1. Neuromuscular Fundamentals
Chapter 2

2. Muscular System
Over 600 muscles (215 pair) approximately 40% to 50% of body weight
Functions
Movement
Protection
Support and Posture
Heat Production

3. Muscular Nomenclature
Usually named because of one or more distinctive characteristics. Often there is a crossover among the various nomenclature.
Shape
Size
Number of Division
Location
Direction
Action
Action & Shape
Action & Size
Point of Attachment
Location & Attachment
Location & Number of Divisions

4. Muscular Shape and Fiber Arrangements
Muscle shape and fiber arrangement play a role in the muscle’s ability to exert force and the ROM through which it can effectively exert force onto the bones to which it is attached. .
Cross-sectional
Ability to shorten
Parallel arrangement (Fibers arranged parallel to length of muscles)
=  ROM )
Flat
Fusiform
Strap
Radiate
Sphincter
Pennate Arrangement (Shorter fibers arranged obliquely to their tendons)
=  Force )
Unipennate
Bipennate
Multipennate
Shape
Fiber Arrangements

5. Muscle Tissue Properties
Irritability — ability to respond to a stimulus
Contractility — ability to contract and develop tension
Extensibility — ability to be stretched beyond resting length
Elasticity — ability to return to original length following stretching
Tonicity — state of
firmness of a muscle due to
nerve stimulation and motor
unit contraction

6. Muscle Terminology
Intrinsic- muscles within or belonging solely to a body part it acts upon
Extrinsic- muscles that originate outside a body part on which it acts
Action- specific movement of a joint resulting from a concentric contraction
Why do Muscles perform their particular actions?
Line of pull
Planes of motion of a joint
Innervation- nerve responsible to provide stimulus to muscle fibers
Amplitude- range of fiber length between maximal and minimal lengthening
Gaster (belly)- portion of muscle that increases in diameter as muscle contracts
Origin- proximal attachment, usually least moveable part
Insertion- distal attachment, usually most moveable part
Exceptions

7. Muscle Contractions Isometric – (Static): muscle contraction in which:
Tension develops, no change in length of muscle
Muscular Force = Resistive Force
Stabilization effect
Isotonic – (Dynamic): muscle contraction in which:
Tension develops, “causing” or “controlling” joint movement
Concentric (positive contraction)
Muscle shortens
Muscular force > Resistive force
Body part moves against (_____) gravity or external force
Acceleration effect
Muscle(s) involved and movement are the ______
Eccentric (negative contraction or “action”)
Muscle lengthens
Muscular force < Resistive Force
Body part moves with (_____) gravity or external force
Deceleration effect
Muscle(s) involved and movements are ______

8. Muscle Force – Velocity Relationship
Concentric contraction against a light resistance = ______ velocity
Increasing resistance = _______ in the maximal velocity the muscle can contract
Continuation of increasing resistance eventually = _________ contraction if equal to muscular force
If resistance increases beyond muscular force = _____ contraction

9. Role of Muscles
Agonist (prime mover): muscle that when contracting concentrically causes joint motion
How do you determine which muscle groups are involved?
Step #1: Identify what movement the resistance is tending to cause
Step #2: The opposite muscle group is involved
If contracting = ______ If relaxing = _______
Antagonist: opposite side of the joint from the agonist

10. Straight leg raise lying supine
Role of Muscles
Stabilizer (fixator): a muscle(s) that contracts to fix or stabilize a bone so that a muscle can do its intended work/movement
Straight leg raise lying supine
Crunch/Curl up
Neck flexion
Bench press

11. Dynamic Stabilization
Role of Muscles
Static Stabilization vs
Dynamic Stabilization

12. Role of Muscles Movement/ Action:
Neutralizer: Muscle that contracts to counteract or neutralize the action of another muscle to prevent undesirable motions
Resulting from the combination of:
The Common action of muscles
The antagonistic action of muscles
Movement/ Action:
Muscles:
Common Actions:
Neutralizing Actions:

13. Role of Muscles
Synergist: A muscle(s) that works with an agonist, is partial antagonist, and contracts to prevent an undesired movement
Agonist(s)
Synergist(s)
Undesired Movement
Making a fist
Kicking a football
Biceps curl (dumbbell)
Note: A muscle tends to perform all its actions when it contracts unless something prevents those movements from occurring.

