Download Function of Muscle

Muscle Function and Anatomy
Function of Muscle
 Motion of joints
 Movement of body fluids - pump blood,
peristalsis
 Regulation of body fluids - bladder
 Body stability
 Heat production - 85%
Muscle Architecture
How Are Muscles Built?
 In circular sections
 Deepest section
contains two proteins
 Myosin
 Actin
 Myosin is surrounded
by actin
Myofibrils
 Bundles of actin
and myosin
Muscle Fiber
 Among others things, a muscle fiber
contains many groups of myofibrils
Fascicle
 A group of muscle fibers bundled
together.
The Whole
Muscle
The Whole Muscle
Muscle Membranes
Tendons
 All 3 membranes converge to form a tendon
which connects the muscle to the bone
Muscle Fiber Arrangement p. 25
 Pennate muscles
cross sectional area – greater force
(strength) production
 Greater
 Parallel muscles
 Longer
muscles – greater range of motion
Muscle Fiber
Arrangement

1.
2.
3.
4.
5.

1.
2.
3.
Parallel muscles
Flat (rectus abdominus)
Fusiform (biceps)
Strap (sartorius)
Radiate (trapezius)
Spincter
Pennate
Unipennate (biceps
femoris)
Bipennate (rectus femoris)
Multipennate (deltoid)
Strap
Types of Muscle Contraction p. 28
 Isometric (Static)
 Isotonic (Dynamic)
 Concentric
 Eccentric
Types of Muscle Contraction
 Concentric contraction - If muscle force
is greater than the resistance
 Static or Isometric contraction - If
muscle force is equal to the resistance
 Eccentric contraction - If muscle force is
less than the resistance
Lengthens
Lengthens
Eccentric Contraction
 Used to control agonist and





prevent over lengthening of
the antagonist.
Example: triceps lowers
dumbbell while biceps
’controls’ the triceps activity
(action).
Causes more damage than
other types
Greater repair required…
…producing a stronger
muscle
Also, results in more muscle
soreness.
TABLE 2.1
Type of Contraction
Isotonic
Isometric
Concentric
Eccentric
Agonist muscle
No change
Shortening
Lengthening
Antagonist
No change
Lengthening
Shortening
Joint angle
No change
In direction of force
In direction of external
resistance
Direction of body part
Against immovable
object
Against gravity or
external force
Consistent with gravity
or external force
Motion
Pressure but no motion
Causes motion
Causes motion
Description
Static
Dynamic shortening
Dynamic lengthening
Muscle force v.
Resistance
F=R
F>R
F<R
Speed
Equal to resistance
Faster than the inertia of
the resistance
Slower than the speed of
gravity or applied inertial
forces
Acceleration or
Deceleration
Zero
A
D
Symbol
=
+
-
ROLE OF MUSCLES
 Agonist – prime mover
 Antagonist – have an action opposite to
the agonist
 Stabilizers – fixate or stabilize the joint
 Synergists – assist or guiding
 Neutralizers – counteract or neutralize
movements
Agonist and Antagonist
Types of Muscle Fibers
 Fast twitch
 Slow twitch
Questions?