The Spermatic Arteries arise from the front of the aorta a little beneath the renal: each of them descends obliquely outwards, lying anterior to the psoas muscle and ureter, which latter it crosses at an acute angle. On the right side, the spermatic artery crosses also, obliquely, the front of the vena cava inferior; sometimes, however, it goes behind it. On the left side the artery passes behind the sigmoid flexure of the colon. In this course the spermatic veins lie to the outside of the corresponding arteries, and the peritoneum covers them in front: sometimes we may find two spermatic veins, one lying at either side of the artery and communicating in front of it by numerous small transverse branches. In the rest of their course the spermatic arteries differ in the male and in the female subject.

In the male, the spermatic artery enters the inguinal canal, and descends on the front of the vas deferens, forming part of the spermatic cord, and becoming extremely tortuous as it approaches its termination : a little above the testis it divides into two branches, one of which enters the head of the epididymis, while the other penetrates the superior margin of the body of the testis, and repairs to the corpus Highmori-anum, from whence they both issue in two sets: one set ramifies on the internal part of the tunica albuginea, and detaches minute vessels at various points to the tubuli testis, around which they coil; the other set pierces the corpus Highmori-anum, and descends along the septa of the testicle from its posterior to its anterior margin.

Sir A. Cooper describes the tunica albuginea as having two layers,—an outer one analogous to the dura mater, and an inner one (in which the vessels ramify) analogous to the pia mater. Cruveilhier dissents from this description, and thinks that "the vessels contained in the tunica albuginea rather resemble the sinuses of the dura mater than the vascular net-work of the pia mater".

In the female, the spermatic artery turns inwards over the common iliac, and passes to the side of the uterus, between the layers of the peritoneum composing its broad ligament: it supplies the ovary, Fallopian tube, and uterus, and anastomoses with the proper uterine arteries. In pregnancy, the branches to the uterus become enormously large and tortuous.