Panjarasthi or parshuka joins with the thoracic vertebrae and sternum to form the skeleton or cage is called thoracic skeleton. It looks barrel shaped. It consists of 12 thoracic vertebrae, 12 pairs of vertebrae and a sternum.
- Rib: The narrow, long, compressed and curved bone in the thoracic skeleton is called rib. Their number is 24. Each Parshuka consists of three parts. Neck, tubercle and body. Parshukas can be divided into two categories. Namely – real Parshuka and fake Parshuka.
(i) Real or True Parshuka: Parshukas which have one end attached to the thoracic vertebrae and the other end to the sternum are called real parshukas. The first 7 pairs of Parshukas are the original Parshukas.
(ii) Dummy or Improper Parshuka: Parshukas in which one end is attached to the thoracic vertebra, but the other end is not connected to the sternum are called Dummy Parshuka. 8th-12th pair of parshukas are duplicate parshukas. Among them, the 8th, 9th and 10th vertebrae join together to form the costal arch. The ends of the 11th and 12th vertebrae are free or floating. These are called floating vertebrae. Between every two vertebrae are external and internal intercostal muscles. The space between the costal cartilages is called the intercostal space.
- Sternum : The compressed bone located in the center of the chest is called sternum. Its length is 15-17 cm. It is a complex bone. It consists of a jugular notch, a clavicle and 7 pairs of parsicular grooves. It consists of three parts. namely manubrium, body and xiphoid process.
Importance of thorax
- It protects the heart and lungs from external injury.
- It participates in the process of exhalation through contraction and expansion.
- The volume of the body cavity increases or decreases through contraction and expansion