Thorax

Published on 11/03/2015 by admin

Filed under Orthopaedics

Last modified 22/04/2025

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8 Thorax

Sternum (Figs 8.1 and 8.2)

RIBS (Fig. 8.5)

There are 12 pairs of ribs.

1–7 are true ribs as they are directly attached to the sternum by the costal cartilage.

8–12 are false ribs; 8–10 are indirectly attached to the sternum by their costal cartilages; 11 and 12 are floating ribs as they are not attached to the sternum.

3rd–9th ribs are considered to be ‘typical’.

The ribs increase in size from 1–7 and then decrease in size.

In vivo the ribs are inclined downwards and forwards. Therefore the posterior ends are at a higher level than the anterior ends.

Atypical ribs

12th rib

Shorter than the 11th rib.

Radiographic appearances of the ribs (Figs 8.8, 8.9 and 8.10, Plate 5)

Costal cartilages (Fig. 8.11)

Formed by hyaline cartilage.

Base is attached to the anterior end of the ribs.

Costal cartilages of the:

1st–7th ribs articulate with the sternum

8th–10th ribs articulate with the costal cartilage of the rib above

11th and 12th ribs end in the muscles of the abdominal wall.

The costal cartilages:

increase in length from the 1st to the 7th

decrease in length from the 8th to the 12th

decrease in width from the 1st to the 12th.