Question

Perichondrium is the covering of
A. Bone
B. Cartilage
C. Decalcified bone
D. Dried bone

Answer 1

Hint: Perichondrium is dense connective tissue sheath which covers cartilage externally and has two layers outer fibrous vascular layer and inner chondrogenic cellular layer. Perichondrium cells have the ability to regrow cartilage to some extent.

Complete answer: Cartilage is a type of skeletal connective tissue. It is elastic tissue which is harder than dense connective tissue but softer than bone. It is found more abundantly in vertebrate embryos because most of the bones forming the skeleton of the adult are cartilaginous in the early stage. The matrix (composed of chondrin) of cartilage is solid and pliable and resists compression. Lacunae are fluid filled spaces present in the matrix and contain cartilage forming cells called chondrocytes.
Cartilage is present in the tip of the nose, outer ear joints, between adjacent bones of the vertebral column, limbs and hands in adults.
Functions of the cartilage:
It provides support and flexibility to the body parts and resists compression.
It smoothes surface at joints and thus prevents the wear and tear of bones due to friction.
Bone is a hard connective tissue and non flexible tissue. It is made up of 70% inorganic matter and 30% organic matter. Bone cells (osteocytes) lie in lacunae singly. Bone is surrounded by a tough sheath called peritoneum.
Decalcified bone: It is a bone that has been treated with dilute HCL and it becomes soft and flexible, containing bone marrow.
Dried bone: It is a bone that has been subjected to high temperature. It does not contain bone marrow.

So the correct answer is option B.

Note: Perichondrium is a fibrovascular membrane and it is absent in articular surface and costal cartilage. Don’t confuse perichondrium (covering of cartilage) with periosteum (covering of bone).