Muscle Groups – There Are Thirteen! Abdominals and Obliques Are One!

six pack
Hey everyone!

Welcome back, or welcome to the page.

Today I would like to talk about muscle groups. Like the title says, there are thirteen different muscle groups in the body. There is no way I can go into detail about all of them in one post, so I will show you all of them, list them, and then go into detail about the Abdominals and Obliques.

Let’s get started!

All The Muscle Groups

muscle groupsDepending on the source, there are between 640 and 850 muscles in the human body. That is a lot!

As an example, it is said that it takes 26 muscles to smile and 62 muscles to frown. All you body builders out there, frown away! LOL!

It would be difficult to talk about all the muscles individually, so we will need to group them together for simplicity’s sake.

As you can see from the diagram, there are about seven major groups: chest, arms, abdomen, legs, shoulders, back, and buttocks.

I will take these groups and break them into smaller sections so I can detail the exercises needed to work each group.

The groupings I have decided on are as follows (in no particular order):

abdominals, obliques, pectoralis, deltoid, trapezius, latissimus dorsi and rhomboids, erector spinae, biceps, triceps, quadriceps, hamstrings, gastrocnemius and soleus, and gluteus maximus.

Even that is quite a few groups of muscles, but bear with me as we tackle one or two at a time.

Abdominals and Obliques

abdominal muscles

There are three layers of muscles in the abdominal wall. From the outside to the inside they are: external oblique, internal oblique, and transverse abdominal. These three muscle are supplemented in front, on each side of the mid line by the rectus abdominis (six-pack). We will go into detail on each of these below.

The function of the abdominals is to work together to support our trunk, allow movement, form a firm wall that protects the internal organs, and to help maintain an erect posture.

Working together with the back muscle, the abdominals form our core muscles which keep us stable and balanced, and also protect the spine.

Let’s talk about each muscle in more detail.

External Oblique

external obliquesThe external obliques is the largest and outermost of the three flat abdominal muscles and they are located on the outer surface of the sides of the abdomen, on each side of the rectus abdominis.

By definition, external obliques are on the outside (external) and the fibers of the muscles run in a slanted direction (oblique is from the Latin word obliquus, which means a slanting direction). If you put your hands in your pockets, their orientation to your body would represent the direction these muscle fibers run.

These muscles extend from the ribs to the pelvis and are responsible for stabilization of the trunk, and together with the internal obliques, the twisting of the trunk. It is important to know what movements the muscles are responsible for, as that will dictate how we train them.

Some exercises that will strengthen the external obliques are:

Bicycle Crunchside plank

Single-Leg Side Plank

Rotating Side Plank

Spiderman Push-Up

Cross-Body Mountain Climber

Russian Twist

Dumbbell/Kettlebell Side Crunch

After we discuss the other muscles, I will suggest a routine of abdominal exercises to train all four groups.

On to the next group!

Internal Oblique

internal obliquesThe internal obliques are located in a similar position as the external obliques, but further away from the surface of the skin, that is, under the external obliques.
As you can see from the above diagram, the internal obliques are also a slanted muscle, but the fibers run in the opposite direction of the external obliques.

They serve a similar function as the externals, in that they are responsible for rotating the trunk. The internal obliques rotate the trunk in the same direction; the left internal oblique will rotate the trunk to the left and the right internal will rotate it to the right.

The externals work opposite to that. The left external oblique will rotate the trunk to the right and the right external will rotate the trunk to the left.

Together, the obliques are responsible for turning the trunk. Also, together, they are responsible for bending the trunk forward and backward, compressing the internal organs.

It is important to have strong obliques to perform our daily functions properly. The exercises that train the internal obliques are the same ones as the external obliques, since they are just acting in opposition to each other. More on exercises later, except to say that to train the obliques properly, there needs to be some twisting exercises, with resistance (added weight), since these muscles are on a slanted orientation. These muscles allow us to twist our torso, so they must be trained in a twisting manner.

