Bone Remodeling and Joint Types

Bone Remodeling

• Osteoclasts are responsible for bone resorption (breakdown).
• Osteoblasts are responsible for bone replacement (building).
• Osteocytes are living bone cells.
• Bone is constantly remodeled in response to pressure, hormones, diet, and other factors.
• Calcium is stored in bones, and can be reabsorbed into the blood when calcium levels are low.
• Osteoblasts deposit collagen and elastin fibres, giving bones flexibility.
• Osteoblasts deposit a matrix of minerals which harden when calcium salts are deposited.

Types of Joints

• Fibrous joints are connected by dense connective tissue with no space or capsule.
• Fibrous joints have limited movement.
• Examples of fibrous joints include the fontanelles of the skull and sockets of teeth.
• Cartilaginous joints have articular surfaces covered with hyaline cartilage.
• Cartilaginous joints allow for limited movement.
• Cartilaginous joints are found between vertebrae and some ribs.

Vertebrae

• Cervical vertebrae are located in the neck, and have a transverse foramen.
• Thoracic vertebrae are located in the mid-back, and have a long spinous process.
• Lumbar vertebrae are located in the lower back, and have a large body.

Synovial Joints

• Synovial joints are freely movable, and include many major joints in the body, such as the knee, hip, shoulder, neck and spine.
• Each synovial joint allows for specific movement.
• A dense connective tissue capsule surrounds synovial joints, containing cartilage covering the end bones, and ligaments stabilizing the joint.
• A synovial membrane lines the capsule and releases synovial fluid, which lubricates hyaline cartilage within the joint, reducing friction.

Shoulder Joint

• The coracoid and acromion processes of the scapula are where the coracoacromial ligament attaches.
• The supraspinatus muscle slides under the coracoid and acromion processes, and may experience impingement injury.
• The AC (acromioclavicular) joint is where the acromion and clavicle connect.
• The clavicle, scapula, and humerus are bones of the shoulder joint.

Knee Joint

• The meniscus is a C-shaped cartilage between the femur and tibia.
• The cruciate ligaments (anterior and posterior) allow for limited twisting of the knee.