Question

Covering around bone is called
A. Perichondrium
B. Periosteum
C. Epiosteum
D. Endosteum

Answer 1

Hint: The periosteum is a white fibrous sheath surrounding the bone which has an outer fibrous layer and an inner cellular layer called cambium. Perichondrium covers the cartilage of developing bone. Epiosteum is not a structure of bone. Endosteum lines the inner surface of the bone.

Complete answer:
The outer covering of the cartilage is named perichondrium. It consists of dense irregular tissue.
The outer covering of a bone is named periosteum. It is made of connective tissues, osteogenic cells, and osteoblasts.
There is not any structure named periosteum.
The medullary cavities (marrow) of bones are lined by the endosteum. It consists of osteogenic cells and scattered osteoclasts.
Periosteum attached in muscle, ligaments, and tendons. It is covered in the surface of the bone.

So, the correct answer is “Option B”.

Additional Information:
The outer layer is mainly composed of collagen. It contains nerve fibers that send pain signals to the brain when damage occurs to the tissue.
Many blood vessels from the membrane penetrate the bone to supply the bone cells called osteocytes.
These perpendicular branches of blood vessels pass into the bone through the Volkmann canals to vessels in the Haversian canals.

Note:
The periosteum is bound to the blood vessels as Sharpey fibers as the fibers from the inner layer penetrate the underlying bone. The inner layer of the periosteum has osteoblasts which are the bone-producing cells. It is most prominent in fetal life and childhood. The periosteum envelopes the bones at all parts except at the surface of joints.