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beginnerSource-checked12 min read

The Chest: An Overview

The rib cage and sternum, and the two big jobs of the chest muscles: pushing and breathing.

Before this: Fundamental Movement Terms

You will be able to

  • Name the bones of the chest (sternum, ribs, costal cartilage).
  • Describe the two main roles of chest muscles: pushing the arms and breathing.
  • Explain how the chest works with the shoulder and upper back.
Simplified front view of the chest showing the sternum in the middle, ribs curving to each side, and the fan-shaped pectoralis major over the upper chest.
Chest region — rib cage, sternum, and pectoralis major (simplified). A beginner-level schematic of the chest's bony frame (sternum and ribs) and the location of the pectoralis major.
Illustration: Anatomy Learning Platform (original) · CC0-1.0 (public domain dedication)

⚠ Safety note

Chest pain or pressure, shortness of breath, dizziness, or pain spreading to the arm or jaw are medical warning signs — seek urgent care. A trainer does not assess chest pain.

The frame: rib cage and sternum

The chest is built on the rib cage — twelve pairs of ribs curving around from the spine to the sternum (breastbone) at the front, connected by flexible costal cartilage. This cage protects the heart and lungs and gives chest and breathing muscles something to pull on.

Two jobs, two muscle groups

Chest muscles do two very different things:

  1. Move the arms (pushing). The pectoralis major is the big fan-shaped muscle you can see and

feel. It powers pushing and pulls the arm across the body. The deeper pectoralis minor and the side-of-ribs serratus anterior position and stabilize the shoulder blade so pushing is smooth.

  1. Breathe. The dome-shaped diaphragm at the base of the rib cage is your main breathing

muscle, helped by the small intercostals between the ribs.

Working with its neighbors

Pushing is never "chest only": the chest teams up with the front deltoid and triceps of the arm, while the upper back lets the shoulder blades glide and the core keeps the torso stable. This is why bench press and push-ups are compound movements.

Sources for this lesson

“The thorax is formed by the ribs, sternum, and costal cartilages; its muscles act on the arm/shoulder and in respiration.”

Anatomy and Physiology 2e — OpenStax, Rice University · Ch. 7.4 The Thoracic Cage; Ch. 11.4–11.5

Peer-reviewed textbook · License: CC BY-NC-SA 4.0 · Last checked 2026-07-19

Take the quiz (2 questions)Explore the Chest

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