754 ^ MANUAL OF ANATOMY 



The spermatic arteries (V) are two in number, right and 

 left, and they arise from the front of the aorta about i inch 

 below the renal arteries. If they arise separately they are 

 close to each other, but they sometimes spring by a common 

 trunk. They are long, slender, somewhat tortuous vessels, which 

 at once diverge, each passing obliquely downwards and out- 

 wards behind the peritoneum. In this course the vessel rests 

 upon the aorta for a short distance, and then upon the psoas mag- 

 nus and its sheath, where it crosses the ureter. The right artery 

 passes in front of the inferior vena cava and behind the terminal 

 part of the ileum, whilst the left passes behind the iliac colon. 

 Subsequently the artery, on its way to the internal abdominal ring, 

 lies upon the terminal part of the external iliac. At the internal 

 ring it approaches the vas deferens to form, with other structures, 

 the spermatic cord. The vessel then passes through the internal 

 abdominal ring, along the inguinal canal, and through the external 

 abdominal ring into the scrotum, where it divides into testicular 

 and epididymal branches. In the abdomen the spermatic artery 

 furnishes ureteric branches to the ureter, and in the scrotum it 

 gives off cremasteric branches to the coverings of the spermatic 

 cord, which anastomose with the cremasteric branch of the deep 

 epigastric. During foetal life the vessel is very short, and takes 

 a transverse course to the testis, which is then lying below and 

 behind the kidney. As the testis, iiowever, descends into the 

 scrotum the vessel gradually becomes much elongated. 



Varieties. — ( i ) One or both spermatic arteries may be absent, in which cases 

 the testis is supplied chiefly by the deferential artery. (2) A spermatic artery 

 may arise from a renal artery. 



The spermatic veins spring from the pampiniform plexus of the 

 spermatic cord at the internal abdominal ring, and are at first 

 two in number on each side, which lie one on either side of the 

 corresponding artery. They subsequently unite to form a single 

 vessel, which on the right side opens at an acute angle into the 

 inferior vena cava, and on the left at a right angle into the left renal 

 vein. There is usually a valve at the point of termination of 

 each vein, though this may be absent. In the left spermatic vein, 

 where it joins the left renal vein, the valve directs the current of 

 blood entering by the spermatic vein in the direction of the inferior 

 vena cava. It also prevents the blood in the left renal vein from 

 entering the spermatic vein by directipg the current over the mouth 

 of the latter vessel. The left spermatic vein is rather longer than 

 the right. 



The spermatic veins orif^inally open .into the lower cardinal veins. The right 

 spermatic vein opens into that portion of the right cardinal vein wliich persists 

 as the lower segment of the permanent inferior vena cava. The upper part of the 

 left spermatic vein is formed from that portion of the left cardinal vein which 

 lies immediately below the left renal vein. In this manner the difference in the 

 mode of termination of the two spermatic veins in the adult is accounted for. 



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