There are long posterior ciliary arteries two on each side of the body.

[1][2] The long posterior ciliary arteries first run near the optic nerve before piercing the posterior sclera[3] near the optic nerve.

They pass anterior-ward - one along each side of the eyeball - between the sclera and choroid to reach the ciliary muscle where they divide into two branches which go on to form the major arterial circle of the iris.

[1] Non-terminal branches of the long posterior ciliary arteries anastomose with branches of the short posterior ciliary arteries.

[2] Upon reaching the ciliary body, the long posterior ciliary arteries ramify superiorly and inferiorly, the branches forming anastomoses with each other and with those of the anterior ciliary arteries to form the major arterial circle of the iris.