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A few short facts:
•Movement of the body is important for
survival.
•There are more than 600 muscles in the
human body
•40% - 50% of body weight
•Muscles pulling on bones is responsible for
movement
•The way muscle is grouped and their
relationship to joints determines the type of
movement they create
Connective tissue surrounding muscles
tissue
•Endomysium – around
muscle cells or fibers
•Perimysium - hold
groups of muscle fibers
together
•Epimysium – covers the
entire muscle group
All these layers attach
the muscle to the bone
so the muscle pulls as
one unit
Broad flat sheet of
connective tissue that
covers muscle groups
called
aponeurosis usually
merges with fibrous
wrappings of another
muscle
You will see that clearly on the cat
Structure of skeletal muscle
Size, shape and fiber
arrangement
The movement and strength
of a muscle is determined by
its overall shape and type of
attachment
Parallel
•Vary in length
but are strap-like
•Fibers are
running parallel
to each other
Convergent
Wide point of
attachment to a
small point of
attachment
Pennate
Feather-like
Fusiform
Close to parallel in
the middle or belly of
muscle but converge
to tendon at both
ends
Spiral
Fibers that twist
Between their points of
attachments
Circular
Called sphincters
Circle around a
body tube or
opening
Most muscles span
at least one joint,
some span two
joints
Names for the attachments of muscles
Origin
The point of attachment that does not
move when the muscle contracts
Insertion
The point of attachment that moves
when the muscle contracts
•Skeletal Muscles act
in groups
•Some contract while
others relax
Prime mover
•Agonist
•The muscle or group of muscles that directly
performs a specific movement
Antagonists
•Muscles that directly oppose the prime mover
•The antagonists is relaxed when the prime
mover is contracting
•Provides precision and control during the
contraction of the prime mover
the name antagonists is misleading
Synergists
•Muscles that contract at the same time as the prime
mover
•Complement the prime mover actions to make a
more effective movement
Fixator
•Joint stabilizers
•Maintain posture or balance
•Example would be the muscles in the front and back
of the thigh stabilizing the leg when standing
Most movements
are very complex
Most muscles
function as prime
mover, antagonists
synergists or
fixators at some
time depending on
the movement
A prime mover in flexing arm at the
elbow is…….
The Antagonist is…….
Is it different
when the arm
is above the
head?
Do you remember levers, which one is which?
In the body: all
movement is made by
3rd class levers. The
muscle insertion is
very close to the joint
being moved.
In the body: face is
the load, the c2
vertebrae is the
fulcrum, the muscles
of the neck and
upper back is the pull
The movement is
strong but it is also
fast
In the body: some
anatomists do not
agree. Some say
raising up on one’s
toes is a 2nd class
lever.
Fulcrum is the toes
point of contact with
the ground, load is
the ankle, pull is the
gastrocnemius
muscle in the lower
leg
Opening mouth
against resistance
Figure 10-4C. Lever classes. A, Class I:
fulcrum (F) between the load (L) and force
or pull (P); B, Class II: load (L) between the
fulcrum (F) and force or pull (P); C, Class III:
force or pull (P) between the fulcrum (F)
and the load (L). The lever rod is yellow in
each.
So……
When a body part is moved the muscle
moving that part usually does not lie over
the part being moved.
The muscle
doing the
moving is
usually
proximal to the
part being
m0ved
Before we go to the lab to
look at the cats we need to
understand how muscles are
named.
If we understand how they are
named the language isn’t as
foreign as it appears at first
glance
Location
brachialis - arm, upper arm
gluteus - buttock
Function
adductor – moving the leg toward the midline of
the body
abductor – moving the part away from the
midline of the body
Shape
deltoid – triangular
Direction of Fibers
rectus – meaning straight
Number of Heads or Divisions
“cep” - means head
triceps, quadriceps
biceps bracahii
Point of Attachment
origin and/or insertion points
Sternocleidomastoid
Size of Muscle
Size compared to size of nearby muscles
gluteus maximus, gluteus medius, gluteus
minimus
When you and your lab partner start
looking at the cat keep these things in
mind
•Use the larger muscles as a guide
•Try to figure out to which bones the two
ends attach
•Determine what is being moved when the
muscle shortens – what is being moved, what
is staying stationary
insertion and origin
•Deltoid
•Pectoralis major
•Latissimus dorsi
•Serratus anterior
•Linea alba
•Rectus abdominis
•External oblique
•Transverse
abdominis
•Internal oblique