The brachioradialis is a prominent muscle located in the forearm, playing a role in arm movement. It contributes to the strength and flexibility of the elbow and forearm, facilitating various everyday tasks.
Understanding the Brachioradialis Muscle
The brachioradialis is a superficial muscle situated on the lateral, or thumb side, of the forearm. It has a fusiform shape, meaning it is wider in the middle and tapers towards its ends. This muscle originates from the upper two-thirds of the lateral supracondylar ridge of the humerus, the long bone of the upper arm, and also from the anterior surface of the lateral intermuscular septum of the arm.
From its origin, the muscle fibers extend downwards, forming a thick tendon around the middle of the forearm. This tendon then inserts distally near the wrist, specifically on the styloid process of the radius, which is the forearm bone on the thumb side. The brachioradialis forms the lateral boundary of the cubital fossa, often referred to as the elbow pit. It is innervated by the radial nerve.
Primary Functions of the Brachioradialis
The brachioradialis muscle plays a significant role in movements of the elbow and forearm. Its primary action is to flex the forearm at the elbow joint. This muscle is particularly effective as an elbow flexor when the forearm is in a neutral or semi-pronated position, meaning the thumb is pointing upwards, similar to holding a beer mug.
Beyond simple elbow flexion, the brachioradialis also assists in moving the forearm towards a neutral position. If the forearm is fully pronated (palm down), the brachioradialis can help supinate it back to neutral. Conversely, if the forearm is fully supinated (palm up), it can assist in pronating it back to the neutral position. It works in conjunction with other elbow flexors like the biceps brachii and brachialis.
How to Locate and Palpate the Brachioradialis
Locating the brachioradialis on your own arm involves a few simple steps, allowing you to feel its presence and contraction. Begin by sitting comfortably and resting your forearm on a table or your lap, with your palm facing inward, as if preparing for a handshake. This position places your forearm in a neutral or semi-pronated state, which is ideal for isolating the muscle.
Next, place your opposite hand along the outer edge of your forearm, starting just below your elbow joint. Gently slide your fingers down towards your thumb side. You should feel a muscle mass in the upper half of this lateral forearm region.
To feel the muscle contract, slowly bend your elbow, bringing your hand towards your shoulder, while keeping your thumb pointed upwards. As you perform this action, apply gentle resistance with your other hand, for example, by hooking your fingers under your bending forearm and pulling slightly downwards. You will feel the brachioradialis muscle harden and become more distinct under your fingertips as it contracts. When you relax your arm, the muscle will soften again. This palpation technique helps confirm you have located the brachioradialis, as it is the most superficial muscle on the radial side of the forearm.
Brachioradialis in Everyday Movement and Exercise
The brachioradialis muscle is engaged in numerous daily activities. Any action requiring bending the elbow with the hand in a neutral or semi-pronated position relies on this muscle. Examples include lifting a cup to drink, carrying a grocery bag by its handle, or using hand tools like a hammer or screwdriver. Its involvement helps stabilize the elbow joint during these movements.
The brachioradialis is targeted in certain movements to enhance forearm strength. Hammer curls emphasize the brachioradialis, as they involve lifting a weight with the palms facing each other, maintaining that neutral forearm position. Other exercises, such as various types of rows or pulling movements where the grip is neutral or slightly pronated, also engage this muscle. Strengthening the brachioradialis can improve grip strength and endurance.