Pelvic Vessels and Lymphatics

Common Iliac Arteries

• Terminal branches of the abdominal aorta, formed by its bifurcation at L4; each descends a short distance before dividing into the internal and external iliac arteries at approximately the level of the pelvic brim/sacroiliac joint.

External Iliac Artery

• Continues from the common iliac artery, running along the medial border of psoas major, exiting the pelvis beneath the inguinal ligament to become the femoral artery (see Lower Limb content).
• Gives off the inferior epigastric artery and deep circumflex iliac artery just before leaving the pelvis, supplying the anterior abdominal wall rather than pelvic viscera, distinguishing its role from the internal iliac artery.

Internal Iliac Artery

• The primary arterial supply to the pelvic viscera, walls, and (via its branches) the perineum and gluteal region.
• Descends a short distance into the lesser pelvis before dividing into anterior and posterior divisions (variable branching pattern, but this two-division framework is the standard teaching model).

Umbilical artery:

• In fetal life, carries deoxygenated blood from the fetus to the placenta; postnatally, the proximal patent portion gives rise to the superior vesical artery/arteries, while the distal portion obliterates to form the medial umbilical ligament, visible as a peritoneal fold on the internal anterior abdominal wall surface.

Superior vesical artery/arteries:

• Arise from the patent proximal umbilical artery; supply the superior/anterosuperior portions of the bladder.

Obturator artery:

• Passes through the obturator canal (with the obturator nerve, superior to the vein) to reach the medial thigh, supplying the obturator externus, adductor muscles, and hip joint region (contributing to the acetabular/hip joint anastomosis, see Lower Limb content).
• Anatomically variable: in a notable minority of individuals, an aberrant obturator artery arises from the inferior epigastric artery instead, crossing close to (or directly over) the femoral ring/lacunar ligament: clinically important, since this variant vessel ("corona mortis" when an anastomotic connection exists between the two possible origins) is at significant risk of laceration during femoral hernia repair, given its unusual proximity to the surgical field.

Uterine artery (females):

• Supplies the uterus, and via anastomosis, contributes to the vaginal and ovarian blood supply; runs within the base of the broad ligament, crossing anterior to and superior to the ureter approximately 2 cm lateral to the cervix, the classic "water under the bridge" relationship (uterine artery = bridge, ureter = water flowing beneath it), of major surgical significance (see Clinical Anatomy below and Section 9).

Vaginal artery (females):

• Supplies the vagina, anastomosing with the uterine artery's vaginal branches (sometimes considered a direct branch of the uterine artery rather than a separate internal iliac branch, depending on individual variation) and with the middle rectal and internal pudendal arteries, forming a rich longitudinal anastomotic network along the vagina.

Middle rectal artery:

• Supplies the middle/lower rectum, anastomosing with the superior rectal artery (from the IMA, supplying the upper rectum) and the inferior rectal artery (from the internal pudendal artery, supplying the anal canal), this triple anastomotic supply (superior, middle, inferior rectal arteries) is a key organising concept for rectal/anal blood supply, spanning three different parent arterial systems (IMA, internal iliac, internal pudendal) and reflecting the hindgut-to-ectoderm transition at the pectinate line.

Internal pudendal artery:

• The main arterial supply to the perineum: exits the pelvis via the greater sciatic foramen, crosses the ischial spine, re-enters via the lesser sciatic foramen to run within the pudendal (Alcock's) canal, giving rise to the inferior rectal artery, perineal artery, and the arteries supplying the external genitalia (dorsal/deep arteries of the penis or clitoris, artery to the bulb); full detail in Section 11.

Inferior gluteal artery:

• Exits the pelvis via the greater sciatic foramen, below piriformis, supplying gluteus maximus and contributing to the anastomotic network around the hip (cruciate anastomosis, see Lower Limb content).

Iliolumbar artery:

• Ascends to supply the iliacus and psoas major muscles and contributes to the posterior abdominal wall's blood supply, anastomosing with the lumbar arteries.

Lateral sacral arteries (superior and inferior):

• Supply the sacrum, sacral canal contents (via small spinal branches through the anterior sacral foramina), and the overlying skin/muscle.

