Honors Anatomy & Physiology Chapter 8. JOINTS aka Articulations 2 Functions: 1. Hold Bones...
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Transcript of Honors Anatomy & Physiology Chapter 8. JOINTS aka Articulations 2 Functions: 1. Hold Bones...
JOINTS
Honors Anatomy & PhysiologyChapter 8
JOINTS
aka Articulations
2 Functions:1. Hold Bones Together2. Allows otherwise rigid
skeleton to have some flexibility
Classification of Joints
Functionally
Named according to how much movement allowed @ joint
Structurally Named
according to presence of fibrous tissue, cartilage, or a joint cavity separate the articulated bones
Functional Joints Synarthrosis
Immovable jointsSkull bones
AmphiarthrosisSlightly movable joints
Symphysis pubis Diarthrosis
Freely movable jointsBall & Socket or Hinge Joints
Structural Joints1. 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 Joints1. 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 role2. Ligaments: prevent excessive or
undesirable motion at the joint3. Muscle tone: muscle tendons that
cross the joint most stabilizing factor
Types of Synovial Joints1. PLANE JOINT
Articular surfaces flat Allow gliding movement (w/out
rotation) Example: intercarpal joints of
wrist & ankle
Types of Synovial Joints2. 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 Joints3. 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 Joints4.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
Types of Synovial Joints5. SADDLE JOINTS Each articular surface has
convex & concave areas Same movements as condyloid
joints Example: twiddling your
thumbs
Types of Synovial Joints6. 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 Movements @
Synovial Joints 1. Gliding relatively flat surfaces move back-
and-forth & side-to-side
Types of Movements @
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 Movements @
Synovial Joints 3. abduction/adduction/
circumductionabduction: movement of bone away
from midlineadduction: movement of bone toward
midlinecircumduction: movement of distal
end of a body part in a circle
Types of Movements @
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 Movements @
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 Movements @
Synovial Joints 6. inversion/ eversion inversion: movement of soles
medially @ intertarsal joints (soles face each other)
eversion: movement of soles laterally @ intertarsal joints
Types of Movements @
Synovial Joints 7. dorsiflexion/ plantar flexion dorsiflexion: bending foot @ ankle
in direction of dorsum (superior surface)
plantar flexion: bending foot @ ankle in direction of plantar surface
Types of Movements @
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 Movements @
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 betweenflexionextensionabductionadductioncircumductionrotation
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