Scalp

scalp the integument covering the top of the head. It consists of three layers of tissue: the skin, an underlying layer of tissue and blood vessels, and the occipitofrontalis muscle stretching from the eyebrows to the back of the head. Except for its abundant growth of hair, the skin of the scalp resembles that of the rest of the body but is especially rich in blood vessels. Hence profuse bleeding may be associated with scalp injuries.

Mastoiditis

Mastoiditis is an infection of the mastoid bone of the skull. The mastoid is located just behind the ear. Mastoiditis is usually caused by a middle ear infection (acute otitis media). The infection may spread from the ear to the mastoid bone of the skull. The mastoid bone fills with infected materials and its honeycomb-like structure may deteriorate. Mastoiditis usually affects children. Before antibiotics, mastoiditis was one of the leading causes of death in children. Now it is a relatively uncommon and much less dangerous condition.