Lymph Nodes of the Head, Neck and Arm
The lymphatic system consists of:
- lymphatic vessels or lymphatics (a network of thin-walled vessels with abundant lymphatic valves)
- lymphatic ducts
- lymphatic trunks
- lymphoid tissue (sites that produce lymphocytes, such as those aggregated in the walls of the digestive tract, the spleen and thymus)
- lymph organs, such as spleen
- lymph nodes
Lymph nodes are small, oval or kidney-shaped bodies, 0.1-2.5 cm long, that lie along the course of lymphatic vessels. They are encapsulated centres of antigen presentation and lymphocyte activation, differentiation and proliferation. They generate mature, antigen-primed, B and T cells, and filter particles, such as microbes, from the lymph by the action of numerous phagocytic macrophages. The lymph is usually a clear, watery, and slightly yellow tissue fluid that enters lymph capillaries, and is similar in composition to blood plasma. A normal young adult body contains up to 450 lymph nodes, of which 60-70 are found in the head and neck, 100 in the thorax and as many as 250 in the abdomen and pelvis.
Lymph nodes are particularly numerous in the following locations:
- posterior abdominal wall
- abdominal mesenteries
- proximal regions of the limbs (axillary and inguinal lymph nodes)
- close to the viscera, especially in the mesenteries, where the greatest number of lymph nodes lie
Lymph Nodes Of The Arm
Lymph nodes of the arm include the cubital and deltopectoral lymph nodes. Superficial lymphatic vessels arising from the lymphatic plexuses in the skin of the fingers, palm, and dorsum of the hand drain lymph from these parts, as well as from the forearm, into the cubital lymph nodes. These are located proximal to the medial epicondyle of the humerus.
Efferent vessels from these lymph nodes ascend in the arm to terminate in the humeral or lateral axillary lymph nodes. Other superficial lymphatic vessels accompanying the cephalic vein also drain the arm, to terminate in the apical axillary lymph nodes, while some drain into the deltopectoral lymph nodes. The humeral axillary lymph nodes also receive deep lymphatic vessels, which are less numerous than the superficial lymphatic vessels. The superficial and deep lymphatics of the upper limb drain initially into the lateral and apical axillary lymph nodes. Axillary or central axillary lymph nodes are drained in turn by the subclavian lymphatic trunk.
Lymph Nodes Of The Head And Neck
Distribution and drainage
In the head and neck, lymph nodes are arranged in two horizontal rings and two vertical chains on either side of the neck. The outer, superficial ring consists of the occipital, preauricular (parotid), submandibular and submental nodes. The inner, deep ring is formed by clumps of mucosa associated lymphoid tissue (MALT) located primarily in the naso- and oropharynx (Waldeyer’s ring).
Lymph nodes in the head and neck are also distributed in terminal and outlying groups. The terminal group is related to the carotid sheath and contains the deep cervical lymph nodes. All lymph vessels of the head and neck drain into this group, either directly from the tissues or indirectly through nodes in the outlying groups. Efferents of the deep cervical nodes form the jugular lymphatic trunk. The right jugular lymphatic trunk collects lymph from the right arm, the right half of the thorax and the right parts of the head and neck. This trunk may end in the jugulosubclavian junction or the right lymphatic duct. Lymph from the left aspect of those regions drain into left jugular trunk ,which usually enters the thoracic duct. It may also join the internal jugular or subclavian vein.
Lymph nodes of the head
Each group of lymph nodes in the head receives lymph from a specific organ or part of the head, and some of these groups of lymph nodes are named according to such parts. The groups include:
- Fascial group of lymph nodes: inferior maxillary, buccinators, infraorbital and the malar lymph nodes
- Submandibular group: preglandular, prevascular, retrovascular, retroglandular and intracapsular lymph nodes
- Parotid group: subfacial orextraglandular, deep intraglandular and suprafasciallymph nodes
- Submental group: anterior, middle and posterior submental lymph nodes
- Sublingual group: anterior/superior and posterior/inferior sublingual lymph nodes
- Mastoid group
- Occipital groups
Lymph nodes of the neck
In the neck, lymph nodes also form groups, as outlined below:
- Anterior cervical group: superficial anterior jugular chain, prelaryngeal and pretracheal lymph nodes
- Retropharyngeal group: lateral and medial retropharyngeal lymph nodes
- Lateral cervical group: supraclavicular or transverse cervical group, superior jugular group, midjugular group, inferior jugular group, and the spinal accessory or posterior triangle group of lymph nodes).
Superior deep cervical lymph nodes are found attached to the upper part of the internal jugular vein. Most are deep to the sternocleidomastoid, but a few extend beyond it. A subgroup of nodes known as the jugulodigastric group, which is located in a triangular region bounded by the posterior belly of digastric, facial and internal jugular veins, is concerned with drainage of the tongue.
Jugulo-omohyoid node lies in relation to the intermediate tendon of omohyoid, and is part of the lymphatic drainage of the tongue.
Paratracheal lymph nodes are situated along the recurrent laryngeal nerves. Efferents pass to the corresponding deep cervical nodes.
Infrahyoid, prelaryngeal and pretracheal lymph nodes lie beneath the deep cervical fascia and drain afferently from the anterior cervical nodes.
Lingual lymph nodes lie on the external surface of hypoglossal and also between the genioglossi, and drain to the upper deep cervical nodes.
Spread of malignant disease in the neck
A good knowledge of lymph nodes of the neck is required to make appropriate nodal clearance and/or avoidance during surgery to treat cancer. It is necessary to know which levels of lymph nodes are likely to be involved in the metastatic spread of a particular cancer arising in the head and neck. Usually, cancers arising in the head and neck have predictable patterns of spread through the chains of lymph nodes in the neck.