This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorder of Metabolism & Connective Tissue, Subject name: Medicine
In a very tall patient with arm span > height the thumb projects beyond palm when flexed. This sign is known as? 
Select and explain. 
A. Arachnodactyly, B. Finger sign, C. Steinberg's sign, D. Wrist sign
C: Steinberg's sign
Answer: C: Steinberg's sign 
Explanation: Ans. (c) Steinberg's sign. * The image shows Thumb sign seen in Marfan syndrome where the hand is clenched without assistance, the entire thumbnail projects beyond the border of the hand (Steinberg's sign) * Other skeletal findings in Marfan's syndrome are 1. Dolichostenomelia (long, thin limbs) 2. Arm span substantially exceeds the height (> 1.05 times height). 3. Long, thin fingers (arachnodactyly) that are hyperextensible. 4. The thumb may be adducted across the narrow palm and may appreciably overlap the 5th finger when encircling the wrist (wrist sign)