Daily Mysteries #3: Are you Missing a Muscle?

As humans, we tend to differ in quite so many ways amongst each other!

Our height, eyes, skin, hair, ... come in all different shapes or forms, yet we all share the same general physical structure: 1 heart, 1 liver, 2 lungs, 1 mouth, 2 ears, ..., 206 bones (as adult), 650 muscles (or 840 depending on the categorization approach).

But, could your body be missing .. a muscle?

Meet the "Palmaris Longus Muscle"

According to several studies, the Palmaris longus muscle (normally visible as a tendon in the wrist) is missing in around 14% of the population. This number even differs immensely among different ethnic groups, with being missing in up to 24% in Caucasian and 26.6% in some Asian populations.
The muscle comes also in varying shapes:

tendinous at the top while muscular at the bottom
a muscle surrounded by two tendons
a tendon with two muscles surrounding it
solely tendinous band
completely missing

Are you missing it?

Checking for the presence of the muscle is quite simple. With your inner arm facing up, twist the palm of your hand slightly upwards and bring your thumb and your pinky into contact. This would make it visible in your anterior wrist's mid-line, should you have it.

How would that affect us?

Practically, this muscle is vestigial, so nothing! The absence of this muscle/tendon has no effect whatsoever on the function or the strength of the grip. Hence why, medically, it is most widely used for wrist tendon grafts due to its length, diameter, and that removing it would cause no functional deformities.

Why is it missing?

Basically it drills down to the conclusion that the muscle was used by our ancestors for purposes of climbing trees and mountains, and that the muscle became quite useless that it went missing through generations for increased numbers of the population.
Its absence is often used to reinforce the theory of evolution.

So, did you test it out? Do you have it or not (I personally do :) )? Let me know in the comments below :)

Cheers!

@mcfarhat

References:

Photo Credits:

My own hand :)

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