Mastoid Process

Mastoid process, overview, development, function and mastoditis.

1. Mastoid Process By Ali S. Mayali Fig 1.0 – Mastoid Process The mastoid is named for the Greek word  mastos meaning breast , and  eidos  meaning  resemblance . This is reflective of the nipple-like shape of the mastoid process.

2. Overview Two projections in the lower rear of the skull that lie below each external auditory meatus on the mastoid portion of the temporal bone. the mastoid provides an attachment for several neck muscles: the posterior belly of the  diagastric, SCM and other muscles. The mastoid process has clinical importance since the tissues in this region contain many interconnected air cells, called the mastoid cells. Fig 1.1 – Mastoid Process

3. Development It is undeveloped in the newborn child and grows only as the result of the pull of the sternocleidomastoid. It can be recognized as a bony projection at the end of the second year . until puberty, it’s composed of cancellous bone, which is less dense and softer than other bones, making it weaker and less stiff. After puberty the mastoid cells develop. Fig 2.0 – Neonate Skull

4. Clinical A newborn has no mastoid process. This means that there is less protection for the facial nerve or CN VII after birth. This nerve arises from the stylomastoid foramina and since there is no mastoid process yet, it develops close to the surface. This makes it prone to injury or damage during surgical procedures such as forceps delivery or operations for treating middle ear problems. Fig 3.0 – Stylomastoid foramen

5. Attachments Sternocleidomastoid. Diagastric posterior belly. Splenius capitis . Longissimus capitis . Fig 4.0 – Muscles attached to the mastoid bone

6. Mastoiditis Mastoid antrum is an air space in the petrous portion of the  temporal bone, communicating posteriorly with the  mastoid air cells  and anteriorly with the  epitympanic recesses  of the middle ear. Mastoid air cells are covered by a mucoperitoneum that is continuous with epithelium of the middle ear cavity providing a potential pathway for spread of infection from the middle ear cavity to the mastoid air cells. A condition known as mastoiditis Fig 5.0 – Mastoid antrum & Cells

7. Mastoiditis Inflammation of mucosal lining of antrum and mastoid air cells system. Earache & discharge , fever and mastoid tenderness. Investigations include Blood CP, CT scan and x-ray. Treatment include antibiotics, myringotomy (tiny incision is created in the eardrum to relieve pressure) and mastoidectomy in severe cases. Pic 1.0 –  protrusion of the  auricle.