Question

Which two pairs of ribs are floating ribs?

Answer 1

Hint: The ribs are curved, flat bones which form the major part of the thoracic cage. Ribs have two ends, anterior end and the posterior end. There are a total of twelve pairs of ribs, all of which articulate with the vertebral column with the help of their posterior end.

Complete answer:
The rib cage consists of the 12 thoracic vertebrae and the 24 ribs, in addition to the sternum anteriorly. The first seven ribs in the rib cage are attached to the sternum with the help of pliable cartilage called costal cartilage and these ribs are called true ribs. Of the remaining five ribs, which are called false ribs, the first three have their costal cartilages connected to the cartilage above them. The last two, the floating ribs, have their cartilages ending up in the muscle in the abdominal wall. The specific configuration of the lower five ribs gives freedom for the expansion of the lower part of the rib cage and for the movements of the diaphragm, which has an extensive origin from the rib cage and the vertebral column. But the motion is limited by the ligamentous attachments between ribs and vertebrae.

On an individual rib, one end has various processes named as facets and bumps. This is the end that articulates with the vertebrae posteriorly. The other end is blunt and smooth and this is the end that connects to costal cartilage.

The human rib cage also called thoracic cage has the very important job of protecting the heart and lungs. The ribs are part of the axial skeleton and are flat bones. The primary job of flat bones is to protect underlying structures present. Other flat bones in the human body are found in the pelvis and the skull.

Note: The sternum has three parts namely manubrium, central thin body and the xiphoid process. The manubrium is the superior end of the sternum, and wider than the rest of the bone, provides articulation points for the both clavicles and for the costal cartilage extending from rib 1. The central thin body provides articulation points for costal cartilage from ribs 2 through 7 also called true ribs. The xiphoid process is sword-like which hangs down at the inferior end of the process, starts out as cartilage, and does not typically ossify into bone until an individual is about 40 years old.