Study Question Twelve

• Q12. What are the similarities and differences in the histology periosteum and endosteum? 
• Superficial layer of compact bone is in turn covered by the periosteum, a connective tissue wrapping that is connected to the deep fascia
• Inside the bone, a cellular endosteum line the medullary cavity. This layer is one cell thick and is an incomplete layer
• The endosteum contains osteoprogenitor cells and covers the trabeculae of spongy bone
• Similarities between periosteum and endosteum include:

  • connective tissue composition
  • bone formation and repair
  • vascular supply
• Periosteum and endosteum similarity of connective tissue composition: are composed of dense connective tissue. They contain cells such as osteoblasts and osteoclasts, which are essential for bone formation and resorption
• Periosteum and endosteum similarity of bone formation and repair: Membranes play roles in bone formation and repair. Periosteum is involved in bone growth and healing, while endosteum is involved in remodeling and repair of bone tissue from the inside.
• Periosteum and endosteum similarity of vascular supply: richly supplied with blood vessels, which is important for the nourishment and metabolic support of bone tissue
• Periosteum and endosteum difference of location:

  • Periosteum is a dense, fibrous membrane that covers the external surface of bones, except at joints. So EXTERNAL
  • Endosteum lines the internal surfaces of bones. It is a thin layer compared to the periosteum. So INTERNAL
• Periosteum and endosteum difference of layer composition:

  • Periosteum outer fibrous layer consists of dense irregular connective tissue, including collagen fibers, fibroblasts, and blood vessels. The inner layer (osteogenic layer) contains osteoblasts
  • Endosteum is a thinner layer composed primarily of a single layer of osteoblasts and osteoclasts with a small amount of connective tissue. It does not have the fibrous outer layer like the periosteum
• Periosteum and endosteum difference of function:

  • Periosteum is a site for bone growth and repair, provides a surface for the attachment of tendons and ligaments, and involved in the vascular supply to the bone
  • Endosteum plays a role in bone remodeling, resorption and formation of bone within the medullary cavities, and maintains the bone marrow environment