one of several charts used in testing visual acuity. Letters, numbers, or symbols are arranged on the chart in decreasing size from top to bottom. A wall chart developed by a Dutch ophthalmologist Hermann Snellen in the 19th century, which is still used today to measure visual acuity.
Popliteal Nodes. The popliteal nodes, or popliteal lymph nodes, include six or seven nodes and are located in the legs near the knees at the popliteal fossa.They service the lower legs and feet for the lymphatic system.opliteal Nodes. The popliteal nodes, or popliteal lymph nodes, include six or seven nodes and are located in the legs near the knees at the popliteal fossa.
lymph nodule. germinal centers in lymph nodes which produce lymphocytes. Called also lymphatic or lymphoid nodule. periarteriolar lymph sheath (PALS). the white pulp, heavily populated with T lymphocytes, that surrounds arteries in the spleen.arge vessels carrying lymph from smaller collecting vessels. Include thoracic duct, right lymphatic duct. lymph heart. a muscular dilatation in a lymph vessel, capable of contraction and moving lymph along the vessel.