Final answer:
The bony landmark for the distal attachment of the subscapularis muscle is the lesser tubercle of the humerus.
Step-by-step explanation:
The bony landmark for the distal attachment of the subscapularis muscle is the lesser tubercle of the humerus. This is a smaller bump located on the anterior aspect of the proximal end of the humerus. The subscapularis muscle attaches to this landmark and plays an important role in shoulder movements and stability.