Thymus, thoracic duct and lymphatic drainage of the thorax Flashcards
What is the thymus, and where is it located?
The thymus is a lymphoid organ located in the anterior superior mediastinum, behind the sternum.
What is the primary function of the thymus?
It is responsible for the maturation and differentiation of T lymphocytes for adaptive immunity.
How does the thymus change with age?
The thymus is large and active during childhood but undergoes involution and is replaced by fat in adulthood.
What are the two main lobes of the thymus, and what do they contain?
The thymus consists of two lobes, each containing a cortex (dense with immature T cells) and a medulla (fewer T cells, contains Hassall’s corpuscles).
What type of immune cells mature in the thymus?
T lymphocytes (T cells) mature in the thymus.
What is the blood supply of the thymus?
The arterial supply comes from the internal thoracic artery and branches from the inferior thyroid and pericardiophrenic arteries.
What is the venous drainage of the thymus?
The venous drainage is via the left brachiocephalic, internal thoracic, and inferior thyroid veins.
What is the lymphatic drainage of the thymus?
The thymus drains into the parasternal, brachiocephalic, and tracheobronchial lymph nodes.
What is the clinical significance of the thymus in myasthenia gravis?
Thymomas are associated with myasthenia gravis due to autoimmune reactions against acetylcholine receptors.
What is the thoracic duct, and what is its function?
The thoracic duct is the main lymphatic vessel that drains lymph from most of the body into the venous system.
Where does the thoracic duct originate?
It originates from the cisterna chyli in the abdomen (at the level of L1-L2).
What is the course of the thoracic duct in the thorax?
The thoracic duct ascends through the posterior mediastinum, between the aorta and azygos vein, and crosses to the left at T4-T6.
Where does the thoracic duct terminate?
It terminates at the junction of the left subclavian and internal jugular veins.
What are the tributaries of the thoracic duct?
Tributaries include intercostal, mediastinal, bronchomediastinal, jugular, and subclavian lymph trunks.
What structures are located near the thoracic duct in the thorax?
The thoracic duct is closely related to the aorta, azygos vein, esophagus, and vertebral column.
What is the clinical significance of thoracic duct injury?
Injury to the thoracic duct can cause lymph leakage into the thorax, leading to chylothorax.
What is chylothorax, and how is it related to the thoracic duct?
Chylothorax is the accumulation of lymphatic fluid (chyle) in the pleural cavity due to thoracic duct injury.
What is the general pattern of lymphatic drainage in the thorax?
The thoracic lymphatics drain into the thoracic duct (left side) and right lymphatic duct (right side).
What are the major groups of lymph nodes in the thorax?
Major thoracic lymph node groups include paratracheal, tracheobronchial, bronchopulmonary, and intercostal nodes.
What are the primary lymph nodes responsible for draining the lungs?
The pulmonary and bronchopulmonary lymph nodes primarily drain the lungs.
How does lymph from the lungs reach the thoracic duct or right lymphatic duct?
Lung lymph drains to the hilar nodes, then tracheobronchial nodes, bronchomediastinal trunks, and finally the thoracic or right lymphatic duct.
What are the lymph nodes associated with the trachea and bronchi?
The tracheobronchial nodes include superior and inferior (carinal) groups, draining the trachea and bronchi.
What is the role of the paratracheal lymph nodes?
Paratracheal nodes drain lymph from the trachea, esophagus, and lungs.
What is the drainage pattern of the esophagus?
The esophagus drains into posterior mediastinal and deep cervical lymph nodes.
How is the breast lymphatic drainage connected to the thoracic lymphatic system?
The breast lymph drains mainly into the axillary nodes, but some drains into parasternal and infraclavicular nodes.
What is the significance of the subpleural lymphatic plexus?
The subpleural lymphatic plexus drains the visceral pleura and superficial lung parenchyma into bronchopulmonary nodes.
How does lymphatic drainage differ between the left and right sides of the thorax?
The left thorax drains into the thoracic duct, while the right thorax drains into the right lymphatic duct.
What is the right lymphatic duct, and what areas does it drain?
The right lymphatic duct drains lymph from the right upper limb, right thorax, and right head and neck.
What is the role of intercostal lymph nodes?
Intercostal lymph nodes drain lymph from the thoracic wall and intercostal spaces into the thoracic duct.
What are common clinical conditions related to the lymphatic drainage of the thorax?
Common conditions include lymphadenopathy, metastasis to thoracic nodes, chylothorax, and lymphoma.
