j ABNORMALITIES OF VEINS. 903 
the obturator artery and to the subsequent enlargement of the anastomosing pubic branches of 
the obturator and deep epigastric arteries. The course of the abnormal obturator artery is of 
importance. From its origin it descends into the pelvis on the inner side of the external iliac 
vein, and in the majority of cases on the outer side of the crural ring, but in three-tenths of the 
cases, and more frequently in males than in females, it descends on the inner side of the ring. 
The obturator artery sometimes gives off an accessory pudic branch which passes along the side 
of the prostate, pierces the triangular igament, and terminates by dividing into the artery of the 
corpus cavernosum and the dorsal artery of the penis. When this occurs the pudic artery is 
small, and it terminates in the artery to the bulb. Occasionally the accessory pudic arises from the 
pudic artery in the pelvis, or from one of the vesical arteries. 
The external iliac artery may be much smaller than usual, especially if the sciatic artery 
persists as the main vessel of the lower hb. It may give off two deep circumflex iliac branches, 
a dorsal artery of the penis, an internal circumflex artery of the thigh, or a vas aberrans, and its 
deep circumflex iliac and deep epigastric branches may arise at higher or lower levels than usual. 
THE ARTERIES OF THE LOWER LIMB. 
The femoral artery is small, and ends in the profunda and circumflex branches, when the 
sciatic artery forms the principal vessel of the lower limb. The profunda branch, which usually 
rises from the outer side of the femoral trunk, about one-and-a-half inches below Poupart’s liga- 
ment, may commence at a higher or a lower level, and from the back or the inner side of the 
femoral trunk. Absence of the profunda has been noted, and in these cases the branches 
usually given off by it spring atesatky from the femoral artery. 
The femoral artery may be double for a portion of its extent, or it may be joined by a vas 
aberrans given off from the external iliac artery. In addition to its ordinary branches, it may 
furnish one or both of the circumflex arteries of the thigh, and sometimes it gives off, near the 
origin of the profunda, a great saphenous artery, such as exists normally in many mammals, 
This vessel descends through Scarpa’s triangle and Hunter’s canal, and accompanies the internal 
saphenous nerve to the inner side of the foot. 
The deep circumflex iliac, the obturator, and the deep epigastric arteries are occasionally 
given off from the femoral. 
The popliteal artery may exceptionally form the direct continuation of the sciatic artery. It 
sometimes divides at a higher or lower level than usual, and the division may be into either two or 
three branches; if three terminal branches are present, they are the anterior and posterior tibial 
and the peroneal arteries, and if only two, either the anterior and posterior tibial, or the anterior 
tibial and the peroneal arteries. 
Occasionally the artery is double for a short portion of its course, and it has been found to 
cross first behind the inner head of the gastrocnemius to the inner side of the knee, and then in 
front of the inner head of the gastrocnemius to regain the popliteal space. The number of its 
branches may be reduced, or they may be increased by the addition of a vas aberrans which con- 
nects it with the posterior tibial artery. Its superficial sural branch may enlarge to form a well- 
marked small saphenous artery. 
The posterior tibial artery may be small or altogether absent, its place being taken by 
branches of the peroneal artery ; again, it may be longer or shorter than usual, in conformity with 
the higher or lower division of the popliteal trunk. The peroneal artery is large if either the 
anterior or posterior tibial arteries are small. The anterior terminal branch of the peroneal is 
almost invariably large when the anterior tibial artery is small ; in some cases, indeed, it replaces 
the whole of the dorsalis pedis continuation of the latter vessel; in others, however, only the 
tarsal and metatarsal branches are so replaced. The peroneal sometimes arises from a stem 
common to it and the anterior tibial artery. 
The anterior tibial artery may be absent, its place being taken by branches of the posterior 
tibial and peroneal arteries. It is longer than normal when the popliteal artery divides at a 
higher level than usual, and in these cases it may pass either behind or in front of the popliteus 
musele. Occasionally the anterior tibial artery and its dorsalis pedis continuation are larger 
than normal, and the terminal part of the dorsalis pedis takes the place, more or less completely, 
of the external plantar artery. 
The internal plantar artery is sometimes very small, and it may be absent; its place is 
taken by branches of the dorsalis pedis or external plantar arteries. The external plantar 
artery also may be small or absent, the plantar arch being formed entirely by the dorsalis pedis. 
ABNORMALITIES OF VEINS. 
Abnormalities or variations of veins are as frequently met with as those of arteries, and they 
are due to similar causes. 
THE SUPERIOR VENA CAVA. 
The superior vena cava may develop on the left side instead of the right. This peculiarity 
is due to the persistence of the left duct of Cuvier instead of that on the right side, and it is 
associated with absence of the coronary sinus, which is replaced by the lower part of the left 
superior vena cava. An exceptional case is recorded in which the opening of the coronary sinus 
= oh 
