Thoracic Cage

Sternum

Sternum Anterior Lateral View

The sternum (aka breastbone) is a flat bone located at the anterior midline of the thorax.

It has a ‘T’ shape – almost like a sword! 🗡

Embryologically the sternum develops from a left and right cartilaginous plates that unite in the midline. It was named after the word ‘Sternon’ which means chest in 17th century Greek. 

It articulates with the clavicle and the costal cartilages of the upper 7 ribs (true ribs), while the 8th, 9th and 10th ribs (false ribs) are indirectly attached with sternum via costal cartilage of the ribs above.

Parts of the Sternum

Clinical Relevance

Angle of Louis

Since the first rib is hidden behind the clavicle, the second rib is the highest rib that can be identified by palpation. Thus, the sternal angle and second rib are important landmarks for the identification and counting of the lower ribs.
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