ARTERIES OF HUMAN LOWER EXTREMITY 63 
The dorsal root of the a. umbilicalis, which may be said -to 
begin at the junction of the two vessels mentioned above, con- 
tinues the transverse direction of the larger of the two, until it 
reaches the dorsal aspect of the Wolffian duct of its own side. In 
this situation it turns ventrally, passing upon the lateral side 
of the duct, which is now enclosed between the two roots of the 
umbilical artery, to join the ventral root. 
As the dorsal root of the a. umbilicalis curves around the 
lateral side of the Wolffian duct it gives origin to the axial artery 
of the lower extremity and to the a. pudenda interna. 
The axial artery, takes an almost transverse, slightly recurrent, 
course towards the surface. It ends by dividing into two 
plex. abdom. ee 
g. umbil. : : 
plex. ae — 
ad. OxXx/s. 
radix vent. 
a. umbilic. 
radix dorsalis. 
Fidel 
Fig. 1 Reconstruction showing the distal end of the aorta; also the arteries 
of the right lower extremity and neighboring parts in a human embryo of 6 
mm. C.J.E.C., 1075). Medial aspect. X 40 diams. 
branches, each of which breaks up into a plexus which passes 
over into the postcardinal venous plexus. The a. pudenda 
interna follows the dorsolateral surface of the Wolffian duct 
towards the urogenital sinus and enters the pelvic arterial plexus. 
In addition to the arteries already described, there are two 
extensive arterial plexuses, which may be called the abdominal 
and pelvic plexuses, respectively. Of these the abdominal 
arises by seven or eight stems from the concavity of the umbilical 
artery somewhat distal to the junction of its two roots. It 
invades the flexor region of the thigh, although it is uncertain 
to what extent, for the lower limb bud is not distinctly circum- 
scribed at this period. 
THE AMERICAN JOURNAL OF ANATOMY, VOL. 25, No. 1 
