KJ

Joints and Movement - Vocabulary Flashcards

Joints: Quick Reference

  • A joint (articulation) is a contact point between two bones; function is movement.
  • Functional classifications:
    • Synarthrosis: without movement (immovable).
    • Amphiarthrosis: slightly movable.
    • Diarthrosis: freely movable.
  • Structural classifications:
    • Fibrous joints: held together by dense fibrous connective tissue.
    • Suture (immovable); fontanels rely on fibrous tissue.
    • Syndesmosis: bones bound by a ligament or interosseous membrane (slightly movable).
    • Gomphosis: teeth in sockets (maxilla and mandible).
    • Interosseous membrane: dense regular tissue between bones (e.g., radius–ulna, tibia–fibula).
    • Cartilaginous joints: held together by cartilage.
    • Synchondrosis: hyaline cartilage; typically immovable (e.g., growth plate area in early life; costochondral joints).
    • Symphysis (fibrocartilage): slightly movable; pubic symphysis and intervertebral discs are examples.
    • Synovial joints: freely movable with a fluid-filled joint cavity; most joints in the body.
    • Common components: joint capsule, synovial fluid, articular cartilage (hyaline), joint space, supporting ligaments, tendons, bursae, tendon sheaths, menisci.
  • Key anatomical parts of synovial joints:
    • Articular cartilage: hyaline cartilage covering bone ends.
    • Joint capsule: encloses the joint, contains synovial fluid.
    • Joint space: space inside the capsule containing lubricating fluid.
    • Accessory structures: ligaments (bone to bone), tendons (muscle to bone), bursae, tendon sheaths, menisci.
  • Ligaments vs tendons:
    • Ligaments connect bone to bone.
    • Tendons connect muscle to bone.
    • Sprain: ligament injury.
    • Strain: muscle or tendon injury.
    • Dense regular connective tissue forms both ligaments and tendons.
  • Knee-specific structures:
    • Collateral ligaments: MCL (medial/tibial collateral) and LCL (lateral/fibular collateral).
    • Cruciate ligaments: ACL (anterior) and PCL (posterior); cross in the knee.
    • Bursae around the knee: prepatellar, suprapatellar, infrapatellar.
  • Common joint disorders:
    • Osteoarthritis (OA): degenerative; pain with movement; bone-on-bone exposure when cartilage erodes.
    • Rheumatoid arthritis (RA): autoimmune; inflammation; movement can improve symptoms as blood flow increases.
  • Synovial joint movement terminology:
    • Flexion: decrease the angle between bones; extension: increase the angle. Hyperflexion / hyperextension denote excessive angles.
    • Rotation: internal (medial) vs external (lateral).
    • Elevation vs depression: lifting vs lowering a body part.
    • Circumduction: distal part moves in a circle.
    • Adduction vs abduction: toward vs away from midline.
    • Supination vs pronation: palm orientation (supination = palm up/forward; pronation = palm down/backward).
    • Inversion vs eversion: sole tilts inward vs outward.
    • Plantar flexion vs dorsiflexion: pointing toes downward vs bringing toes upward.
    • Opposition: thumb touching other digits (unique to the opposable thumb).
  • Six types of synovial joints (structure governs movement, but all share basic synovial features):
    • Planar (gliding): movement in one plane; limited sliding; examples: carpals, tarsals.
    • Pivot: rotation around an axis; e.g., radius–ulna joint; C1–C2 atlas–axis.
    • Hinge: flexion/extension; e.g., elbow, interphalangeal joints, knee.
    • Saddle: concave-convex arrangement allowing reciprocal movement; unique for the thumb (carpometacarpal joint of the thumb).
    • Ellipsoid (condylar): biaxial; rounded/elliptical articular surfaces; e.g., radiocarpal joint.
    • Ball-and-socket: multiaxial; greatest mobility; e.g., shoulder, hip.
  • Movement coupling and opposites:
    • Flexion and extension are complementary; hyper- versions denote excessive range.
    • Rotation pairs: internal vs external; medial vs lateral.
  • Naming and future module prep:
    • Muscles will often be named for action and attachment (e.g., flexor carpi radialis, adductor magnus, pronator teres), as well as relative size and position (major/minor, inter-, supra-).
    • The knee notes (ligaments, bursae) provide common exam reference points for joint stability and injuries.
  • Quick notes on joints at a glance:
    • Many joints remain freely movable unless trauma or disease limits mobility.
    • The epiphyseal plate area becomes bone when growth ends; the cartilage is replaced by bone, forming a single continuous bone (epiphyseal line).
    • Synovial joints include a synovial cavity with lubricating fluid to reduce friction and nourish cartilage.
  • Practical recall tips:
    • Remember anatomical terms by root meanings (syn-, di-, amphi-; plan-, hinge-, ball-and-socket, etc.).
    • Link injury types to tissues (sprain → ligaments; strain → tendons/muscles).
    • OA vs RA patterns: OA worsens with use; RA can improve with movement as blood flow increases.
    • Knee stability relies on cruciate and collateral ligaments plus surrounding bursae and menisci.
      180^
      B0
      may be used to illustrate full extension in some joints during discussion; real values vary by joint.