The mastoid process is a bony projection located below the external ear canal. It provides attachment points for neck muscles and contains air cells. In infants and children, the mastoid process is not fully developed and contains softer bone, making the nearby facial nerve more vulnerable. As the mastoid process grows and the air cells develop during puberty, it provides more protection for the facial nerve. Mastoiditis is an infection of the mastoid air cells that can develop from a middle ear infection. It causes ear pain, discharge and tenderness and is usually treated with antibiotics or surgery.

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.