From the Research
When the elbow is completely flexed, the triceps brachii muscle is responsible for extending or lifting the elbow up. This is based on the most recent and highest quality study available, which investigated the functions of the triceps brachii in humans 1. The triceps brachii is the only muscle that lies along the posterior humerus and plays a crucial role in elbow extension.
Elbow Extension Mechanism
The mechanism of elbow extension involves the contraction of the triceps brachii muscle, which pulls the forearm away from the shoulder, creating elbow extension. Other muscles, such as the anconeus, also contribute to elbow extension, but the triceps brachii is the primary muscle responsible for this action.
Comparison with Other Muscles
In contrast, the biceps brachii muscle is responsible for elbow flexion, not extension. The biceps brachii contracts to pull the forearm toward the shoulder, creating elbow flexion 2, 3. While the brachialis and brachioradialis muscles also contribute to elbow flexion, they are not responsible for elbow extension.
Clinical Implications
Understanding the role of the triceps brachii in elbow extension is important for clinical practice, particularly in the diagnosis and treatment of elbow injuries or conditions that affect elbow function. For example, a study on the comparison of isometric triceps brachii force measurement in different elbow positions found that the most reliable measurement was at 30 degrees of flexion 4. This highlights the importance of considering the position of the elbow when assessing triceps brachii function.
Key Points
- The triceps brachii muscle is responsible for elbow extension.
- The triceps brachii contracts to pull the forearm away from the shoulder, creating elbow extension.
- Other muscles, such as the anconeus, also contribute to elbow extension, but the triceps brachii is the primary muscle responsible for this action.
- Understanding the role of the triceps brachii in elbow extension is important for clinical practice.