Wormian bones are seen in all EXCEPT:
**Core Concept**
Wormian bones are small, irregular bones found within the sutures of the skull. They are a normal variant but can also be associated with various pathological conditions. The presence of Wormian bones is often used as a radiological marker in the diagnosis of certain genetic and metabolic disorders.
**Why the Correct Answer is Right**
Wormian bones are typically seen in conditions that affect bone growth and development, such as osteogenesis imperfecta, cleidocranial dysplasia, and Down syndrome. In these conditions, the abnormal bone growth and development lead to the formation of small, irregular bones within the sutures of the skull. The presence of Wormian bones can also be seen in conditions that affect the bone matrix, such as rickets and osteomalacia.
**Why Each Wrong Option is Incorrect**
**Option A:** is incorrect because Wormian bones are not typically seen in healthy individuals, although they can be a normal variant in some cases.
**Option B:** is incorrect because cleidocranial dysplasia is a condition that is associated with the presence of Wormian bones.
**Option C:** is incorrect because Down syndrome is a condition that is associated with the presence of Wormian bones.
**Clinical Pearl / High-Yield Fact**
Wormian bones can be a useful radiological marker in the diagnosis of certain genetic and metabolic disorders. They are often seen in conditions that affect bone growth and development, and their presence can be an important clue in the diagnosis of these conditions.
**Correct Answer: D. Normal individuals.**