Bone Structure and Function

Study Notes

Bones are composed of:
- Compact bone: dense, compact tissue that forms the outer layer of bones
- Cancellous bone: spongy, porous tissue that forms the inner layer of bones
Bone tissue is made up of:
- Osteocytes: mature bone cells that maintain bone tissue
- Osteoblasts: bone-forming cells that produce bone matrix
- Osteoclasts: bone-resorbing cells that break down bone tissue
Bone structure functions:
- Support and protection of internal organs
- Movement and leverage through muscle attachments
- Blood cell production and storage of minerals

Origins: the point of attachment of a muscle to a bone that remains relatively stationary during muscle contraction
Insertions: the point of attachment of a muscle to a bone that moves during muscle contraction
Types of muscle attachments:
- Tendons: fibrous connective tissue that attaches muscles to bones
- Ligaments: fibrous connective tissue that attaches bones to other bones
- Aponeuroses: flat, sheet-like tendons that attach muscles to bones
Muscle attachments enable:
- Movement and stabilization of joints
- Transmission of forces from muscles to bones

Joints: structures that connect two or more bones and allow for movement
Types of joints:
- Synovial joints: freely movable joints that allow for a wide range of motion (e.g. shoulder, elbow, knee)
- Cartilaginous joints: partially movable joints that allow for limited motion (e.g. spine, ribcage)
- Fibrous joints: immovable joints that provide stability and support (e.g. skull, teeth)
Joint movement is enabled by:
- Articular cartilage: smooth, flexible tissue that covers the ends of bones in synovial joints
- Synovial fluid: lubricating fluid that reduces friction between bones in synovial joints

Bones consist of two main layers: compact bone and cancellous bone.
Compact bone is dense and forms the outer layer of bones.
Cancellous bone is spongy and porous, forming the inner layer of bones.
Bone tissue is composed of three types of cells: osteocytes, osteoblasts, and osteoclasts.
Osteocytes maintain bone tissue, osteoblasts produce bone matrix, and osteoclasts break down bone tissue.
Bone structure performs three main functions: supporting and protecting internal organs, enabling movement and leverage through muscle attachments, and producing blood cells and storing minerals.

Muscle attachments consist of origins and insertions.
Origins are the points of attachment of a muscle to a bone that remains stationary during muscle contraction.
Insertions are the points of attachment of a muscle to a bone that moves during muscle contraction.
There are three types of muscle attachments: tendons, ligaments, and aponeuroses.
Tendons attach muscles to bones, ligaments attach bones to other bones, and aponeuroses are flat, sheet-like tendons that attach muscles to bones.
Muscle attachments enable movement and stabilization of joints and transmit forces from muscles to bones.

Joints are structures that connect two or more bones and allow for movement.
There are three types of joints: synovial, cartilaginous, and fibrous joints.
Synovial joints are freely movable and allow for a wide range of motion.
Cartilaginous joints are partially movable and allow for limited motion.
Fibrous joints are immovable and provide stability and support.
Joint movement is enabled by articular cartilage and synovial fluid.
Articular cartilage covers the ends of bones in synovial joints, allowing for smooth movement.
Synovial fluid reduces friction between bones in synovial joints, facilitating movement.