Articulations Flashcards
Types of joints:
Based on range of motion
1) Synarthrosis: immovable
Example: cranial sutures & epiphyseal cartilage
2) Amphiarthrosis: slightly moveable
Example: radius/ulna shafts & Pubic symphysis
3) Diarthrosis: freely moveable (synovial joints)
Example: joints in limbs
Joint classifications based on cartilage type
1) Fibrous cartilage- sutures (2 bones connected by ligaments)
2) Cartilaginous- synchondrosis & symphysis
3) synovial- all joints
Diarthrosis (synovial joints)
Joint structure, articular cartilage, synovial membrane, joint cavity contains synovial fluid, joint capsule, periosteum
Function of synovial fluid
1) lubrication; low friction coefficient
2) nourishment for chondrocytes; regulated by joint movement
3) shock absorption; distributes forces evenly over articular cartilages
Diarthrosis
Accessory structures
- not all joints have these *
- bursa
- meniscus
- extracapsular/ intracapsular ligament
- tendons
- fat pad
Diarthrosis
Functions of accessory structures
1) menisci- fibrous cartilage pads for shock absorption
2) fat pads- fill spaces created when joint changes shape
3) ligaments & tendons - support joints & limit movement
4) bursae- synovial fluid-filled pockets surrounded by synovial membrane. Reduce friction/ shock absorption
Joint vs. mobility (range of motion)
Factors affecting mobility
- shape of articulating surfaces
- types/quantity of accessory structures
Very strong = less mobility
Can’t be both
Structure= function
Joint movements
Types of planes
1) coronal plane
Joints: shoulder, hip, wrist, metatarso-phalangeal, & metacarpo-phalangeal
2) sagittal plane
Joints: vertebral column joints, elbow, hip, knee, wrist, fingers, toes
3) transverse plane
Joints: atlas/axis joint, shoulder, hip, radioulna joints (supination & pronation only)
Joint movements
- abduction: movement away from body
- adduction: movement away from body
- flexion: decreases the angle or distance between two bone segments
- extension: increases the angle or distance between two bone segments
- rotation
- pronation/supination
- lateral flexion
- depression/ elevation (shrug shoulders)
- retraction/ protraction (jaw)
Special movements of ankle
- eversion/ inversion
- dorsiflexion/ plantarflexion
Axis of motion
1) Mono axial: movement in 1 planes
Example: ankle & elbow
2) biaxial: movement in 2 planes
Example: ribs & wrist
3) triaxial: movement in 3 planes
Example: shoulder & hip
Joints
Arthroses
Connection between bones that may or may not permit movement
Gliding joint
Amphiarthrosis, Slight movement
Mono axial
Example: sternoclavicular, acromioclavicular, intercarpal, intertarsal joints
Pivot joint
Rotation
Mono axial
Amphiarthrosis
Example: atlas/axis joint
Saddle joint
Biaxial
Angular motion
Example: first carpometacarpal joint
