Common Iliac Nodes - Location, Diagram, Function

The common iliac lymph nodes are a group of deep pelvic lymph nodes located along the common iliac arteries and veins. They receive lymph from the internal and external iliac nodes, as well as directly from pelvic organs, and serve as an intermediate station before lymph flows upward to the paraaortic (lumbar) nodes. These nodes play a crucial role in the lymphatic drainage of the pelvis, lower limbs, and parts of the abdominal wall.

Structure

The common iliac lymph nodes are typically grouped into three subdivisions based on their anatomical position:

Subdivision	Location	Receives Lymph From
Lateral common iliac nodes	Lateral to the common iliac vessels	External iliac nodes, pelvic wall
Medial common iliac nodes	Medial to the vessels, near midline	Internal iliac nodes
Promontory (interiliac) nodes	Near the sacral promontory, at the bifurcation of the aorta	Overlapping drainage from both internal and external iliac nodes

These nodes act as conduits, channeling lymph from the pelvis and lower limbs into the upper retroperitoneal lymphatic system.

Location

The common iliac lymph nodes lie:

Alongside the common iliac arteries and veins
Extending from the bifurcation of the aorta (L4) to the pelvic brim
Anterior to the L5 vertebral body and near the sacral promontory

Function

These nodes serve as a key relay point in the pelvic and lower body lymphatic system:

Draining node groups: Receive lymph from internal and external iliac nodes
Filtering and immune surveillance: Participate in pathogen recognition and immune response
Upstream drainage: Send efferent lymph to the lumbar (paraaortic) lymph nodes via ascending lymphatic vessels

Clinical Significance

Common iliac lymph nodes are involved in numerous clinical contexts, especially in oncology and imaging:

Pelvic cancers: Frequently involved in the spread of prostate, bladder, cervical, endometrial, and rectal cancers
Staging and prognosis: Node involvement affects cancer staging (e.g., N-staging in FIGO and TNM systems)
Lymphadenopathy: May occur in infections, tuberculosis, or lymphoma; enlarged nodes are detectable on CT, MRI, or PET-CT
Surgical dissection: Common iliac node dissection is often part of extended pelvic lymphadenectomy during oncologic surgeries
Radiation planning: These nodes are targeted in pelvic radiotherapy fields for gynecologic, urologic, and colorectal cancers

The common iliac lymph nodes represent a vital crossroads in the lymphatic drainage network, linking pelvic and lower limb structures to the central abdominal lymphatic system. Their predictable anatomical position and frequent involvement in malignancy make them essential in diagnosis, treatment planning, and surgical navigation.