Question
Please identify the anatomical structure indicated in the provided image.
| A. |
Abductor pollicis brevis
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| B. |
Extensor pollicis brevis
|
| C. |
Abductor pollicis longus
|
| D. |
Extensor pollicis longus
|
Show Answer
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Correct Answer � D
Explanation
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The Extensor Pollicis Longus (EPL) is a muscle in the forearm that is part of the deep group of the posterior compartment. Its primary function is to extend the thumb at the carpometacarpal and interphalangeal joints, contributing to movements like opening the hand wide and manipulating objects.
Clinical Significance
De Quervain’s Tenosynovitis: This is a common condition affecting the tendons on the thumb side of the wrist, often involving the sheath through which the EPL tendon passes. It causes pain and swelling near the base of the thumb.
Tendon Injuries: The EPL is vulnerable to injury, particularly in fractures of the distal radius (e.g., Colles’ fracture) where the tendon can be damaged or severed.
“Blackberry Thumb”: Overuse of smartphones can lead to strain of thumb tendons including the EPL, causing pain and dysfunction, often referred to colloquially as “Blackberry thumb.”
