Chapter 8: Joints Flashcards
(50 cards)
Joints (Articulations)
Articulation:
*site where 2 or more bones meet
Functions of joints:
- give skeleton mobility
- hold skeleton together
2 Classifications:
- Functional
- structural
Functional Classification of Joints
Based on
*Amount of movement joint allows
Three functional classifications:
*Synarthroses—immovable joints
Syn= together, arthro= joint
- Amphiarthroses—slightly movable joints
- Diarthroses—freely movable joints
Structural classification of joints
Based on
- Material binding bones together
- Presence/absence of joint cavity
Three structural classifications:
- Fibrous joints
- Cartilaginous joints
- Synovial joints
Fibrous Joints
- Bones joined by dense fibrous connective tissue
- No joint cavity
- Most synarthrotic (immovable)
* depends on length of connective tissue fibers
Three types:
- sutures
- syndesmoses
- gomphoses
Fibrous Joints- suture
Joint held together with very short, interconnecting fibers, and bone edges interlock. found only in the skull
Fibrous Joints- syndesmosis
joint held together by a ligament. fibrous tissue can vary in length, but is longer than in sutures. (fibula and tibia)
Fibrous Joints- gomphosis
“peg in socket” fibrous joint. periodontal ligament holds tooth in socket.
Cartilaginous joints
- Bones united by cartilage
- No joint cavity
- Not highly movable
Two types:
Synchondroses
*(synarthrosis - immovable)
*bones united by hyaline cartilage
Symphyses
- (amphiarthrosis –slightly movable)
- bones united by fibrocartilage
- symphyses are amphiarthrosis joints (slightly moveable), especially the pubic symphysis during pregnancy
Synovial joints
- Bones seperated by fluid-filled joint cavity
- all are diarthrotic
- include- all limb joints; most joints of the body
- have 6 distinguishing features
- articular cartilage
- joint (synovial) cavity
- articular (joint) capsule
- synovial fluid
- different types of reinforcing ligaments
- nerves and blood vessels
Synovial joints- Articular cartilage
- hyaline cartilage
* prevents crushing of bone ends
Synovial joints- joint (synovial) cavity
-small, fluid-filled potential space
Synovial joints- articular joint capsule
- 2 layers
- external fibrous layer- dense irregular connective tissue
*inner synovial membrane- loose connective tissue. makes synovial fluid.
Synovial joints- synovial fluid
- Viscous, slippery filtrate of plasma and hyaluronic acid
- Lubricates and nourishes articular cartilage
- Contains phagocytic cells to remove microbes and debris
Synovial joints- different types of reinforcing ligaments
Capsular:
Thickened part of fibrous layer
Extracapsular:
Outside the capsule
Intracapsular:
Deep to capsule; covered by synovial membrane
Synovial joints- nerves and blood vessels
- nerve fibers detect pain, monitor joint position (proprioception) and stretch
- capillary beds supply filtrate for synovial fluid
Other features of some synovial joints
Fatty pads:
For cushioning between fibrous layer and synovial membrane or bone
Articular discs (menisci): Fibrocartilage separates articular surfaces to improve "fit" of bone ends, stabilize joint, and reduce wear and tear
Structures associated with synovial joints
Bursae:
- Sacs lined with synovial membrane (Contain synovial fluid)
- Reduce friction where ligaments, muscles, skin, tendons, or bones rub together
Tendon Sheaths:
Elongated bursa wrapped completely around tendon subjected to friction
When someone has “slipped a disc” of the vertebral column, which type of joint is disrupted?
Symphysis
3 stabilizing factors at synovial joints
- shapes of articular surfaces (minor role)
- ligament number and location (limited role)
- Muscle tendons that cross joint (most important)**
- muscle tone keeps tendons taut (extremely important in reinforcing shoulder and knee joints and arches of the foot)
structural and functional characteristics of body joints
Slide 25 (PPW A)
Synovial joints: movements allowed
All muscles attach to bone or connective tissue at no fewer than two points:
*Origin—attachment to immovable bone
*Insertion—attachment to movable bone
Muscle contraction causes insertion to move toward origin
Movements occur along transverse, frontal, or sagittal planes
Synovial joints: range of motion
- Nonaxial
- Uniaxial
- Biaxial
- Multiaxial
Nonaxial
Slipping movements only
Uniaxial
movement in one plane