chapter 14 - articulations

• what are joints and how do we classify them?

  connections; based on degree of motion they allow
• joint functions:

  • stability
  • e,g, skull sutures, teeth etc.
  • movement
  • head, shoulders, knees and toes etc.
  • bone growth
  • epiphyseal plates
• functional classification:

  1. synarthrosis: no movement
  2. amphiarthrosis: small degree of movement
  3. diarthrosis: free movement in one or more planes
• structural classification

  based on:

  1. type of connective tissue involved
  2. presence/absence of fluid-filled spaces between bones

  types:

  1. fibrous joints: dense regular connective tissue
  2. cartilaginous joints: cartilage between bones
  3. synovial joints: space filled with synovial fluid
• fibrous joints are also synarthrosis (sutures & domphoses) and amphiarthrosis (syndesmoses) joints
• cartilaginous joints are synarthrosis (synchondroses, 1st sternocostal joint, costochondral joints) and amphiarthrosis (symphyses)
• synovial joints are diarthrosis (nonaxial, uniaxial, biaxial, and mutliaxial)
• synovial joints

  • all synovial joints are diarthroses (allow movement)
  • muscle contract across synovial joints
  • insertion moves toward the origin
• insertion: attached to moveable bone

  origin: attached to relatively immobile bone

  belly: portion between origin and insertion
• unhappy triad includes:

  1. medial collateral ligament
  2. medial meniscus
  3. anterior cruciate ligament
• the most freely movable joint in the human body is the ____ joint

  shoulder
• a ballerina who stands on the tips of her toes is performing _____

  plantarflexion
• plantarflexion: standing on balls of feet and toes heel toward head

  dorsiflexion: standing on heel with toes toward head
• bursa: fluid-filled sacs lined by synovial membrane
• tendon sheaths: elongated cylindrical synovial membrane surrounding tendons around synovial joints (long bursa)
• the anterior cruciate ligament in the knee joint prevents hyperextension
• in the knee joint, the medial meniscus is ____

  fibrocartilage
• which of the following is unique to the thumb?

  saddle joint