Transcript C. Arrangement of Fasciculi

C. Arrangement of Fasciculi
1. Skeletal muscle fibers(cells) are
arranged with in the muscle in bundles
called fasciculi
2. The muscle fibers are arranged in a
parallel fashion within each bundle, but
with respect to the tendons can take one
of four forms
a. Parallel- parallel with
longitudinal axis of the muscle and
end with flat tendons
b. Fusiform- nearly parallel with
a fat belly ending in flat tendons
c. Pennate- short fasciculi with
tendons almost the entire length
1. Unipennate- only to one
side of the tendon
2. Bipennate- both sides of a
central tendon
3.. Multipennate- attach
obliquely from many
directions to several tendons
d. circular- arranged in a circular
pattern and enclose an orifice
e. This arrangement correlates
with power and R.O.M.
D. Group Actions
1. Most movements are coordinated by
several skeletal muscles acting in groups
a. Arranged in antagonistic pairs
at the joints
2. A muscle that produces the desired
action is the prime mover or agonist
a. The antagonist produces the
opposite action
3. Most movements also involve
muscles called synergists, which serve
to steady a movement preventing
unwanted movements and helping the
prime mover
a. Some synergists also act as
fixators to stabilize
4. Under different conditions and
depending on the movement and which
point is fixed, many muscles act as all 4
of the above movers