Honors Anatomy & Physiology Chapter 8

JOINTS  aka Articulations  2 Functions: 1. Hold Bones Together 2. Allows otherwise rigid skeleton to have some flexibility

Classification of Joints  Functionally  Named according to how much movement joint  Structurally  Named according to presence of fibrous tissue, cartilage, or a joint cavity separate the articulated bones

Functional Joints  Synarthrosis Immovable joints Skull bones  Amphiarthrosis Slightly movable joints  Symphysis pubis  Diarthrosis Freely movable joints Ball & Socket or Hinge Joints

Structural Joints 1. Fibrous Joints Bones united by fibrous tissue Joint connecting distal tibia & fibula 2. Cartilaginous Joints Bone ends connected by cartilage Pubic symphysis 3. Synovial Joints Articulating ends of bone separated by joint cavity

4 Features of Synovial Joints 1. Articular Cartilage Hyaline cartilage covers ends of bones 2. Fibrous Articular Capsule Joint surfaces enclosed by capsule of fibrous CT Capsule lined by synovial membrane 3. Joint Cavity Contains synovial fluid 4. Reinforcing Ligaments Reinforce fibrous articular capsule

General Structure of a Synovial Joint  Articular Cartilage  Joint Cavity  Articular Capsule  Synovial Fluid  Reinforcing Ligaments  Nerves & Blood Vessels  Some also have: menisci, bursae, tendon sheaths outside the joint proper

Factors Influencing Stability of Synovial Joints  Joints must be stabilized to avoid dislocation  Stability of a joint depends on 3 factors: 1. Articular surfaces: overall minor role 2. Ligaments: prevent excessive or undesirable motion at the joint 3. Muscle tone: muscle tendons that cross the joint most stabilizing factor

Types of Synovial Joints 1. PLANE JOINT Articular surfaces flat Allow gliding movement (w/out rotation) Example: intercarpal joints of wrist & ankle

Types of Synovial Joints 2. HINGE JOINT  cylindrical end of bone fits into trough-shaped surface of another bone  Angular movement allowed in 1 plane  Examples: elbow, knee, interphalangeal joints

Types of Synovial Joints 3. PIVOT JOINT  Rounded end of 1 bone fits into sleeve or ring of another bone  allows 1 bone to rotate along its long axis  Example: joint between atlas & dens of axis

Types of Synovial Joints 4.CONDYLOID JOINT  “knuckle-like”  Egg-shaped end of 1 bone fits into oval concavity in another bone  Allows for moving bone to travel side-to-side & back-and-forth but cannot rotate along its long axis  Example: metacarpophalangeal joint

4. CONDYLOID JOINT

Types of Synovial Joints 5. SADDLE JOINTS  Each articular surface has convex & concave areas  Same movements as condyloid joints  Example: twiddling your thumbs

Types of Synovial Joints 6. BALL & SOCKET JOINTS  Spherical head of 1 bone fits into a round socket formed by 1 or more bones  Allows movement is 3 dimensions(most freely moving of synovial joints)

Types of Synovial Joints  1. Gliding  relatively flat surfaces move back-and-forth & side-to-side

Types of Synovial Joints  2. flexion/extension/ hyperextension:  opposite movements flexion: decrease in angle between articulating bones extension: increase in angle between articulating bones hyperextension: continuation of extension beyond the anatomical position

Types of Synovial Joints  3. abduction/adduction/ circumduction abduction: movement of bone away from midline adduction: movement of bone toward midline circumduction: movement of distal end of a body part in a circle

Types of Synovial Joints  4. elevation/depression:  elevation: upward movement of part of body (closing mouth, shrugging shoulders)  depression: downward movement of part of body (opening mouth, returning elevated shrugged shoulders to anatomical position)

Types of Synovial Joints  5. protraction/retraction  protraction: movement of part of body anteriorly in transverse plane  retraction: returning a protracted part of body to anatomical position

Types of Synovial Joints  6. inversion/ eversion  inversion: movement of soles intertarsal joints (soles face each other)  eversion: movement of soles intertarsal joints

Types of Synovial Joints  7. dorsiflexion/ plantar flexion  dorsiflexion: bending ankle in direction of dorsum (superior surface)  plantar flexion: bending ankle in direction of plantar surface

Types of Synovial Joints  8. supination/pronation  supination: movement of forearm in which palm is turned anteriorly  pronation: movement of forearm in which distal end of radius crosses over distal end ulna & palm is turned posteriorly

Types of Synovial Joints  9. opposition  movement of thumb in which thumb moves across palm to touch tips of the fingers on same hand

Ball - & - Socket Joint  ball-like surface of one bone fits into a cuplike depression of another bone  permits movement around 3 axis + all directions in between flexion extension abduction adduction circumduction rotation

SPRAINS  Ligaments or tendons reinforcing a joint are damaged by excessive stretching or tearing  Both have poor blood supply so heal slowly

ARTHRITIS  “inflammation of a joint”  General term for >100 different diseases  Most wide-spread, disabling disease in USA  Onset: same symptoms: joint stiffness & swelling  Synovial membrane inflammed  thickens  less synovial fluid  increased friction

Rheumatoid Arthritis  Autoimmune disorder  Adult onset or Juvenile onset  Women 3x more often than men  Any synovial joint could be affected, often symmetrical involvement  disfiguring

Rheumatoid Arthritis

Osteoarthritis  Most common form of arthritis  Chronic degenerative condition: “wear-and- tear”  Affects articular cartilage (eventually breaks down)  increased friction  bone spurs develop  restricts movement

Osteoarthritis