Each metacarpal includes a foundation, shaft and a head. The medial and lateral surfaces from the metacarpals are concave, allowing for attachment from the interossei muscles. The center finger, being the longest, provides balance and power throughout gripping and lifting responsibilities, serving as an anchor for the other fingers. From https://www.theorthopaedicandpainpractice.com/what-are-the-different-bones-found-in-my-hand/