6.4 The gross structure of all bones consists of compact bone sandwiching spongy bone

Bone gross anatomy

compact and spongy bone

External layer of bone

compact

Internal layer of bone

spongy (trabecular)

Spongy bone is composed of

trabeculae

Open spaces between trabeculae filled with

red or yellow bone marrow

Structure of short, irregular, and flat bones consist of

thin plates of spongy bone covered by compact bone

Compact bone in short, irregular, and flat bones is covered by

connective tissue membrane that includes: periosteum and endosteum

Periosteum

outside (exterior) connective tissue of compact bone

Endosteum

inside (interior) connective tissue of compact bone

Structure of a typical Long Bone

• Epiphyses

• Diaphysis

• Membranes

• Blood vessels and nerves

• Hematopoietic tissue in bones

Epiphyses

at proximal and distal ends of long bones

• hyaline cartilage

• epiphyseal plate

Epiphyses composition

compact bone

spongy bone

Epiphyses hyaline cartilage

cushions and absorbs stress during movement

also called articular cartilage

Epiphyseal plate

Growth plate → epiphyseal line

• disc of hyaline cartilage

  • grows during childhood to lengthen the bone

Diaphysis

• shaft of bone

• thick collar of compact bone

• medullary cavity

Medullary cavity

yellow marrow in adults

This thin layer can be found between the marrow and compact bone

spongy bone

Membranes of long bones

periosteum and endosteum

Periosteum

• dense irregular

• double-layered membrane

• covers external surface of the entire bone except joint surfaces

Outer fibrous layer of periosteum is

dense irregular connective tissue

Inner osteogenic layer of periosteum

• osteroprogenitor cells

• osteoclasts and osteoblasts

Fibers that connect periosteum to bone

perforated fibers

Endosteum

delicate connective tissue membrane covers internal bone surfaces

Nutrient artery and vein

nutrient foramen

Nutrient artery

• supplies bone marrow and spongy bone

• branches to supply compact bone

Hematopoietic tissue

red bone marrow

Infants red bone marrow

found in medullary cavity and all area of spongy bone

Adult red bone marrow

• red bone marrow is replaced by yellow marrow from infant

• RBM only found in cavities between trabeculae of spongy bones