What are Lymph Nodes?
Lymph nodes are small, bean-shaped structures surrounded by a capsule of connective tissue responsible for the normal functioning of the immune system, which vary in sizes, from 1 millimeter to more than 20 millimeters in diameter. Throughout the human body, there are about 500 to 600 lymph nodes which are disseminated widely in clusters mostly in the underarm, neck, groin, chest and abdomen. These organs are made up of numerous types of cells and tissues, among these, white blood cells and lymphoid tissues are more profuse. These can be found all throughout the body and act as garrisons of B cells, T cells and other immune cell and also as filters or traps for foreign particles and bacteria that travel through the body in the lymph fluid.
Lymph nodes have clinical significance. They are the main sites where many immune reactions are initiated. These structures can become inflamed and enlarged due to a variety of medical reasons, ranging from minor throat infection to life-threatening situations such as cancer. In the process of an infection, the lymph nodes may swell which can be related to the proliferation of B cells in the germinal centers resulting to swollen glands. The condition of the lymph nodes is very important especially in cancer as cancer staging is also based to the extent of involvement of the lymph nodes which then decides the medical treatment to be utilized and for establishing a prognosis.
Whenever the lymph nodes become inflamed, biopsy can be performed. Specific medical conditions affect these structures with distinctive consistency and location.
Lymph Nodes Locations
With the exemption of relatively few individual nodes, most of the lymph nodes do come together in groups in specific body areas. The group locations of greatest clinical importance include the following areas, namely, groin, armpit, neck, under the jaw and chin, behind the ears and on the back of the head.
Lymph nodes of the head and neck
Cervical lymph nodes
The cervical lymph nodes are divided into anterior and posterior cervical lymph nodes. The anterior cervical, both involving the superficial and deep rest over and below the Sternocleidomastoid muscles. They drain the internal composition of the throat, as well as sections of the posterior pharynx, tonsils and thyroid gland. On the other hand, the posterior cervical lymph nodes are structures which extend in a line subsequent to the Sternocleidomastoid muscles but further on the trapezius, from the point of the mastoid segment of the temporal bone to the clavicle. When a person develops an upper respiratory tract infection, these nodes are commonly enlarged.
Preauricular lymph nodes
The preauricular deep parotid lymph nodes, which are about one to three in digits, rest immediately in front of the tragus.
Tonsilar or Sub-mandibular lymph nodes
The tonsilar and sub-mandibular lymph nodes are organs which are situated just beneath the mandibular angle, all along the base of the jaw on whichever periphery. They draw off the tonsilar and posterior pharyngeal region together with the structures located in the floor of the mouth and the maxillary anterior, bicuspid and the first and second molars, and all the mandibular teeth excluding the central incisors.
Sub-mental
Submental lymph nodes are situated just beneath the chin. Lymphs from the central incisors and the lower lip’s midline and tip of the tongue drain from these nodes.
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Supraclavicular lymph nodes
The supraclavicular lymph nodes are located in the cavity over the clavicle, just on the side to where it merges with the sternum. Lymph from the abdomen and thoracic cavity drains through these nodes. The Virchow’s node is a left supraclavicular node which picks up the lymph drainage from for the most parts of the body particularly the stomach passing through the thoracic duct and is thus an premature location of metastasis for a number of malignancies.
Lymph nodes of the thorax
Lymph nodes of the lungs
The lymph drainage is pumped out from the lung tissues by way of the subsegmental, segmental, lobar and interlobar lymph nodes to the hilar lymph nodes which are positioned around the hilum of each lung. The drainage streams subsequently to the mediastinal lymph nodes.
Mediastinal lymph nodes
The mediastinal lymph nodes comprise a number of lymph node groups, particularly along the trachea, down the esophagus, between the lungs and the diaphragm. Lymphatic dusts are present in the mediastinal lymph nodes where the lymph drainage is drawn off to the left subclavian vein.
Lymph nodes of the arm
Lymph from the whole arm drains through the lymph nodes located in the arm. These nodes are then divided into two divisions, namely, the superficial and the deep. The former nodes are provided by the lymphatics present all the way through the arms yet, specifically abundant on the palms and flexor aspects of the fingers.
Superficial lymph glands of the arm
The superficial lymph glands of the arm include the supratrochlear and the deltoideopectoral glands. The former is positioned on top of the medial epicondyle of the humerus, medial to the basilica vein. These nodes drain the C7 and C8 dermatomes while the latter glands are placed between the pectoralis major and deltoid muscles inferior below the clavicle.
Deep lymph glands of the arm
The deep lymph glands of the arm encompass the axillary glands, which are about twenty to thirty individual glands and which can be sub-classified into five divisions namely, lateral glands, anterior or pectoral glands, posterior or sub-scapular glands, central or intermediate glands, and lastly the medial or subclavicular glands. These nodes are large and are clustered deep within the underarm and upper chest regions. These nodes drain the arm, the upper part of the chest wall comprising the breasts.
Lymph nodes of the lower limbs
Inguinal lymph nodes
This is a type of lymph node in the inguinal region, found in the upper inner thigh near the pelvis. The lymph from the legs and external genitals drains through these nodes. There are two types of inguinal lymph node; namely, the superficial and the deep types. There are ten superficial inguinal nodes and five deep inguinal nodes.
