Functional Characteristics of Muscle Tissue
Functional Characteristics of Muscle Tissue
Muscle is the only body tissue with the properties of:
Irritability Ability to respond to a stimulus
Stimulation produces a muscle contraction
Stimulus can be internal or external
Contractility Ability to shorten or contract
Results in increasing tension between its ends
Length may shorten, lengthen or remain the same
Extensibility Ability to stretch in response to a force
Elasticity Ability to recoil when stretch force is removed and muscle returns to its resting length
Skeletal Muscles
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They attach to bones through tendon. Proximal attachment is usually the origin; the distal
attachment is usually the insertion
Muscles work on bones (levers) to produce movement
The muscle must cross (act on) a joint to produce movement at that joint. It will have an
attachment proximal to the joint and an attachment distal to the joint
The direction of the movement produced is determined by the line of pull (LOP) of the
muscle and how/where the muscle crosses the joint
The farther away from the joint the origin and insertion are, the greater the mechanical
advantage is for that muscle
Some muscles are divided into parts (anterior, posterior and middle) with each part having
different functions because of the different lines of pull
These are all concepts that are utilized with exercised and must be considered by the PTA
For example, instructing a patient in an exercise that does not follow the line of pull will be less
effective, and could place additional stress on damaged tissues
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