Joints Skeletal System - Part 3

Joints With one exception (the hyoid bone), EVERY bone in the body forms a joint with at least one other bone. Joints have 2 functions: Hold bones together Give skeleton mobility Also known as articulations

Classification of Joints Functional – how much movement allowed Synarthroses - immovable Amphiarthroses - slightly movable Axial skeleton Diarthroses - freely movable Appendicular Skeleton

Classification of Joints Structural – what the joint is made of Fibrous - bones joined by fibrous connective tissue; no joint cavity Cartilaginous - bones joined by cartilage; no joint cavity Synovial - bones separated by fluid filled cavity

Fibrous Joints Characteristics Almost no movement allowed Sutures – irregular bone edges interlock by connective tissue (ex: skull bones) Syndesmosis – joint connected by long fibers that allow a small amount of movement (ex: tibia and fibula joint)

Cartilaginous Joints Characteristics Slight movement allowed Bones connected by cartilage Found in the pelvis and intervertebral column

Synovial Joints General Structure Articular cartilage Synovial (joint) cavity Articular capsule Synovial fluid Reinforcing ligaments (fibrous tissue connecting bones)

Synovial Joints Bursae - flattened sacs filled with synovial fluid Tendon sheath - elongated bursa which wraps around a tendon

Different joint types are located in various areas throught your body!

Synovial Joints Gliding (plane) joint Only gliding or slipping movements allowed Ex: Wrist joints

Synovial Joints Hinge Joint Only angular movement allowed Cylindrical projection fits into a notch Ex: ulna and humerus Ex: tibia and femur Ex: interphalangeal joints

Synovial Joints Pivot Joint Rounded end of one bone protrudes into sleeve or ring of bone or ligaments Ex: atlas (C1) and axis (C2) Ex: radioulnar joint

Synovial Joints Condyloid Joint Rounded (convex) articulating surface of one bone fits into concave depression on the other bone Side to side and back and forth movement Ex: radio-carpal joints Ex: metacarpal- phalangeal joints

Synovial Joints Saddle Joint Each articular surface has both convex and concave areas – look like saddles Ex: carpo-metacarpal joint of the thumb (so you can twiddle your thumb)

Synovial Joints Ball and Socket Spherical head of one bone articulates with cuplike socket Provides greatest rotational flexibility Ex: shoulder, hip

Dislocation Occurs when a bone is forced out of its normal position in a joint cavity

Inflammatory and Degenerative Conditions Bursitis An inflammation of a bursa, usually caused by a blow or friction Symptoms are pain and swelling Tendonitis Inflammation of tendon sheaths typically caused by overuse Symptoms are similar to bursitis

Joint Disorder - Arthritis More than 100 different types of inflammatory or degenerative joint diseases Most common crippling diseases in the U.S. Symptoms – pain, stiffness, and swelling of joint(s) Chronic forms include osteoarthritis (OA), rheumatoid arthritis, and gouty arthritis

Rheumatoid Arthritis X-ray

Osteoporosis Bone-thinning disease Affects half of women over 65 and 20% of men over 70 Sneezing can cause bone to break they are so brittle After menopause estrogen levels (female hormone) drop, this is one of the causes of osteoporosis Other factors: Low calcium and low protein diet Lack of vitamin D Smoking Sedentary lifestyle

Osteoporosis