THE VEINS. 329 
2. V. hypogastrica (or iliaca interna) (z).—The hypo- 
gastric or internal iliac vein joins the medial side of the 
external iliac to form the common iliac (w). Its branches 
follow the branches of the corresponding artery except that 
the vein from the bladder (umbilical vein) joins the V. hemor- 
rhoidalis media. Also the vena glutea inferior receives a 
large superficial communicating branch (Fig. 163, #') from the 
vena saphena parva. This branch leaves the saphena parva 
(Fig. 163, 2) at the popliteal space, and passes over the lateral 
surface of the biceps muscle to its proximal end. Here it 
passes between the biceps and caudofemoralis to join the vena 
glutea inferior. 
3. V. iliaca externa (Fig. 127, page 310).—This vein fol- 
lows the corresponding artery, collecting the blood from the 
posterior extremity. Its branches are the same and have in 
general the same distribution as those of the artery. The vein 
has, however, certain branches in addition to those of the 
artery, resulting in a somewhat different general arrangement 
of vessels; it will be necessary therefore to give an account of 
the system of veins from the foot and lower leg. 
The blood is collected from the foot into two sets of veins 
which may be distinguished as the deep and the superficial 
sets. The veins of the deep set are those which accompany 
the branches of the popliteal and anterior tibial arteries. Those 
of the superficial set are larger and carry most of the blood. 
On the dorsum of the foot blood is collected from the third, 
fourth, and fifth digits by two or three superficial metatarsal 
veins, which unite opposite the proximal end of the metatarsus 
into a single vein. This receives a similar branch coming from 
the dorsum of the second digit, and has numerous branches in 
the ankle region which form here a network, communicating 
with the vena saphena parva (Fig. 163, £), and with branches 
from the plantar side of the foot. From this network two or 
three main veins pass proximad on the medial side of the leg, 
along with the branches of the arteria saphena, and unite with 
a similar vein from the plantar side of the foot to form the vena 
saphena magna (Fig. 127, 4, page 310), which accompanies 
the arteria saphena to join the femoral vein (a). 
