Which head of the triceps brachii is attached to the posterior surface proximal to the radial groove of the humerus?

The lateral head of the triceps brachii is indeed attached to the posterior surface proximal to the radial groove of the humerus. This specific region of attachment is significant because it plays a role in the muscle's function during arm extension. The lateral head is primarily involved in extending the elbow joint and is particularly active when the arm is straightened against resistance.

The location of the lateral head allows it to contribute effectively to the overall strength and mechanics of elbow extension. Its position near the radial groove is advantageous because it accommodates the radial nerve, which runs in proximity to this region. Understanding the anatomy and origin points of the triceps brachii, especially the lateral head, is important for both anatomical studies and practical applications in fields like physical therapy and sports medicine.