胸腺位于胸腔上纵隔的前部,分左、右叶,呈长扁条状,质地柔软。胸腺上端达胸腔上口,下端至心包的上部,前面大部分被肺和胸膜所掩盖,后面附于心包及大血管前面。胸腺在出生后两年内生长很快,在两岁时,其相对体积最大,重量已达10-15克, The thymus is located on the anterior part of the mediastinum in the chest and is divided into left and right lobes. It is long and flat and has a soft texture. The upper part of the thymus reaches the upper part of the chest cavity and the lower part reaches the upper part of the pericardium. The front part is mostly covered by the lungs and the pleura, and is attached behind the pericardium and the great vessels. The thymus grows rapidly within two years after birth. At the age of two years, it has the largest relative volume and its weight has reached 10-15 grams.