Joints Anatomy Flashcards

Joints

Overview

  • Joints are articulations of bones.
  • Functions:
    • Hold bones together.
    • Allow for mobility.
  • Classified by:
    • Functionally: focuses on the amount of movement.
    • Structurally: based on the material binding them and presence or absence of a joint cavity.

Functional Classification of Joints

  • Synarthroses: Immovable joints.
  • Amphiarthroses: Slightly movable joints.
  • Diarthroses: Freely movable joints.

Structural Classification of Joints

  • Fibrous joints:
    • Generally immovable.
  • Cartilaginous joints:
    • Immovable or slightly movable.
  • Synovial joints:
    • Freely movable.

Fibrous Joints

  • Bones connected by fibrous tissue: dense regular connective tissue.
  • No joint cavity.
  • Slightly immovable or not at all.
  • Types:
    • Sutures.
    • Syndesmoses.
    • Gomphoses.
Sutures
  • Only between bones of skull.
  • Fibrous tissue continuous with periosteum.
  • Ossify and fuse in middle age: now technically called “synostoses” = bony junctions.
Syndesmoses
  • In Greek: “ligament”.
  • Bones connected by ligaments only.
  • Amount of movement depends on length of the fibers: longer than in sutures.
Gomphoses
  • Is a "peg-in-socket".
  • Only example is tooth with its socket.
  • Ligament is a short periodontal ligament.

Cartilaginous Joints

  • Mostly Amphiarthrosis
  • Bones connected by cartilage.
  • Lack a joint cavity.
  • Not highly movable.
  • Two types:
    • Synchondroses (singular: synchondrosis).
    • Symphyses (singular: symphysis).
Synchondroses
  • Literally: “junction of cartilage”.
  • Hyaline cartilage unites the bones.
  • Immovable (synarthroses).
  • Examples:
    • Epiphyseal plates.
    • Joint between first rib’s costal cartilage and manubrium of the sternum.
Symphyses
  • Literally “growing together”.
  • Fibrocartilage unites the bones.
  • Slightly movable (amphiarthroses).
  • Resilient shock absorber.
  • Provide strength and flexibility.
  • Hyaline cartilage on articular surfaces of bones to reduce friction.
  • Examples:
    • Intervertebral discs.
    • Pubic symphysis of the pelvis.

Synovial Joints

  • Articulating bones are separated by a joint cavity.
  • Include most of the body’s joints.
  • All are diarthroses (freely movable).
  • All contain Synovial fluid found in the joint cavity.
Features of Synovial Joints - Diarthroses
  • Articular cartilage (hyaline cartilage) covers the ends of bones.
  • Joint surfaces are enclosed by a fibrous articular capsule.
  • Have a joint cavity filled with synovial fluid.
  • Ligaments reinforce the joint.
Structures Associated with the Synovial Joint
  • Bursae – flattened fibrous sacs.
    • Lined with synovial membranes.
    • Filled with synovial fluid.
    • Not actually part of the joint.
  • Tendon sheath
    • Elongated bursa that wraps around a tendon.
Types of Synovial Joints Based on Shape
  • Plane joint
  • Hinge joint
  • Pivot joint
  • Condyloid joint
  • Saddle joint
  • Ball-and-socket joint
  • Nonaxial
  • Uniaxial
  • Biaxial
  • Multiaxial

Inflammatory Conditions Associated with Joints

  • Bursitis – inflammation of a bursa usually caused by a blow or friction.
  • Tendonitis – inflammation of tendon sheaths.
  • Arthritis – inflammatory or degenerative diseases of joints.
    • Over 100 different types.
    • The most widespread crippling disease in the United States.
Clinical Forms of Arthritis
  • Osteoarthritis
    • Most common chronic arthritis.
    • Probably related to normal aging processes.
  • Rheumatoid arthritis
    • An autoimmune disease – the immune system attacks the joints.
    • Symptoms begin with bilateral inflammation of certain joints.
    • Often leads to deformities.

Joint Summary: Types of Joints

  1. Synovial:
    • Classifications:
      • Immovable: Synarthrotic
      • Slightly Movable: Amphiarthrotic
      • Freely Movable: Diarthrotic
    • 4 Features:
      • Capsule or Ligaments
      • Synovial Membrane
      • Articular Cartilage
      • Joint cavity w/ synovial fluid
    • Types:
      • Ball & Socket: Shoulder
      • Hinge: Elbow
      • Pivot: (Atlas/Axis)
      • Ellipsoidal: Phalanges
      • Saddle: Thumb
      • Gliding: Wrist
  2. Fibrous:
    • Features:
      • Connected by fibrous tissue
      • Immovable or slightly movable
    • Types:
      • Sutures: Skull
      • Syndesmosis: Interosseous
      • Gomphosis: Teeth
  3. Cartilaginous:
    • Features:
      • Joined by cartilage
      • Slightly Movable
    • Types:
      • Synchondroses: Ribs (hyaline cartilage)
      • Symphysis: Pubic Symphysis, Intervertebral Discs (Fibrocartilage)