“A nerve was originally a sinew or a tendon — the Romans could not tell the difference between the fibers that move your muscles and the fibers that carry your sensations. The word covered both.”
Nervus in Latin meant sinew, tendon, or bowstring — anything fibrous and strong in the body. The Romans did not distinguish clearly between nerves and tendons. Both looked like cords. Both connected things. The Greek equivalent, neuron, had the same ambiguity. Galen of Pergamon, writing in the second century CE, began to separate the concepts, but the Latin word nervus continued to cover both for centuries.
By the seventeenth century, anatomists had established that nerves were distinct from tendons: nerves carried sensation and commands from the brain, while tendons attached muscles to bones. The word 'nerve' narrowed to mean the sensory/motor fibers, and 'tendon' (from Latin tendere, to stretch) claimed the structural fibers. The two-thousand-year confusion was over. The word split in two.
The figurative meanings multiplied. 'Nerve' as courage appeared by the early 1800s — having the nerve to do something. 'Nerves' as anxiety appeared around the same time — suffering from nerves, a nervous condition. Victorian medicine treated 'nervous complaints' as a legitimate diagnostic category. The word that meant a physical fiber in the body became a metaphor for emotional resilience and its failure.
Modern neuroscience has revealed that the human body contains approximately 7 trillion nerves, carrying electrical signals at speeds up to 120 meters per second. The nerve is an electrical cable. The Romans, who saw a bowstring, were closer to the truth than they knew — a nerve transmits force, just not the kind they imagined.
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Nerve is four words in one. The anatomical nerve carries signals. Having nerve means having courage. Being nervous means lacking it. Having the nerve means having audacity. The body and the metaphor are tangled as thoroughly as the Romans' nerves and tendons once were.
The word carries both strength and fragility. 'She has nerve' is a compliment. 'He's a nervous wreck' is a diagnosis. The same Latin fiber became both courage and collapse.
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