Final answer:
The muscle attached to the intertubercular sulcus is the biceps brachii muscle, located on the anterior side of the upper arm. It is responsible for flexing the forearm at the elbow joint and supinating the forearm.
Step-by-step explanation:
The muscle attached to the intertubercular sulcus is the biceps brachii muscle. The intertubercular sulcus, also known as the bicipital groove, is a narrow groove located between the greater and lesser tubercles of the humerus. The biceps brachii muscle is located on the anterior side of the upper arm and is responsible for flexing the forearm at the elbow joint and supinating the forearm.