42 - Uterine artery

*The uterine artery arises from the anterior trunk of the internal iliac artery(hypogastric artery) .
*Its course is at first downwards and forwards until it reaches the parametrium when it turns medially towards the uterus.
*It reaches the uterus at the level of the internal os, where it turns upwards, at right angles, and follows a spiral course along the lateral border of the uterus to the region of the uterine cornu.
*Here it sends a branch to supply the fallopian tube and ends by anastomosing with the ovarian artery.
*The tortuosity is lost when the uterus enlarges during pregnancy.
*During the vertical part of its course it sends branches which run transversely and pass into the myometrium. These are called the arcuate arteries.
*From these arcuate arteries, a series of radial arteries arise, almost at right angles.
*These radial arteries reach the basal layers of the endometrium, where they are termed as the basal arteries.
*From these are derived the terminal spiral and straight arterioles of the endometrium.
*THE LEAST VASCULAR PART OF THE UTERUS IS THE MIDLINE.

*The branches of the uterine artery are :
1. Ureteric artery
2. Descending vaginal artery- These unite to form the anterior and posterior azygos artery of the vagina. This is of great importance during the Total hysterectomy.
3. Circular cervical
4. Arcuate -- radial -- basal -- spiral and straight arterioles of the functional layer of the endometrium.
5. Anastomotic branch with the ovarian artery

*The relation of the uterine artery to the ureter is of great importance.
*The uterine artery crosses above the ureter in the parametrium where it gives off an important ureteric branch to that structure.
*The artery runs transversely while the ureter runs approximately anteroposteriorly through the ureteric canal of the parametrium.

*The ovarian artery is derived from the AORTA.