Bone Anatomy, Structure, and Growth

Flashcards covering bone gross anatomy, periosteum, endosteum, diploë, vascularization, innervation, and bone marrow.

What is the metaphysis of a long bone?

The region of a long bone where the bone widens and transfers forces between the diaphysis and the epiphysis.

What is the epiphyseal plate and what is its function?

A thin layer of hyaline cartilage located in the metaphysis of a juvenile long bone that provides for continued growth in bone length.

What is the epiphyseal line?

A thin, defined area of compact bone in adults that represents the remnant of the epiphyseal plate.

What is the periosteum?

A tough sheath that covers the outer surface of bone, except for areas covered by articular cartilage.

What are the structure and functions of the outer fibrous layer of the periosteum?

It consists of dense irregular connective tissue that protects the bone from surrounding structures, anchors blood vessels and nerves to the surface, and serves as an attachment site for ligaments and tendons.

Which cell types compose the inner cellular layer of the periosteum, and what is its main function?

It is primarily composed of bone stem cells (osteoprogenitor cells) and osteoblasts, which produce circumferential layers of bone matrix and are responsible for growth in bone width.

What are perforating fibers (Sharpey's fibers)?

Numerous collagen fibers running perpendicular to the diaphysis that anchor the periosteum to the bone.

What is the endosteum and where is it located?

A relatively delicate layer of connective tissue containing cells and reticular fibers that lines all internal surfaces of bone within the medullary cavity.

Which cells are contained in the endosteum?

Osteoprogenitor cells and osteoblasts, which are active during bone growth, repair, and remodeling.

How are osteoclasts formed and recruited during bone remodeling according to the text?

Osteoclasts do not compose the endosteum or periosteum; instead, osteoblasts in the endosteum or periosteum signal cells in the bone marrow to form osteoclasts and migrate to the remodeling area.

How does the gross anatomy of short, flat, and irregular bones differ from long bones?

Their external surface is composed of compact bone covered by periosteum, their interior is composed entirely of spongy bone, and they lack a medullary cavity.

What is diploë?

The layer of spongy bone sandwiched between roughly parallel segments of compact bone in a flat bone of the skull.

How do blood vessels enter and exit typical bones?

Blood vessels enter from the periosteum, typically via one nutrient artery entering and one nutrient vein exiting through a small hole called a nutrient foramen.

What type of nerves innervate bone and what is their function?

Mainly sensory nerves enter through the nutrient foramen to innervate bone, periosteum, endosteum, and marrow cavity to relay nerve impulses when the skeleton is injured.

Which long bone structures are responsible for growth in length versus growth in width?

Growth in bone length is provided by the epiphyseal plate, whereas growth in bone width is driven by the periosteum.

What is red bone marrow (myeloid tissue) composed of and what is its primary function?

It contains reticular connective tissue, developing blood cells, and adipocytes; its primary function is forming the blood cells of the body (hematopoietic).