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Topographic Anatomy · Topographic Anatomy of the Pelvis and Perineum

Vessels and Nerves of the Lesser Pelvis

Vasa et nervi pelvis minoris

The topographical anatomy of the lesser pelvis covers the branching system of the internal iliac artery, venous drainage, lymph nodes, and nerve plexuses providing innervation to the pelvic organs and the lower limb.

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Main arteryA. iliaca interna divides into trunks near the sacroiliac joint
Anterior trunkGives off visceral branches and supplies the pelvic organs
Posterior trunkLocated deeper, gives off parietal branches to the pelvic walls
Sacral plexusFormed by the L4–S3 branches on the piriformis muscle
3 min readFor medical studentsUpdated 09/24/2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesReviewed by medical editor: Aulov A. A., general practitioner · 09/24/2026

Internal iliac artery and its trunks

The main source of blood supply to the organs and walls of the pelvic cavity is the internal iliac artery (a. iliaca interna). At the level of the upper border of the iliopsoas muscle, it divides into two main trunks:

  • Anterior trunk — lies more superficially. It gives off visceral branches to the organs, as well as some parietal branches.
  • Posterior trunk — is located deeper and gives off predominantly parietal branches to the muscles and walls of the pelvis.

The veins of the lesser pelvis follow the course of the arteries. The v. iliaca interna itself is a thin-walled structure lying medially and deeper than the corresponding artery.

Free video lessonTopographic anatomy of the pelvis: levels, fasciae, cellular spaces

Visceral and parietal branches

The arterial branch system provides blood supply to all anatomical structures of the region:

  1. Anterior trunk (visceral and parietal branches):
  2. Umbilical artery (a. umbilicalis) with superior vesical branches (aa. vesicales superiores).
  3. Inferior vesical artery (a. vesicalis inferior), which lies deeper.
  4. Uterine artery (a. uterina) and middle rectal artery (a. rectalis media).
  5. Obturator artery (a. obturatoria), passing into the obturator canal.
  6. Terminal branches: internal pudendal artery (a. pudenda interna) and inferior gluteal artery (a. glutea inferior).
  1. Posterior trunk:
  2. Iliolumbar artery (a. iliolumbalis), forming important anastomoses and a collateral blood flow pathway.
  3. Lateral sacral arteries (aa. sacrales laterales).
  4. Superior gluteal artery (a. glutea superior) — the largest branch, passing into the suprapiriform foramen.
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Pelvic nerve plexuses

Innervation of the area is represented by somatic and autonomic structures:

  • Sacral plexus (plexus sacralis) — formed by the anterior branches of L4–S3 on the anterior surface of the piriformis muscle. Some of its branches exit through the suprapiriform foramen (n. gluteus superior), while the sciatic, inferior gluteal, and posterior femoral cutaneous nerves exit through the infrapiriform foramen.
  • Obturator nerve (n. obturatorius) — formed by segments L2–L4, runs along the lateral wall of the pelvis.
  • Pudendal plexus (plexus pudendus) — is located near the lower border of the piriformis muscle and forms the pudendal nerve (n. pudendus).
  • Inferior hypogastric plexus (plexus hypogastricus inferior) — an autonomic plate containing sympathetic fibers, parasympathetic ganglia, and sensory elements.

Briefly: answers to topical questions

Which nerves exit the pelvic cavity through the infrapiriform foramen?

The following nerves exit through the infrapiriform foramen:

  • Inferior gluteal nerve (n. gluteus inferior).
  • Sciatic nerve (n. ischiadicus) — the largest nerve in the body.
  • Posterior cutaneous nerve of the thigh (n. cutaneus femoris posterior).
  • Pudendal nerve (n. pudendus) — as part of the pudendal neurovascular bundle.

Which anatomical structures pass through the obturator canal?

The obturator neurovascular bundle passes through the obturator canal:

  • Obturator artery (a. obturatoria).
  • Obturator vein (v. obturatoria).
  • Obturator nerve (n. obturatorius).

From which spinal segments is the pudendal plexus (plexus pudendus) formed?

Sources indicate that the pudendal plexus forms the pudendal nerve (n. pudendus) with a segmental composition of S2–S4.

With which arteries does the iliolumbar artery form anastomoses?

The iliolumbar artery (a. iliolumbalis) divides into two branches that form anastomoses:

  • Lumbar branch (r. lumbalis) — anastomoses with the lumbar and intercostal arteries.
  • Iliac branch (r. iliacus) — anastomoses with the deep circumflex iliac artery (a. circumflexa ilium profunda) and the gluteal arteries.

Class and exam questions

Into which trunks does the internal iliac artery divide and at what location?

It divides into anterior and posterior trunks at the level of the upper margin of the iliopsoas muscle, which corresponds to the level of the sacroiliac joint.

Which branches arise from the anterior trunk of a. iliaca interna?

The anterior trunk gives off visceral branches (umbilical, inferior vesical, uterine, middle rectal) and parietal branches (obturator, internal pudendal, and inferior gluteal).

What forms the sacral plexus and where is it located?

The sacral plexus is formed by the anterior branches of spinal nerves L4–S3 and is located on the anterior surface of the piriformis muscle.

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What else to study on this topic

  • Variant anatomy of the obturator artery
  • Clinical significance of the iliolumbar artery during vessel ligation
  • Topography of the supra- and infrapiriform foramina
  • Structure and functions of the inferior hypogastric plexus
  • Lymphatic system of the pelvis and location of lymph nodes

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Other topics in the section "Topographic Anatomy of the Pelvis and Perineum"

Bones and Ligaments of the PelvisPelvic Muscles and Pelvic DiaphragmPelvic FasciaPeritoneal Topography in the Lesser Pelvis CavityPelvic Cellular SpacesTopography of the RectumTopography of the Urinary BladderTopography of Male Pelvic OrgansTopography of the UterusTopography of Uterine Adnexa and VaginaTopography of the PerineumIschioanal FossaMale Genital RegionFemale Genital Region
Entire section "Topographic Anatomy of the Pelvis and Perineum"

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