Superior gluteal artery:

• Exits the pelvis via the greater sciatic foramen, above piriformis, the largest branch of the internal iliac artery, supplying gluteus medius, minimus, and tensor fasciae latae (see Lower Limb content).

Internal iliac vein:

• Formed by the confluence of veins corresponding to the arterial branches (though the venous pattern is typically more plexiform and variable than the arterial pattern), joining the external iliac vein to form the common iliac vein, and the IVC.

Pelvic venous plexuses:

• Extensive, richly interconnected venous networks surrounding each pelvic organ, draining via multiple small tributaries into the internal iliac vein (rather than following a single named vein per organ, in contrast to the arterial supply's more discrete named branches), this plexiform arrangement provides extensive collateral drainage capacity but also makes pelvic venous bleeding (e.g., in pelvic fracture or obstetric haemorrhage) notoriously difficult to control surgically, given the diffuse, multidirectional nature of the bleeding source.

Rectal venous plexus:

• Surrounds the rectum and anal canal, with an internal component (submucosal, related to the anal cushions and haemorrhoidal disease) and an external component (below the internal anal sphincter); drains via the superior rectal vein (to the portal system, via the IMV) and the middle/inferior rectal veins (to the systemic system, via the internal iliac vein and internal pudendal vein respectively), this plexus is therefore a key portosystemic anastomosis site.

Vesical plexus:

• Surrounds the bladder (particularly its base/neck) and, in males, extends to invest the prostate (prostatic plexus); drains to the internal iliac vein.

Prostatic plexus (males):

• Surrounds the prostate, receiving the deep dorsal vein of the penis; drains to the internal iliac vein (via the vesical plexus) and also communicates with the internal vertebral venous plexus (Batson's plexus), a valveless venous network providing a direct, bypass route for pelvic venous blood (and, clinically significantly, metastatic tumour cells, particularly from prostate cancer) to reach the vertebral column and beyond without first passing through the lungs, explaining the characteristic pattern of vertebral/axial skeletal metastasis seen in prostate cancer.

Uterine and vaginal plexuses (females):

• Surround the uterus, cervix, and vagina, draining to the internal iliac vein via the uterine and vaginal veins; also contribute to the ovarian venous drainage pattern indirectly via anastomotic connections, though the ovarian veins themselves drain independently (the right ovarian vein drains to the IVC and the left to the left renal vein, mirroring the testicular vein pattern).

• Pelvic lymphatic drainage broadly follows the arterial supply, organised into several named node groups along the major vessels, converging on the common iliac and then para-aortic (lumbar) nodes before reaching the cisterna chyli/thoracic duct.

External iliac nodes:

• Receive drainage from the lower limb (via the deep inguinal nodes), the anterior abdominal wall below the umbilicus, and the more superficial/anterior pelvic structures (bladder neck, prostate, part of the cervix/upper vagina in females), lie along the external iliac vessels.

Internal iliac nodes:

• Receive drainage from the pelvic viscera supplied by the internal iliac artery's branches (bladder, rectum, prostate/seminal vesicles, cervix, upper vagina, and the perineum via the internal pudendal vessels), lie along the internal iliac vessels.

Common iliac nodes:

• Receive efferents from both the external and internal iliac node groups, draining onward to the para-aortic nodes.

Sacral nodes:

• Small group along the median/lateral sacral vessels, receiving drainage from the posterior pelvic wall, rectum, and cervix (a notable direct pathway for cervical cancer spread, alongside the more commonly emphasised parametrial/internal iliac routes).

Superficial inguinal nodes:

• Receive drainage from the lower limb, the anterior abdominal wall below the umbilicus, the perineum, the external genitalia (including the testis's scrotal skin only, not the testis itself: see Abdomen content for the testis's distinct para-aortic drainage), the anal canal below the pectinate line, and (in females) the lower vagina and vulva.

Deep inguinal nodes:

• Small group within the femoral canal (see Lower Limb content), receiving efferents from the superficial inguinal nodes and glans penis/clitoris directly, draining onward to the external iliac nodes.