The origin of the mid-gut (mesenteron), outer layers become continuous, forming respectively the amnion that has no chitinous lining in the developed insect, is the disputed and the serosa (fig.
Quick Answer. Possible causes of swollen lymph nodes behind the ears include an ear infection, an abscessed tooth, a cold, the flu or another infection, according to MedlinePlus. Lymph nodes also commonly appear beneath the jaw, on the back of the head, or on the neck, armpit or groin.
The Eustachian tube can be blocked, or obstructed, for a variety of reasons. 1  The most common cause is a cold (upper respiratory infection). 2  Sinus infections and allergies may also cause swelling of the tissue lining the Eustachian tube. Simply put, a stuffy nose leads to stuffy ears.