Bone · Chest

Sixth rib

A typical rib whose cartilage, with those of the fifth and seventh, receives the upper attachment of rectus abdominis and forms part of the front wall of the chest just above the costal margin. Its shaft is among the longest in the series. On its outer surface the uppermost digitation of external oblique interlocks with a slip of serratus anterior, the two muscles fitting together like clasped fingers. Below this level the costal cartilages begin to curve upward rather than run straight to the breastbone.