Human Rib Cage Anatomy: 12 Pairs of Ribs and Their Classification

The adult human rib cage consists of 12 pairs of ribs (24 total), each attaching posteriorly to thoracic vertebrae.

Classification by Sternum Attachment

• True Ribs (1–7): Direct costal cartilage attachment to sternum.
• False Ribs (8–10): Indirect attachment via the 7th rib's cartilage.
• Floating Ribs (11–12): No anterior attachment; embedded in abdominal musculature.

Rib Structure

• Head: Articulates with vertebral bodies.
• Neck: Connects head to tubercle.
• Tubercle: Articulates with transverse process.
• Shaft: Curved body.
• Costal Groove: Protects intercostal neurovascular bundle.

Functions

• Protects heart, lungs, and great vessels.
• Respiratory mechanics: bucket-handle and pump-handle motions expand the thorax.
• Muscle attachment sites for respiration and posture.