The lymphatic system, or lymphoid system, is an organ system in vertebrates that is part of the immune system, and complementary to the circulatory system. It consists of a large network of lymphatic vessels, lymph nodes, lymphoid organs, lymphatic tissue and lymph. Lymph is a clear fluid carried by the lymphatic vessels back to the heart for re-circulation. The Latin word for lymph, lympha, refers to the deity of fresh water, "Lympha".
A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that include B and T cells. Lymph nodes are important for the proper functioning of the immune system, acting as filters for foreign particles including cancer cells, but have no detoxification function.
Lymph is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues to be recirculated. At the origin of the fluid-return process, interstitial fluid—the fluid between the cells in all body tissues—enters the lymph capillaries. This lymphatic fluid is then transported via progressively larger lymphatic vessels through lymph nodes, where substances are removed by tissue lymphocytes and circulating lymphocytes are added to the fluid, before emptying ultimately into the right or the left subclavian vein, where it mixes with central venous blood.
The lymphatic vessels are thin-walled vessels (tubes), structured like blood vessels, that carry lymph. As part of the lymphatic system, lymph vessels are complementary to the cardiovascular system. Lymph vessels are lined by endothelial cells, and have a thin layer of smooth muscle, and adventitia that binds the lymph vessels to the surrounding tissue. Lymph vessels are devoted to the propulsion of the lymph from the lymph capillaries, which are mainly concerned with the absorption of interstitial fluid from the tissues. Lymph capillaries are slightly bigger than their counterpart capillaries of the vascular system. Lymph vessels that carry lymph to a lymph node are called afferent lymph vessels, and those that carry it from a lymph node are called efferent lymph vessels, from where the lymph may travel to another lymph node, may be returned to a vein, or may travel to a larger lymph duct. Lymph ducts drain the lymph into one of the subclavian veins and thus return it to general circulation.
Lymphadenopathy or adenopathy is a disease of the lymph nodes, in which they are abnormal in size or consistency. Lymphadenopathy of an inflammatory type is lymphadenitis, producing swollen or enlarged lymph nodes. In clinical practice, the distinction between lymphadenopathy and lymphadenitis is rarely made and the words are usually treated as synonymous. Inflammation of the lymphatic vessels is known as lymphangitis. Infectious lymphadenitis affecting lymph nodes in the neck is often called scrofula.
Inguinal lymph nodes are lymph nodes in the groin. They are situated in the femoral triangle of the inguinal region. They are subdivided into two groups: the superficial inguinal lymph nodes and deep inguinal lymph nodes.
The periaortic lymph nodes are a group of lymph nodes that lie in front of the lumbar vertebrae near the aorta. These lymph nodes receive drainage from the gastrointestinal tract and the abdominal organs.
The neck dissection is a surgical procedure for control of neck lymph node metastasis from squamous cell carcinoma (SCC) of the head and neck. The aim of the procedure is to remove lymph nodes from one side of the neck into which cancer cells may have migrated. Metastasis of squamous cell carcinoma into the lymph nodes of the neck reduce survival and is the most important factor in the spread of the disease. The metastases may originate from SCC of the upper aerodigestive tract, including the oral cavity, tongue, nasopharynx, oropharynx, hypopharynx, and larynx, as well as the thyroid, parotid and posterior scalp.
The stylopharyngeus muscle is a muscle in the head. It originates from the temporal styloid process. Some of its fibres insert onto the thyroid cartilage, while others end by intermingling with proximal structures. It is innervated by the glossopharyngeal nerve. It acts to elevate the larynx and pharynx, and dilate the pharynx, thus facilitating swallowing.
The sentinel lymph node is the hypothetical first lymph node or group of nodes draining a cancer. In case of established cancerous dissemination it is postulated that the sentinel lymph nodes are the target organs primarily reached by metastasizing cancer cells from the tumor.
Cervical lymph nodes are lymph nodes found in the neck. Of the 800 lymph nodes in the human body, 300 are in the neck. Cervical lymph nodes are subject to a number of different pathological conditions including tumours, infection and inflammation.
The axillary lymph nodes or armpit lymph nodes are lymph nodes in the human armpit. Between 20 and 49 in number, they drain lymph vessels from the lateral quadrants of the breast, the superficial lymph vessels from thin walls of the chest and the abdomen above the level of the navel, and the vessels from the upper limb. They are divided in several groups according to their location in the armpit. These lymph nodes are clinically significant in breast cancer, and metastases from the breast to the axillary lymph nodes are considered in the staging of the disease.
The preaortic lymph nodes lie in front of the aorta, and may be divided into celiac lymph nodes, superior mesenteric lymph nodes, and inferior mesenteric lymph nodes groups, arranged around the origins of the corresponding arteries.
The superior deep cervical lymph nodes are the deep cervical lymph nodes that are situated adjacent to the superior portion of the internal jugular vein. They drain either to the inferior deep cervical lymph nodes or into the jugular trunk.
The submental lymph nodes are 2-3 lymph nodes situated in the submental triangle, between the anterior bellies of the digastric muscle and the hyoid bone.
The submandibular lymph nodes, are some 3-6 lymph nodes situated at the inferior border of the ramus of mandible.
The superior mesenteric lymph nodes may be divided into three principal groups:
The gastric lymph nodes are lymph nodes which drain the stomach and consist of two sets, superior and inferior:
Oropharyngeal cancer, also known as oropharyngeal squamous cell carcinoma and tonsil cancer, is a disease in which abnormal cells with the potential to both grow locally and spread to other parts of the body are found in the oral cavity, in the tissue of the part of the throat (oropharynx) that includes the base of the tongue, the tonsils, the soft palate, and the walls of the pharynx.
Carcinoma of the tonsil is a type of squamous cell carcinoma. The tonsil is the most common site of squamous cell carcinoma in the oropharynx. It comprises 23.1% of all malignancies of the oropharynx. The tumors frequently present at advanced stages, and around 70% of patients present with metastasis to the cervical lymph nodes. . The most reported complaints include sore throat, otalgia or dysphagia. Some patients may complain of feeling the presence of a lump in the throat. Approximately 20% patients present with a node in the neck as the only symptom.
