294 CLINICAL APPLIED ANATOMY. 



constant, nor are they restricted to this variety of the disease. 

 They may be met with in myxoedema and in association with 

 some goitres, and are due to prominence of the supraclavicular 

 fatty tissue. Their occurrence is favoured by the absence of 

 superficial muscles and other resistant coverings in the situations 

 where they are found. 



THE THYMUS GLAND. 



Enlargement of the thymus is met with in very diverse 

 conditions. The chief of these are Graves's disease, rickets, 

 myxcedema, acromegaly, leukemia, and lymphadenoina. In the 

 condition known as lymphatism, enlargement of the gland is 

 associated with increase in the lymphoid tissue of the pharynx, 

 bowel, and other parts of the body. The thymus may also be 

 the seat of inflammation, tuberculosis, and new growths. It is 

 important to bear in mind that wide variations in the size of the 

 gland occur. The older estimates of its weight appear to be 

 excessive. The average weight from birth up to the age of two 

 years is from seven to ten grammes (quarter to half an ounce). 

 After two, the gland remains stationary for some time, but a 

 rapid diminution, accompanied by degenerative changes, occurs 

 at puberty. Eemnants of the gland are present to an advanced 



Enlargement of the thymus is difficult to detect during life 

 owing to the position of the gland behind the manubrium and 

 upper part of the gladiolus. It may, however, give rise to the 

 following signs : Fulness at the root of the neck, venous engorge- 

 ment of the neck, dulness behind the sternum, cardiac irregularity 

 or dilatation, and dyspnoea. The fulness at the root of the neck 

 is due to the fact that both lobes of the gland are prolonged for 

 a short distance upwards along the sides of the trachea ; indeed, 

 the pointed extremity of each lateral lobe can be traced upwards 

 in the fully-developed fcetus, under the lateral lobes of the 

 thyroid gland to the thyro-hyoid membrane. The venous 

 engorgement is explained by the relations of the left innominate 



