Upper limb cases

Case 1 A 23-year-old male reports that he was playing “hoops” with friends from college, tripped as he was driving to the basket, and fell on his outstretched right hand with the palm down. Two days later, he phoned his anatomist father and related that his right wrist was painful. Later that day, he visited his father who noted that the wrist was slightly swollen, tender, but without deformity. He instructed his son to extend the right thumb, thereby accentuating the anatomical “snuff box,” which is extremely tender to deep palpation. His father told him a radiograph is needed.

What is the most likely diagnosis? What is the most likely anatomic defect?

Objectives 1. Be able to describe the bones and joints of the wrist. 2. Be able to describe the anatomy of the radius and ulnar as it relates to the transmission of forces in the upper limb and its effect on the forearm bones. 3. Be able to describe the boundaries of the anatomical snuff box and its clinical significance.

1 A 23-year-old accountant trips over a briefcase and falls onto his outstretched hand. A carpal bone fracture is suspected. Which of the following bones is most likely fractured? A. Scaphoid B. Lunate C. Triquetrum D. Pisiform E. Capitate

2 You are examining a radiograph of a patient’s wrist and note malalignment (dislocation) of one of the carpal bones. Which of the following is most likely to be the dislocated carpal bone? A. Scaphoid B. Lunate C. Triquetrum D. Capitate E. Hamate

3 A 24-year-old male slips on a banana peel and falls onto his outstretched hand. Which of the following structures transmits the force from the radius to the ulna? A. Triangular fibrocartilage B. Interosseous membrane C. Scaphoid bone D. Ulnar collateral ligament E. Radial collateral ligament

Case 2 A 34-year-old pregnant woman complains of tingling of her right index and middle fingers over a 2-month duration. She notes some weakness of her right hand and has begun to drop items such as her coffee cup. She has otherwise been healthy and denies any trauma or neck pain.

What is the most likely diagnosis? What is the anatomic mechanism for this condition?

Most likely diagnosis: Carpal tunnel syndrome Anatomical mechanism: Compression of the medial nerve as it passes through the carpal tunnel of the wrist

1.Be able to describe the structures that form and pass through the carpal tunnel. 2. Be able to describe the course, branches, and muscles innervated by the median nerve in the forearm and hand. 3. Be able to describe the skin areas supplied by the median nerve in the hand. 4. Be able to describe the course of the ulnar nerve at the wrist as it relates to the carpal tunnel.

1 You are examining an axial (cross-section) magnetic resonance imaging (MRI) scan of the wrist and have identified the carpal tunnel. Which of the following is the structure that forms the anterior wall of the tunnel? A. Palmar aponeurosis B. Volar carpal ligament C. Flexor retinaculum D. Extensor retinaculum E. Deep fascia

2 If the median nerve were severed in an industrial accident at the wrist, which of the following muscles would still retain their function? A. Flexor pollicis brevis B. Abductor pollicis brevis C. Opponens pollicis D. Lumbricals of the index and middle fingers E. Lumbricals of the ring and little fingers