MUSCULAR%20SYSTEM

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MUSCULAR SYSTEM

• Structure of the Muscles

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Muscles

• Comprise a large part of the human body
• Nearly half our body weight comes from muscle
  tissue
• If you weigh 140 lbs, 60 lbs is from muscle
  attached to bones
• Over 650 different muscles

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Responsibilities of Muscle System

• 3 main
• Body movement (voluntary and involuntary)
• Body form and shape, to maintain posture
• Body heat, to maintain body temperature

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Types of Muscle

• 3 types
• Skeletal
• Smooth
• Cardiac
• Described as
• Striated
• Spindle shaped
• nonstriated

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Skeletal (figure 7-1 pg 123)

• Attached to the _________
• Called striped or striated b/c they have cross
  bandings (striations) of alternating light and
  dark bands running perpendicular to the length
• Voluntary muscle b/c contains nerves under
  voluntary control
• Multinucleate
• Sarcolemma is the muscle cell membrane and the
  cytoplasm is sarcoplasm

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Smooth (visceral) figure 7-2

• Small and spindle shaped
• Single nuclei
• No striations
• Unattached to bones
• Involuntary muscles controlled by the autonomic
  nervous system
• Found in the walls of internal organs

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Cardiac figure 7-3

• Found only in the ____________
• Striated, branched, and involuntary
• Membranes of adjacent cells are fused at
  intercalated discs
• Requires continuous supply of oxygen to function
• Cardiac muscle cells begin to die after 30
  seconds of no oxygen

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Sphincter/Dilator Muscles

• Special circular muscles in the openings b/t the
  esophagus and stomach stomach and small
  intestine and in the walls of the anus, urethra,
  and mouth
• Open and close to control the passage of
  substances

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• Look at table 7-1 pg 125
• Summarizes the characteristics of the 3 major
  muscle types

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Naming Skeletal Muscles

• Named by location, size, direction, number of
  origins, location of origin and insertion, and
  action
• However, not all muscles are named in this manner
• Look at figures 7-6 and 7-7 pg 130 and look how
  the muscles are named

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• Location.
• Size..
• Direction of fibers.
• Number of origins.
• Location of origin and insertion
• Action flexor
• Extensor
• Depressor

• Frontalis forehead
• Gluteus maximus largest muscle in the buttock
• External abdominal oblique edge of the lower
  rib cage
• Biceps two-headed muscle in humerus
• Sternocleidomastoid origin in sternum
• Flexor capri ulnaris flexes the wrist
• Extensor carpi ulnaris extends the wrist
• Depressor anguli oris depresses the corner of
  the mouth raises and lowers body parts

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• There are 656 muscles in the human body
• 327 antagonistic muscle pairs and 2 unpaired
  muscles
• Unpaired muscles orbicularis oris and the
  diaphragm
• The muscles can be divided and subdivided into
  the following regions
• Head, neck, and trunk and extremities

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Head Muscles

• Muscles of expression
• Muscles of mastication (chewing)
• Muscles of the tongue
• Muscles of the pharynx
• Muscles of the soft palate

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Neck Muscles

• Muscles moving the head
• Muscles moving the hyoid bone and the larynx
• Muscles moving the upper ribs

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Trunk and Extremity Muscles

• Muscles that move the vertebral column
• Muscles that move the scapula
• Muscles of breathing
• Muscles that move the humerus
• Muscles that move the forearm
• Muscles that move the wrist, hand, and finger
  digits
• Muscles that act on the pelvis
• Muscles that move the femur
• Muscles that move the leg
• Muscles that move the ankles, feet, and toe digits

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Muscles of the Head and Neck

• Control human facial expressions such as
• What are some examples? (think of feelings)
• Refer to table 7-2 and figure 7-8
• Muscles of mastication control the mandible,
  raising it to close the jaw and lowering it to
  open the jaw.
• Refer to table 7-3 and figure 7-8
• Muscles that move the head cause extension,
  flexion, and rotation
• Refer to table 7-4 and figure 7-8

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Muscles of the Upper Extremities

• Help to move the scapula and humerus and forearm,
  wrist, hand, and fingers
• Refer to table 7-5 and figure 7-9

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Muscles of the Trunk

• Control breathing and the movements of the
  abdomen and the pelvis
• Refer to table 7-6 and figure 7-10

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Muscles of the Lower Extremities

• Assist in the movement of the femur, leg, ankle,
  foot, and toes
• Hamstrings comprised of semitendinosus, biceps
  femoris, and semimembranosus muscles
• Tendons of these muscles attach posteriorly to
  the tibia and fibula (can be felt behind the
  knee)
• Responsible for flexing the knee
• Refer to table 7-7 and figure 7-11