"Lymph Nodes

All the small and medium-sized lymph vessels open into lymph nodes which are situated in strategic positions throughout the body. The lymph drains through a number of nodes, usually 8 to 10, before returning to the blood. These nodes vary considerably in size: some are as small as a pin head and the largest are about size of an almond.

Lymph nodes have a surrounding capsule of fibrous tissue which dips down into the node substance forming partitions, or trabeculae. The main substance of the node consists of reticular and lymphatic tissue containing many lymphocytes and macrophages. As many as four or five afferent Iymph vessels may enter a lymph node while only one efferent vessel carries lymph away from the node. Each node has a concave surface called the hilum where an artery enters and vein and the efferent lymph vessel leave. The large numbers of lymph nodes situated in strategic positions throughout the body deep and superficial groups.

Lymph nodes are found throughout the body the picture shows the positioning of some of the major groups of lymph nodes.

[1] Mastoid and Sub occipital nodes of the head

[2] Cervical lymph nodes of the neck

[3] Axillary lymph nodes under the arms

[4] Inguinal lymph nodes of the groin area

[5] Popliteal noded behind the knee

An enlargement of these nodes is common in inflammation and malignant disease. As a result palpation (feeling) of the neck, armpits and the groin area is an important part of clinical investigation"