The Sternum (Breastbone): Anatomy, Function, and Common Conditions
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD | Last reviewed: October 17, 2026
Quick Answer: What is the sternum, or breastbone?
The sternum, or breastbone, is a flat, T-shaped bone at the front and center of the chest that works with the ribcage to protect the heart and lungs and connects to the collarbones and ribs. [1] It measures about 6 inches long. [1] Sternum pain has many causes, including costochondritis and fractures; [1] most are not serious, but persistent pain should be evaluated.
What the research says
Bracing can correct a protruding sternum (pectus carinatum) without surgery. A systematic review of 8 studies of measured dynamic compression bracing (1,185 patients; median age 14; 87% male) found that, over a mean follow-up of 16 months, 29% had completed treatment and 44% were still in treatment; 6% dropped out. Mild chest discomfort occurred in 12%, skin lesions in 5.1%, and recurrence in 2.6% (de Beer et al., Seminars in Pediatric Surgery, 2018) [2].
Many sternal fractures are isolated, and low-risk patients may not need admission. In a community hospital review of 5,632 blunt trauma patients, chest CT was done in 2,578 and found sternal fractures in 63; 31.7% were isolated injuries and overall mortality was 3.2%. The authors concluded that patients with a sternal fracture, a normal electrocardiogram and normal cardiac enzymes, and no other major injury may be safely discharged. This was a single-center retrospective study (Kunhivalappil et al., Surgery Research and Practice, 2023) [3].
Sternal fractures in children are usually isolated and low-risk. In a single-center review of 65 children and young people with sternal fractures, 77% were isolated injuries, and there were no cardiac injuries, aortic injuries, or deaths (Chalphin and Mooney, Journal of Pediatric Surgery, 2019) [4].
What is the anatomy of the sternum (breastbone)?
The sternum is not one uniform piece. It has three bony parts that, with the cartilage connecting it to the ribs, give the chest wall both rigidity and the flexibility needed for breathing. The overall shape resembles an upside-down sword: the manubrium is the handle, the body is the blade, and the xiphoid process is the tip. [1]
Part | Description | Main Connections |
Manubrium | The wide, handle-like top portion | The collarbones (clavicles) and the first set of ribs; its lower edge borders the body, where the second set of ribs attach |
Body | The flat, narrow, longest part in the center | The third through seventh sets of ribs |
Xiphoid process | The small, pointed lowest part, made mostly of cartilage | A muscle attachment point; it gradually calcifies into bone with age |
What functions does the breastbone (sternum) perform?
The sternum’s main job is protection. Together with the ribcage, it shields the heart, lungs, esophagus, stomach, and major blood vessels from injury. [1] It also provides support: it connects to the collarbones and the ribs through cartilage, and muscles of the chest and upper abdomen attach to it. [1]
The bone itself does not move your chest or torso. However, the cartilage that joins the sternum to the ribs allows the small motions that happen with every breath. [1] Behind the sternum sits the thymus gland, part of the lymphatic system, which trains white blood cells called T-cells. [1]
What common conditions and disorders affect the sternum?
Pain at or around the sternum can come from the bone itself, the cartilage and muscles around it, or organs behind it. [1] Understanding the pattern of pain helps decide what to do next.
Condition | Description | Common Symptoms |
Costochondritis | Inflammation of the cartilage that attaches the ribs to the sternum, caused by infection, injury, or arthritis | Sharp, stabbing pain and tenderness, often worse with activity, deep breaths, or coughing |
Sternal fracture | A break in the bone, most often from blunt trauma such as a car accident, sports injury, or fall | Pain that worsens with coughing or deep breathing, tenderness, bruising, swelling, and sometimes shortness of breath |
Pectus carinatum | A condition in which the sternum sticks out more than it should (pigeon chest) | Often no symptoms; occasional chest pain in certain positions or activities |
Muscle strain | Injury to a muscle or tendon attached to the sternum, from overuse, sports, or hard coughing | Localized aching, tenderness, or pain with movement or deep breaths |
Substernal pain, felt behind or below the sternum, is most often linked to digestive problems such as acid reflux or a hiatal hernia. [1] Lung conditions such as bronchitis, pneumonia, and pleurisy can also cause discomfort in the center of the chest. [1]
When chest pain is an emergency
Sternum pain from a muscle or cartilage problem usually starts suddenly and is tender to the touch, but chest pain can also signal a heart attack. Seek immediate medical attention for pressure, squeezing, or fullness in the center of the chest that may spread to the arm, jaw, or teeth, especially with cold sweats, nausea, shortness of breath, or lightheadedness. [1] See a provider if pain follows direct trauma, lingers, or gets worse over time. [1]
How can you keep your sternum and chest healthy?
