Subaortic nodes

At a glance

English

Subaortic nodes

Latin (TA2)

Nodi subaortici

System

Lymphatic

Region

Trunk

Side

Single, on the midline

About the subaortic nodes

The subaortic nodes are the most medial members of the common iliac group. They sit in the angle between the two common iliac arteries, immediately below the point where the abdominal aorta divides, which is usually at the level of the fourth lumbar vertebra. The nodes rest in front of the lower lumbar vertebral bodies and the sacral promontory, with the left common iliac vein passing behind or beside them on its way to join the right vein and form the inferior vena cava.

Because they sit in the midline between the right and left iliac chains, these nodes act as a meeting point for both sides of the pelvis. They are sometimes listed together with the promontorial nodes that lie over the upper sacrum, and the boundary between the two sets is not sharp.

Lymph comes to them from the nodes further down the pelvis: the internal and external iliac nodes, the median and lateral sacral nodes, and the promontorial nodes. Through those stations they carry lymph that began in the pelvic walls, the lower limbs, the rectum and the urinary bladder. Their outflow climbs to the lateral aortic nodes, also called the lumbar nodes, beside the aorta, and from there lymph reaches the lumbar trunks and the cisterna chyli.

Their position makes them a common site of spread for cancers of the pelvic organs, including tumours of the rectum and bladder, and for lymphoma. Enlarged nodes here can be seen on CT as a soft tissue mass in the aortic fork, and surgeons removing pelvic nodes for staging will often take this group as the upper limit of a pelvic dissection. Care is needed because the left common iliac vein and the sympathetic fibres of the superior hypogastric plexus lie close by.

Course and drainage

Begins at

Afferent vessels from the internal and external iliac nodes and the sacral and promontorial nodes, carrying lymph from both sides of the pelvis.

Drains into

Efferent vessels pass upward to the lateral aortic (lumbar) nodes and on to the lumbar trunks.

Drains

Collects lymph from both halves of the pelvis and the lower limbs. A key station for spread of rectal and bladder cancer and of lymphoma, marking the top of a pelvic node dissection.