Give me a hand!
In this activity using your hand you will make observations and answer
questions to gain a better understanding of how specialised the primate hand
has become.
Hold your hand out in front of you with the back of your hand towards your face.
1.
Describe how the thumb’s position differs from that of the fingers.
2.
Explain two advantages of the thumb being in this position.
Now turn your hand over and observe the palm. Touch each of your fingers with
your thumb.
3.
What did you notice about the way your thumb could move? Can your
other fingers move in a similar way?
© WestOne Services 2010
SCIENCE1437
1
4.
What is the name given to this specialised movement?
5.
Pick up a pen and hold it in a writing position. What is the name of this
type of grip?
6.
Now pick up a pen and wrap your fingers and thumb around the pen. What
is the name of this type of grip?
7.
The diagram below is of a human hand with the palm facing towards you.
Which hand is the diagram showing?
8.
There are two muscles labelled on the diagram below. Use references to
help you establish which one would move the thumb towards the other
fingers and which one would move the thumb back to its original position.
a)
Thumb forward
b)
Thumb back
© WestOne Services 2010
SCIENCE1437
2
Reproduced with the permission of the Science Teachers Association of Western Australia Inc
Opposability is made possible by a special bone located at the base of the
thumb called the trapezium.
Locate this on the diagram. Then using your right hand, palm upwards facing
towards you, locate where this bone would be in your thumb.
With your right hand held out, palm up, straighten your fingers so that they lie
side by side. Now move your thumb across to touch your little finger.
9.
Which way does your thumb nail point before and after moving your thumb
across?
This ability to rotate through 45 around its own longitudinal axis is made
possible due to a special type of joint found only in the human hand, the saddle
joint.
10. In summary, write a list of the structures and functions that are adaptations
for object manipulation.
© WestOne Services 2010
SCIENCE1437
3