True about peripheral nerve injury in upper limb-a) Radial nerve injury cause anaesthesia over anatomical snuff boxb) Median nerve injury cause wrist dropc) Ulnar nerve injury cause claw handd) Index finger anesthesia is caused by median nerve injurye) Thumb anaesthesia is caused by ulnar nerve injury
**Core Concept**
Peripheral nerve injuries in the upper limb can cause distinct patterns of sensory and motor deficits, depending on the specific nerve affected. These deficits are a result of the specific functions and distribution of sensory and motor fibers within each nerve.
**Why the Correct Answer is Right**
The correct answer, **acd**, is based on the specific patterns of sensory and motor deficits associated with radial, ulnar, and median nerve injuries.
* Radial nerve injury typically causes anaesthesia over the anatomical snuff box, which is a result of the loss of sensory fibers within the radial nerve. The radial nerve is responsible for supplying sensation to the back of the hand and the thumb, index, middle finger, and radial half of the ring finger.
* Ulnar nerve injury typically causes claw hand, which is a result of the loss of motor fibers within the ulnar nerve. The ulnar nerve is responsible for supplying motor innervation to the intrinsic muscles of the hand, including the interossei and lumbricals.
* Median nerve injury can cause a variety of deficits, including wrist drop (due to loss of motor fibers) and index finger anaesthesia (due to loss of sensory fibers). The median nerve is responsible for supplying sensation to the palmar surface of the thumb, index, middle finger, and radial half of the ring finger.
**Why Each Wrong Option is Incorrect**
* **Option A:** Radial nerve injury does not cause wrist drop, as wrist drop is typically associated with median nerve injury.
* **Option B:** Median nerve injury does not typically cause wrist drop, as wrist drop is typically associated with radial nerve injury. However, median nerve injury can cause wrist drop if the posterior interosseous nerve is injured.
* **Option D:** Index finger anaesthesia is caused by median nerve injury, not ulnar nerve injury. The ulnar nerve supplies sensation to the little finger and the ulnar half of the ring finger.
* **Option E:** Thumb anaesthesia is not typically caused by ulnar nerve injury, as the ulnar nerve supplies sensation to the little finger and the ulnar half of the ring finger.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that the specific pattern of deficits associated with a peripheral nerve injury can provide valuable clues about the affected nerve and the location of the injury.
**✓ Correct Answer: C. acd. Radial nerve injury cause anaesthesia over anatomical snuff box, Ulnar nerve injury cause claw hand, Median nerve injury cause index finger anesthesia.**