Coracobrachialis Muscle

What is your coracobrachialis muscle?

Your coracobrachialis is a small muscle at the front and top of your upper arm. It starts from your shoulder joint and inserts into your upper arm bone about halfway down, on the armpit side. This is what its name means: Coraco- refers to your coracoid process, the bony projection on your scapula that serves as the muscle’s attachment site. -Brachialis refers to your upper arm, where the muscle ends.

It’s not one of your most prominent arm muscles, and it doesn’t play a large role in moving your arm. But your coracobrachialis muscle can become tight from certain activities, and it can be a hidden source of shoulder pain or arm pain. The nerve that feeds into it — your musculocutaneous nerve — runs from your shoulder all the way down your arm, and it can refer pain from one area to another along the way.

What does the coracobrachialis muscle do?

Functionally, your coracobrachialis isn’t a very significant muscle. But it plays a supporting role in:

• Flexion: bringing your upper arm forward, like to shake hands or take something given to you
• Adduction: bringing your arms back down to your sides from an “airplane” position
• Internal rotation: bringing your arms inward toward your body, like to hug yourself
• Shoulder stability: holding your upper arm bone within your shoulder socket when it rotates

If your coracobrachialis muscle were injured, you’d still be able to perform these actions, but they might be more difficult. You might feel some weakness, soreness or instability when using your arm for:

• Lifting and carrying weight close to your body, like schoolbooks or a small child
• Pushing a heavy door open, performing pushups or swimming with a breaststroke
• Reaching diagonally across your body, like to fasten your seatbelt or tie your opposite shoe
• Playing sports with overhead throwing or pulling motions, like baseball, football or archery

Where is your coracobrachialis muscle located?

You might see your coracobrachialis muscle if you flex your biceps in the mirror. It’s the slender muscle that crosses from the front of your shoulder joint over the edge of your armpit to your forearm. If you put two fingers on your collarbone and follow it to your shoulder, you’ll find the bump of the coracoid process, where the muscle attaches. Pressure here should return some sensation from the muscle.

From here, the muscle runs down the inside of your upper arm to the midpoint. Your chest muscle (pectoralis major) passes over it, traveling from your chest across the front of your shoulder to attach to your upper arm. Your coracobrachialis lies deeper, tucked in the groove between your biceps and triceps muscles. If you put your fingers in here and squeeze your arm into your side, you might feel it pop out.

What conditions or disorders can affect your coracobrachialis muscle?

Any general muscle disorder or injury can affect your coracobrachialis, though most aren’t likely to. Since it’s not close to the surface, it’s not as exposed to injury as other muscles, and you probably don’t use it as heavily. But athletes and people with jobs that involve repetitive tasks may be more at risk of overusing their coracobrachialis. The most likely conditions to affect your coracobrachialis muscle are:

• Repetitive strain injury. Using your muscle a lot without giving it enough rest can strain it. When muscle strains don’t get the chance to heal, they can cause your muscle to stiffen and calcify.
• Myofascial pain syndrome. Repetitive strain can lead to chronic inflammation in your muscle and fascia. This can produce chronic pain that’s localized around a hard knot or trigger point.
• Nerve entrapment. Rarely, excessive exercise can make your coracobrachialis muscle bulk up so much that it compresses your musculocutaneous nerve. Entrapment causes symptoms like numbness, tingling or pain along the path of the nerve, which runs down your whole arm.

How can I tell if my coracobrachialis muscle is causing pain?

Soreness in your coracobrachialis muscle may be hard to identify, especially if you’re not familiar with it or its location. Complicating matters, the muscle can refer pain anywhere along the path of your musculocutaneous nerve, from your shoulder down your forearm. So, if you have unexplained shoulder pain or arm pain, you might want to try to find your coracobrachialis muscle and check it for stiffness.

If pressing on the muscle hurts or makes your shoulder or arm pain worse, it’s probably the source of your pain. If you feel a hard knot in the muscle that’s extra sore when you press on it, that’s a myofascial trigger point. Working the knot out will relieve the pain. Symptoms of musculoskeletal nerve entrapment can include numbness on the inside of your forearm or weakness when flexing your elbow.

What should I do about coracobrachialis muscle pain?

If you’ve strained your muscle, the best treatment is rest. If your muscle has become stiff and tight, massage might help. Consider visiting a sports medicine physician or a physical therapist for hands-on treatment. If you have myofascial pain, you might benefit from trigger point therapy (myofascial release). If you have symptoms of a pinched musculocutaneous nerve, consult your healthcare provider.