Digital Anatomy Companion Site

F. The Thoracic Cage

msonnenfeld

|

Learning Objectives

  1. Understand the structure and function of the thoracic cage, including the sternum, ribs, costal cartilages, and thoracic vertebrae.
  2. Identify the parts of the thoracic cage
  3. Distinguish between true, false, and floating ribs
  4. Understand how ribs articulate with the thoracic vertebrae

Introduction

The thoracic cage is a protective and supportive structure that forms the chest wall. It includes the sternum, thoracic vertebrae, ribs, and costal cartilages (made of hyaline cartilage). Together, these elements:

  • Shield vital organs such as the heart and lungs and other structures in the thoracic cavity
  • Provide attachment points for muscles involved in
    • breathing
    • upper limb movement
    • moving the pectoral (shoulder) girdles (clavicles/scapulae)
    • supporting the position of the vertebral column

You’ll learn this anatomy through:

  • Lab skeletons and disarticulated bones
  • 3D interactive models
  • Labeling and review activities

✅ Nice work! Now let’s dive into the anatomy visually.

Start by watching these animations to gain a broad overview of the thoracic cage’s structure.

  1. AnatomyTOOL: Sternum Overview

Learn the three parts of the sternum and their anatomical relationships.

2. AnatomyTOOL: Rib Cage Overview
Explore how the ribs connect to the sternum and thoracic vertebrae.

3. AnatomyZone: The Thoracic Cage Video (5:23)
Review rib classification, rib-sternum articulation, and intercostal spaces.

💬 Challenge:
Now that you’ve seen the thoracic cage in motion, which part stands out to you the most? Is it the way the ribs articulate with the vertebrae, the structure of the sternum, or the flexibility of the costal cartilages?
Pick a favorite feature and explain why it caught your attention!

Now that you’ve reviewed the thoracic cage in motion, it’s time to explore it interactively!

👉Explore the Thoracic Cage on Sketchfab.

🔍 What to do:

  • Rotate and zoom to view the thoracic cage from different angles
  • Identify key bones: ribs, sternum, and thoracic vertebrae
  • Observe how the bones articulate and support breathing
  • Use this model to build spatial understanding before lab work

💡 Tip:
Try locating the floating ribs and tracing how the true ribs connect to the sternum. Can you spot the costal cartilages?

👉Click here to use this interactive InnerBody tool to dive into the bones of the thoracic cage.

📌 What to do:

  • Click each bone to view its name
  • Use the Anatomy Explorer menu for descriptions
  • Rotate and zoom to view the thoracic cage from different angles
  • Focus on ribs, sternum, and thoracic vertebrae

Perfect for building spatial understanding before lab work!

These detailed 3D models from BlueLink let you closely examine thoracic vertebrae and the features that articulate with the ribs.

👉BlueLink 3D: First Thoracic Vertebra (T1)

Explore how T1 is designed to connect with the first rib. Look for the superior costal facet and transverse costal facet—key sites for rib articulation.

👉BlueLink 3D: Eighth Thoracic Vertebra (T8)

Compare T8 to T1 and observe how vertebral features change further down the thoracic spine. Can you spot the demifacets where ribs 8 & 9 articulate?

💬 Challenge:
The costal facets aren’t labeled—can you find them yourself? Rotate the models and look closely at the sides of the vertebral body and transverse processes. What clues help you identify where the ribs would attach?

💡 Tip: Use the posterior and lateral views to get the best angle on the articulation surfaces. Think about how the rib head and tubercle would fit into these surfaces.

Ready to dive deeper? Use the dropdowns below to explore the structure and classification of the sternum and ribs. Then, test your knowledge with the interactive labeling activities.

Components to Identify:

  • Sternum
    • Manubrium (uppermost bone that articulates with clavicle & 1st rib)
    • Mesosternum (middle bone known as the body)
    • Xiphoid process (lowest bone)

🧩 Try this:

The human rib cage is typically composed of 12 pairs of ribs, though some people may have 11 or 13.

Type of RibRib NumbersAttachment
True Ribs1–7Directly attached to the sternum via individual costal cartilage
False Ribs8–12Do not attach directly to the sternum
➤ Typical False Ribs8–10Attach to the sternum indirectly via cartilage of rib 7
➤ Floating Ribs11–12No anterior attachment to the sternum at all — they end in the posterior abdominal wall

Additional Thoracic Cage Features

  • Intercostal Spaces: The gaps between ribs, filled with intercostal muscles that assist in breathing.
  • Costal Cartilage: Flexible hyaline cartilage that connects the anterior ends of the ribs to the sternum, allowing for chest expansion during respiration.

🧩 Try this:

✅ Test Your Knowledge

Identify the Fourth Right Rib
Test your knowledge of rib features by identifying two parts of the fourth right rib.
👉 Launch activity

Beat the Clock: Rib Articulation Game
How fast can you match rib numbers to their vertebral and sternal articulations?
👉 Start the game

Beat the Clock: Identify Parts of the Rib Cage
Challenge yourself to locate and name thoracic cage components under time pressure.
👉 Play now

Beat the Clock: Identify Parts of the Rib Cage
Challenge yourself to locate and name thoracic cage components under time pressure.
👉 Play now