The lymphatic system is a critical component of the body’s protective mechanisms, functioning to drain tissue fluid, plasma proteins and other cellular debris back into the bloodstream. This collection of substances is known as lymph, which is subsequently filtered by lymph nodes before returning to the circulation via the venous system. This article will explore the anatomy of lymphatic drainage throughout the upper limb - the lymphatic vessels, lymph nodes, and its clinical correlations.
Superficial Lymphatic Vessels
The superficial lymphatic vessels of the upper limb originate from lymphatic plexuses in the skin of the hand consisting of networks of lymphatic capillaries beginning in the extracellular spaces. These vessels then travel up the arm in close proximity to the major superficial veins- vessels shadowing the basilic vein are the chief lymphatic vessels that enter the cubital lymph nodes located medially to the vein, and proximally to the medial epicondyle of the humerus. The vessels that originate from these nodes continue up the arm, and terminate at the lateral axillary lymph nodes.
The vessels shadowing the cephalic vein generally cross the proximal part of the arm and shoulder before entering the apical axillary lymph nodes. However, some of the vessels end in the more superficial deltopectoral lymph nodes instead.
Deep Lymphatic Vessels
The deep lymphatic vessels of the upper limb follow the major deep veins (i.e. radial, ulnar and brachial veins), terminating in the humeral axillary lymph nodes. They are responsible for draining lymph from joint capsules, periosteum, tendons and muscles. Additionally, some additional lymph nodes may be found along the ascending path of these deep vessels.
The majority of the upper extremity lymph nodes are located in the axilla, which can be divided anatomically into five distinct groups-
Axillary lymphadenopathy is a clinical situation that refers to enlargement of the axillary lymph nodes. Common causes of this condition include infection of the upper limb, which can result in lymphangitis (inflammation of the lymphatic vessels, with tender, enlarged lymph nodes).
In addition, benign and malignant tumors may also cause axillary lymphadenopathy. Therefore, it is important for clinicians to pay special attention to any changes in the size or consistency of these nodes, as they can provide useful information with regards to the underlying pathology.
Moreover, axillary lymphadenopathy can be managed when caused by an infectious etiology, as the underlying infection can be treated with antibiotics, thus reducing its signs and symptoms. In some cases, the affected nodes may need to be surgically removed if they become too large.
In conclusion, this article has explored the anatomy and clinical relevance of lymphatic drainage in the upper limb. The lymphatic system is a highly efficient mechanism that has many important functions, and understanding the anatomical intricacies of the lymphatic vessels and nodes is a critical part of understanding how the body is able to protect itself from external threats.
The vessels that are shadows to the cephalic vein in the upper extremity commonly cross the proximal area of the arm and shoulder to enter into the apical axillary lymph nodes. However, some exceptions occur when they instead enter the more shallow deltopectoral lymph nodes.
The deep lymphatic vessels of the upper limb trace the path of the major deep veins, for example, radial, ulnar and brachial veins, and terminate at the humeral axillary lymph nodes. These vessels are responsible for draining lymph away from joint capsules, periosteum, tendons, and muscles. Along the ascending path of the deep vessels, there are also additional lymph nodes that can be found.
Most of the lymph nodes in the upper extremity are located in the axilla. They can be separated into five distinct groups, based on their anatomical location:
Axillary lymphadenopathy refers to an enlargement of the axillary lymph nodes. Common causes of this phenomenon include infection of the upper limb, causing lymphangitis (inflammation of the lymphatic vessels, with enlarged and tender lymph nodes), infection in the pectoral region and breast, and metastasis of breast cancers.
Removing and analyzing the axillary lymph nodes is typically a critical practice for staging breast cancers. However, disruption of the lymphatic drainage away from the upper limb can lead to lymphoedema, a condition in which accumulated lymph in the subcutaneous tissue causes enlarged and painful swelling of the upper limb. Furthermore, there is a risk of the long thoracic nerve (which could lead to a winged scapula deformity) or the thoracodorsal nerve to be damaged during this procedure.
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