Bone Tissue and the Skeletal System: Structure, Classification, and Function

Bone Tissue and the Skeletal System

Functions of the Skeletal System

The skeletal system is essential for providing structure, protection, and support to the human body. It also plays a critical role in movement, mineral storage, and blood cell production.

• Supports the Body: The skeleton forms the rigid framework that supports soft tissues and maintains the body’s shape.

• Facilitates Movement: Bones act as levers and points of attachment for muscles, enabling movement at joints.

• Protects Internal Organs: Bones such as the skull and rib cage shield vital organs from injury.

• Produces Blood Cells (Hematopoiesis): Red bone marrow within certain bones generates red and white blood cells and platelets.

• Stores and Releases Minerals and Fat: Bones store minerals like calcium and phosphorus, and release them into the bloodstream as needed. Yellow marrow stores fat.

Classification of Bones

Bones are classified based on their shapes and functions. This classification helps in understanding their roles in the body.

• Long Bones: Cylindrical in shape and longer than they are wide. Examples: humerus, femur, metacarpals, metatarsals.

• Short Bones: Cube-like in shape, with equal length, width, and thickness. Examples: carpals (wrist bones), tarsals (ankle bones).

• Flat Bones: Thin and often curved. Examples: scapulae (shoulder blades), cranial bones (skull), sternum (breastbone).

Continuation of Bone Classification

• Irregular Bones: Complex shapes that do not fit into other categories. Examples: vertebrae, many facial bones.

• Sesamoid Bones: Small, round bones shaped like a sesame seed, embedded within tendons. Example: patella (kneecap), variable number in tendons.

Key Anatomy Terms

Understanding bone anatomy is crucial for identifying bone structure and function.

• Diaphysis: The tubular shaft of a long bone.

• Epiphysis: The proximal and distal ends of a long bone.

• Metaphysis: The narrow area between the diaphysis and epiphysis at each end of the bone.

• Medullary Cavity: The hollow region in the diaphysis, filled with yellow marrow (fat storage).

Continued Bony Anatomy Terms

• Epiphyseal Plate: Area of bone growth in length (also called growth plate), located in the metaphysis. It is made of hyaline cartilage in growing children.

• Epiphyseal Line: The visible line that remains after the epiphyseal plate has stopped growing in length after childhood.

• Endosteum: Lining of the medullary cavity; site of bone growth, repair, and remodeling.

• Periosteum: A fibrous membrane that covers the outer surface of bone; serves as a site for ligament and tendon attachment and contains cells important for bone growth and repair.

Additional info:

• Hematopoiesis: The process of blood cell formation, which occurs in the red marrow of certain bones.

• Yellow Marrow: Consists mainly of adipose tissue and serves as an energy reserve.