In ‘Down’s syndrome’ the shape of the head is –
**Core Concept**
Down's syndrome, also known as trisomy 21, is a genetic disorder caused by an extra copy of chromosome 21. This condition affects physical and intellectual development, leading to various characteristic features.
**Why the Correct Answer is Right**
Individuals with Down's syndrome often exhibit a characteristic facial and cranial morphology, including a flat face, a short neck, and a specific head shape. The head shape in Down's syndrome is typically described as brachycephalic, meaning it is shorter in length than average. This is due to the premature closure of the cranial sutures, leading to a more compact skull. The brachycephalic head shape is a result of the altered growth and development of the cranial bones.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the characteristic head shape in Down's syndrome.
**Option B:** While individuals with Down's syndrome may exhibit a short neck, this is not a defining feature of their head shape.
**Option C:** This option is not accurate, as the head shape in Down's syndrome is typically brachycephalic, not dolichocephalic (longer in length).
**Clinical Pearl / High-Yield Fact**
A key feature of Down's syndrome is the presence of a single palmar crease, also known as a simian crease, which is a transverse crease across the palm. This is a useful clinical finding to aid in diagnosis.
**Correct Answer:** C.