Bone · Chest

Eighth rib

The first of the false ribs: its cartilage does not reach the breastbone but curves upward to join the cartilage of the seventh, and it is that junction which forms the costal margin. The shaft is typical in every other respect and has begun to shorten. External oblique arises from its outer surface, interdigitating here with serratus anterior above and latissimus dorsi behind.