First of all, let’s know the kind of motions your muscles do to let you perform a particular task. So there are four major types of muscle movements.


It is that muscle movement that brings two body parts like your upper arm and forearm closer together. For Example: When you lift heavy weight to build your tripes.


This movement on the other hand increases the space between two of your body parts. For Example: While walking, you have both Flexion and Extension movements in action.


In this movement, one of your body parts moves away from the center of your body. For Example: When you lift your arm out that makes it move away from your body. 


In this movement, one of your body parts moves towards the center of your body. For Example: When you bring your arm back from the last position that makes it move towards your body.

Now let’s get into the complex part of your arm muscles. This part makes up your strength and posture of your arm.

Upper Arm Muscles

As we are told, do more pullups to maintain our upper body strength. Just like that, in these muscles, we need to do more exercises like weight lifting and push-ups to maintain our upper arm strength. Upper Arm Muscles are divided into two different compartments: Posterior Compartment and Anterior Compartment.

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1. Anterior Compartment

You can find it in front of the major bone of your upper arms called Humerus. There are 3 muscles in this compartment;

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Biceps brachii

In normal or simpler words, we call them Biceps. It has two heads, one that starts just before your elbow joins with your shoulder, i.e. at the front and back of your shoulder. The other one ends near your elbow. This muscle helps you to perform abduction and flexion simultaneously.


They are located below your biceps. It is a bridge between your Humerus and Ulna; one of the main bones in your forearm. It helps in flexing your forearm.


They are located near your shoulders. This performs abduction as well as flexion of your upper arm and shoulder.

2. Posterior Compartment

This compartment can be found behind your humerus. It has two muscles to support it.

Triceps brachii

Normally we also call them triceps muscles that run along your humerus and lets you perform flexion and extension movements in your forearm.


It is a triangular-shaped muscle that helps your extended elbow rotate your forearm easily. 

Forearm Muscles

You may notice one thing: that your forearm has comparatively more muscle than your Upper Arm. That’s because its Posterior and Anterior compartments are further divided into 3 different layers.

Woman doing push-ups

Anterior Compartment

Superficial Layer

  • Flexor carpi ulnaris : This muscle helps in flexing and adducts your wrist.
  • Palmaris longus : This muscle is absent in 14% of the total population of the world. It helps with the flexion of your wrist. 
  • Flexor carpi radialis : This muscle lets you perform abduction movement on your wrist and hand. 
  • Pronator teres : This lets your forearm rotate and allows your palm to face your body. 

Intermediate Layer

Flexor digitorum superficialis: This muscle helps in flexing your second, third, and fourth fingers. 

Deep layer

Flexor digitorum profundus: This muscle also flexes your fingers and helps your wrist to move towards your body.

Flexor pollicis longus: Your thumb flexion did due to these muscles only.

Pronator quadratus: This muscle works just like Pronator teres in the Superficial layer.

Posterior Compartment 

You can find this compartment running alongside the top of your forearm. It performs movements like an extension on your fingers and wrist. It is divided into 2 layers only. That’s because it has no intermediate layer.

Superficial Layer

Brachioradialis: With this muscle, you can easily flex your forearm at your elbow.

Extensor carpi radialis longus: This muscle helps you to extend and abduct your hand at your wrist joint.

Extensor digitorum: This muscle helps you in providing an extension to your second, third, and fifth fingers.


This blog carries all the information regarding the arm muscles. Arms are a crucial part of our body that are extensively used in every major activity we do daily. There is so much more to know about your arm muscles. Now you know that your arm can’t just be heavyweights. But it has so complex science behind it. Thank your arms before praising your strength.

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