The Head includes the Crown — Keter — and the Mental Powers within it.
Every Partzuf's Head includes Keter and the Mental Powers (Chochmah, Binah, Daat). The Head is the beginning of the entire governmental order.
Op. 101 generalises the Op. 95 Skull-and-Brain anatomy across all Partzufim. Every Partzuf has a Head; every Head includes Keter and the Mental Powers; the Head is the operational origin of the Partzuf's governance.
The Head is not just the top of a Partzuf's anatomy; it is the place where the governmental order is born. From the Head — through Keter at the apex and the Mental Powers within it — the governance extends through the rest of the Partzuf's body, all the way to the legs and the operational extremities.
This is structurally important. When the cosmic government acts, the action originates at the Head and propagates downward. Without the Head, the body has no operational direction; with the Head, the body becomes a coherent operational anatomy.
The rule applies to every Partzuf — Atik Yomin, A"A, Abba and Imma, Zeir Anpin (Z"A), Nukva. Each has its Head; each Head has its Keter and its Mental Powers; each is the origin of its Partzuf's specific governance.
Op. 116 (Z"A's upper-internal structure: body / Mochin / Keter, with two upper-source channels) is Op. 101 applied to Z"A specifically. Op. 124 (Daat in Z"A) is the operational Daat doctrine grounded in Op. 101's Mental-Powers framework.