First, behind the earlobe is the location of an important lymph node in the body, which filters and fights foreign invading viruses and bacteria. Second, superficial to the surface are the superficial lobes of the mastoid and parotid glands, while deeper down are the sternocleidomastoid muscle, the blood vessels of the neck, the facial nerve, and the deep lobe of the parotid gland. The mastoid is part of the middle ear cavity and develops gradually with age, so that the size of the mastoid is not exactly the same for each person or even for the same person bilaterally. The papillae are attached to the sternocleidomastoid muscle and usually have enlarged superficial lymph nodes on the surface. Deep inside the nipple there is the facial nerve and the stalk, and deep inside the stalk and the diastasis there are also the arteries and veins and nerves of the neck, so the back of the earlobe is a very important part of the body.