A true rib is a type of rib in the human rib cage. There are typically seven pairs of true ribs that are attached right to the sternum via cartilage. False ribs, on the other hand are the bones that are not directly attached to the sternum; instead, but attached to the true ribs via cartilage. Most humans also have two pairs of floating ribs, which are not attached to anything but the spine. The rib cage helps protect vital organs in the chest.
The human rib cage consists of the sternum, cartilage, 12 thoracic vertebrae, and 12 pairs of ribs. Contrary to what some people may believe, men and women both have a total of 24 ribs. These are flat thin bones that curve around a person's chest. They are attached the thoracic vertebrae in the spine.
The first seven sets of ribs are considered true ribs. A true rib is connected to the spine in the back and the sternum, or breastbone, in the front. Costal cartilage connects each true rib to the sternum in the front of the body.
Underneath the true ribs are three pairs of false ribs. These ribs are a bit shorter than true ribs. Unlike a true rib, a false rib is only indirectly attached to the breastbone. Instead, false ribs are connected to the true ribs above them with costal cartilage.
Most humans also have two sets of floating ribs under the false ribs. These ribs are shorter than other types of ribs. A floating rib is shorter than a true rib and a false rib. Although the back of floating ribs are attached to the spine in the back of the body, the front part of these ribs aren't attached to anything. They got their name, because they are not attached to anything but the spine and they “float”.
The main purpose of the rib cage is protection. This rigid skeletal structure covers a number of vital internal organs, particularly the heart and lungs. Parts of the liver and stomach are also protected by the rib cage. If this structure was not in place, these organs would be much more susceptible to injury and damage.
Along with the spine, the rib cage also helps support the upper body in a human. It is responsible for the shape of the chest. The intercostal muscles between each rib also helps a person breath. Some of these muscles help the chest cavity expand, which makes it easier for the lungs to fill with air. Other intercostal muscles help shrink the size of the chest cavity, which helps expel the air as a person exhales.