A 69-year-old man has numbness in the middle three digits of his right hand and finds it difficult to grasp objects with that hand. He states that he retired 9 years earlier, after working as a carpenter for 50 years. He has atrophy of the thenar eminence ( Fig ). Which of the following conditions is the most likely cause of the problems in his hand?,

**Core Concept**
The patient's symptoms, including numbness in the middle three digits and difficulty grasping objects, along with thenar atrophy, are indicative of a specific type of nerve compression. This condition is related to the anatomy of the wrist and the median nerve, which is responsible for motor and sensory innervation to the hand.

**Why the Correct Answer is Right**
The patient's symptoms are consistent with carpal tunnel syndrome (CTS), a condition caused by compression of the median nerve as it passes through the carpal tunnel in the wrist. The median nerve provides motor innervation to the thenar muscles, which are responsible for thumb movement and opposition. Compression of this nerve can lead to atrophy of the thenar muscles, as seen in this patient. The numbness in the middle three digits is due to sensory innervation of the median nerve.

**Why Each Wrong Option is Incorrect**
**Option A:** Radial nerve palsy would cause weakness of wrist extension and sensory loss on the back of the hand, which does not match this patient's symptoms.

**Option B:** Ulnar nerve palsy would cause weakness of intrinsic hand muscles, leading to claw hand deformity, and sensory loss on the little finger and half of the ring finger.

**Option C:** Thoracic outlet syndrome would cause pain and weakness in the arm, particularly with activities that involve lifting the arm above the head.

**Option D:** Dupuytren's contracture is a condition that causes nodules and cords in the palmar fascia, leading to flexion contracture of the fingers, and does not typically cause numbness or thenar atrophy.

**Clinical Pearl / High-Yield Fact**
Carpal tunnel syndrome is a common condition, especially in individuals with a history of repetitive wrist motion or trauma, and can be exacerbated by conditions such as diabetes, hypothyroidism, and pregnancy.

**Correct Answer:** C. Carpal tunnel syndrome.

✓ Correct Answer: A. Compression of the median nerve in the carpal tunnel