TE

Joints

  • Joints (articulations): Where two or more bones meet.

  • Functions: Give skeleton mobility, hold skeleton together.

  • Structural classification (what binds bones, cavity present?):

    • Fibrous – dense connective tissue, no cavity.

    • Cartilaginous – cartilage, no cavity.

    • Synovial – fluid-filled cavity.

  • Functional classification (movement allowed):

    • Synarthroses – immovable.

    • Amphiarthroses – slightly movable.

    • Diarthroses – freely movable.

Slide 4: Fibrous Joints

  • Bones joined by dense fibrous connective tissue.

  • No cavity, mostly immovable.

  • Types:

    • Sutures – rigid, interlocking joints (skull).

    • Syndesmoses – connected by ligaments (variable movement).

    • Gomphoses – peg-in-socket (teeth).

Slide 5: Cartilaginous Joints

  • Bones united by cartilage, no cavity.

  • Immovable or slightly movable.

  • Types:

    • Synchondroses – hyaline cartilage (e.g., epiphyseal plates).

    • Symphyses – fibrocartilage (e.g., intervertebral discs, pubic symphysis).

Slide 6: Synovial Joints

  • Bones separated by fluid-filled cavity.

  • All diarthrotic (freely movable).

  • Found in most limb joints.

  • Features: bursae, tendon sheaths, multiple movement types.

Slide 7: General Structure of Synovial Joints

  • Articular cartilage (hyaline): prevents bone ends from crushing.

  • Joint cavity: small, fluid-filled space.

  • Articular capsule:

    • Fibrous outer layer.

    • Synovial membrane (makes synovial fluid).

  • Synovial fluid: viscous, lubricates, nourishes cartilage, contains phagocytes.

Slides 8–12: Joint Tissue Composition

  • Non-bone tissues: bind, cushion, stabilize joints.

  • Fatty pads: cushion between capsule and bone.

  • Menisci (articular discs): fibrocartilage that improves bone fit, stabilizes, reduces wear.

  • Bursae: fluid sacs reduce friction at ligaments/muscles/tendons.

  • Tendon sheaths: elongated bursae wrapping tendons.

Slides 13–16: Types of Synovial Joints

  • Plane joints: flat surfaces glide (carpals, tarsals).

  • Hinge joints: uniaxial, flexion/extension (elbow, phalanges).

  • Pivot joints: rotation around axis (C1–C2, radioulnar).

  • Condyloid joints: biaxial, flex/extend, abduct/adduct (knuckles, wrist).

  • Saddle joints: biaxial, greater range than condyloid (thumb).

  • Ball-and-socket joints: multiaxial, most movement (shoulder, hip).

Slides 17–23: Movements Allowed by Synovial Joints

  • Muscles attach at origin (fixed) & insertion (movable); contraction moves insertion toward origin.

  • Planes of movement: sagittal, frontal, transverse.

Types of movements:

  • Gliding: flat bones slide (carpals, tarsals, vertebrae).

  • Angular:

    • Flexion – decreases angle.

    • Extension – increases angle.

    • Hyperextension – beyond normal.

    • Abduction – away from midline.

    • Adduction – toward midline.

    • Circumduction – limb describes cone.

  • Rotation: bone turns on long axis.

    • Medial (toward midline).

    • Lateral (away).

  • Special movements:

    • Supination/pronation (radius & ulna).

    • Dorsiflexion/plantar flexion (foot).

    • Inversion/eversion (foot).

    • Protraction/retraction (jaw).

    • Elevation/depression (shoulders, jaw).

    • Opposition (thumb to fingers).