Okay, let's tackle this question. The question is about the ideal regional anesthetic technique for a child with a dislocated fracture of the first metacarpal. First, I need to recall the anatomy of the hand and the nerves involved in the first metacarpal area. The first metacarpal is part of the thumb, so the relevant nerves would be the median nerve and the radial nerve. The median nerve innervates the lateral three and a half digits, including the thumb's palmar surface. The radial nerve supplies the dorsal aspect of the thumb and index finger.

For a fracture in this area, the anesthetic should block both the sensory and motor nerves. The first metacarpal is near the wrist, so possible techniques might include a wrist block or a digital block. A digital block would target the nerves as they enter the finger, but for a metacarpal fracture, a more proximal block might be better. The radial and median nerves run in the forearm and can be blocked at the wrist. A volar wrist block could anesthetize both the radial and median nerves, covering the thumb. Alternatively, a digital block might be used, but since the injury is at the metacarpal level, a block at the wrist would be more appropriate to ensure adequate anesthesia for the entire area involved in the fracture.

Looking at the options, if one of them is a volar wrist block, that would be the correct answer. Other options like a brachial plexus block (like an interscalene) would be too proximal for a hand procedure. A digital block might be too distal and not cover the entire metacarpal area. A Bier block is a general anesthetic technique, not regional. So the ideal technique here is a volar wrist block targeting the median and radial nerves. The key is to block both nerves to cover the thumb's innervation.

**Core Concept**
This question tests knowledge of regional anesthesia techniques for hand injuries. The first metacarpal (thumb base) is innervated by the **median nerve** (palmar surface) and **radial nerve** (dorsal surface), requiring blockade of both nerves for optimal anesthesia.

**Why the Correct Answer is Right**
A **volar wrist block** (blocking the median and radial nerves at the wrist) is ideal for thumb/base-of-metacarpal injuries. It anesthetizes the sensory branches supplying the thumb’s palmar (median nerve) and dorsal (radial nerve) surfaces. This technique avoids complications of more proximal blocks (e.g., brachial plexus) while ensuring adequate coverage for metacarpal procedures.

**Why Each Wrong Option is Incorrect**
**Option A:** *Digital block* targets nerves at the finger level, insufficient for metacarpal fractures requiring proximal coverage.
**Option B:** *Bier block* is intravenous regional anesthesia for upper extremity procedures, but it carries risks in children and is less precise than nerve blocks.
**Option C:** *Brachial plexus block* (e.g., interscalene) is overly broad and unnecessary for localized thumb injuries.

**Clinical Pearl / High-Yield Fact**
Remember the **“thumb rule”**: thumb injuries require blocking both **median** and **radial nerves**. Volar wrist blocks

✓ Correct Answer: C. Axillary block