What is the Pyramidalis?

Meshell Powell

The pyramidalis is a muscle that is located in the rectus sheath that is found in the peritoneal region of the body. This muscle is not considered to be very important in humans. In fact, a significant number of normal, healthy adults do not even have a pyramidalis muscle.

When the pyramidalis is damaged or inflamed, it causes pain in the abdomen.
When the pyramidalis is damaged or inflamed, it causes pain in the abdomen.

The origin of the pyramidalis muscle is at the pubic crest. The pubic crest is basically a thick, projecting ridge that forms the border of the pubic bone. From there, the pyramidalis inserts itself into the linea alba. This is a median line resembling a tendon located on the abdominal wall between the rectus muscles. The primary job of the pyramidalis is to tighten the linea alba.

Stress may contribute to myofascial pain.
Stress may contribute to myofascial pain.

The linea alba is commonly referred to as a white line. This white line consists of a line of connective tissue that extends from the pubic bone up to the breastbone. When this muscle is damaged or inflamed, it typically causes pain in the lower middle portion of the abdomen. There are several medical conditions that can cause pain in this area of the body.

The pyramidalis is not considered to be a muscle that is vital to humans. It is actually estimated that 20 percent of humans do not even have this muscle present in the body. Sometimes the pyramidalis is present on one side of the body but not the other. In other cases, there are two pyramidalis on one side, with the doubled muscles often being unequal in size. Many scientists believe that this muscle is left over from the days of humans being similar to marsupials containing pouches, and as such, has lost most of its function in the process of evolution.

Myofascial pain sometimes affects the pyramidalis muscle, causing mild to moderate pain. Myofascial pain results from a condition that causes chronic muscle pain related to various trigger points within the body. This condition can vary in intensity from mild to completely debilitating. Treatments can include medication as well as physical therapy.

Once trigger points in myofascial pain syndrome have been activated, many factors can contribute to the muscle pain. Some of these triggers can include strenuous exercise, improper posture, or even emotional stress. A condition known as fibromyalgia often accompanies myofascial pain syndrome. This can be a very debilitating condition on its own, but when present together, these muscle conditions frequently require medical supervision and management in an effort to reduce the pain and increase the body's ability to function.

Fibromyalgia often accompanies myofascial pain syndrome.
Fibromyalgia often accompanies myofascial pain syndrome.

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Discussion Comments


@Bertie68 - I think that the evolutionary process got a little confused with the pyramidalis muscles. Some people have them, some don't, some who have them, have them only on one side of the abdomen, and some have two on one side! I wonder how long it will take before they are no longer found in anyone's body?

I think that some parts of our body are probably getting less and less useful. With our sedentary lifestyle, some of our muscles are not used as much.

It's too bad that these basically useless pyramidalis muscles don't do much good, but can cause pain. For example, myofascial pain and fibromyalgia can affect these muscles.


It's fascinating that about one-fifth of we humans don't have a pyramidalis muscle that the rest of us have, but don't need. Evolution certainly works in strange ways. I wonder if there are human body parts that are subtly starting to become not so important in our body systems? And maybe they will become obsolete in the evolutionary process.

So since this pyramidalis muscle connects to the linea alba tendon in the abdominal wall and gives the tendon support and strength. Does that mean that those who have this muscle are stronger in the abdominal area?


@ElizaBennett - No one really knows what the pyramidalis muscle used to be for. So I guess no, it doesn't do anything important for our close evolutionary relatives.

The only theory I've heard of is that it might be a leftover from pouched marsupials! Just one of those things, like male nipples.


Sounds like it's a lot like your appendix - it can't really help you, but it can cause all sorts of trouble! Although I'm guess that unlike the appendix, it can't be removed.

Why do we even have a pyramidalis muscle? Does it do something important for apes or something like that? I think I heard that the appendix, for instance, might be important in digesting raw meat or something like that.

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