Upper Limb — MCQs

Upper Limb Indian Medical PG Practice Questions and MCQs

Question 831: Which spinal nerves contribute to the formation of Erb's point?

A. C4 and C5
B. C5 and C6 (Correct Answer)
C. C6 and C7
D. C6 and T1

Explanation: ***C5 and C6*** - Erb's point is a key anatomical landmark on the brachial plexus, specifically located at the **superior trunk**. - This point receives contributions from the **ventral rami** of both the **C5 and C6 spinal nerves**. *C4 and C5* - While C5 is a contributor, the **C4 nerve root** typically contributes to the **cervical plexus** and the phrenic nerve, not the superior trunk of the brachial plexus relevant to Erb's point. - Involvement of C4 would suggest a more superior injury, distinct from classic Erb's palsy. *C6 and C7* - The **C7 nerve root** primarily forms the **middle trunk** of the brachial plexus. - Erb's point is specifically defined by the union of C5 and C6, forming the superior trunk. *C6 and T1* - **T1** is a primary contributor to the **inferior trunk** of the brachial plexus. - Although C6 is involved in Erb's point, T1's role is in the lower part of the plexus, associated with Klumpke's paralysis.

Question 832: A 35-year-old man presents with numbness and weakness in the fourth and fifth fingers of his right hand, and examination reveals a claw hand deformity. Which nerve is most likely injured?

A. Median nerve
B. Ulnar nerve (Correct Answer)
C. Radial nerve
D. Musculocutaneous nerve

Explanation: ***Ulnar nerve*** - **Ulnar nerve injury** at the elbow or wrist leads to weakness in the intrinsic muscles of the hand supplied by the ulnar nerve, including the **interossei** and the medial two **lumbricals**, resulting in a **claw hand deformity** of the fourth and fifth fingers [1]. - Sensory disturbances from ulnar nerve damage typically involve the palmar and dorsal aspects of the **medial 1.5 digits** (pinky finger and half of the ring finger), aligning with the patient's numbness in the fourth and fifth fingers [1]. *Median nerve* - Injury to the median nerve would primarily affect the **first three and a half digits** (thumb, index, middle, and half of the ring finger), leading to **ape hand deformity** or **carpal tunnel syndrome** symptoms [1]. - The median nerve innervates the **thenar muscles** and lateral two lumbricals; its damage would cause weakness in thumb opposition and flexion of the index and middle fingers [1]. *Radial nerve* - Radial nerve damage typically results in **wrist drop**, due to paralysis of the wrist and finger extensors, and sensory loss over the posterior aspect of the forearm and hand [1]. - It would not cause a claw hand deformity or specific numbness in the fourth and fifth digits. *Musculocutaneous nerve* - The musculocutaneous nerve innervates muscles of the anterior compartment of the arm (e.g., **biceps brachii** and **brachialis**), and provides sensation to the lateral forearm. - Injury to this nerve would primarily cause weakness in elbow flexion and forearm supination, and numbness in the lateral forearm, but not hand deformities or specific numbness in the fourth and fifth digits.

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Arm and Cubital Fossa

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Joints of Upper Limb

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Nerves of Upper Limb

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Arterial Supply and Venous Drainage

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Muscles and Their Actions

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Applied Anatomy and Clinical Correlations

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Surface Anatomy and Landmarks

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Upper Limb — MCQs

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