The twelfth rib is the shorter of the two floating ribs (with the eleventh), articulating only with the T12 vertebral body and having no anterior attachment. It is entirely free-floating in the posterior flank musculature. It marks the posterior boundary of the thoracic cavity and the superior boundary of the posterior flank. The kidney lies immediately anterior to the twelfth rib in the retroperitoneum.
| Articulations |
|
|---|---|
| Landmarks |
|
| Ossification | As per other ribs, primary centres fusing at skeletal maturity. |
Costovertebral angle (CVA) tenderness by percussion at the twelfth rib lateral to the erector spinae indicates renal inflammation or infection (pyelonephritis). Posterior flank incisions for renal and adrenal surgery use the twelfth rib as an anatomical landmark, with the rib occasionally removed for improved access. Twelfth rib fractures from posterior rib trauma indicate significant force and are associated with renal and adrenal injuries.
With the person sitting or lying face down, find the lower edge of the rib cage at the side of the trunk and follow it backward. The 12th rib is the last short rib whose free tip lies in the flank behind the 11th; trace it medially and upward until it disappears under the erector spinae. It can be very short and hard to feel in some people.
A blow to the flank can fracture the twelfth rib, which may be associated with kidney injury.
Irritation of intercostal or subcostal nerves by a hypermobile lower rib causes flank and loin pain.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
