intro to lower extremity anatomy

• Anatomical planes


  • Sagittal plane
  • Frontal (coronal) plane
  • Transverse (horizontal) plane
• Sagittal plane


  Left and right halves, direction: anterior (ventral), posterior (dorsal)
• Frontal (coronal) plane


  Front and back half, direction: lateral, medial, superior, inferior, cranial (head), caudal (tail)
• Transverse (horizontal) plane


  Slices from head to foot
• Proximal


  Toward body
• Distal


  Toward hand or foot
• Terms to describe motion within the limbs

  • Flexion: bend the joint
  • Extension: straighten the joint
  • Abduction: away from body midline
  • Adduction: toward body midline
  • Medial rotation
  • Lateral rotation
  • Inversion: tilting medial border of foot upwards
  • Eversion: tilting lateral border of foot upwards
• Major joints of lower limbs

  • Sacroiliac joint
  • Pubic symphysis
  • Hip joint
  • Knee joint
  • Ankle joint
• Sacroiliac joint


  Os coxa (innominate/hip bone) articulates with sacrum
• Pubic symphysis


  Pair denominates articulate with each other
• Hip joint


  Femur articulates with hip bone at a socket (acetabulum)
• Knee joint


  Femur, tibia, patella articulate together
• Ankle joint


  Tibia, fibula, and talus
• Major characteristics of synovial joints (freely moving)

  • Outer fibrous capsule
  • Articular cavity: lined by synovial membrane and filled with synovial fluid (lubricate motion of joint)
  • Layer of cartilage (hyaline) over the end of each bone that articulates
• Synovial joints


  Provide a nearly frictionless environment in which the bones can move against each other
• Structure of simplest synovial joint

  • Fibrous membrane
  • Synovial membrane: bound articular cavity
  • Hyaline cartilage
• Structure of complicated synovial joints

  • Fat pad: inside fibrous capsule but outside synovial membrane
  • Articular disc/meniscus: between two bones, turn flat surface into a more rounded cup
  • Bursa: little water balloon full of synovial fluid lubricating passage of skin, muscles, tendons, or ligaments over bony eminences of body
• Types of joints in the human body

  • Pivot joint: uniaxial, round process of bone fits into a bony ligamentous socket -> rotation
  • Ball and socket joint: multiaxial, femur articulates with acetabulum of hip joint
  • Plane joint: uniaxial, allow gliding
  • Hinge joint: uniaxial, allow motion in a single direction (flexion and extension only)
  • Saddle joint: biaxial, saddle-shaped heads permit motion in two different planes, complex combination of movements in many directions
  • Condyloid joint: biaxial, allow motion in many directions, permit flexion and extension, abduction and adduction, and circumduction
• the fibula is located laterally, it's smaller than the tibia
• The tibia is the larger bone on the medial side