The brachioradialis is a shallow, fusiform muscle located on the lateral side of the upper arm and which flexes the upper arm at the elbow. It joins distally to the styloid process of the radius via the brachioradialis tendon, and proximally on the humerus’ lateral supracondylar ridge. It creates the cubital fossa’s lateral limit or the elbow pit near the elbow. Depending on the position of the upper arm, the brachioradialis has the ability of supination as well as pronation.
Despite the fact that most of the muscle content of the brachioradialis is seen from the front part of the forearm, it is a back compartment muscle, therein innervated via the radial nerve. The brachioradialis is only one of the 4 muscles that receive direct innervation/input from the radial nerve.
- The brachioradialis facilitates flexing of the upper arm near the elbow. When it is supinated, then the brachioradialis has a tendency to pronate when it flexes, while in a pronated position, it tends to supinate when it flexes. This also helps the brachii of the biceps.
- The brachioradialis acts as a more powerful flexor of the elbow when the upper arm is between pronation and supination, i.e., in mid-position at the radioulnar joint. In a pronated position, the brachioradialis is used more during flexion of the elbow, as in this position the brachii of the biceps is mechanically disadvantaged.
- The brachioradialis helps stabilize the elbow during fast extension and flexion when in mid-position, like in hammering. The muscle is antagonistic with the anconeus and the brachii of the triceps and synergistic with the biceps brachii and brachialis.
- As the brachioradialis is inserted/located somewhat away from the elbow’s fulcrum, the joint torque generated by it is less than that generated by the biceps or the brachialis. The muscle is mainly effective when such muscles have already slightly flexed near the elbow. It flexes the upper arm near the elbow, particularly when there is a need for rapid movement and during lifting of a weight along with slow flexion of the upper arm.
The Brachioradialis Reflex
- Also called supinator reflex, the brachioradialis reflex is seen via a neurological test via direct striking of its tendon, i.e., at its connecting point into the radial styloid process at the base of the wrist about 4 inches lateral to the thumb’s base, with a hammer when the arm is in a relaxed state. The radial nerve carries or transmits this reflex.
- The brachioradialis reflex should cause minor extension of the wrist, and/or supination, radial deviation, and minor elbow flexion.
Some of the common causes of brachioradialis pain are listed below:
- Any type of injury which strains or damages the brachioradialis muscle can cause pain. Trauma to the muscle due to a fall or a blow can damage the tissue. If the muscle is strained beyond its physical capacity, like trying to lift weights above one’s ability, then it can cause a tear or a pull of the brachioradialis. Overextension of the muscle beyond its natural capability can also cause pulls and strains. Patients with such injuries, strains, pulls, tears, etc., will usually experience sharp pain of the muscle in the early stages, which may then progress to a continuous achy pain along with stiffness, swelling, numbness, and/or tenderness.
- Frequent or excessive use of the brachioradialis muscle, like those in jobs with repetitive actions of the forearms, can also result in brachioradialis pain. Repetitive motions like holding, twisting, and lifting may cause pain of the elbows, the brachioradialis, and the nearby muscles. Tennis and racquetball players are especially prone to suffering from such pain. The pain may not stop and/or may aggravate if the repetitive motion is not stopped.
- Brachioradialis may sometimes occur due to problems in some other muscles or areas of the body. It may be noted that nerves originating from the cervical spine’s C6 and C5 vertebrae cross the radial nerve and later extend nerve fibers into the brachioradialis. Thus, any kind of damage, injury, or trauma to the spine can exert pressure on the nerve roots present in the area and cause spasms and pain in the upper arm. It is also possible for brachioradialis pain to be pain that radiates from the pronator and supinator muscles or other surrounding muscles.
Presented below are some strength-training exercises for the brachioradialis muscle. It is important to warm up via cardio exercises, etc., for about 5 to 10 minutes, before commencing brachioradialis workouts, as listed below:
- Reverse curls: Curls normally help strengthen the biceps. However, when a barbell is gripped differently, then the emphasis shifts to the brachioradialis muscle. Extend the arms downwards with the palms facing the body and hold the barbell. Flex the elbows and raise the bar towards the shoulders. Ensure that the upper arms are still and the elbows remain tight to the sides during this workout.
- Preacher curls: It is the same as standard preacher curls with a barbell, but the grip is overhand.
- Hammer curls: Hold a dumbbell in each hand and let the hands hang on the sides with the palms facing the body. Now, without changing the wrist position, raise the dumbbells towards the shoulders.