14. Role of Muscles
If the stabilizer muscle is a non-antagonistic muscle  it is called a “____________”
If the stabilizer muscle is an antagonistic muscle  it is called a “____________”
If the stabilizer muscle is an antagonistic muscle + a common action it is called a “____________”

15. Central Nervous System

16. Peripheral Nervous System

17. Myotome

18. Dermatome

19. Stretching

20. Myotatic Reflex (Stretch Reflex)

22. Inverse Myotatic Reflex

23. Neuromuscular Concepts
Motor Unit
All or none principle
Increasing Fiber Recruitment

24. Click here

25. Neuromuscular Concepts
Muscular Length- Tension Relationship
The greatest muscle tension can be developed when a muscle is stretched. Why?
Greatest tension: Between 100% and 130% of resting length
Least tension: Muscle shortened to approx. 50 – 60% of resting length
Seated leg extension
Prone hamstring curl
Vertical jump

26. Active & Passive Insufficiency
Active Insufficiency:
When a muscle becomes shortened to the point at which it cannot generate or maintain active tension
Passive Insufficiency:
When the opposing muscle becomes stretched to the point at which it can no longer lengthen and allow movement

27. Neuromuscular Concepts
Angle of Pull
The angle between the 1) line of pull of the muscle and the 2) bone on which it inserts
Rotary components– that muscular force that acts perpendicular to the long axis of the bone/lever
When angle of pull is 90° =____% rotary force
Note: at all other degrees of angle of pull one or two of the other components of force (non-rotary) is operating “in addition to” the rotary component.
Non-Rotary Component
Angle of pull >90°
Angle of pull <90°
Angle of pull = 90°
If angle of pull is <90° =___________
Why?
If angle of pull is >90° =___________

28. Neuromuscular Concepts
Angle of Resistance
The angle between the:
1) direction of resistance and the
2)lever to which the resistance is attached or applied
Differentiate between applied and attached
The angle of resistance is zero if the center of gravity at the segment lies on a line between the _________ and the ___________
Rotary Component
At a 90° angle of resistance 100% of the energy of resistance is causing the lever to __________________________________
At a 0° angle of resistance 100% the energy of resistance is causing either:
___________________ element
There is no force causing movement of the bone/lever around its axis
90º

29. Biarticular Muscles & Movement Patterns
Concurrent Movement Pattern – Muscle movement pattern that allows the muscles to maintain a relatively constant length and tension at both joints as go through a range of motion.
Parallel Squat
Rectus Femoris Contraction = __________
Hamstrings = ___________
Biceps Femoris Contraction = __________
Quadriceps = ___________
Lombard’s Paradox?
Involves comparison between two antagonistic muscles
Both muscles must be biarticular
Parallel Squat:
Rectus Femoris
Biceps Femoris
Knee
Hip
MFA
Rectus Femoris
4.4
3.9
Knee
Biceps Femoris
3.4
6.7
Hip

30. Countercurrent Movement Pattern
Muscle movement pattern that results from the concentric contraction of a biarticular muscle that produces its intended movements. Results in increased tension and stretch of the antagonist muscle.

31. Guidelines for Muscle Testing and Exercise
Test both sides – comparison
“Isolate” the muscle
Stabilize the proximal segment
Apply a 90º angle of resistance
Apply resistance to the distal end of distal segment
To overcome a deformity
Stretch tight muscle groups
Strengthen the weak muscle groups
Maintain ______ _________ (24-7)
External force is usually required

32. Questions Person has a weak right biceps.
To strengthen, would you perform biceps curl with a barbell?
Person has a weak left triceps.
Would push-ups be a good exercise to strengthen the left triceps?
Person has weak right rhomboids.
How would you strengthen?
How would you isolate the soleus to stretch/strengthen?
How would you isolate the gluteus maximus?

33. Stages of Development of Acquired Musculoskeletal Deformities
First Degree (curable by exercise – strengthening the weak, stretching the tight)
A. Soft tissue:
Changes in muscle tone and habitual posture
B. Bone tissue:
No bony change
C. Corrective treatment:
The patient can himself correct the position of the affected part
Second Degree (improvable by exercise)
A. Soft tissue:
Contracture of soft tissue structures
B. Bone tissue:
Slight degree of bony change
C. Corrective treatment:
Patient cannot himself correct the deformity, but can be corrected to some extent by another person (external source)
Third Degree (little if any change achieved with exercise)
A. Bone tissue:
Serious bony change

34. Lateral Line of Gravity Anterior Line of Gravity
Posture
The relationship of body segments to one another
Lateral Line of Gravity
Anterior Line of Gravity