Muscle groups

There are over 650 named skeletal muscles in the human body, although some figures go up to as many as 840. The dissension comes from those that count the muscles within a complex muscle.

 

These muscles can be divided into 7 different muscle groups. There are 3 large muscle groups:

  • Legs
  • Chest
  • Back

And 4 smaller muscle groups:

  • Biceps
  • Triceps
  • Shoulders
  • Abdominals (abs)

 

muscle anatomy human body

A muscle is a tissue structure of cells that have the ability to contract so that movement is possible. There are three different forms of muscle tissue: striated, smooth and cardiac muscle tissue. The striated muscles are the only muscles that we can consciously control.

 

A muscle mainly consists of fibers. There are two types of muscle fibers: slow and fast muscle fibers. They differ by the speed with which they contract. Slow muscle fibers can produce a lot of energy but relatively less force. A good example are the muscles in your back, which are constantly tightened.


Fast muscle fibers are made in such a way that they can produce strength because they quickly contract in a short time. Fast muscle fibers can be found in i.a. your arms.

 

Push vs pull exercises

Each muscle group has to be trained in it's own way. There is a distinction between so called push and pull exercises.

 

A push exercise is an exercise that trains the muscle when you perform a movement away from the body. Examples of push exercises are the leg press and the bench press. Your legs, chest, triceps and shoulder muscles are trained via push exercises.

 

Pull exercises are exercises that train the muscle when you perform a movement towards the body. Your back, biceps and abdominal muscles are trained via pull exercises.

 


Different muscle groups

Legs

leg muscle upper leg

Your legs are the biggest muscle group of your body. It is defined by the muscles in your upper leg and your lower leg.

 

Your upper leg consists of 5 muscles that you can isolate: at the front is your quadriceps that runs from your hip to your knee. At the inside of your quadriceps is the vastus medialis which can be targeted via adductor exercises and at the outside of your quadriceps is the vastus lateralis which can be targeted via abductor exercises.

 

At the back you have the hamstring (semitendinosus). The hamstrings start at the bottom of the pelvis. They cross the knee joint and end at the lower leg. And your buttocks consists of the gluteal muscles.  This is a group of three muscles: the gluteus maximus, gluteus medius and gluteus minimus.

 

leg muscle lower leg

Your lower leg is defined by the calf muscle (musculus triceps surae). Your calf muscle consists of two different parts.

 

The musculus gastroncemius covers about 70% of the total calf muscle and attaches between the knee joint and the heel bone. The soleus muscle covers the remaining 30% of the calf muscle and is located below the musculus gastron cemius.

Chest

chest muscle anatomy

The chest muscle (pectoralis major) consists of 3 parts. Simply stated these are the top part (clavicularis) that is located between the collarbone and upper arm, the middle part (sternocostalis) that is located between the sternum and upper arm and the bottom part (abdominalis) that is located between the rectus sheath and the upper arm.

 

The position in which you perform a chest exercise determines which part of the chest you isolate. If you are in a horizontal (flat) position, you focus on the middle part of the chest muscle. If you are in an incline position (head higher than your feet) you focus on the top part of the chest muscle. And if you are in a decline position (head lower than your feet), you focus on the lower part of the chest muscle.

 

Besides the 3 muscles mentioned above, it’s also possible to isolate the inside of your chest muscle. This can be seen as the fourth area of the chest muscle that you can train. By isolating and training all 4 areas separately, you will see maximum results of your chest workout.

 

Back

The back is a complex muscle group. For most athletes a muscular back is an important goal. But at the same time it's also a muscle group where often injuries occur. The lower back in particular can be a vulnerable part of your body.

The upper back consists of 3 large muscles: the trapezius that runs from your neck to your shoulders, the latissimus dorsi on the sides of your body that attaches between the hip and the armpit and the rhomboidus that is located in the middle next to the spine.

 

The muscle in the lower back, the quadratus lumborum, is located on either side of the spine in the lower back region.

 

Biceps

muscle group biceps bicep muscle

The biceps (biceps brachii) is the two-headed upper arm muscle. Biceps literally means 'two-headed'. The top of the muscle consists of a long head (caput longum) and a short head (caput breve). Both heads attach to the shoulder blade. At the bottom the bicep attaches to the radius.

The bicep can be divided into two different parts which you can both isolate during your workout: the ‘head’ of the bicep at the top near the shoulder joint and the ‘central’ muscle that covers the majority of the upper arm.

 

Normal curls

The central muscle is trained via ‘normal’ curls and pull ups; the starting position of your hands is with your palms facing forward.

 

Hammer curls

The head of the bicep is trained via hammer curls. By rotating your hands inwards so that your palms face each other, the focus shifts from the central part to the top part of the bicep. It is the same position like you would hold a hammer, hence the name hammer curls.


Triceps

Your biceps determines the size of your upper arm? Wrong! Two thirds of the size is determined by your triceps and 'only' a third by your biceps. In that sense, the triceps deserve extra attention because it defines your upper arm. 

 

Its full name is musculus triceps brachii, shortened to triceps. It’s a so called three-headed muscle and is located along the back of the upper arm. The triceps consists of 3 different muscles. The biggest muscle is the long head muscle that starts at the shoulder blade and attaches to the ulna. The smaller lateral head muscle is located at the outside of the upper arm. The third muscle is the medial head muscle. It's harder to target because it lies underneath the other two muscles, lying deeper into the upper arm.

 

Shoulders

muscle group shoulders

The biggest shoulder muscle is the deltoid muscle. It derives its name from its triangular (delta) shape. The deltoid defines the shape and size of your shoulders. It attaches between the shoulder blade and the upper arm.

 

A second smaller shoulder muscle called infraspinatus is located behind the shoulder blade at the back of the shoulder joint, close to the trapezius.

Abdominals

The abdominals are located in the abdomen region which constitutes the part of the body between the chest and pelvis. The function of the abdominals is to put pressure on the stomach to effectuate body functions such as sneezing, peeing and breathing.

 

There are 3 different parts that can be distinguished within the entire abdominal structure.

 

At the front of the abdomen is the rectus abdominus. These are the muscles that are being referred to when people talk about a six pack. There are 3 muscles on each side and it extends the entire length of the anterior abdominal wall.

 

Beneath the rectus abdominus are the 2 lower abdominals, the musculus pyramidalis

 

At each side of the body, above the hip joint, are the musculus obliquus located. They are part of the entire external oblique muscle structure that is situated on the lateral and anterior parts of the abdomen. Each side consists of 5 different horizontal muscles that increase in size from above downward.