Anatomy of Bones and Bone Markings Quiz

Bone Markings and Attachments

• Bone markings are surface features of bones, which are not smooth but scarred with bumps, holes, and ridges.
• Sites of attachments for muscles, tendons, and ligaments are part of bone markings.
• Passages for nerves and blood vessels are also categories of bone markings.
• Projections and processes grow out from the bone surface.
• Depressions or cavities are indentations in the bones.

Microscopic Anatomy of Bone

• Osteocytes are mature bone cells.
• Lacunae are tiny cavities arranged in concentric circles, containing osteocytes.
• Osteon (Haversian System) is a unit of bone, consisting of a central (Haversian) canal, lacunae, and lamellae.
• The central canal carries blood vessels and nerves.
• Perforating (Volkman's) canals are perpendicular to the central canal and carry blood vessels and nerves.
• Canaliculi are tiny canals that radiate from the central canal to lacunae, forming a transport system that connects all bone cells to the nutrient supply through the hard bone matrix.

Types of Bone Cells

• Osteocytes are mature bone cells.
• Osteoblasts are bone-forming cells.
• Osteoclasts are bone-destroying cells that break down bone matrix for remodeling and release of calcium.

Bone Development and Growth

• In embryos, the skeleton is primarily hyaline cartilage.
• During development, much of this cartilage is replaced by bone.
• Cartilage remains in isolated areas, such as the bridge of the nose, parts of ribs, and joints.
• Epiphyseal plates allow for growth of long bone during childhood.
• Bone growth involves the formation of new cartilage, osteogenesis, and bone remodeling.

Bone Formation

• Ossification (osteogenesis) is the process of bone formation, which occurs in four situations:
  • During embryological and fetal development
  • When bones grow before adulthood
  • When bones remodel
  • When fractures heal
• Bones thicken due to the action of osteoblasts and osteoclasts.

Classification of Bones

• Flat bones are thin and flattened, usually curved, with thin layers of compact bone around a layer of spongy bone.
• Examples of flat bones include the skull, ribs, and sternum.
• Irregular bones have an irregular shape and do not fit into other bone classification categories.
• Examples of irregular bones include vertebrae and hip bones.

Gross Anatomy of a Long Bone

• The diaphysis (shaft) makes up the bone's length and is composed of compact bone.
• The epiphysis (end of the bone) articulates with other bones and is composed mostly of thin layers of spongy bone.
• The periosteum is the outside covering of the diaphysis, protected by a fibrous connective tissue membrane.
• Sharpey's fibers are connective tissue fibers that secure the periosteum to the underlying bone.
• Arteries supply bone cells with nutrients.