The heart is primarily situated in the mediastinum, the central compartment of the chest, spanning multiple intercostal spaces generally from the second to the fifth or sixth intercostal space. While it occupies this broader range, specific parts of the heart are most closely associated with particular intercostal spaces.
Understanding the Heart's Position in the Chest
The human heart is a vital organ, nestled obliquely behind the sternum (breastbone) and between the lungs, with a significant portion extending to the left of the midline. Its precise location relative to the intercostal spaces is crucial for clinical assessments such as auscultation (listening to heart sounds) and palpation.
The Base of the Heart and the Second Intercostal Space
The base of the heart—which is actually its superior aspect, not the bottom—is primarily located around the second intercostal space. This area is particularly significant for assessing certain heart valves.
- Locating the Second Intercostal Space: You can easily find this space by first identifying the sternal angle, a prominent ridge felt on the sternum. The sternal angle is directly attached to the second rib. By gently sliding your fingers over to the right sternal border and then down into the space immediately below the second rib, you will be in the second intercostal space.
- Clinical Significance: This specific location is considered the base of the heart and is where the aortic valve is best assessed during a physical examination due to its anatomical proximity.
The Apex of the Heart
In contrast to the base, the apex of the heart is the inferolateral tip of the left ventricle. It typically points downwards and to the left.
- Apex Location: The apex is commonly found in the fifth intercostal space, approximately at the midclavicular line (an imaginary line running vertically down from the middle of the clavicle).
- Clinical Significance: The apical impulse, also known as the point of maximal impulse (PMI), can often be felt or sometimes seen at this location, providing valuable diagnostic information about heart function.
Overall Span and Variability
The heart's exact position can vary slightly among individuals due to factors like body build, respiratory phase, and diaphragm position. However, its overall span remains consistent:
- Superior Border: Generally at the level of the 2nd costal cartilage.
- Inferior Border: Extends to the 5th or 6th costal cartilage on the left.
- Right Border: Extends from the 3rd to the 6th costal cartilage slightly to the right of the sternum.
- Left Border: Extends from the 2nd costal cartilage to the apex in the 5th intercostal space.
Key Anatomical Landmarks and Heart Location
Understanding the relationship between the heart and the intercostal spaces is fundamental in anatomy and clinical practice. Here's a summary:
| Anatomical Landmark | Associated Intercostal Space(s) | Significance |
|---|---|---|
| Base of the Heart | Second Intercostal Space | The superior portion of the heart, particularly important for the assessment of the aortic valve. It can be located by finding the sternal angle, which aligns with the second rib, then moving to the space below. |
| Apex of the Heart | Fifth Intercostal Space | The lowest, most pointed part of the heart (left ventricle). Its impulse (PMI) is often palpable here, typically at the midclavicular line. |
| Overall Heart Span | Second to Fifth/Sixth | The entire heart organ resides within this range of intercostal spaces, mostly on the left side of the sternum, enclosed within the mediastinum. |
| Sternal Angle | Aligns with the Second Rib | A crucial anatomical landmark for identifying the second rib and, consequently, the second intercostal space. Find more about the sternal angle's importance at TeachMeAnatomy or Kenhub. |
| Midclavicular Line | N/A | An imaginary vertical line drawn from the midpoint of the clavicle, used as a reference point to locate the apex of the heart (at the 5th intercostal space) and other structures. Explore more anatomical landmarks at OpenStax. |
In summary, while the heart is broadly present across several intercostal spaces, the second intercostal space marks the location of its base and the optimal point for aortic valve assessment, and the fifth intercostal space is key for the heart's apex.
