THE MALE GENITAL ORGANS 245 



(b) The umbilical artery (a. umbilicalis), a branch of the 

 hypogastric, which has not yet been exposed (p. 255), 

 passes along the side of the bladder to the vertex accom- 

 panied by the vesical vein. From the umbilical artery 

 near its beginning, branches are given off to the ureter (a. 

 ureterica) and related portions of the genital ducts. 



The Male Genital Organs 



1. Continue the median ventral incision of the skin backward along 

 the symphysis to the free end of the penis. Reflect the skin on 

 both sides and clear away the connective tissue so as to expose 

 fully the body of the penis and its attachments to the ischium, 

 and on one side continue the exposure to a point beyond the scro- 

 tum. Note the cremaster muscle (m. cremaster), a thin layer of 

 muscle fibres forming the outer layer of each scrotal sac (sac 

 of the testis) after removal of the skin and subcutaneous tissue. 

 Though situated directly under the latter, it is continuous with 

 the internal oblique muscle of the abdominal wall, and also 

 contains fibres from the transverse muscle. It is supplied with 

 blood from the external spermatic artery (p. 223). Make a 

 longitudinal incision through this muscle, cutting forward into 

 the abdominal cavity. After the two flaps are spread apart, 

 the following features may be made out: 



(a) The parietal layer (lamina parietal is) of the tunica vagi- 

 nalis propria, a layer of peritoneum continuous with that 

 of the abdominal wall, forms the internal lining of the sac 

 of the testis (cf. p. 137 and Fig. 75). The sac is widely 

 open to the abdominal cavity, so that the testis passes 

 freely from one cavity to the other, a condition more 

 prirriitive than that when the scrotal sac is closed off. 

 (6) The male reproductive gland, the testis, and its associated 

 vessels and duct occupy the cavity of the sac, the testis 

 being suspended from its dorsal wall. The gland has the 

 form of an elongated oval ,^ about two to three centimetres 

 in length and seven or eight millimetres wide in the mature 

 adult. 



(c) The gubernaculum, a short connective tissue cord contain- 



