Naming Muscles

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Naming Muscles
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Muscles causing movement

• Skeletal Muscle an organ made of several
  different types of tissue including muscle
  tissue, vascular tissue and nervous tissue

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• Tendon attaches the skeletal muscle to bone and
  pulls on bone when the muscle contracts

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Joints

• Skeletal muscles usually cross one or more
  joints. When a muscle contracts it pulls one
  bone closer to another
• One bone stays in place while the other moves

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Parts of a skeletal muscle

• Origin the attachment of a muscle on a
  stationary bone
• Insertion the attachment of a muscle on the
  movable bone
• Belly the fleshy portion of muscle between the
  origin and insertion

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Group Actions

• Most movements occur because groups of muscles
  work together, generally grouped in opposing
  pairs
• Ex abductors and adductors
• Ex extensors and flexors

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• Agonist muscle that produces the desired
  movement
• Antagonist muscle that relaxes when the agonist
  contracts
• Synergists another skeletal muscle that moves
  in the same general direction as the agonist
  increasing the force
• Fixators stabilize the origin and hold other
  joints still so the agonist can work more
  efficiently

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Principle Skeletal Muscles

• With over 700 skeletal muscles in the body, it
  will be easier to first learn the naming system
  and then learn specific muscles region by region

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Naming Skeletal Muscles

• Muscles are named according to the direction the
  fibers run, the size of the muscle, the shape of
  the muscle, the action the muscle produces, the
  number of origins the muscle has and/or the
  location of the muscle

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Directions

• The following terms refer to the direction the
  muscle fibers run in relation to the midline.

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Rectus

• Parallel to the midline

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Transverse

• Perpendicular to the midline

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Oblique

• Diagonal to the midline

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Size

• Relative to other muscles in that group

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Maximus

• Largest

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Minimus

• Smallest

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Longus or Longissimus

• Longest

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Latissimus

• Widest

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Magnus

• Large

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Major

• Larger

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Minor

• smaller

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Vastus

• great

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Shape

• General shape of the muscle

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Deltoid

• Triangle

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Trapezius

• Trapezoid

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Serratus

• Saw-toothed

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Rhomboid

• Diamond Shaped

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Orbicularis

• Circular

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Pectinate

• Comb-like

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Piriformis

• Pear shaped

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Platys

• Flat

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Quadratus

• square

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Gracilis

• slender

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Action

• Based on the action the muscle performs

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Flexor/Extensor

• Flexor decreases the angle between bones
• Extensor increases the angle between bones

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Abductor/Adductor

• Abductor moves a bone away from the midline
• Adductor moves a bone toward the midline

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Levator/Depressor

• Levator elevates body part
• Depressor lowers body part

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Supinator/Pronator

• Supinator turns palms up
• Pronator turns palms down

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Sphincter

• Decreases the size of an opening

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Tensor

• Makes a body part rigid

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Number of Origins

• Biceps 2 heads
• Triceps 3 heads
• Quadriceps 4 heads

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Location

• Muscles named for the structures that they are
  by. Examples include the sternocleidomastoid
  muscle (runs from the sternum across the clavicle
  to the mastoid process) and the temporalis (near
  the temporal bone)