THE RIBS:::
There are twelve pairs of ribs bilaterally situated they are curved flat strip shaped bones joined at the back with the thoracic vertebrae each pair of the ribs forms an elliptical elastic arch all these ribs are combined together with their respective cartilages the back bone (12 thoracic vertebrae ) and the sternum situated in front and centrally to form the thoracic cage which is an elastic framework with movable sides ribs move with every breath of respiration thoracic cage acts as a mobile cage for protection to the organs of the chest especially the heart and the lungs
Ribs are not on a horizontal plane but inclined downwards and forwards with their lower edges everted these ribs are raised and lowered during inspiration and expiration of air thus alternately increasing and decreasing the chest cavity respectively in anterior posterior and lateral planes the last five pairs are called false ribs and of these the eleventh and the twelfth pairs are termed as floating ribs during respiration maximum movement is found in the lower part of the thorax
besides protecting the organs in the thorax the thoracic ribs also give attachment to various muscles on the back and front the most important attachments are however the intercostal muscles (external and internal ) in between the corresponding ribs this gives rise to thoracic respiration the lower ribs on their inner side give attachment to the respiratory muscle the diaphragm diaphragm also serves as the musculotendinous partition between the thorax and abdomen which contracts during inspiration and relaxes during expiration
0 Comments