Joints Ch. 9 Flashcards
Joints
- Rigid elements of the skeleton meet at joints or articulations
- Greek root “arthro”means joint
- Structure of joints enables resistance to crushing, tearing, and other forces
FunctionalClassification of Jointsbased on amount of movement
- Synarthroses—immovable; common in axial skeleton
- Amphiarthroses—slightly movable; common in axial skeleton
- Diarthroses—freely movable; common in appendicular skeleton; all synovial joints are diarthoses
StructuralClassification of Joints
- Based on material that binds bones together
* Presence or absence of a joint cavity
Structural Classifiction of Joints
- Fibrous
- Cartilaginous
- Synovial
Fibrous Joints
- Bones are connected by fibrous dense regular connective tissue rich in collagen fibers
- Do not have a joint cavity
- Most are immovable (synarthroses)
Types of Fibrous Joints
- Sutures (short fibers)
- Syndesmoses (longer fibers)
- Gomphoses (periodontal ligaments)
Fibrous Joints: Sutures
- Bones are tightly bound by a minimal amount of fibrous tissue with short fibers
- Occur between the bones of the skull
- Allow bone growth so the skull can expand with brain growth during childhood
- Fibrous tissue ossifies in middle age to produce synostoses(= closed sutures)
Fibrous Joints: Syndesmosis
•Bones are connected exclusively by ligaments (dense regular connective tissue),fibrous tissue with relatively long fibers
•Amount of movement depends on length of fibers
–Distal tibiofibular joint articulation—synarthrosis with minimal or no movement
–Interosseous membrane between radius and ulna has quite long fibers which enables some movement between these bones
Fibrous Joints: Gomphoses
- Tooth in a socket
- Connecting ligament—the periodontal ligament
- Immobile
Tooth Structure
- Longitudinal section of tooth in bone alveolus
- Enamel
- Dentin
- Pulp cavity
- Root canal
- Cementum
- Apical foramen
- Periodontal ligament
StructuralClassification of Joints
- Fibrous •Cartilaginous
* Synovial
Cartilaginous Joints
- Bones are united by cartilage
- Lack a joint cavity
- Immobile to slightly mobile
Cartilaginous Joint Types
- Synchondroses: hyaline cartilage, immobile
* Symphyses: fibrocartilage, slightly mobile
SynchondrosisCartilaginous Joint
Bones United by HyalineCartilage
•Epiphyseal plates
•Joint between first rib and manubrium
Symphysis Cartilaginous Joint
- Fibrocartilageunites bones
- Fibrocartilage resists tension & compression stresses and can act as a shock absorber
- Slightly movable joints that provide strength with flexibility–intervertebral discs–pubic symphysis
- Hyaline cartilage is also present as articular cartilage on the bony surfaces to reduce friction between bones during movement
Synovial Joints
- Most movable type of joint•All are diarthroses(movable joints) and contain a fluid-filled joint cavity
- Adjoining bones are covered with articular cartilage and are separated by a joint cavity
- Joint cavity is enclosed within an articular capsule with the inner layer lined with synovial membrane
General Structure of Synovial Joints
•Articular cartilage
–Ends of opposing bones are covered with hyaline cartilage
–Absorbs compression
•Joint cavity(synovial cavity)
–Unique to synovial joints
–Cavity is a space that contains synovial fluid
What is connective tissue made of? Could be question on the best
LOOK UP
Ligaments
- Extend over the outer surface of the articular capsule and contribute to joint stability
- Anchored in periosteum of adjacent bones
- Dense regular connective tissue
Articular Capsule of Synovial Joints is enclosed in a two-layered capsule
•Fibrous capsule—dense irregular connectivetissueis continuous with periosteal layer of adjoining bones; strengthens joint
- Synovial membrane—loose connective tissue
* Lines inner layer of joint capsule and covers internal joint surfaces not covered by cartilage- Functions to make synovial fluid
Synovial membrane
•Rich blood supply to synovial membrane forms extensive capillary beds that provide blood filtrate that forms synovial fluid
Synovial Fluid
- Produced by synovial membrane
- Present in joint cavity
- Is a viscous fluid with consistency similar to raw egg white
- Contains glycoprotein molecules secreted by fibroblasts
How Synovial Joints Function
- Synovial joints—lubricating devices
- Friction could overheat and destroy joint tissue
- As synovial joints are subjected to compressive forces
- Fluid is squeezed out as opposing cartilages touch
- Cartilages ride on the slippery film
Sensory Fibers Richly Innervate Synovial Joints
- Detect pain
* Most monitor how much the capsule is being stretched
Three Basic Movements of Synovial Joints
- Gliding—one bone across the surface of another
- Angular movement—movements change the angle between bones
- Rotation—movement around a bone’s long axis
Synovial Joint Types
GREAT SUMMARY SLIDE
- Plane is nonaxial: intercarpal & intertarsal
- Hinge is uniaxial: elbow, ankle & interphalangeal
- Pivot is uniaxial: proximal radio-ulnar and between atlas (C1) and dens of axis (C2) which allows the skull to rotate on the neck’s axis
- Chondyloid is biaxial: metatarsophalangeal, metacarpophalangeal & wrist
- Saddle is > biaxial: sternoclavicular & 1stcarpometacarpal
- Ball & Socket is multiaxial: shoulder & hip
SLIDE found on 7