Types of Joints in the Human Body

Joints

• Joints are where two or more bones connect, allowing for movement.
• There are three main types of joints: fibrous, cartilaginous, and synovial.

Types of Joints

• Fibrous joints: made of tough fibrous tissue, does not allow for movement (e.g. skull).
• Cartilaginous joints: made of cartilage and allows for restricted movement (e.g. vertebrae).
• Synovial joints: allows for complete movement (e.g. hip and elbow).

Synovial Joints

• Periosteum: a coating of the bone that supplies it with blood cells.
• Hyaline cartilage: protects the end of bones and absorbs shocks.
• Synovial membrane: a sac that produces and dispenses synovial fluid, which lubricates the joint.
• Joint cavity: filled with synovial fluid.
• Bursa: allows skin, ligaments, and tendons to glide over each other.
• Fibrous connective tissue: provides strength to the joint.
• Articular capsule: an envelope made of fibrous connective tissue and synovial membrane that encloses the joint.

Ligament vs. Tendons

• Ligament: connects bones, made of white connective tissue, flexible but not elastic, avascular.
• Tendon: connects bones to muscles, made of collagen (fibrous protein), vascular.

Types of Joints

• Pivot joints: bone inside a ring-shaped bone, allows for rotation (e.g. neck and forearm).
• Hinge joints: convex and concave (parallel), allows for flexion/extension (e.g. ankle, knee, and elbow).
• Saddle joints: convex and concave (perpendicular), allows for flexion/extension (e.g. thumb, carpo-metacarpal).
• Plane joints: bone that slides over a flat bone, allows for flexion/extension (e.g. ankle and wrist).
• Ball-and-Socket joints: rounded head of bone inside a cup-shaped bone, allows for movement in all directions (e.g. hip and shoulder).
• Ellipsoid joints: ovoid-shaped head of bone inside a concave ellipsoid shape bone, allows for movement in all directions but rotation (e.g. wrist, radiocarpal, and hand, metacarpophalangeal).

Joint Related Injuries

• Joint dislocation: when a bone is displaced from its joint, often caused by falls and collisions (e.g. shoulder and fingers).
• Joint separation: damage to the ligament of the shoulder joint where the clavicle meets the scapula, often caused by direct falls/hits to the shoulder, car accidents, and sports injuries.
• Osteoarthritis: loss of cartilage in joints, often caused by age, obesity, sex, genetics, and joint injuries (e.g. hands, knees, hips, and vertebrae).
• Bursitis: inflammation of the bursa at a point of friction between bone, ligament, and tendon, often caused by repetitive movement (e.g. elbow and shoulder).
• Tendinitis: inflammation of tendons, often caused by irritation from prolonged or abnormal movement.
• Knee ligament tears: tearing of the knee ligament, often caused by sudden twisting motion (e.g. ACL), direct hit (e.g. PCL), blow to the inner or outer knee (e.g. MCL and LCL).
• Meniscal tears: tear of the meniscus (pad of cartilage that absorbs shocks), often caused by twisting motion when the knee is bent/pivot attempt (e.g. knee, may hear a popping sound).
• Osgood Schlatter Syndrome: affects the epiphyseal plate of the tibial tuberosity, often caused by overloading or overusing the plate, leading to inflammation and irritation.

Injury Treatment

• Recognition: SHARP (swelling, heat, altered, red, pain).
• Treatment: PEIR (pressure, elevate, ice, restrict).