RANGE
The word range may be used in two senses. First, it may refer to the amount of movement which occurs in a joint. Secondly, it may refer to the amount of shortening or lengthening of a muscle as it acts to produce or control movement.
Range of movement at a joint This is the total quantity of movement when a joint is moved to its full extent. The names of the movements are those anatomical names which are normally applied (see Chapter 3) and the method of recording range is well laid down in the book Joint Motion published by the American Orthopaedic Association.
One may measure and record the amount of range of movement in a certain direction, e.g. the range of abduction of the shoulder joint is 90°. The range of adduction of the shoulder joint is 90°. This is normal range. If, however, the range is limited the available range can be recorded when a zero starting point is necessary and the recording could be from 10° of abduction to 80° of abduction, i.e. the first 10° and last 10° of movement are absent and the available range is 70°.
MUSCLE
When a muscle contracts and performs a movement it is said to have acted through a certain range. When a muscle is fully stretched and contracts to the limit of its normal capacity it is described as having contracted and produced a movement in full range. For purposes of description full range is broken down into three components which overlap.
Outer range of contraction is from full stretch of the muscle to mid point of the full range. Inner range of contraction is from the above-mentioned mid point to full contraction. Middle range of contraction is any distance between the middle of the outer range and the middle of the inner range. Middle range of
contraction is that in which many muscles work most of the time when they are producing movement.
Extreme inner range is more difficult to perform because it requires a contraction of a greater number of
motor units of which a muscle is composed and usually also the muscle is pulling with an adverse angle of pull which diverts some of the effort to distracting the two joint surfaces.
Extreme outer range is also difficult because usually the angle of pull is adverse and some of the effort is diverted to compressing the two joint surfaces and, in addition, the muscle may have to overcome inertia and be working against a long or heavy weight arm. It is possible when some movements occur that in moving from full outer to full inner range, with the body in certain positions, gravity may resist the movement when outer range is performed and assist the movement when inner range is performed. When this occurs the same muscles will not be working throughout the range of movement. The last part of the range of movement (gravity assisted) will be controlled by the antagonists working in their outer range but working in isotonic lengthening. It is thus possible to describe muscle work by mode of action, i.e. type of muscle activity (isotonic shortening or lengthening or isometric) and, in the former case, to describe the range of the muscle work.
In the movement from A–B the elbow flexors are working in isotonic
lengthening in outer range (pulled by gravity). In the movement
from D–E the elbow extensors are working in isotonic shortening in
outer range (resisted by gravity); from B–C the elbow extensors are
working in isotonic lengthening in outer range (pulled by gravity).
In the movement from D–E the elbow extensors are working in
isotonic shortening in outer range (resisted by gravity); from E–F
the elbow flexors are working in isotonic lengthening in outer range
(pulled by gravity)
THOSE ABOVE ARE COLLECTED FROM SOME BOOKS AND
WEBSITES..
THANK YOU,
SRIKUMARAN PHYSIOTHERAPY
CLINIC & FITNESS CENTER
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