Joints of the Rib Cage
Joints of ribs:
Joints of heads of ribs:
First rib and the last three ribs have a single synovial joint with the corresponding vertebrae while the remaining ribs have two synovial joints: one with the corresponding vertebra and one with the immediate above. These joints are formed by the heads of the ribs with the body of vertebrae.
Joints of tubercles of ribs:
The tubercle of each rib articulates with the transverse process of the corresponding vertebra through a synovial joint. The tubercles are absent on the eleventh and twelfth ribs and therefore no such joints occur for these ribs.
Joints of costal cartilages:
Costochondral joint means the joint between the rib and its costal cartilage. These are cartilaginous joints and no movements are possible here.
Joints of costal cartilages with sternum:
The first costal cartilage of both sides attach to the manubrium sterni. At this joint, no movement is possible. The second costal cartilage articulates with the body of sternum and the manubrium sterni by a synovial joint where movement is possible. The third to seventh costal cartilages articulate with lateral border of the body of sternum at mobile synovial joints. The mobility of these joints allows the movements of respiration to take place in the rib cage. The sixth, seventh, eighth, ninth and tenth costal cartilages are jointed with each other along the borders by synovial joints. The eleventh and twelfth ribs are floating, which means that they do not articulate in front with the sternum and are embedded in the musculature of abdominal wall.
Movements of ribs and costal cartilages:
The costal cartilage of the first rib is fixed to the manubrium and no movement is possible. The raising and lowering of the thoracic cage during respiration are accompanied by corresponding movements in the joints of heads and tubercles of all ribs. In this way the neck of each rib can rotate around its own axis.
Joints of the sternum:
They include the manubriosternal joint, xiphisternal joint and joints with the costal cartilages.
Manubriosternal joint: It is a fibrocartilaginous joint between the manubrium sterni and the body of sternum. A small amount of angular movement is possible at this joint. This movement occurs during respiration.
Xiphisternal joint: It is also a fibrocartilaginous joint and occurs between the xiphoid process and body of sternum. The capability of occurring movements may be present but there is no significance of movements at this joint. The xiphoid process fuses with the body of sternum during middle ages.
Joints with costal cartilages: As explained above.