The costal margin is the curved lower edge of the front of the rib cage, formed on each side by the joined costal cartilages of ribs 7-10. The two margins meet at the xiphisternal joint and enclose the infrasternal (subcostal) angle, and together they mark the upper border of the abdomen.
| Articulations |
|
|---|---|
| Landmarks |
|
| Ossification | The costal cartilages are hyaline cartilage and stay mostly unossified, though patchy calcification is common from middle age onward. |
The liver edge on the right and an enlarged spleen on the left are felt just below the costal margin as the person breathes in deeply, and gallbladder tenderness (Murphy sign) is tested where the right margin meets the edge of rectus abdominis. In breathing and posture assessment the margins should widen on inhalation; a flared or elevated margin is often noted in trunk control work. In severe chronic obstructive lung disease the lower margins may move inward on inspiration (Hoover sign).
With the person lying on their back, knees bent to relax the abdomen, place your fingers on the xiphoid process at the lower end of the sternum. Slide them down and outward along the firm, curved lower edge of the rib cage on each side; this edge is the costal margin, and it becomes sharper as the person breathes out. Follow it laterally to its lowest point at the 10th costal cartilage in the flank, remembering that the free tips of ribs 11 and 12 lie further back.
Hypermobile 8th-10th costal cartilages slip and catch on the rib above, causing sharp pain and clicking along the lower costal margin.
A blow to the lower chest can break the cartilage itself; it is painful but easily missed on plain X-ray because cartilage is not visible.
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.
