Floating ribs are called by that name because they are not attached to the sternum (breastbone) at the front of the body.
Here's a more detailed explanation:
Most ribs in the human body connect to the sternum via costal cartilage. These are called true ribs (ribs 1-7). Ribs 8-10 connect to the sternum indirectly, via the costal cartilage of the rib above. These are called false ribs. However, the last two ribs (ribs 11 and 12) only attach to the vertebrae in the back. They do not have any anterior (front) attachment to the sternum or other ribs. Since they only connect to the spine and are "free" at their anterior ends, they are referred to as floating ribs. These ribs are relatively smaller and end with cartilaginous tips.
Here’s a breakdown in table format:
| Rib Type | Rib Number(s) | Anterior Attachment |
|---|---|---|
| True Ribs | 1-7 | Directly to the Sternum via their own costal cartilage |
| False Ribs | 8-10 | Indirectly to the Sternum via the cartilage of rib 7 |
| Floating Ribs | 11-12 | No Anterior Attachment (only attached to the vertebrae) |
In summary, the term "floating" describes the characteristic of these ribs being anchored only to the vertebral column, without a ventral connection, setting them apart from the true and false ribs.
