This 'Useless' Body Part Has A Potential Health Benefit That Can't Be Overlooked

As impressive an example of evolution as the human body is, it's also full of seemingly useless parts, from male nipples to muscles that allow some people to wiggle their ears. While these two examples don't actually serve much of a purpose in the modern world (though there may be some advantage to wiggling your ears), many of these ostensibly redundant body parts actually do serve hidden purposes. In fact, vestigial body parts are often considered by biologists to still provide some form of function even if they lost their primary purpose thousands of years ago.

That seems to be the case for the pyramidalis muscle, which is considered vestigial but arguably serves several important purposes even while experts remain divided. This paired triangular muscle sits in the abdominal wall and is thought by some experts to be a remnant of marsupials' pouches which evolved into something much smaller in primates. Other studies show it evolved along with human anatomy, suggesting it had something to do with our erect posture. Whatever the case, the muscle might seem as though it isn't all that important, especially since it has been found to be absent in a significant proportion of people. A 2020 study published in the journal Clinics looked at 30 cadavers and found that 13.33% didn't actually have a pyramidalis muscle.

So, how can a muscle that some people don't even have carry out any important functions? Well, some experts believe the pyramidalis can be useful for a number of reasons, even if it's not a crucial aspect of our anatomy.

The pyramidalis muscle remains somewhat of a mystery despite several studies being carried out into its origin and function. The muscle is thought to strengthen the abdominal wall and help tense the linea alba, a band of tissue running down the front of our abdomens. The pyramidalis also contracts along with other abdominal muscles, which suggests it contributes to contracting the abdominal wall, which in turn allows us to protect our abdominal organs and also helps with things like forced respiration, singing, and even defecation.

That said, it's not entirely clear just how much the muscle helps with these processes. Researchers who carried out the 2020 Clinics study, for example, noted that the absence of a pyramidalis muscle doesn't cause any apparent loss of function, making the muscle's actual purpose somewhat unclear. On the other hand, the team noted that the muscle can be helpful for surgeons looking for a reference point for abdominal incisions, is useful for grafts, and can even serve as a source of stem cells. 

A separate 2017 study published in the Journal of Clinical and Diagnostic Research also listed several obvious benefits conferred by this mysterious muscle, including its use in treating severe dysuria and in microsurgical transfer for the treatment of small foot and ankle wounds. As the researchers in that study concluded, with all of this in mind, the role of the pyramidalis muscle "cannot be overlooked." Even while the muscle remains a significant mystery and isn't even present in all of us, much like the "useless" part of your spine that's actually important, it clearly isn't completely redundant.