■ Each Rib is a curved bone having Head Neck and Body. Head has two Articular Surfaces for attachment of the respective and superior Thoracic Vertebra. They also have a tubercle around their necks.
■ Ribs have Costal Cartilage at their Anterior Termination.
■ Ribs are further divided into True and False Ribs.
True Ribs are first seven pairs of Ribs which join to the Sternum anteriorly, directly through Costal Cartilage.
False Ribs are 8th to 12th pairs of the Ribs as they don’t articulate with the Sternum Directly. First three (8th,9th and 10th) pairs joins with Sternum by joining with Costal Cartilage of the 7th Rib through their Costal Cartilage. The last two (11th and 12th) pairs don’t articulate with the Sternum hence named as Floating Ribs.
Each Rib, except last two pairs, has following three Articulations :
- Direct Vertebral Articulation is through Articular Surfaces of the Head of the Rib. It is a Synovial Joint with respective and superior Thoracic Vertebrae.
- Transverse Process Articulation is to the Transverse Process of the respective Vertebra of the Tubercle of the Rib. It is also a Synovial joint.
- Sternal or Costal Articulation is to the Sternum through Costal Cartilage anteriorly. It is a Flat Joint.
Last two pairs have first two articulations but don’t join with the Sternum.
- Ribs form a flexible Thoracic Cage which allows movement. Movements of the Ribs are through its respective Muscles and Diaphragm. These movements are involved in Respiration.
- Ribs also provide Protection to the underlying viscera of the body.