Traverse Abdominis

traverse abdominisThe traverse abdominal muscle (TVA) is the deepest of the abdominal muscles, located inside the internal obliques and the rectus abdominis (six-pack) and it wraps around the core horizontally.
The TVA is recruited into action any time a limb is moved. It ensures the trunk, the pelvis, and the core are stable before any movement takes place. You might even say it is your body’s built in weight belt or girdle, since it resists flexion of the lower back. The TVA also keeps the neck in a neutral position during core training, and helps to improve posture, muscle balance, and stabilization. A strong TVA provides a solid foundation for any movement.

The TVA also assist with respiration by compressing the internal organs during exhalation.

I hope it is obvious to you that we need to exercise the TVA regularly to ensure safety during all other workouts.TVA breathing

The first exercise I will mention is a breathing exercise which will strengthen the TVA. This exercise can be done on all fours, on your back, or standing. I prefer standing. Take a breath and then breath out of your nose. Without taking another breath, and by focusing on your TVA, breath out some more, pulling your stomach in while holding your breath. Do this one more time. You should be focused on pulling your TVA (belly button area) toward your spine. Hold this for as long as possible (20 or 30 seconds), and then repeat. Try to find a time every day when you can do this exercise. I do it while I am brushing my teeth every morning and evening. It only takes a few seconds, but you will reap the benefits.

Other exercises that train the TVA are: Foot-Hand Bear Crawls, Forward Ball Roll, Hollow Body Holds, and Planks.

Rectus Abdominis – The Six Pack

rectus abdominisFinally, you say, the six-pack. This is the abdominal muscle that everyone wants to have showing, The classic six-pack.

The rectus abdominis muscle is a paired muscle that runs vertically on each side of the anterior wall of the abdomen. They are attached at either end to the sternum and the pelvic bone and function, with the other abdominal muscles, to bend the whole body forward or sideways. They are also activated when we have a bowel movement or cough.

Since its main purpose is to pull the rib cage and the pelvic bone closer together, the classic sit-up is often used to train the six-pack. But we need to be aware of the strain the sit-up puts on our bodies. Sit-ups are really an exercise that trains the hip flexors, and repeated sit-ups can cause the hip flexors to tighten up leading to lower back pain. Instead, here are a few exercises to train the rectus abdominals: forearm plank, reverse crunch, scissors flutter kicks, toe taps, and flat bench lying leg/hip raises. All of these exercises train the rectus abdominis in it’s plain of motion: pulling the rib cage and pelvic bone closer together.

The Abdominal Muscle Workout

The key to abdominal workouts (and there are many) is to work the muscles from the bottom up and from the top down, while not forgetting the obliques or the core muscles. There needs to be some twisting of the trunk, some lifting of the torso and legs, and some static holds. I have included a chart below. My suggestion is to choose one exercise from each column, perform 8 – 12 reps or a 30-second hold (depending on the exercise), and do three sets. That should give all your ab muscles a great workout.

ab exercisesIf you are unsure of how to perform any of the exercises I listed, or any of the exercises in the chart, a simple Google search of any exercise will give you a quick video tutorial to follow.


I cannot leave the section on abdominal exercise without talking about nutrition and eating habits. food

You can do as many of the above exercise as you want, and there is no guarantee that anyone will see your six-pack. That is due to the simple fact that our entire body is covered in a layer of fat (some more than others) that covers the muscles.

Until you do something about what you are eating, your abs will remain hidden beneath your fat. You will need to lower your body fat percentage significantly to show off the abs you are working hard to build.

The abs are in there. You just need to get rid of the fat so you can show them off.

More on that in another post.

Last Words

So there you have it.

All the information you could ever want on abdominal muscles and how to train them.arnold abs

I hope you found this information interesting and useful. Remember, before you start any exercise program, consult with your doctor to ensure you will be able to perform the exercises in good health.

Thanks for listening.

If you have any questions or comments, please leave them below.

See you in the next post.

Have a great day!


Tom Fitzsimmons

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