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Arm Anatomy 101

Arm Anatomy 101

Our arm muscles tend to showcase how hard we work in the gym or how dedicated we are to our yoga practice. They present one of the most impressive muscle groups on our bodies, and their definition has the power to turn heads or even warrant a random arm squeeze from strangers.

How do we achieve that beautifully defined, strong look? The first step is to understand how the guns work, and where to point them, with some basic arm anatomy.

Anterior Arms

There are three muscles that make up the front of the arms- biceps brachii, brachialis and brachioradialis.

Biceps Brachii

The biceps are involved in the movement of two joints- the shoulder and the elbow. The word bicep translates to ‘two heads’, which explains the muscle’s two points of origin in the shoulder. One point begins at the front of the scapula and the other just above the shoulder joint. Both extend down and attach to the top of the inner forearm (radius). Using a supinated grip in training is the most effective way to work your biceps.


The brachialis runs from the middle of the upper arm (humerus) to the outer side of the forearm (ulna). Its main function is to assist flexion of the elbow joint. Neutral grip exercises (like hammer curls), encourage a direct line of pull and therefore maximise the growth of this muscle.


The brachioradialis is the long forearm muscle, which stretches from the humerus and attaches at the end of the radius. It’s used to flex the forearm at the elbow. Pronated grip exercises (including pronated grip pull-ups) isolate the brachioradialis, creating a beneficial workout for the muscle.

Posterior Arms

The biceps tend to steal the thunder for the most part, however the triceps deserve equal attention, considering they make up 75% of the muscles of the upper arm. Triceps means “three heads”, meaning there are three points of origin to the muscle- the lateral head, the medial head and the long head.

Lateral Head

The lateral head starts at the upper humerus and attaches to the elbow.

Medial Head

The medial head begins on the backside of the humerus and attaches to the elbow.

Long Head

The long head attaches to the elbow from the scapula.

The triceps are given the best workout through elbow extension and overhead elbow extension. Exercises that move the elbow from a flexed position to an extended position (triceps dips, weighted parallel bar drop, cable kick-back- to name a few!), work all three heads of the triceps equally. Once the weight is moved above the head (overhead dumbbell extension) the long head is isolated.

All of the arm muscles are designed to excel in strength and speed. Ensure you consider the anterior and exterior arm muscles when training and pay attention to the muscles that can be isolated. You’ll be kissing those guns in no time.