What is the thymus and what is its main function?

The thymus is a primary lymphoid organ located in the superior mediastinum. Its main function is to support T-cell maturation and establish immune tolerance through processes like positive and negative selection.

Where is the thymus located in the body?

The thymus is situated in the superior mediastinum, posterior to the manubrium and anterior to the pericardium. It is a bilobed, retrosternal organ.

How does the thymus change with age?

The thymus grows until around 3 years of age, then gradually involutes during puberty, being replaced by fat. This involution leads to a weakened immune response in aging, increasing risks for infections and autoimmune diseases.

What are the clinical conditions associated with thymus dysfunction?

Key conditions include myasthenia gravis, often linked to thymic hyperplasia; DiGeorge syndrome, involving congenital thymic agenesis and immunodeficiency; and Severe Combined Immunodeficiency (SCID), where genetic defects cause early thymic disappearance.

What is the blood supply to the thymus?

The thymus receives arterial supply from sources like the inferior thyroid and internal thoracic arteries. Venous drainage occurs via tributaries to the left brachiocephalic and internal thoracic veins.

What are ectopic thymus variants?

Ectopic thymus occurs in about 50% of individuals, often found in the anterior neck deep to the sternocleidomastoid muscle. It can mimic lymphadenopathy or tumors but is usually benign.

How is the thymus involved in T-cell development?

The thymus facilitates T-cell maturation through positive and negative selection, ensuring only non-self-reactive T-cells survive. This process involves structures like Hassall’s corpuscles in the medulla.

Thymus – Anatomy, Function & Clinical Relevance

❓ Frequently Asked Questions