Muscle Function and Anatomy

1
Muscle Function and Anatomy
2
Function of Muscle

• Motion of joints
• Movement of body fluids - pump blood, peristalsis
  
• Regulation of body fluids - bladder
• Body stability
• Heat production - 85

3
Muscle Architecture
4
How Are Muscles Built?

• In circular sections
• Deepest section contains two proteins
• Myosin
• Actin
• Myosin is surrounded by actin

5
Myofibrils

• Bundles of actin and myosin

6
(No Transcript)
7
Muscle Fiber

• Among others things, a muscle fiber contains many
  groups of myofibrils

8
(No Transcript)
9
(No Transcript)
10
Fascicle

• A group of muscle fibers bundled together.

11
The Whole Muscle
12
The Whole Muscle
13
Muscle Membranes
14
Tendons

• All 3 membranes converge to form a tendon which
  connects the muscle to the bone

15
Muscle Fiber Arrangement p. 25

• Pennate muscles
• Greater cross sectional area greater force
  (strength) production
• Parallel muscles
• Longer muscles greater range of motion

16
Muscle Fiber Arrangement
Strap

• Parallel muscles
• Flat (rectus abdominus)
• Fusiform (biceps)
• Strap (sartorius)
• Radiate (trapezius)
• Spincter
• Pennate
• Unipennate (biceps femoris)
• Bipennate (rectus femoris)
• Multipennate (deltoid)

17
Types of Muscle Contraction p. 28

• Isometric (Static)
• Isotonic (Dynamic)
• Concentric
• Eccentric

18
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

19
Lengthens
Lengthens
20
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.

21
TABLE 2.1 Type of Contraction Type of Contraction Type of Contraction
TABLE 2.1 Isometric Isotonic Isotonic
TABLE 2.1 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 gt R F lt 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 -
22
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

23
Agonist and Antagonist
24
Types of Muscle Fibers

• Fast twitch
• Slow twitch

25
Questions?