Here's why:

* Infraspinatus: This muscle is located in the back of the shoulder and helps with external rotation of the arm. Its insertion point (where it attaches) is on the greater tubercle of the humerus (the upper arm bone).

* Deltoid: This muscle covers the top of the shoulder and helps with arm abduction (lifting the arm away from the body) and rotation. Its origin (where it starts) is on the clavicle (collarbone), acromion (part of the shoulder blade), and scapula (shoulder blade).

Therefore, the Infraspinatus's insertion overlaps with the Deltoid's origin on the greater tubercle of the humerus.