There isn't much variation in cervical vertebra number, though. There is an exception: sometimes, the 7th cervical vertebra is found to undergo a partial homeotic transformation and forms a pair of ribs, which are normally found only on thoracic vertebrae. Humans develop cervical ribs with a frequency of about 0.2%; do they also develop cancers? The answer is yes, with a frequency 125 times greater than the general population.
Tuesday, January 24, 2006
I remember being taught that cervical ribs were a relatively harmless congenital anomaly. True, it's been years since I practiced clinical medicine, but is this widely known? Is it true?