Which statements are true about the lymph nodes of the head, face, & neck? Select all that apply.

Cervicofacial lymph nodes are integral components of the lymphatic system responsible for immune surveillance, filtration of lymphatic fluid, and maintenance of interstitial fluid balance through drainage into venous circulation via the thoracic duct and right lymphatic duct pathways. Rationale: A. Always palpable is incorrect because normal lymph nodes are typically non-palpable or barely palpable in healthy individuals. Palpability occurs only when nodes are enlarged due to infection, inflammation, or malignancy. Therefore, constant palpation is not a normal physiological finding. B. Saliva production is a function of salivary glands such as parotid, submandibular, and sublingual glands, not lymph nodes. Lymph nodes do not have secretory exocrine functions. Their role is immunologic rather than digestive, making this statement anatomically incorrect. C. Tenderness occurs in lymph nodes during acute infection due to inflammatory cytokine release, increased vascular permeability, and immune cell proliferation. This leads to capsular stretching and pain on palpation, commonly seen in bacterial or viral infections affecting head and neck regions. D. Pathogen filtration is a primary lymph node function where lymphocytes and macrophages trap and destroy infectious organisms and abnormal cells. This immune surveillance mechanism prevents systemic spread of pathogens through lymphatic circulation, forming a key component of host defense. E. Fluid return occurs as lymph nodes facilitate drainage of interstitial fluid back into venous circulation via lymphatic vessels. This maintains fluid balance, prevents edema, and ensures proper plasma volume regulation through continuous lymphatic transport system function.