Which head of the triceps brachii is found attached distal to the radial groove?

The medial head of the triceps brachii is the one attached distal to the radial groove. This is an important anatomical detail because the triceps brachii consists of three heads: the long head, lateral head, and medial head, which all originate from different locations on the humerus and scapula.

The medial head specifically originates from the posterior surface of the humerus, inferior to the radial groove, allowing it to play a crucial role in elbow extension. The radial groove itself serves as a landmark for differentiating the positions of the heads. By being positioned distal to this groove, the medial head is well-associated with the radial nerve's pathways and related structures, emphasizing its unique position in comparison to the other heads.

Understanding the precise locations of the muscle origins and insertions is vital for studying movements and injuries related to the arm.