Eleventh Rib

Key Features & Anatomical Relations

The eleventh rib is one of the two floating ribs of the thoracic cage. It is longer and more curved than the twelfth rib. It is considered an atypical rib because it has no neck or tubercle and has only one articular facet on its head.

The eleventh rib is classified as a flat bone and includes the following bony features:

- parts: head, body, and costal end;

- surfaces: internal and external surfaces, and superior and inferior borders;

- landmarks: angle, costal groove, and articular facet on the head.

More information regarding these and other bony features can be found in the Parts, Surfaces, and Landmarks tabs for this bone.

The eleventh rib is located:

- superior to the twelfth rib;

- inferior to tenth rib;

- lateral to the eleventh costal cartilage and eleventh thoracic vertebra.

It articulates with the:

- eleventh costal cartilage at the eleventh costochondral joint;

- eleventh thoracic vertebra at the joint of head of eleventh rib.

Ossification

Ossification of the eleventh rib occurs at ossification centers found in the:

- body, which appears in utero during the second month;

- head, which appears during puberty.

The ossification center for the head fuses with the body of the eleventh rib within the fourteenth to twentieth years (Cunningham, Scheuer and Black, 2016).

Variations

In some individuals:

- the eleventh rib may be fused with adjacent ribs;

- the costal end of the eleventh rib may be bifid in appearance (Tubbs, Shoja and Loukas, 2016).

Surface Anatomy

The costal end of the eleventh rib is easily palpated and is located by palpating one rib down from the tenth rib.

List of Clinical Correlates

- Fracture of eleventh rib

- Aplasia of eleventh rib

References

Cunningham, C., Scheuer, L. and Black, S. (2016) Developmental Juvenile Osteology. Elsevier Science.

Tubbs, R. S., Shoja, M. M. and Loukas, M. (2016) Bergman's Comprehensive Encyclopedia of Human Anatomic Variation. Wiley.