topic 3 pt 2

• What do muscles, their tendons, and bones act together as to move parts of the body?

  Lever systems
• What happens when a muscle contracts?

  It creates tension on the tendons and pulls the bony points of attachment closer to one another
• What factors determine movement in the body?

  The relative positions of bone, joint, and muscle
• How do muscles attach to bones?

  Via a tendon or an aponeurosis
• What is a tendon?

  A thick cord-like structure that attaches muscles to bones
• What is an aponeurosis?

  A sheet-like structure that attaches muscles to bones
• Which muscles do not attach to bones?

  Muscles of facial expression
• How is muscle action assessed?

  Based on joints crossed, relative position of muscle to joint, bony attachments, and line of pull
• What must a muscle or its tendon do to cause movement?

  It must cross a joint
• Which muscle crosses the elbow anteriorly to cause flexion?

  Biceps brachii
• Which tendon crosses the knee anteriorly to cause extension?

  The tendon of the quadriceps
• Which muscle crosses both the hip and the knee joints?

  Rectus femoris
• How does the relative position of a muscle to a joint affect movement?

  Muscles crossing the joint anteriorly will flex, while those crossing posteriorly will extend
• What action does the anterior aspect of the elbow joint cause?

  Flexion
• What action does the posterior aspect of the elbow joint cause?

  Extension
• What terms should be used instead of origins and insertions when referring to bony attachments?

  Proximal and distal
• What are the two situations possible regarding muscle attachments?

  Shortening of muscle brings points together or one point might be fixed
• In which direction do muscle fibers shorten?

  In the direction of the fascicles
• What are the different types of muscle fascicle directions?

  • Circular (e.g., orbicularis oris)
  • Convergent (e.g., pectoralis major)
  • Parallel (e.g., sartorius)
  • Unipennate (e.g., extensor digitorum longus)
  • Fusiform (e.g., biceps brachii)
  • Bipennate (e.g., rectus femoris)
  • Multipennate (e.g., deltoid)
• How are muscles named?

  • By shape
  • By number of heads
  • By direction of fascicles
  • By region or attachment
  • By action
  • Further qualifiers
• What are examples of muscle names based on shape?

  • Deltoid (triangular)
  • Rhomboid (rhomboid)
  • Quadratus (4-sided)
  • Orbicularis (circular)
  • Trapezius (trapezoid)
  • Gracilis (slender)
  • Serratus (finger-like)
  • Piriformis (pear-shaped)
• How are muscles named based on the number of heads?

  • Biceps (2 heads)
  • Triceps (3 heads)
  • Quadriceps (4 heads)
  • Muscle bellies may be described as short, long, medial, lateral, etc.
• How are muscles named based on the direction of fascicles?

  • Transversus abdominus (transverse)
  • Internal oblique (obliquely placed)
  • Rectus abdominus (“six pack”, straight)
  • External oblique (obliquely placed)
  • Mnemonic: “Spare TIRE around their abdomen”

  
• How are muscles named based on region or attachment?

  • Infraspinatus (below spine of scapula)
  • Iliacus (in iliac fossa)
  • Gluteals (in gluteal region)
  • Intercostals (between ribs)
  • Suprahyoids (above hyoid bone)
  • Frontalis (on frontal bone)
• How are muscles named based on action?

  • Flexor digitorum (flexes the digits)
  • Extensor (extends something, e.g., extensor digitorum longus)
  • Supinator (supinates the forearm)
  • Adductor (adducts something, e.g., adductor brevis)
  • Levator (raises something, e.g., levator scapulae)
• What are further qualifiers used in muscle naming?

  • Major, minor (e.g., pectoralis major and minor)
  • Longus, brevis (e.g., adductor longus and brevis)
  • Maximus, medius, minimus (e.g., gluteus maximus, medius, etc.)
  • Magnus (e.g., adductor magnus)