Could we all be Olympians?
The winter Olympics is now in full flow and we can sit back and marvel at the athletic abilities of the contestants. It would be nice to think that we could all achieve peak performance like them, but the truth is that some people's bodies are better equipped for certain things than others.
You would think that everybody had exactly the same muscle structure, wouldn't you? Well, by and large, we do, yet there are sometimes subtle differences. You see, in anatomy we describe each muscle as having an origin and an insertion. Its origin is the bone it is anchored to, and its insertion is to the bones or structure that it has the function of moving. Both the origin and the insertion can vary slightly in individuals. That slight change in position may affect the function very slightly. And that change may be an advantage or a disadvantage.
In addition to these subtle differences there are, in fact, muscles that are 'coming' or 'going.' This is utterly fascinating, since they represent an element of proof about Charles Darwin's theory of evolution, because these 'coming and going' muscles are muscles that are appearing in a species or ones that are disappearing.
The palmaris longus is a muscle that can be made to stand out at the wrist by flexing your palm towards the forearm. It will be apparent as a cord-like tendon. It is absent in about fifteen per cent of the population. Not having one does not affect the strength of the wrist or the hand. It is a muscle that is used in other species to expose the claws! We don't do that any longer, so it is a gradually disappearing
muscle.
The peroneus tertius muscle in the foot is an appearing muscle. Not everyone has it. It is an appearing muscle in the species. It gives the foot additional mobility and may be an advantage in runners, dancers, skaters and skiers.
In anatomy we talk about vestigiality. This refers to structures or organs that no longer have a function in a species. They are another indication of the evolution of a species. And we humans have several of these.
The occipito-frontalis muscle extends from the back of the head (the occiput) to the forehead (the frontal bone). In many animals it helps to keep the head from falling. In humans it has become a sheet-like structure called an aponeurosis that forms part of the scalp. It no longer holds the head up, since we are erect creatures, but it helps to raise the eyebrows and crease the forehead in facial expression.
Finally you may notice another example when you get goosebumps while watching the Olympics. Here you are experiencing the effect of a vestigial reflex. It is designed to make fur or hair stand on end, to make you look bigger, or to trap air in the hair to retain heat.
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Wednesday 23 May 2012
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