What is the primary function of the epitrochlear lymph node?

The primary function of the epitrochlear lymph node is to assess infection in the upper limb. Epitrochlear lymph nodes are located near the elbow and are part of the lymphatic system. They play a critical role in the immune response by filtering lymphatic fluid that drains from the forearm and hand. When there is an infection or inflammation in the upper extremities, these nodes respond by becoming enlarged and tender, indicating their involvement in the immune defense.

While other options describe functions that are important in different contexts, they do not pertain specifically to the role of the epitrochlear lymph node. For instance, the production of hormones is a function of glands such as the thyroid or adrenal glands rather than lymph nodes. Regulating blood flow is primarily a vascular function, associated with blood vessels and the heart. Filtering toxins is a general function of the liver and kidneys, rather than being a specific role of lymph nodes. Thus, assessing infection stands out as the primary and correct response relating to the epitrochlear lymph node's function.