The index finger is the first finger on the average human hand; it's the one next to the thumb and furthest away from the little finger, sometimes known as the 'pinkie'. Then we have the middle finger (the longest one) and the ring finger, so called due to the tradition of wearing engagement and wedding rings on the third finger of the left hand in the UK1.
All fingers, also known as 'digits', have three bones, which are called phalanges; the thumb (like the big toe) has just two phalanges. The knuckles are at the end of the metacarpals (the name of the five bones that run from the wrist through the palm of a hand). The average person's pair of hands contains approximately one-quarter of all their body's bones. The muscles used to move the fingers and thumbs are located in the forearm. These muscles are continuous with tendons, which travel through the wrist to reach the hand and then branch out to the individual fingers and thumbs. If you spread out your hands palms-down and wiggle your fingers, you can see evidence of these muscles. Interestingly, the ring finger and little finger share part of the same muscle, which in some circumstances makes it difficult or even impossible to move the ring finger independently. Try clenching your fist, and then try to straight just the ring finger, without moving the other fingers, you'll find it can't be achieved. However, if you stretched your thumb across your palm, and hold the little finger down, it can now be achieved.
The skin on the fingers is loose and stretchy. It appears wrinkled and there are minute grooves on the underside of the fingers. All this is what gives fingers their flexibility, gripping and even juggling capabilities.
Try this experiment: you'll need a smooth plastic bag and a bar of soap. Place the smooth plastic bag over your hand and then, using the index finger and thumb, attempt to pick up the soap by positioning the index finger on one side of the soap and the thumb on the other, maintaining the vertical angle of both. Now take hold of the soap by squeezing the index finger and thumb together. Squeezing hard, lift the plastic-covered hand upwards and observe what happens. After recovering the soap from wherever it shot off to, attempt the same with your hand without the plastic bag. Notice that the soap stays firmly clamped in your hand and has not gone shooting off into a corner. This is because of the grooves on your fingers and hands.
So What's Special About The Index Finger?
The index finger, also known as the first finger or forefinger, is the hardest-working finger on your hand. It has various solo functions and functions with just one other finger, or the thumb. The following is just a sample of them.
One of the most common uses for the index finger is pointing.
To attract the attention of someone within arm's reach, the index finger may be employed to gently poke his or her arm or shoulder. If you know them well enough, it could be used for a playful poke to their ribs.
Bending the index finger towards you repeatedly is used as a signal to beckon another person to come to you.
Contact lens wearers tend to favour the index finger for placing their contact lenses into their eyes.
The index finger can also be used artistically, as an alternative to a brush when using various different kinds of paint, including chocolate body paint. Your choice of canvas can be varied, including paper, pavement or walls (which could be termed graffiti) or parts of your own or someone else's body (with their permission, of course), such as face painting. You could also use you index finger to draw, write or make patterns in the sand on a beach.
When making a telephone call, whether by a dial or a push-button design, it's usually operated by the index finger.
In social settings the index finger can be raised to attract the attention of pub or restaurant staff, to order refreshments or to obtain the bill. And when you leave those establishments, the index finger can be employed to hail a taxi.
It's the most common finger used for picking the nose, by those that admit that they do.
As if that's not uncouth enough, the index finger is the finger usually employed to pick out belly button fluff, as well as the finger used to poke in other orifices of the human body, including the ear (for the digging out of any ear wax).
The index finger can be a useful exterminator of small insects, such as ants. If they dare to venture too close to you, simply squash them with your index finger.
The term 'trigger finger' has two meanings. It can mean the finger, usually the index finger, used for pressing the trigger on a gun or power tool, such as a drill. Trigger finger is also a medical term for a condition in which the tendons become inflamed and thicken, causing difficulty in bending or straightening of the finger.
There is an old action rhyme called 'Dance, Thumbkin, Dance', in which the index finger is referred to as the 'foreman'.
Some umpires during a cricket match will raise their hand, index finger pointing skyward, to signal that a batsman is given 'out'.
The Index Finger and Middle Finger
These two are used to make the V-sign.
The back-to-front V-sign is used as a form of insult.
Smokers generally hold their cigarette between these two fingers.
The index finger and middle finger are the ones normally positioned on a computer mouse. The middle finger will do the right-clicking, while the index finger will do the left-clicking. Where a wheel is present, it also controls the scroll or presses down on the wheel to bring up the scroll icon.
You can wish yourself or someone else good luck by crossing your index and middle finger.
There is a belief among children, and maybe even some adults, that if you cross your index and middle finger and hold them behind your back while telling a lie, then the lie doesn't count as being a lie at all.
The Index Finger and the Thumb
The index finger is most commonly used with the opposable thumb to form a pinching or gripping motion in order to pick up small or thin objects such as pins, pens or pencils. For most larger objects, all of the fingers are used in conjunction with the thumb in order to improve the grip on the object. Another use is to employ the tip of the index finger and thumb to form a circle, as a visual signal meaning 'okay'.
Among the numerous other uses the index finger and thumb have is flicking small objects, such as small pieces of screwed-up paper off of the office desk. Knitting, crocheting and general needlework all require a lot of work from the index finger and thumb.
1 In countries such as Germany, Norway and Poland it's worn on the right ring finger.