Rib 5 (left) — true rib

Function

Its cartilage joins the lower sternum; the rib lies over the region of the heart's apex.

Landmarks

• Costal groove
• Angle

Articulations (joints)

• T4–T5 vertebrae
• Sternum via fifth costal cartilage

Clinical relevance

The apex beat (PMI) is normally palpated in the fifth intercostal space, mid-clavicular line — displaced in cardiomegaly.