The phrase “heart strings” often calls to mind a powerful emotional reaction, a feeling of deep sympathy or fondness. This familiar idiom, describing something that “tugs” at one’s deepest feelings, has a surprising foundation in the physical anatomy of the human body. The concept of “heart strings” bridges the worlds of biology and language. This exploration will delve into the literal cords that exist inside the heart and the history of how they inspired this enduring emotional expression.
The Anatomical Reality
The physical structures that gave rise to the term “heart strings” are known scientifically as the Chordae Tendineae. These are thin, fibrous cords that resemble small pieces of string. They are composed primarily of collagen, providing the toughness and tensile strength necessary for their function. These cord-like structures are located within the lower chambers of the heart, the ventricles. They serve as tethers between the heart muscle and the valves that control blood flow. Specifically, the Chordae Tendineae connect the small, cone-shaped papillary muscles projecting from the ventricular walls to the leaflets of the atrioventricular (AV) valves. These AV valves include the tricuspid valve on the right side and the mitral valve (or bicuspid valve) on the left side.
Function and Mechanism
The purpose of the Chordae Tendineae is to maintain the integrity of the heart’s valve system during the powerful contractions of the ventricles. When the ventricles contract (systole), pressure increases dramatically as they push blood out to the lungs and the rest of the body. This pressure tries to force the valve leaflets backward into the upper chambers, the atria.
The “heart strings” prevent this backward movement, or prolapse, of the valve leaflets. As the ventricular muscles contract, the attached papillary muscles also contract, pulling tension onto the Chordae Tendineae. This action holds the valve leaflets firmly closed, preventing the backflow of blood (regurgitation) into the atria.
This mechanism ensures that blood flows in a single direction: from the atria into the ventricles, and then out into circulation. If the Chordae Tendineae rupture or become damaged, the valve will not close completely, allowing blood to leak backward and impairing pumping efficiency.
The Origin of the Idiom
The transformation of this anatomical structure into a figure of speech occurred centuries ago, long before modern medical understanding of the heart’s function. Historically, as far back as the 15th century, it was believed that tendons or similar fibrous structures supported the heart within the chest. These literal “strings” were thought to be directly connected to a person’s deepest affections and vulnerabilities.
This belief led to the figurative use of the term. The idiom “tugging at the heartstrings” emerged as a metaphor for an external stimulus—like a sad story or a touching scene—that elicits a strong emotional response.
The visual of a string being pulled or plucked evokes a sudden, visceral reaction, much like a musician plucking a string. The phrase captures the idea that these emotional cords are under tension, capable of being stirred by an external force.