The Anatomy of the Brachialis Muscle

A Muscle That Bends Your Elbow

The brachialis is a muscle located in your arm near the crook of your elbow. This muscle works to flex (or bend) your elbow when your hand and forearm are in a pronated position with your palm facing down.

It works closely with your biceps brachii and brachioradialis muscles to ensure that your elbow bends properly. Injury to the brachiails muscle may cause pain and limit your ability to use your arm normally.

Anatomy of the brachialis muscle.

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Anatomy

The brachialis muscle originates from the front of your humerus, or upper arm bone. It arises from the distal part of the bone, below your biceps brachii muscle. It then courses down the front of your arm, over your elbow joint, and inserts on the coronoid process and tuberosity of your ulna. The brachialis muscle, along with the supinator muscle, makes up the floor of the cubital fossa of your elbow.

Nerve innervation to the brachialis muscle is the musculocutaneous nerve and some parts of the radial nerve. This corresponds to a spinal level of cervical five and six. Blood supply to the muscle is provided by branches of the brachial artery and recurrent radial artery.

Function

The function of the brachialis is to flex your elbow especially when your forearm is in the pronated, or palm down, position. It has a large cross sectional area, and is able to produce more strength than the biceps brachii.

Many people think the biceps brachii is a major flexor of your elbow; flexion is actually accomplished by the brachialis and brachioradialis muscles. The biceps brachii serves primarily to supinate your forearm, turning it into a palm up position. If your forearm is fully pronated, the biceps brachii is at a mechanical disadvantage, and the brachialis is the primary flexor of the elbow joint.

Your healthcare practitioner can easily test the strength of your brachialis muscle. To do this, simply sit in a chair with your elbow bent. Turn your forearm over into a pronated position, and have someone press down, attempting to straighten your elbow. If you are able to withstand the force of someone pushing your arm, then brachialis strength is considered to be adequate.

Associated Conditions

The brachialis muscle muscle may be injured if a forceful or repetitive strain is placed upon it, especially if your elbow is in a pronated position when the force is applied. Climbers, throwing athletes, and people who participate in racquet sports may suffer from a brachialis injury due to overuse or repetitive strain. Symptoms of brachialis injury may include:

  • Pain in the front of your elbow
  • Swelling in the front of your elbow
  • Difficulty extending your elbow (this may place stress over the injured brachialis tendon)
  • Weakness when bending your elbow, especially when your forearm is in the pronated position

People suffering from neck pain with cervical radiculopathy may experience brachialis weakness, especially if cervical level five or six is involved.

If you suspect you have injured your brachialis muscle, visit your physician right away. They can assess your condition and guide you to the correct treatment.

Diagnosis of a brachialis injury involves a clinical examination of elbow range of motion and strength, X-ray to assess for possible fracture, and magnetic resonance imaging (MRI) to assess the soft tissues in your anterior elbow.

Rehabilitation

If you have suffered an injury to your brachialis, you may benefit from a course of physical therapy (PT) to recover. Initial treatment of your brachialis injury may include the P.O.L.I.C.E. principle. This stands for protection, optimal loading, ice, compression, and elevation.

Protection of your injured brachialis muscle may include wearing a sling or splint to allow your arm to rest and heal. Optimal loading may involve exercise to improve the way your brachialis functions. Gentle stretching of the muscle may be performed, and progressive strengthening may be done over the course of several weeks to improve the ability of your brachialis to handle stress and loads.

Ice and compression are done initially to limit swelling of the muscle tissue. About a week after your injury, heat may be applied to improve circulation to the muscle and to allow it to stretch a little more easily.

The brachialis muscle may also be heated with a device called ultrasound. During this physical therapy treatment, a specialized wand is used to introduce ultrasonic waves through your skin and into the muscle. This causes the cells in your muscle and tendon to expand and contract, heating the tissue.

Ultrasound is done prior to stretching to improve tissue extensibility. Caution should be used; most studies on ultrasound show that while it increases tissue temperature, it does not shorten overall healing time or improve overall functional mobility. It simply heats the tissue.

Massage may also be an effective treatment for brachialis injury. Massage can help decrease pain, improve blood flow, and improve tissue extensibility to the muscle. It is often performed prior to stretching.

If you are experiencing pain in the front of your elbow due to a brachialis injury, you may benefit from using electrical stimulation to the area. Transcutaneous electrical neuromuscular stimulation (TENS) may be used to decrease pain. With less pain, you may be able to fully engage in your rehab program for your injured brachialis.

Most injuries to your brachialis (or any other muscle) heal within about six to eight weeks. If you continue to experience pain or limited mobility after that time, you should check in with your doctor for further assessment. A tear of the muscle, which is extremely rare, must be ruled out. If your brachialis muscle is torn, surgery may be performed to repair it.

A Word From Verywell

The brachialis is a muscle in the front of your elbow that flexes, or bends, the joint. It does this when your forearm is in a palm down, pronated, position. Injury to the muscle may cause pain and difficulty using your arm normally. By understanding the anatomy and function of the brachialis muscle, you can be sure to have a successful rehab process and quickly and safely return to your previous level of activity.

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