The mastoid process is a part of the skull located just behind the ear. It is part of the temporal bone, the large bone that runs along the middle bottom of the skull. Several different roles are filled by this bone, and it is one of the areas of the bone structure that usually clearly differs between men and women. Men have a more pronounced mastoid process than women and this can be helpful when examining human remains belonging to an unidentified person.
This part of the skull projects from the temporal bone and is roughly pyramidal or conical in shape. One important role for this bone is as a point of attachment for several muscles, the splenius capitis, longissimus capitis, diagastric, and sternocleidomastoid. These muscles are one reason the mastoid process tends to be larger in men, because men have bigger muscles as a general rule and thus require larger points of attachment.
The term “mastoid” is derived from the Greek word for “breast,” a reference to the shape of this bone. The temporal bone contains another protrusion, the styloid process, located in close proximity to the mastoid process. The styloid process also serves as a point of attachment for muscles and has a distinctive pointed shape akin to that of a stylus, explaining the origins of the name.
Inside the mastoid process there are a number of air-filled cavities known as mastoid cells. These cells communicate with the middle ear. They can be involved in ear infections when the ear becomes plugged and infectious material drains into the mastoid cells. Treatment for such infections requires antibiotics, and sometimes irrigating the ear to remove material that has built up is also necessary. An ear, nose, and throat specialist can accurately diagnose and treat infections of the middle ear before they contribute to the development of hearing loss and other potential complications.
Blows to the head can cause damage to the temporal bone and mastoid process. When the temporal bone is injured, there is usually a concern that the brain is injured as well as a result of the trauma. In cases where people experience fractures or bruises to the temporal bone, including the mastoid process, they can be identified with medical imaging studies. Treatment is usually concerned with addressing any damage to the brain first, and then determining whether action needs to be taken to repair or stabilize the fracture.