A 26 years male person has got injury to mid-arm. Patient developed wrist drop, finger drop and loss of sensation on dorsum of hand. Patient is able to do elbow extension. The diagnosis is
## **Core Concept**
The question tests the understanding of radial nerve injury, specifically its clinical presentation and the motor and sensory functions affected. The radial nerve is responsible for wrist and finger extension, and sensation over the dorsum of the hand. Elbow extension is primarily controlled by the triceps brachii, which is innervated by the radial nerve but has a different point of innervation.
## **Why the Correct Answer is Right**
The patient's symptoms of wrist drop, finger drop, and loss of sensation on the dorsum of the hand point towards a radial nerve injury. The radial nerve runs down the back of the humerus and is particularly susceptible to injury in the mid-arm region. The fact that the patient can still perform elbow extension suggests that the injury is likely below the level where the radial nerve branches to the triceps brachii, which typically occurs more proximally. This pattern of injury is consistent with a radial nerve lesion in the mid to distal humerus.
## **Why Each Wrong Option is Incorrect**
- **Option A:** Incorrect because the description does not match a typical ulnar nerve injury, which would primarily affect the little and ring fingers and cause clawing of these fingers.
- **Option B:** Incorrect because a median nerve injury would result in thenar atrophy, weakness of thumb opposition, and sensory loss over the palmar surface of the thumb, index, and middle fingers, not wrist drop or loss of sensation on the dorsum of the hand.
- **Option C:** This seems to be the correct answer based on the question but let's evaluate option D.
- **Option D:** Incorrect because the symptoms described do not align with a combined injury or a different type of nerve injury that would spare elbow extension.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the **radial nerve** is often injured in the mid-arm region due to fractures of the humerus. The classic presentation includes wrist drop and inability to extend the wrist and fingers, but elbow extension may be preserved if the injury is distal to the branches supplying the triceps.
## **Correct Answer:** . Radial nerve injury below the level of triceps branch.