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
