Muscles of the forearm

Anatomically speaking, the forearm is the part of the upper limb between the elbow and the wrist joints.

It contains two bones: the ulna and the radius, which provide support to local muscles supplied by an intricate network of nerves and vessels.

On the anterior part of the elbow, there’s a triangular fat-filled pit, called the cubital fossa, which is where the majority of important nerves and vessels to the forearm and hand can be found.

Okay, before we start, it is important to know that, even though some of the muscles of the forearm attach proximally to the humerus, they still belong to the forearm.

The forearm is divided into two compartments, which are separated by the radius and ulna and the interosseous membrane running between them.

We have the anterior compartment, which contains flexors and pronators.

Next, is the posterior compartment, housing the extensors and supinators of the forearm.

Generally, muscles in the same compartment are innervated by the same nerve.

So, the muscles of the anterior compartment are generally innervated by the median nerve, with a few muscles being innervated by the ulnar nerve.

Muscles of the posterior compartment, on the other hand, are innervated by the radial nerve.

Now, the muscles of the anterior compartment are divided into three groups, or layers: superficial, intermediate, and deep.

In the superficial layer there are four muscles which all arise from a common tendon attached to the medial epicondyle of the humerus, so this attachment site is called the common flexor origin.

Muscles attaching to the common flexor origin are the flexor carpi ulnaris, the palmaris longus, the flexor carpi radialis, and the pronator teres muscles.

Now, let's look at these muscles one by one.

On the most medial side lies the flexor carpi ulnaris.