What do you call the space between your chest? An anatomy primer

September 26, 2025 •

3 min read

The human chest is a complex region, housing several vital structures behind and between the ribs. What do you call the space between your chest? The answer depends on whether you are referring to the surface or the deep internal cavity.

Quick Summary

The visible groove between the breasts is anatomically known as the intermammary cleft, or intermammary sulcus. The deeper, central compartment within the chest cavity, located between the lungs, is the mediastinum, which contains the heart and other vital organs.

Key Points

Intermammary Cleft: The external, visible groove between the breasts is anatomically called the intermammary cleft or sulcus.
Mediastinum: The deep, central compartment between the lungs that contains vital organs like the heart and trachea is the mediastinum.
Sternum: The bony structure running down the center of the chest, known as the breastbone, is the sternum, which protects the mediastinum's contents.
Intercostal Spaces: The areas located between the individual ribs are known as the intercostal spaces, which contain muscles, nerves, and blood vessels.
Surface vs. Deep: For the most accurate description, it's crucial to distinguish between the visible surface space (intermammary cleft) and the deep, internal chest cavity (mediastinum).

Demystifying the Chest: Surface vs. Internal Space

While many people refer to the central part of the chest simply as 'the space between your chest,' proper anatomical language distinguishes between the exterior and interior regions. The common perception of this area is often the visible indentation on the surface, but the body contains a crucial, organ-filled cavity beneath the surface.

The Intermammary Cleft: The Surface-Level Groove

On the surface, the groove between the breasts is known as the intermammary cleft or intermammary sulcus. This visible division runs vertically along the sternum, or breastbone. Its appearance varies between individuals based on anatomy and body composition. The deep layer of skin here attaches to the sternum's periosteum, providing foundational support for the breasts. Colloquially, especially in fashion, this area is termed 'cleavage'.

The Mediastinum: The Deep Internal Cavity

Deep within the chest lies the mediastinum, a central compartment situated between the lungs' pleural cavities. This critical space extends from the sternum to the vertebral column and from the thoracic inlet to the diaphragm.

The mediastinum houses essential organs and structures, including the heart, great vessels, trachea, esophagus, thymus gland, nerves, and lymph nodes.

Comparing the Different Chest Spaces

Understanding the distinct anatomical areas is aided by comparison:


Feature	Intermammary Cleft	Mediastinum	Intercostal Space
Location	Visible groove on the chest surface, between breasts.	Central cavity between lungs, deep inside chest.	Space between individual ribs.
Depth	Superficial.	Deep; contains organs.	Intermediate; between ribs.
Content	Skin, superficial fascia.	Heart, great vessels, trachea, esophagus, etc.	Intercostal muscles, nerves, vessels.
Common Term	Cleavage (non-anatomical).

The Sternum: The Bony Centerpiece

The sternum, or breastbone, is the flat bone at the chest's center. It connects the intermammary cleft area and protects the mediastinum. Composed of the manubrium, body, and xiphoid process, the sternum articulates with the ribs via costal cartilages, forming the thoracic cage's front.

A Closer Look at the Intercostal Spaces

Distinct from the central spaces are the intercostal spaces, located between each rib. There are 11 on each side, filled with intercostal muscles, nerves, and blood vessels crucial for respiration. These muscles facilitate chest cavity expansion and contraction.

How Various Spaces Interact During Respiration and Movement

Respiration involves the diaphragm and intercostal muscles working together, causing slight changes in the intercostal spaces that support lung function. The thoracic cage, formed by the ribs and sternum, shields the mediastinum's vital contents during movement. This interaction between bones, muscles, and tissues allows for essential chest wall mobility.

Potential Medical Considerations Related to the Chest Space

Issues can arise in these areas. Pneumomediastinum, where air enters the mediastinum, can compress organs. Surface conditions like psoriasis can affect the intermammary cleft. Differentiating surface issues from deeper problems is vital for accurate diagnosis and treatment.

Learn more about the intricate details of the mediastinum's structure and function on the Cleveland Clinic website.

Conclusion: More Than One Answer to a Simple Question

There's no single term for the space between your chest; it depends on whether you mean the visible surface or the deep internal cavity. The intermammary cleft is the surface groove, while the mediastinum is the deep, organ-filled space. Understanding these terms provides a more precise view of chest anatomy.

Frequently Asked Questions

The intermammary cleft is the anatomical term for the groove between the breasts. "Cleavage" is the popular, non-anatomical term used more commonly in reference to the visual display of this area in the context of fashion and attire.

The mediastinum is a central compartment housing several vital organs. These include the heart, the great blood vessels (aorta and superior vena cava), the trachea, the esophagus, and the thymus gland, along with nerves and lymph nodes.

The sternum (breastbone) is the central, flat bone at the front of the chest that, along with the ribs, forms the protective thoracic cage. Its primary function is to shield the vital organs contained within the mediastinum from injury.

The mediastinum is the central cavity located between the lungs, holding major organs. In contrast, the intercostal spaces are the smaller gaps found between the individual ribs, containing muscles, nerves, and blood vessels.

Yes, various medical conditions can cause pain in and around the chest space. These can range from internal issues like a mediastinal tumor or infection (mediastinitis) to external conditions affecting the skin in the intermammary cleft, such as psoriasis.

A widened mediastinum is a clinical sign that can be seen on an X-ray, where the central chest space appears wider than normal. This can indicate a number of conditions, such as an aortic dissection, a mediastinal tumor, or mediastinitis.

The distance or gap between the breasts, referred to as the intermammary distance, is determined by an individual's unique genetics and anatomical structure. Factors like bone structure, breast tissue, and the insertion points of muscles influence this distance.