L1.1 - Articular System

• Articulation or Joint - physical connection between two bones
• Functions of Articular System

  1. Holds bones together
  2. Allows movement
  3. Makes bone growth possible
• Arthrology - study of joints
• Synarthrosis - immovable joint
• amphiarthrosis - slightly movable joint
• diarthrosis - freely movable joint
• fibrous joint

  • bones are united by fibrous connective tissue
  • allows little to no movement
• sutures

  • fibrous joint between the bones of the skull
  • immovable due to interlocking junctions between the bones and short numerous connective fibers
• syndesomes - fibrous joints where bones are separated by some distance and are held together by ligaments
• gomphoses - consists of pegs fitted into sockets and held in place by ligaments
• cartilaginous joints - unite two bones by cartilage
• synchondrosis - bones are joined together by hyaline cartilage
• symphysis - bones are joined together by fibrocartilage
• synovial joints - freely movable joints but their flexibility does vary
• articular hyaline cartilage - prevent friction between articulating bones
• two-layered joint cartilage

  inner layer: strengthen joint

  outer layer: secrete synovial fluids
• synovial fluid

  • reduce friction between articular cartilages
  • nourish articular cartilage
  • rid the joint of waste
• ligament - connect one bone together
• plane or gliding joints - consist of two opposed flat surfaces that glide over each other
• saddle joints

  • consist of two saddle-shaped articulating surfaces oriented at right angles to one another
  • allow movement in two planes
• hinge joints

  • consists of a convex cylinder of one bone applied to a corresponding concavity of the other bone
  • permit movement in one plane
• pivot joints

  • consist of the rounded end of one bone fitting into a ring formed by the other bone
  • restrict movement to rotation around a single axis
• ball and socket joints

  • consist of a ball at the end of one bone and a socket in an adjacent bone into which portion of the ball fits
  • allows a wide range of movement in any direction
• ellipsoid or condyloid

  • a modified ball and socket joint in which the joint surfaces are elongated
  • the shape of the joint limits its range of movement nearly to a hinge motion but in two planes
• skull is an example of synarthrosis joint
• knee, elbow and wrist are examples of diarthrosis
• base of the thumb, and trapezium of the wrist are examples of saddle joints
• elbow and knee joints are examples of hinge joints
• shoulder and hip are example of ball and socket joints