Anatomy of the Lymphatic System
LYMPHATICS
OBJECTIVES
§ Describe the major structures of the lymphatic system and the roles that it plays in disease fighting and the distribution of metabolic products.
§ Describe the anatomical relationship to the venous system, and the physiological relationship to the portions of the nervous system mediating the stress response.
§ Describe the major nodal sites in the head and neck.
§ Be able to predict the lymphatic drainage of major head and neck regions. Know what is special about the tongue
Components of the Lymphatic System
§ The lymphatic system, as part of the circulatory system, starts with its capillaries, which begin blindly in tissue spaces.
§ The lymphatic system is closely aligned to the venous system
§ ultimately, the lymph is returned to the venous system at the base of the neck.
§ The lymphatic system contains specialized collections of tissue, including the spleen, thymus, tonsils, and nodes.
Pericervical Collar
§ This is a collection of nodal points that receive lymphatic drainage from more superior regions of the face and scalp.
§ The groups making up this ring are typically:
(1) occipital, (2) posterior auricular, (3) parotid, (4) buccal, (5) submandibular, and (6) submental.
Cervical Organization
§ Superficial cervical nodes lay along the external jugular vein,
§ whereas the deep cervical nodes lay along the internal jugular vein.
§ There are two prominent collections of named nodes that are important: (1) jugulodigastric and (2) juguloomohyoid.
§ These are so-named because they generally are located at the intersection of these muscles and the internal jugular vein.
§ In addition to these, there is a collection of pretracheal and retroharyngeal nodes
§ The deep cervical nodes are often further subdivided into superior deep and inferior deep groups.
§ The jugulodigastric and juguloomohyoid are part of the superior deep group.
§ The inferior deep group are those that are found along the subclavian vessels and are of considerable clinical significance.
Draining Principals
§ The routing of lymph is generally straightforward.
§ By-in-large, lymph drainage follows the ‘down & in’ principal.
§ superior regions drain inferiorly, and superficial regions drain deep.
§ Of course, by the nature of the lymphatic network, there is much potential variation.
§ But, this is also one of the reasons that cancer, once within the lymphatic system, can be disseminated so widely.
§ In any event, lymph collected from all parts of the body enters the venuous system in the root of the neck.
§ For example, the right lymphatic duct empties at the junction of the right subclavian and internal jugular veins.
§ The thoracic duct enters the neck slightly off of the midline behind esophagus to join at the junction of the left subclavian and internal jugular veins.
Supraclavicular (or sentinel nodes)
§ A very important clinical point is that the inferior deep group of nodes, which includes the supraclavicular collection of nodes, receive drainage from the vast majority of body regions.
§ These nodes set in the final common pathway of lymphatic drainage from the entire body.
§ For instance, cancer arising from the breast or pelvic region may present in these nodes.
§ Therefore, inspection of these nodes is important in any comprehensive assessment.
§ These nodes are not typically palpable.
Clinical Correlates
The drainage from the tongue
§ deserves special mention because of the frequency that this structure in involved in cancerous conditions.
§ The anterior two-thirds of the tongue typically drains into submental nodes and submandibular nodes, but may also bypass these pericervical nodes to drain directly in the deep cervical nodes.
§ The posterior one-third of tongue join the deep cervical nodes directly.
§ Furthermore, drainage from the central portions of the tongue may drain bilaterally, and is especially the case for the tip of the tongue.
§ This fact can make managing the spread of cancer particularly devastating, as essentially the entire neck can be involved.
Another important drainage pattern to know is from the larynx
§ Its lymphatic drainage follows the venous drainage;
§ hence, drains both superiorly and inferiorly.
§ From there, lymph drains into the deep cervical set of nodes.
Tags: buccal, cancer in nodes, cervical nodes, circulatory system, drainage from tongue, internal jugular veins, jugulodigastric, juguloomohyoid, lymphatic drainage, LYMPHATICS, occipital, parotid, Pericervical Collar, posterior auricular, submandibular, submental, Supraclavicular, thoracic duct
