Chapter 6- Joints Flashcards
articulation
where bone meets
- another bone
- cartilage
- teeth
function of joints
- give skeleton mobility
- hold skeleton mobility
classification of joints
- functional
- structural
functional classification
amount of movement joint allows
1) synarthroses- immovable
2) amphiarthroses- slightly movable
3) diarthroses- freely movable
structural classification
based on material binding bones and presence of joint cavity
1) fibrous- collagen
2) cartilaginous- holding bone to something else
3) synovial- mostly diarthroses
fibrous joints
- sutures
- syndemoses
- gomphoses
sutures
- rigid, interlocking joints
- immovable joints for brain protection
- short connective tissue fibres
- growth during youth
- sutures ossify and fuse in middle age
syndemoses
- bones connected by ligaments
- fibre length varies so movement varies:
- little to no movement at distal tibiofibular joint
- large amount of movement at interosseous membrane of radius/ulna
gomphoses
- peg-in-socket teeth joints
- fibrous connection is periodontal ligament
cartilaginous joints
-bones unites by cartilage
-no joint cavity
-not highly movable
2 types
-synchondroses
-symphyses
synchondroses
- bar/plate of hyaline cartilage unites bone (epiphyseal plate, cartilage of 1st rib with manubrium)
- all are synarthrotic (no movement)
symphyses
- fibrocartilage unites bone
- resists tension in one axis (hyaline cartilage)
- strong, flexible, amphiarthroses (slightly movable)
synovial joints
- bones separated by fluid-filled joint cavity
- all are diarthrotic (freely movable)
- all limbs and most joints
features of synovial joints (6)
- articular cartilage
- joint cavity
- articular capsule
- synovial fluid
- reinforcing ligaments
- nerves and blood vessels
articular cartilage
- hyaline cartilage (frictionless cartilage)
- prevents crushing of bone ends
- prevents bones from rubbing
joint cavity
- small, fluid-filled potential space
- shape can change
articular capsule
2 layers
- external fibrous layer: dense irregular connective tissue, strong collagen
- inner synovial membrane: loose connective tissue, more areolar. makes synovial fluid allowing for frictionless movement
synovial fluid
- viscous, slippery filtrate of plasma and hyaluronic acid
- lubricates and nourishes articular cartilage
- has phagoncytic cells to remove microbe and debris
reinforcing ligaments
1) capsular: thickened part of fibrous layer
2) extracapsular: outside capsule
3) intracapsular: deep to capsule, covered by synovial membrane
double jointed
- loose, stretchy joint capsule and ligaments
- ligaments allow for greater range of motion than normal
nerves and blood vessels
- nerve fibers detect pain, monitor joint position and stretch
- capillary beds supply filtrate for synovial fluid
fatty pads
- for cushioning between fibrous layer and synovial membrane or bone
- hip and knee
articular discs
- fibrocartilage separates articular surfaces to improve fit of bone ends
- stabilize joint and reduce wear and tear
- knees (menisci) , jaw etc.
bursae
- sacs lined with synovial membrane containing synovial fluid
- reduce friction
tendon sheaths
elongated bursa wrapped around tendon subjected to friction
stabilizing factors of synovial joints
1) shapes of articular surfaces
2) ligament number and location
3) muscle tendons that cross joint (muscle tone keeps tendons taut) most important factor
origin and insertion
- all muscles attach at no fewer than 2 points
- origin: attachment to immovable bone
- insertion: attachment to movable bone, the one that gets pulled
- insertion moves toward origin
- movement occurs along transverse, frontal, or sagittal planes
types of synovial joint motion (4)
1) gilding
2) angular movements
3) rotation
4) special movements
gliding
- flat bone over another similar surface
- not fixed around pivot point
- intercarpal joints, inter tarsal joints, articular processes of vertebrae
angular movements
- flexion, extension, hyperextension
- abduction, adduction
- circumduction
flexion, extension, hyperextention
- increase or decrease angle between 2 bones
- movement alone sagittal plane
- flexion: decrease angle
- extension: increase angle
- Hyperextension: excessive extension beyond normal range of motion
abduction, adduction
- movement along frontal plane
- abduction: movement away from midline
- adduction: movement toward midline
circumduction
- involves flexion, abduction, extension, and adduction of limb
- limb describes cone in space
- proximal end stays stationary, distal end goes in circular motion
- only upper and lower limbs
rotation
- turning of bone around its own axis
- toward or away from midline
- medial and lateral rotation
- between C1 and C2 vertebrae, rotation of humerus and femur, pronation and supination
synovial joint shapes (6)
- plane joints (wrist)
- hinge joints (elbow)
- pivot joints (radioulnar)
- condylar joints (MCP)
- saddle joints (CMC)
- ball-and-socket joints (hip, shoulder)
special joint movements (6)
- pronation & supination
- dorsiflexion & plantar flexion
- inversion & eversion
- protraction & retraction
- elevation & depression
- opposition
