Gives body shape and support• Protection for vital organs• Vital bodily functions (heartbeat, digestion,

excretion of waste, etc.)• Contractions create heat to maintain a normal

body temperature

Skeletal Muscles

• Make up approx. 40% of body mass• Work in pairs• Named for shape, location, function• Connected to bones by tendons• Can grow in size with repeated resistance work• Can contract quickly, but get tired easily and must rest

sterno-mastoid

• Head movement• “yes” and “no”

Trapezius (upper back, neck)

• Pulls head and upper arms back• “yes” and “no” movement• Work with deltoids to lift arms

Trapezius (developed)

Pectorals (chest)

• Move arms to center of body Press away

Deltoid (shoulder cap)

• Lifts arms to shoulder height• Named for Greek letter “D”

Biceps

• Flexes forearm; palm up

Triceps

• Extends forearm;• Fixes elbow when writing

Brachioradialis

• Flexes forearm, palm down

Latissimus dorsi

• Pulls arms down and back; give body “V” shape

For real???????

Abdominals

Protects internal organsHelps hold body erect

Gluteus maximus

• Lifts leg backward• Helps hold body erect

Hamstrings

Flex knee to buttocks

Quadriceps (quads)

Four muscles groupsExtends lower leg

Sartorius

• Longest muscle• Allows leg crossing

Tibialis

Pulls toes toward face

Gastrocnemius (calf)

Extends toes

Achilles Tendon

• Connects calf muscle to heel Named for Achilles ofmythological fame

Human Muscular Anatomy

“I’ll be back!