Not present in the proximal row of carpal bone?
**Core Concept**
The proximal row of carpal bones consists of four bones: scaphoid, lunate, triquetrum, and pisiform. These bones form the radiocarpal joint and play a crucial role in wrist movement and stability.
**Why the Correct Answer is Right**
The correct answer is the carpal bone that does not belong to the proximal row. The scaphoid, lunate, and triquetrum bones are indeed part of the proximal row. However, the pisiform bone is a sesamoid bone embedded within the flexor carpi ulnaris tendon and is not part of the proximal row. It articulates with the triquetrum bone to form a small joint.
**Why Each Wrong Option is Incorrect**
**Option A:** Scaphoid - Incorrect because the scaphoid is a key component of the proximal row of carpal bones.
**Option B:** Lunate - Incorrect because the lunate is also a part of the proximal row.
**Option C:** Triquetrum - Incorrect because the triquetrum is part of the proximal row, forming a joint with the pisiform.
**Clinical Pearl / High-Yield Fact**
The proximal row of carpal bones is often remembered using the mnemonic "SLT" (Scaphoid, Lunate, Triquetrum), which helps students recall the bones that form this critical part of the wrist anatomy.
**Correct Answer: D. Pisiform.**