Lymph nodes are small, bean-shaped glands that are part of the body’s lymphatic system. This system is a network of vessels and organs that isolates and neutralizes foreign agents. Lymph nodes function as filters for lymph fluid, a clear fluid that circulates, collecting waste and foreign particles. These structures are distributed widely throughout the body, with clusters found in various regions.
Locating Inguinal Lymph Nodes
Inguinal lymph nodes are located in the groin area, the region where the thigh meets the abdomen. They are situated within the femoral triangle, a space in the upper, inner thigh. This area is bounded by the inguinal ligament superiorly, the sartorius muscle laterally, and the adductor longus muscle medially.
There are about 10 inguinal lymph nodes on each side, divided into two main groups: superficial and deep. The superficial inguinal lymph nodes lie closer to the surface of the skin, just beneath the inguinal ligament.
The deep inguinal lymph nodes are situated deeper within the upper thighs, within the femoral sheath and medial to the femoral vein. Fewer deep nodes exist, typically one to three, but sometimes up to five. The topmost deep inguinal lymph node, Cloquet’s node, is located beneath the inguinal ligament. These nodes can sometimes be felt through gentle palpation in the groin crease, along the pubic bone, and towards the inner thigh.
Their Role in the Body’s Defenses
Inguinal lymph nodes play a role in the body’s immune system by filtering lymph fluid from specific areas. They receive lymphatic drainage from the legs, feet, external genitalia, the anal canal (below the pectinate line), and the inferior aspect of the anterior abdominal wall.
As lymph fluid flows through these nodes, immune cells, such as lymphocytes and macrophages, filter out harmful substances. These substances include bacteria, viruses, parasites, and abnormal cells. When antigens are detected, B-cell lymphocytes produce antibodies to tag foreign invaders for destruction, while T-cell lymphocytes destroy infected cells.
What Swollen Inguinal Lymph Nodes Indicate
When inguinal lymph nodes become swollen, a condition known as lymphadenopathy, it signals that the body is fighting an infection or inflammation. Common causes include infections or injuries in the areas these nodes drain, such as cellulitis in the lower leg or foot, or conditions like athlete’s foot. Sexually transmitted infections (STIs), such as syphilis, chancroid, and lymphogranuloma venereum, are also frequent causes.
While often a sign of infection, they can sometimes indicate more serious conditions. Certain cancers, such as lymphoma or melanoma, can cause these nodes to enlarge. Metastatic cancer from primary sites in the pelvic organs or lower extremities, including squamous cell carcinoma of the vulva, penis, or anus, may also spread to these nodes. Persistent or unusually large swelling warrants medical consultation to determine the underlying cause and ensure appropriate diagnosis and treatment.