**Core Concept:** Saturday Night Palsy is a clinical syndrome characterized by acute unilateral شلل العصب الزندي (Upper Limb Distal Part) due to vascular occlusion caused by retroperitoneal fat shift after massive weight loss.

**Why the Correct Answer is Right:** Saturday Night Palsy is named after the sudden weight loss that typically occurs after a binge eating session on a Saturday night, leading to retroperitoneal fat shift. This fat shift compresses the retroperitoneal structures, including the Ulnar Nerve, at the level of the elbow causing the characteristic symptoms and signs of Ulnar Nerve palsy.

The ulnar nerve is a mixed sensory and motor nerve that innervates the intrinsic muscles of the hand, sensory innervation to the ulnar half of the small finger and half of the ring finger, and provides cutaneous innervation to the medial half of the little finger and half of the ring finger.

**Why Each Wrong Option is Incorrect:**

A. Ulnar Nerve Palsy (Option A) is not the correct answer as Saturday Night Palsy is a specific type of Ulnar Nerve Palsy caused by the described mechanism.

B. Radial Nerve Palsy (Option B) is not the correct answer because Saturday Night Palsy specifically affects the Ulnar Nerve, not the Radial Nerve.

C. Brachial Plexus Palsy (Option C) is not the correct answer as Saturday Night Palsy is a specific type of Brachial Plexus Palsy caused by the described mechanism affecting the Ulnar Nerve.

D. Cervical Radiculopathy (Option D) is not the correct answer as Saturday Night Palsy is a specific type of Cervical Radiculopathy caused by the described mechanism affecting the Ulnar Nerve.

**Clinical Pearl:** The correct diagnosis of Saturday Night Palsy is essential due to the potential for misdiagnosis with other causes of Ulnar Nerve Palsy (e.g., trauma, compression, or inflammation). Early recognition and management can prevent permanent nerve damage and improve recovery in these cases.