This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Upper limb, Subject name: Anatomy
[{'content': 'Medial boundary of anatomical snuffbox is formed by \nSelect and explain. \nA. Extensor pollicis longus, B. Extensorpollicis brevis, C. Abductor pollicis longus, D. Flexor carpi ulnaris', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANATOMICAL SNUFF BOX:-Elongated triangular depression seen on the lateral side of the dorsum of hand when the thumb is hyperflexed. BOUNDARIES:1. Anterolaterally-tendon of abductor pollicis longus,tendon of extensor pollicis brevis.2. Posteromedially-tendon of extensor pollicis longus.3. Floor-scaphoid and trapezium.4. Roof-skin and superficial fascia.Contents:-1. Radial aery.Structures crossing the roof deep to skin:-1. Cephalic vein.2. Terminal branch of superficial radial nerve. Pulsations of radial aery felt here.Tenderness felt here indicates fracture of scaphoid bone.Cephaloc vein at this site can be used for giving iv fluids. {Reference: Vishram Singh , page no.171} Figure 9.33,page no:122 BD chaurasia', 'role': 'assistant'}]