The mastoid is located in the bone cavity behind the ear, intersecting with the mastoid below the right side of the temporal bone, which is the conical protuberance felt behind the earlobe. It is symmetrical on both sides. The mastoid is an important part of the outer ear canal, middle ear, and inner ear, and is also the attachment site for most of the muscles of the head. Below it are muscles such as the sternocleidomastoid and the temporalis. The mastoid is composed of many air cells of different sizes and shapes, interconnected. According to the amount of air and the degree of aerification in the air cells, the mastoid can be divided into aerated mastoid, associated ossified mastoid, and bony partition type mastoid. If the mastoid is well aerated, the earbone can be felt to be prominent and丰满.

When inflammation occurs in the middle ear, the mastoid connects to the middle ear through the largest air cell, the tympanic antrum, and inflammation is prone to spread to the mastoid, forming middle ear mastoiditis. Clinically, acute middle ear mastoiditis mainly manifests as acute and chronic purulent middle ear mastoiditis, with main symptoms including: otorrhea, earache, hearing loss, tinnitus, tenderness over the posterior mastoid area, and even symptoms such as redness, swelling, heat, and pain on the posterior auricular skin.

In clinical terms, due to the concealed location and complex structure of the mastoid, it is not often mentioned in daily life. Therefore, when related inflammation occurs, it is easily overlooked and usually requires X-ray or CT scans for an accurate diagnosis. When treating mastoiditis, it is necessary to thoroughly remove the mastoid lesions to prevent residual lesions and recurring inflammation.