Supporting the sternum and ribcage means keeping your bones strong and protecting your chest from unnecessary trauma. Eat a balanced diet that includes calcium and other bone-supporting minerals, stay physically active with weight-bearing exercise and good posture, and use proper safety gear during contact sports and other high-impact activities.
Conclusion
The sternum is a vital structural and protective part of the body. From its sword-like shape to its role in shielding the heart and lungs, it is a central pillar of the chest. Many causes of sternum pain come from muscles, cartilage, or the digestive tract and are not life-threatening, but persistent pain should be evaluated to protect the chest and the organs behind it.
Call to Action
If you have persistent chest or sternum pain, trouble breathing, or any concern after a chest injury, talk to a healthcare professional. If you have signs of a heart attack, get emergency help right away.
Frequently Asked Questions
What exactly is the sternum?
The sternum is a flat, T-shaped bone at the center and front of the chest, commonly called the breastbone.
How long is the average sternum?
The average sternum measures about 6 inches from top to bottom.
What are the three parts of the sternum?
The manubrium (top), the body (middle), and the xiphoid process (bottom tip).
What is the purpose of the xiphoid process?
The xiphoid process is a point where muscles attach. It is made mostly of cartilage and gradually calcifies into bone as you age.
Which organs does the sternum protect?
Together with the ribcage, it shields the heart, lungs, esophagus, stomach, and major blood vessels.
What is costochondritis?
Costochondritis is inflammation of the cartilage that connects the ribs to the sternum, causing sharp, stabbing pain and tenderness.
Can a sternum be fractured?
Yes. Sternal fractures most often result from blunt force trauma, such as car accidents, sports injuries, and falls.
What is pectus carinatum?
Also called pigeon chest, it is a condition in which the sternum sticks out more than it should. Most people have no symptoms.
What organ is located directly behind the sternum?
The thymus gland, which is part of the lymphatic system, sits behind the breastbone.
Does the sternum help with breathing?
The bone itself does not move your chest, but the cartilage that connects it to the ribs allows the small motions that occur with each breath.
What causes pain behind the sternum?
Pain behind or below the sternum (substernal pain) is usually due to digestive conditions such as acid reflux or a hiatal hernia, though lung conditions can also cause it.
How does the sternum connect to the rest of the skeleton?
The sternum connects to the collarbones and to the ribs through cartilage, with the first seven pairs of ribs attaching directly.
Can coughing cause sternum pain?
Yes. Intense or chronic coughing can strain the chest muscles and tendons that attach to the sternum.
Is sternum pain always a sign of a heart problem?
No, it is often musculoskeletal or digestive. But chest pain can also signal a heart attack, so pressure or squeezing in the chest, especially with sweating, nausea, or shortness of breath, needs emergency care.
When should I see a provider for sternum pain?
See a provider if the pain follows direct trauma, lingers, gets worse over time, or comes with difficulty breathing.
Related Reading
Rib Cage (Thoracic Cage): Anatomy, Function, Bones, Joints and Common Problems describes the ribs and cartilage that join the breastbone.
Costochondritis: What It Is, Why It Hurts, and How Long It Lasts explains inflamed rib cartilage that causes chest wall pain.
Pectus Excavatum: What a Sunken Breastbone Means for Your Heart, Lungs, and Confidence covers a sunken breastbone and the options to correct it.
Sternotomy: Procedure, Recovery Timeline, Wires and Warning Signs describes the breastbone incision used for open heart surgery.
Sources
Cleveland Clinic. Sternum (Breastbone). Cleveland Clinic. Last updated February 27, 2024. https://my.clevelandclinic.org/health/body/sternum-breastbone
de Beer SA, Blom YE, Lopez M, et al. Measured dynamic compression for pectus carinatum: a systematic review. Semin Pediatr Surg. 2018;27(3):175-182. PMID: 30078489. DOI: 10.1053/j.sempedsurg.2018.06.001
Kunhivalappil FT, Almansoori TM, AbdulRahman MS, et al. Management of blunt sternal fractures in a community-based hospital. Surg Res Pract. 2023;2023:8896989. PMID: 36949736. DOI: 10.1155/2023/8896989
Chalphin AV, Mooney DP. Pediatric sternal fractures: a single center retrospective review. J Pediatr Surg. 2019;55(7):1224-1227. PMID: 31711745. DOI: 10.1016/j.jpedsurg.2019.10.002
Medical disclaimer
The information provided in this article is for educational purposes only and is not intended as medical advice. Always seek the guidance of a qualified healthcare provider regarding any medical condition or treatment.
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