Muscle Function and Naming Quiz

Muscle Function Classification

• Muscles are categorized based on their function in movement.
• Prime movers (agonists) are the main muscles for a specific action.
• Antagonists oppose prime movers, providing resistance and control.
• Synergists assist prime movers by adding force or preventing undesirable movements.
• Fixators are synergists that stabilize bones, crucial for posture.

Naming Skeletal Muscles

• Muscles are named using seven criteria.
• Location: Temporal bone = temporalis.
• Shape: Trapezoid shape = trapezius.
• Size:
  • Maximus = large (gluteus maximus).
  • Minimus = small (gluteus minimus).
  • Longus = long.
  • Brevis = short.
• Direction of fibers:
  • Rectus = parallel.
  • Transversus = perpendicular.
  • Oblique = at an angle (rectus femoris).
• Number of origins:
  • Biceps = two origins.
  • Triceps = three origins.
  • Quadriceps = four origins.
• Origin and insertion points:
  • Sternocleidomastoid - origin on the sternum and clavicle, insertion on the mastoid process.
• Type of motion produced:
  • Flexor.
  • Extensor.
  • Adductor.

Muscle Shapes

• Fascicle arrangement creates muscle shape and function:
  • Circular: Concentric rings, like eye and mouth muscles.
  • Convergent: Spread then converge to a tendon, like pectorals.
  • Fusiform: Tapered at both ends, like biceps.
  • Parallel: Straight fascicles parallel to the long axis, like sartorius.
  • Pennate: Fascicles at angles to tendons, increasing power but shortening less,
    • Unipennate: Muscle on one side of the tendon.
    • Bipennate: Muscle on both sides like a feather.
    • Multipennate: Multiple feathers inserted into a single tendon.

Muscle Shortening and Power

• All skeletal muscles can only shorten by about 30% during contraction.
• Parallel muscles shorten more, generating less power.
• Pennate muscles shorten less, producing greater force.

Major Muscle Groups

• Review images of major muscle groups.
• More detailed muscle study is required for those in the medical field.