The cisterna chyli is a specialized anatomical structure within the human lymphatic system, a dilated sac that plays a role in managing fluid balance and transporting nutrients. It is a normal variation, present in many individuals. This structure functions as a temporary holding area for lymph before it continues its journey towards the bloodstream.
Anatomy and Location
The cisterna chyli is found in the abdominal region, positioned behind the abdominal aorta and anterior to the first and second lumbar vertebrae (L1 and L2). This sac marks the beginning of the thoracic duct, the body’s largest lymphatic vessel.
It is retroperitoneal, meaning it lies behind the peritoneum, the membrane lining the abdominal cavity. Its morphology can vary, appearing as a single dilated sac, tubular, or reticular. The cisterna chyli is a confluence point where several major lymphatic trunks merge before forming the thoracic duct.
Collecting Lymphatic Fluid
The cisterna chyli serves as a primary collection point for lymph from the lower limbs, pelvic organs, and many abdominal organs. The right and left lumbar lymphatic trunks, which drain lymph from the pelvis, kidneys, adrenal glands, and much of the abdominal wall, flow into the cisterna chyli.
The intestinal lymphatic trunk also empties into this sac, bringing lymph from the stomach, intestines, pancreas, and spleen. This collected lymph, along with chyle (lymph rich in fats), then flows upwards into the thoracic duct. The thoracic duct transports this fluid through the diaphragm to drain into the junction of the left subclavian and internal jugular veins in the neck, returning it to the bloodstream.
Role in Dietary Fat Absorption
The cisterna chyli plays a role in the absorption and transport of dietary fats. After food is digested, fats are processed into tiny particles called chylomicrons. These chylomicrons are too large to directly enter the bloodstream, so they are absorbed into specialized lymphatic capillaries within the intestines.
Once absorbed, these fat-rich chylomicrons form a milky fluid known as chyle. The cisterna chyli is the initial major recipient of this chyle from the intestinal lymphatic trunks. This process allows absorbed dietary fats and fat-soluble vitamins to bypass the liver, directly entering systemic circulation for distribution.
Clinical Implications of Dysfunction
Dysfunction of the cisterna chyli or associated lymphatic pathways can lead to several health issues. One condition is chylous ascites, the accumulation of chyle in the abdominal cavity. This occurs when an obstruction or leakage in lymphatic vessels causes chyle to pool.
Such impairment can disrupt the normal flow of lymph and chyle, leading to fluid imbalances and impaired nutrient transport. These issues can arise from trauma, tumors, or surgical interventions in the abdominal region. Understanding the cisterna chyli’s anatomy and function aids in diagnosing and managing lymphatic drainage problems.