MUSCLES

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MUSCLES
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MUSCLES

• Human has nearly 650 muscles
• Making up half your body weight
• Bones cannot move on their own

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Frontalis

• Located in head above eye socket
• Action
• Controls eyebrow movement
• frontalis

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Deltoids

• Located at shoulder
• Action
• Arm rotation

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Pectoralis major

• Located ventral / chest
• Action
• Moves humerus

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Biceps brachii

• Located in upper arm / ventral
• Action
• Flexes elbow (raise forearm)

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Abdominal muscles

• Located on ventral / abdomen region
• Action
• Pulls chest downward (bowing)
• Acts in vertebrae rotation
• Twist at waist

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Satorius

• Stretched diagonally across femur from pelvis to
  behind the patella
• Longest muscle of body
• Action Hip rotation Knee rotation

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Rectus femoris

• Located ventral of thigh
• Action
• Knee extensor
• (straightens leg)

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Trapezius

• Extends from neck to back
• Action
• Shoulder shrug
• Scapulas meeting

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Triceps brachii

• Located on dorsal humerus
• Action extends arm (straightens)

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Gluteus maximus

• Location buttocks region
• Action Extends femur
• Regains erect position
  after stooping

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Biceps femoris

• Located at dorsal of thigh
• Action
• Flexes knees

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TENDONS

• Connects muscle to bone or
• muscle to muscle
• Longest tendon is
• Achilles tendon
• If cut you would not be able to walk

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MUSCLE CONTRACTION

• Requires energy
• ALL OR NOTHING response
• Force is determined by the number of muscle
  fibers stimulated
• More fibers more force

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Skeletal muscles

• Work in pairs
• A. One end is attached to bone
• B. Stretched across joint
• C. Fastened to periosteum at one point on bone

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MUSCLE ATTACHMENT

• ORIGINwhere muscle attaches to stationery bone
• INSERTION
• where muscle attaches to moving bone

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To RAISE forearm

• BICEPS
• Origin scapula
• Insertion radius
• Biceps contract bicep shortens
• Triceps relaxes tricep lengthens
• forearm raises

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To LOWER forearm

• TRICEPS
• Origin scapula
• Insertion radius
• Biceps relaxes bicep lengthens
• Triceps shortens triceps contracts
• Forearm lowers

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• FLEXOR
• Causes joint to bend
• Example biceps /biceps femoris
• (elbow) (knee)
• EXTENSOR
• Causes joint to straighten
• Example triceps /rectus femoris
  (elbow) (knee)

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MUSCLE FATIGUE

• Physiological inability of a muscle to contract
• Energy availability is NOT able to keep up with
  its use
• Results in buildup of LACTIC ACID
• cause of muscle soreness
• will persist until all lactic acid
  is carried away