Veterinary Gross Anatomy

STRUCTURE OF BONE

Microscopic structure

• The bone is one of the varieties of connective tissue, consisting of bone cells or osteocytes, parallel rows of fine collagen fibres, which are embedded in the amorphous ground substance.
• The ground substance or matrix is impregnated with regularly arranged crystals of calcium salts.
• The deposition of the mineral matter renders the intercellular substance hard and impermeable, forming thin plates or lamellae.

Macroscopical/Gross structure

• The gross structure of the bone shows differences in the arrangement of these bony lamellae, forming either compact or cancellated bone.

Compact bone

• It is dense, white and hard and forms the outer shell of a bone. It is found aggregated in portions where there is greatest strain on the bone is exerted.
• Bone is arranged in the form of concentric system called the Haversian system or Osteone.

Cancellated or Spongy bone

• It is made up of delicate plates, which intercross each other forming a meshwork with spaces containing marrow.
• Cancellated bone is found in the epiphyses of long bones and is always covered by a layer of compact bone.
• Haversian systems are absent.