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
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Flexion/Extension
Abduction/Adduction
Circumduction
Rotation
Protraction/Retraction
Protraction / Retraction
Types of Movement
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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 pusforming 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