ARTICULATIONS

WHAT IS A JOINT?

• A site where two or more bones meet.• Provides mobility• Weakest point of skeleton

Joint Structure

• Fibrous connective membranes• Sutures – connected by short fibers from

the periosteum (becomes synostosis in adult)• Syndesmoses – connected by ligaments

(distal end of tibia & fibula)•Gomphoses -- “peg in sockets” (tooth

sockets)

Joint Structure

• Cartilaginous - hyaline cartilage holding joint together• Synchondroses– cartilage unites

bones (epiphyseal plates & costal joints)• Symphyses – connected by

fibrocartilage (pubic symphysis, vertebral joints)

Joint Structure

• Synovial joints – separated by a fluid containing joint cavity•Diarthroses - freely moveable joints such

as shoulder, knee, hip, and most others

Joints classified by function

• Synarthroses –NO MOVEMENT • (sutures, gomphoses, synchondroses,

some syndesmoses)

• Amphiarthroses – –SLIGHT MOVEMENT• (symphyses, some syndesmoses

Joints by function• Diarthroses - FREELY MOVABLE

•Plane (gliding) - tarsals and carpals•Condyloid (ellipsoid) –

metacarpophalangeal joints•Pivot - Atlas/Axis; Radius/Capitulum• Saddle - Thumbs•Hinge – Elbow, Knee•Ball and socket – Shoulders, Hips

Suture

Synchrondroses

Syndesmosis

Symphyses

Synovial Joint

Ball & Socket Joint

Condyloid Joint

Hinge Joint

Pivot Joint

Saddle Joint

Plane (Gliding) Joint

Structure of Diarthrotic Joint

• Two or more opposing bones• Joint capsule of connective tissue surrounds

joint cavity• Joint cavity lined with synovial membrane• Articular cartilage – covers ends of bone• Menisci (articular disks) - cartilage pads (knee)• Bursae – flattened sacs filled with synovial fluid• Ligaments – attach bone to bone• Tendons – attach muscle to bone

Synovial Joint

Types of Movement

• Flexion/Extension• Abduction/Adduction• Circumduction• Rotation• Protraction/Retraction

Protraction / Retraction

Types of Movement

• Elevation/Depression• Inversion/Eversion• Pronation/Supination• Dorsiflexion/Plantar flexion

Supination / Pronation

Elevation / Depression

Inversion / Eversion

Joint Injuries

• Sprains - ligaments stretched or torn• Cartilage Injuries - torn cartilage rarely

repairs because it’s avascular)• Dislocations (luxation) - bones moved out

of alignment

Knee Joint

Inflammatory/Degenerative Conditions

• Bursitis - inflammation of a bursa caused by blow or friction

• Tendonitis - inflammation of tendons caused by overuse

• Arthritis

Arthritis– >100 different types; affecting 1 out of 7–Osteoarthritis - Wear & Tear; affects 85%–Rheumatoid Arthritis - Autoimmune•May occur at any age; Most common around

40-50; Affects 1-2% of Americans• Immune cells attack joint tissue causing

scarring & ossification• Ankylosis = stiff deformed joints

–Gouty Arthritis (Gout)• Caused by build up of Uric Acid

Other Bone Disorders

• Rickets - soft bones; lack of calcium due to vitamin D deficiency

• Osteoporosis - excessive bone loss• Paget’s disease - excessive bone formation• Osteomyelitis - Inflammation caused by pus-

forming bacteria• Achondroplasia - defective endochondral

bone growth; form of dwarfism

• Osteosarcoma - form of bone cancer• Scoliosis - abnormal lateral curvature of

the spine• Kyphosis - abnormal thoracic curvature• Lordosis - abnormal lumbar curvature• Herniated Disk (Ruptured or Slipped Disk)

- compression on intervertebral disk presses on nerves