joints Flashcards
Structural classification of joints
Fibrous = held together by dense collagen fibers (dense regular connective tissue) Cartilaginous = bones held together by cartilage synovial = bones held together by ligaments
Functional classification of joints
Synarthrosis = immovable Amphiarthrosis = slightly movable Diarthrosis = freely movable
Types of Fibrous joints
- Sutures = occur b/t bones of skull –> synarthrosis (synostosis)
- Syndesmoses = interosseous membrane –> b/t tibia/fibula and radius/ulna –> amphiarthrosis
- Gomphoses = cone-shaped peg fits into socket –> teeth in mandible/maxilla –> synarthrosis
Cartilaginous joints
- Synchondroses = hyaline cartilage at epiphyseal growth plate and first rib/manubrium –> synarthrosis
- Symphyses = discs of fibrocartilage –> pubic symphysis and intervertebral discs –> amphiarthrosis
Articular Capsule
- sleeve-like capsule enclosing synovial cavity
- composed of 2 layers: outer fibrous (continuum of periosteum) and inner synovial membrane (synoviocytes)
NO EPITHELIUM
Synovial Fluid
- Secreted by synovial membrane
- reduces friction
- transports oxygen, nutrients, and waste to and from cartilage
Accessory ligaments and articular discs
- Anterior and posterior cruciate ligaments
- medial and lateral (tibial and fibular) collateral ligaments
- menisci = pads of fibrocartilage that allow bones to fit better
Nerve and blood supply to joints
- nerve endings respond to degree of movement and stretch at a joint
- arterial branches from several different arteries merge around joint before penetrating the articular capsule
bursae
- sac like structures with fluid similar to synovial fluid
- b/t tendons and ligaments
- cushions movement of body parts
Tendon sheath
Wraps around tendons to reduce friction
- prominent in wrists
- Ganglion cyst = tendon sheath bubbles up at wrist and fills with synovial fluid
4 types of synovial joint movement
- Gliding = simple side-to-side movement w/ limited range at intercarpal joint
- Angular movements = change angle between articulating bones –> flexsion/extension, ab/adduction, lateral flexsion, circumduction
- Rotation = bone revolves around its own longitudinal axis –> shaking head no, rotating humerus, turning knee inward (hip)
- Special movement = elevation/depression, protraction/retraction, inversion/eversion, dorsiflexion/plantar flexion, supination/pronation, opposition
Range of Motion (ROM)
refers to range, measured in degrees of a circle through which bones of a joint can be moved
Things that affect range of motion
- shape of bones
- strength/tension of ligaments
- arrangement/tension of muscles
- contact of soft parts
- hormones (relaxin)
- disuse (movement stimulates production of synovial fluid)
How are joints affected with age?
- decrease in synovial fluid
- articular cartilage thins
- osteoarthritis could happen
- stretching and aerobics helps to minimize these effects
osteoarthritis
- “degenerative arthritis”
- damage to articular cartilage
- usually from wear and tear of weight-bearing joints and distal finger joints
- sometimes a gene codes for weaker collagen
- bone spurs could develop around area of friction
- restricts movement
- main reason for hip and knee replacements
Rheumatoid arthritis
- unknown cause
- affects smaller joints (fingers, wrists, ankles, feet)
- affects synovial membrane –> swollen and inflamed –> thickens with time and clings to articular cartilage
- cartilage breaks down (more lysosomal enzymes)
- fibrous tissue forms at end of bones
- ossification and bone fusion
Intervertebral disc anatomy
- outer fibrocartilage = anulus fibrosis
- inner elastic gelatinous material = nucleus pulposus
slipped disc
- anulus fibrosis is pushed into vertebral foramen
- due to weakened posterior longitudinal ligaments (which connect vertabrae bodies)
herniated disc
nucleus pulposus breaks through anulus fibrosus into vertebral forament
