Sacral lymph nodes

Sacral lymph nodes are a group of deep pelvic lymph nodes located along the anterior surface of the sacrum. They lie in close association with the middle sacral vessels and are part of the posterior pelvic lymphatic drainage network. Though smaller and less numerous than other pelvic nodes, they play an important role in receiving lymph from posterior pelvic organs and the lower rectum. They also serve as a communication point between internal iliac and lateral lumbar lymphatic pathways.

Structure

Sacral nodes are typically small, rounded, and embedded in connective tissue along the midline of the posterior pelvic cavity. They consist of the typical lymph node architecture, including a fibrous capsule, subcapsular sinus, cortex with lymphoid follicles, and a medullary core.

Node Grouping

• Usually arranged in 1–3 small nodes on each side of the middle sacral artery
• Grouped along the concavity of the sacrum between the rectum and the sacral promontory

Location

The sacral lymph nodes are located in the presacral space of the pelvis. They lie posterior to the rectum and anterior to the sacrum, near the origins of the sacral nerves and middle sacral vessels.

Function

• Lymphatic drainage: Receives lymph from:
  • Posterior pelvic wall
  • Lower rectum and anal canal (especially above pectinate line)
  • Prostate and cervix (posterior portions)
• Immune filtering: Filters lymph for pathogens and malignant cells
• Communication pathway: Connects internal iliac, external iliac, and lateral lumbar nodes

Clinical Significance

• Rectal cancer spread: Sacral nodes may harbor metastatic deposits in advanced rectal malignancies
• Surgical relevance: May be removed during total mesorectal excision (TME) or posterior pelvic dissections
• Lymphadenopathy: Less commonly enlarged, but may indicate deep pelvic or spinal pathology