The anatomy of fear

By Ruslan Kulski ·  · From 500 Words: A Scary Moment

Via Facebook comes the above video of boy scaring girl with the threat of spiders.

In this textbook example of a scary moment, we see Pally reacting to a fear stimulus triggered by her husband Ben.

Science can tell us the entire internal biological process that provokes this reaction, but what can it teach us about boys teasing girls?

Now I’m not a physiologist, but let's break down the video and look for some answers.

The word ‘spider’ is made by the vibration of Ben’s larynx and sent via sound waves through the air into Pally’s ear. Tiny hairs in her cochlear convert the sound to nerve impulses that are sent to the brain. 

The primary auditory cortex receives the signals and they make their way to the mid brain where the hypothalamus activates the hypothalamic–pituitary–adrenal axis which releases hormones and adrenaline. Pally's heart rate increases, nutrients are released to power the muscles and she gets tunnel vision. 

The video cuts off here but the fascinating biological ballet continues off camera.

The flexor digitorum muscles pull the hand into a fist on Pally’s right and grip the table on the left. The bicep and the pectoralis major are the primary muscles used in flipping the table. 

Her quadricepses concentrically contract, propelling Pally out of her chair. 

At this stage, a sinuous intertwining of facial muscles forms an expression on Pally's face which causes Ben's own fear response to kick in. 

It’s the leg muscles, both her quads and her hamstrings that deliver most of the power behind the punch. Pally's metacarpophalangeal joint forms the knuckle that makes contact with Ben’s nose. Ben’s lacrimal glands then secrete lacrimal fluid, the build up of which causes a runny nose and tears. 

Subsequently, the index finger's distal phalange bone summons the ambulance.

While it’s amazing that all of this complex physiology happens unconsciously and pays off hilariously in milliseconds, the much more complex process of placating an angry wife requires a lot of thought and can take ages. But it's worth it.

Published 31 Jan 2013. 

1 Comment

  • Alex Smee


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