Page 60 - ASOP ROT Study Guide

B. THE UPPER EXTREMITY

In this section you will study the anatomy and physiology of the upper limb. This is the part of the
body commonly known as die "arm". The unit starts by describing the main features of the upper
limb and the method by which this is suspended from the rest of the skeleton. Then the shoulder,
elbow and wrist joints are described along with their associated muscles, nerves and movements.
The section concludes with a sub-section on the hand and thumb.

7. STRUCTURE & FUNCTION OF THE UPPER LIMB
7 . 1 Function
The main role of the upper limb is to position the hand in space. In contrast to the lower limb,
therefore, the joints of the upper limb are designed to achieve a wide range of movement rather
than to provide stability.
The development of the hand as an instrument for exploring and modifying the environment is of
great significance to humans. The upper limb allows us to position a hand on any part of our body,
to reach out our hands to manipulate or sense objects in our environment and to communicate with
each other. We can use our hands to gather information about the size, shape, texture and
temperature of an object, and to manipulate objects with great skill and precision or to grip them
powerfully. A very special feature of our hand is the thumb which "opposes" the other digits,
making it easier to hold and manipulate objects. This, combined with a highly specialized muscle
and nerve supply, makes the hand a highly sophisticated yet powerful tool.

7.2 General Layout
The upper limb (illustrated below) consists of three segments of bones and joints: the arm, the
forearm and the hand. The shoulder, elbow and wrist joints define the ends of these segments
and allow them to move relative to each other. The side of the upper limb seen when the palm of
the hand is uppermost is the flexor (anterior) surface. The opposite surface (the back of the hand),
is the extensor (posterior) surface.

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