Structure of bone

Structure of bone consists Microscopic and Macroscopic structure or gross structure, these are described below-

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.

Macroscopic or Gross structure

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

Based on arrangement of bony lamellae, bones are known as compact bone or cancellated/spongy bone-

1. Compact bone

Compact bone 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.

2. Cancellated or Spongy bone

Cancellated or Spongy bone 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 in spongy bone.