The primary blood supply to the uterus is the uterine artery, which arises from the internal iliac artery. It provides rich vascularization crucial for the endometrium and myometrium. During surgeries like hysterectomy, careful ligation of the uterine artery near the ureter is essential to avoid ureteral injury. The uterine artery anastomoses with the ovarian artery, but it remains the main source of uterine blood flow. Understanding this anatomy is vital for minimizing intraoperative bleeding and preserving adjacent structures.

Reference: Gray's Anatomy, Susan Standring, 42nd Edition.