Diseases Of Bones & Joints

Diksha Bhatla

Diseases Of Bones & Joints

21 Jun 2022

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Introduction

INTRODUCTION TO THE HUMAN SKELETON

The human skeleton is the internal framework of the body. It is composed of 270 bones at birth. This total decreases to 206 bones by adulthood after some bones have fused together. The bone mass in the skeleton reaches maximum density around age 30. The human skeleton can be divided into the axial skeleton and the appendicular skeleton. The axial skeleton is formed by the vertebral column, the rib cage and the skull. The appendicular skeleton, which is attached to the axial skeleton, is formed by the pectoral girdles, the pelvic and the bones of the upper and lower limbs. The individual bones are attached in such a way that a large variety of co-ordinate movements are made possible in different parts of the body. These movements are made possible by skeletal muscles, the fact that the bones act as levers, cartilage which reduces friction and ligaments which prevent dislocation and the presence of movable joints. The site or place where two or more bones of the skeleton are attached to each other is called a joint or place of articulation.

Types of Joints:

Joints can be classified according to the degree and type of movement they allow. The following types of joints can be recognized:

a) Fibrous (or immovable) Joints: These joints are firmly held together by a thin layer of strong connective tissue. There is no movement between the bones such as the sutures of the skull and the teeth in their sockets.

b) Cartilaginous Joints: Cartilaginous joints are joints where the articular surfaces of the bones forming the joints are attached to each other by means of white fibro-cartilaginous discs and ligaments which allow only a limited degree of movement. Examples are the cartilaginous joint between the vertebrae, the cartilage in the symphysis which binds the pubic bones together at the front of the pelvic girdle, and the cartilage in the joint between the sacrum and the hip bone.

c) Synovial Joints: Synovial joints are freely movable joints and shows free movement including flexion (bending), extension (straightening or bending), abduction (away from the middle of the body), adduction (towards the midline), rotation, supination (turning the palm up, inversion (turning the sole of the foot inward) and eversion (turning the sole of the foot outward).

Functions of the Skeleton

1. Support: The skeleton is the framework of the body, it supports the softer tissues and provides points of attachment for most skeletal muscles.

2. Protection: The skeleton provides mechanical protection for many of the body’s internal organs, reducing the risk of injury to them.

For example, cranial bones protect the brain, vertebrae protect the spinal cord, and the ribcage protects the heart and lungs.

3. Assisting in Movement: Skeletal muscles are attached to bones, therefore when the associated muscles contract they cause bones to move.

4. Storage of Minerals: Bone tissues store several minerals, including calcium (Ca) and phosphorus (P). When required, bone releases minerals into the blood, facilitating the balance of minerals in the body.

5. Production of Blood Cells: The red bone marrow inside some larger bones produce blood cells (RBC, WBC and Platelets)

6. Storage of Chemical Energy: With increasing age some bone marrow changes from ‘red bone marrow’ to ‘yellow bone marrow’.

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