THE ABDOMINAL WALLS 257 



the scrotum, and as it lies in front of the pubis after leaving 

 the subcutaneous inguinal ring. Surrounded by its coverings, 

 it lies immediately beneath the skin and the two layers of 

 superficial fascia (p. 240). The constituents of the cord (i) 

 the ductus (vas) deferens, (2) numerous blood-vessels, (3) 

 lymphatics, and (4) nerves are enclosed in the three coverings 

 which have already been described. 



(1) The Ductus Deferens lies posteriorly in the cord and is 

 surrounded by the pampiniform plexus of veins. It possesses 

 a small lumen and a very thick muscular wall, and consequently 

 can easily be distinguished when the spermatic cord is examined. 

 Its artery of supply, from the superior vesical, is closely applied 

 to the duct. 



(2) The Pampiniform Plexus of Veins ascends to the abdominal 

 inguinal (int. abd.) ring, and there forms the spermatic vein. 

 The External Spermatic (Cremasteric) Artery is derived from the 

 inferior epigastric -and is mainly distributed to the coverings. 

 The Internal Spermatic Artery, a branch of the abdominal aorta, 

 descends anteriorly in the cord and supplies the testis and 

 epididymis. 



(3) The Lymphatics ascend from the testis and join the 

 lumbar or lateral aortic glands. 



(4) The External Spermatic Nerve is a branch of the genito- 

 femoral (genito-crural). It supplies the cremaster muscle and 

 a sensory twig to the tunica vaginalis (Mackenzie). Numerous 

 sympathetic nerves run down on the coat of the internal 

 spermatic artery from the aortic plexus. 



During attacks of renal colic, abnormal stimuli pass from 

 the ureter by the sympathetic to the lower thoracic and upper 

 lumbar segments. As a result, a viscero-sensory reflex is 

 established. Pain is felt in the loin (p. 354) and shoots down 

 to the testis (ext. spermatic nerve ; L. i and 2), but does not 

 affect the overlying skin of the scrotum (S. 2, 3, and 4). At the 

 same time a viscero-motor reflex may be set up, and the resulting 

 contraction of the cremaster muscle (ext. sperm, nerve) draws 

 the testis up towards the subcutaneous inguinal ring. 



Descent of the Testis. At an early period of development 

 the testis lies at the brim of the pelvis near the abdominal 

 inguinal ring. It is attached to the lateral wall of the abdomen 

 by a mesentery, the mesorchium, and is connected by the 

 gubernaculum to the integument which forms the lowest part 

 of the scrotum. This cord consists of condensed mesoderm, 



17 



