ARTERIES OF HUMAN LOWER EXTREMITY 65 
fifth lumbar segmental arteries have thus regained their inde- 
pendence, and, like the other segmental arteries in this region, 
pass to the spinal cord without branching. 
The axial artery passes distally into the lower limb, crossing 
the n. tibialis posteriorly from the medial to the lateral side. 
It then follows the posterior aspect of the skeletal mesenchyme 
throughout the leg into the sole. In the latter situation it 
breaks up into a flattened plexus which extends somewhat beyond 
a. iliac. ext. 
@. iliac. com. 
a. hypog. _n genitofem. 
rr perfor. tarsi. n. femor. 
@. GXIS. 
rete dorsal 
rete plant~ n pe 
a pudend int. a. femor. a. epigast. inf. 
r. Saphen. 
2 @. axis... Com. Sup—_~=5 7}: 
r. perf, tarsi. 
rete dorsal. 
n. peron. 
Fig. 2 Reconstruction showing the arteries of the right lower extremity in a 
human embryo of 8.5 mm. (C.E.C., 9). Medial aspect. 20 diams. 
Fig. 3 Reconstruction showing the arteries of the right side of the pelvis, 
right thigh, leg, and dorsum of the foot in a human eubrye) of 12mm. (M.E. 
C.,H. 14). Medial aspect. X 20 diams. 
the extremities of the plantar nerves. Just as it is breaking up 
into the plantar plexus the axial artery gives origin to two or 
three branches which pierce the mesenchymal skeleton of the 
foot to reach the dorsum. Upon the dorsum of the foot the 
perforating branches produce another flattened plexus. The 
two plexuses (or retia) of the foot are separated from one another 
by the mesenchymal skeleton of the foot, the plantar rete lying 
between the latter and the plantar nerves. 
