Anatomy Physiology

The human skeletal system is amazingly complex. Even a structure as seemingly simple as your arm has quite a few bones, each of which can have a multitude of muscles attached to it. There are two primary bones in the human forearm, the radius and the ulna. The ulna is the larger of the two and is located on the medial side of the forearm (with the arm in the proper anatomical position). This article will take a look at the muscles attached to the ulna.

In order for a muscle to move a joint, it must cross that joint. This means that the muscles you feel in your forearm aren’t the ones that actually move the forearm. The muscles that move the ulna are mostly in your upper arm.

The largest of the muscles that attach to your ulna is the triceps brachii, commonly referred to as just the triceps. This is the big muscle on the backside of your upper arm. It attaches to the ulna after crossing the elbow joint. By crossing the elbow, it’s contraction allows you to extend the elbow joint. 

Some anatomists call part of the lower triceps by a different name – the anconeus muscle. Yes, there are debates over this sort of thing in the world of anatomy. I was taught that there is no such thing as the anconeus – it’s part of the triceps. But my teaching was not necessarily definitive – it’s an ongoing debate.

The brachialis muscle attaches to the ulna near the elbow joint. This is a small muscle that supports to the biceps. Interestingly, the biceps does not attach to the ulna – it attaches to the radius, the other muscle in the forearm.

Attached to the ulna are a series of muscles that control the movements of the hand and wrist. Hang on, there are a lot of them. Here they are:

There are the extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus muscles. These are used to extend the thumb (the opposite movement from making a fist). The extensor carpi ulnaris extends and adducts the wrist.

The extensor indicis muscle allows you to extend your index finger (second digit).

The supinator muscle attaches near the elbow joints and assists the biceps in supinating the forearm (a twisting motion used when you use a screwdriver).

The flexor digitorum superficialis and flexor digitorum profundus are two muscles in your forearm that are used to flex the fingers and wrist. The flexor carpi ulnaris is located in the forearm and helps flex the wrist.

The pronator teres muscle is attached near the elbow joint and helps pronate the forearm. Not a big surprise given the name. The pronator quadratus does a similar job, but is located more near the wrist.

So there you are, a list of the muscles that attach to the ulna. Of course, there is a lot more to learn about these muscles. Each of them attach to different points of the ulna, and they receive blood supplies and innervation from a variety of arteries and nerves.