Four carpal bones are present at what age: DNB 09
**Core Concept**
The question is testing the knowledge of carpal bone development in humans. The carpal bones are a group of eight small bones in the wrist that form the carpal tunnel. They develop and ossify at different stages of human growth.
**Why the Correct Answer is Right**
The four carpal bones that are present at birth are the capitate, hamate, triquetrum, and pisiform. These bones are initially cartilaginous and start to ossify during fetal development. By the time a child is born, these bones have already begun to ossify, but they are not yet fully developed. The remaining four carpal bones (scaphoid, lunate, trapezium, and trapezoid) develop and ossify later in childhood.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the four carpal bones present at birth are not the scaphoid, lunate, trapezium, and trapezoid. These bones develop and ossify later in childhood.
* **Option B:** This option is incorrect because the four carpal bones present at birth are not the capitate, hamate, triquetrum, and scaphoid. The scaphoid develops and ossifies later in childhood.
* **Option C:** This option is incorrect because the four carpal bones present at birth are not the capitate, hamate, triquetrum, and pisiform. This option is missing the pisiform.
* **Option D:** This option is incorrect because it is not a complete list of the four carpal bones present at birth.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the carpal bones develop and ossify at different stages of human growth. The four carpal bones present at birth are the capitate, hamate, triquetrum, and pisiform.
**Correct Answer:** D.