Mastoid process

Looks like

A thumb-tip bump of the skull just behind and below the ear, honeycombed inside with small air cells.

What it does

Anchors the neck muscle that turns the head (sternocleidomastoid) and others behind it.

Keeping it well

The air cells can fill with pus after an ear infection (mastoiditis): a red, swollen, painful bump behind the ear pushing the ear forward needs a doctor the same day.

Related conditions

• Achondroplasia
• Acromegaly
• Brain abscess
• Cholesteatoma
• Fractures
• Fragility fracture
• Frailty & falls in older age
• Hyperparathyroidism
• Osteogenesis imperfecta (brittle bone disease)
• Osteomalacia & rickets
• Osteomyelitis (bone infection)
• Osteoporosis
• Paget's disease of bone
• Sarcoma
• Traumatic brain injury (moderate to severe)
• Vitamin B1, C and other deficiencies
• Vitamin D deficiency