This is your heart.
During the Pledge of Allegiance or the National Anthem, Americans – ah, some Americans – put
their hands over their hearts.
And this isn't just in the U.S. too.
People around the world automatically put their right hand over the left side of their
chest just under the shoulder level with the armpit, because that's where the heart is,
There, you're actually covering your left lung, not your heart.
Despite what you see depicted on t.v. in the media, your heart isn't quite where they say
Yes, you do feel your heart beat more on the left side of your chest which adds to this
perception but I'll soon explain why that is.
So, the heart is a muscular organ with four chambers – right atrium, right ventricle,
left atrium and left ventricle.
It's about two hundred and fifty to three hundred and fifty grams about the size of
a fist and it pumps blood through the blood vessels of the circulatory system.
The right atrium collects the deoxygenated blood which passes to the right ventricle
then pumped to the lungs to receive oxygen.
The newly oxygenated blood returns to the heart and at the left atrium passes through
the left ventricle before finally being pumped out to the rest of the body.
Now, you can see the heart is not on the left or the right side.
It's actually located in the center of the chest bound by the sternum and ribs, the spine
closely behind it with both ventricles lying on the diaphragm.
It's enclosed in a protective sac called the pericardium and it's wedged between the two
But note, it's not symmetrical.
There's a tilt which makes it seem like it's more to the left than it actually is.
The heart is cone-shaped with the narrow end or apex pointing roughly to the left hip and
the broader end or base – the base actually being the upper part – pointing to the right
Here, the muscle wall surrounding the left heart specifically the left ventricle is much
thicker than the right.
Here's a view from the back.
This causes the heart to offset slightly to the left and along with being the largest
of the four chambers, it gives that considerable impression of being more to the left side.
But why is this muscle mass uneven to start with?
Why isn't the heart symmetrical?
Well, there are actually many theories on this but, in general, we can explain a lot
just by sticking to one of the basic principles of anatomy – form follows function.
The reason why we're symmetrical or roughly symmetrical on the outside can be explained
by locomotion – the way we move.
For example, if we had asymmetric legs, as a species, we wouldn’t get very far, literally
Internally, it's a different story.
There isn’t that same requirement and as such, you can see a whole lot of asymmetries
specifically in the torso area.
A symmetrical heart positioned perfectly in the center of the chest which sure look nice
but we know that the left and right sides of the heart serve different functions.
So it shouldn't be a surprise that they also looked different.
The left ventricle needs the strength to generate enough force to pump blood through the entire
body whereas the right ventricle just needs to pump blood to the lungs – that's a much
This also explains why you feel your heartbeat more on the left side of the chest.
The left ventricle generates the highest pressure.
Now, another point to consider is space.
During our evolution, nature had to fit complex organs in the most efficient of ways in the
tiny space of a human body.
Some things have to go on the right, some on the left, the center, some things tilted
and thus the result, a lack of internal symmetry.
The heart happens to be in the center but with that slight offset, it leaves less room
for the left lung.
There's a depression there known as the cardiac notch where the surface of the lung rests
against the heart.
This makes our left lung smaller than our right lung – one asymmetry leading to another.
As for why the heart is located where it is in the middle of the thoracic cavity, well,
there, it's nicely protected by the rib cage.
Imagine if the heart was in a more vulnerable part of the body, maybe, your leg or, say,
You'd get angina every time you'd shake someone's hand.
So, the heart in the center of the chest with the left tilt is what most of us have.
Most – that's right.
Not all of us share this alignment.
There are cases where people have their hearts more to the right side of the body.
This is called dextrocardia, a rare congenital disorder affecting approximately one in twelve
There's also another rare condition called situs inversus or oppositus where the major
visceral organs of the individual are reversed or mirrored from their normal positions.
This makes the right atrium, now the left atrium, and the left atrium, the right atrium,
and the same with the ventricles.
The deoxygenated blood would now be received by the left atrium.
It can be a little confusing.
In the past, many people with situs inversus went through life unaware of their unusual
anatomy as they tended to live normal, healthy lives without complications.
Their organs were just in reverse – meaning, oftentimes, the normal functioning relationship
between the organs was maintained and unchanged.
Interesting fact: Spanish singer-songwriter Enrique Iglesias is one such notable case
of someone with situs inversus.
So far, we haven’t yet covered the most extreme case of displacement of the heart
which would be this.
It's a rare syndrome where the heart is located outside the chest through a split sternum
dangerously shielded by only a thin layer of skin.
This happens approximately once in two hundred thousand births with only a few cases surviving
This girl has what's called pentalogy of Cantrell with ectopia cordis – no, I did not make
There's a spectrum of anatomical locations the heart can be with this condition, not
just the outside chest but also the neck and abdomen.
For these latter cases, the heart really is not where you think it is.
As for the pledge or during the national anthem, having your heart under the shoulder and level
with the armpit sure isn't as extreme in comparison but considering even rare conditions, it's
never actually quite there.
Perhaps, from now on, if you ever find yourself in such a situation and wanting to be anatomically
correct, you might want to consider moving your hand closer to the center of the chest
to where your heart really is.
Thanks for watching.
We hope you enjoyed this topic.
Let us know your thoughts.
Did you think the heart was on the left, the center, maybe somewhere else – drop us a
comment down below.
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Alright guys, I'll see you next time.