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42-1 muscle architecture, Arrangements of fascicles - Coggle Diagram
42-1 muscle architecture
Muscle architectural characteristics include;
Amount of pennation(arrangement of fibers in relation to axis of force)
Muscle fiber length
Muscle length
Muscle mass
Physiological cross sectional area (PCSA)
Muscle fiber length and PCSA
are the 2 most important characteristics
Long muscle fiber
-Increased number of sarcomeres in series (decides the amount of shortening and lengthening)
-shorten over great distance
PCSA: Measure of cross sectional area of muscle perpendicular to the orientation of the
fibers
-Amount of force is directly proportional to number of sarcomeres in parallel
-More fibers more force
Arrangements of fascicles
Fusiform muscles
Muscles that have a parallel fiber arrangement
Parallel to the long axis of the muscle and to each other
Extend through out the length of the muscle
In general produce greater ROM, compared with pennate muscles
Examples
Sternocleidomastoid
Sartorius
Rectus abdominis
Pennate muscles
Fiber arrangement oblique to the long axis of the muscles
Shorter fibers and more in number compared to
fusiform muscles
Examples
Unipennate:
-flexor policis longus
-fascicles fan out only on one side of the central tendon
Bipennate:
-biceps femoris & tibilais anterior
-Fascicles are set obliquiley on both side of the central
tendon
Multipennate:
-Soleus & Subscapularis
-Oblique fasciscles converge on several tendons tendons
Oblique angle disrupts the direct relationship between length of the fiber and
the distance required to move a bony lever
Only a portion of the force of a pennate muscle is directed to produce ROM
Pennate muscles have increased PCSA, making up for the loss of force due to
pennation
A – Fusiform
B - Unipennate
C – Bipennate
D - Multipennate