1. 1-1
Planes of Motion
• Imaginary two-dimensional surface
through which a limb or body segment
is moved
• Motion through a plane revolves around
an axis
• There is a ninety-degree relationship
between a plane of motion & its axis
2. 1-2
Cardinal planes of motion
• 3 basic or traditional
– in relation to the body, not in
relation to the earth
• Anteroposterior or Sagittal
Plane
• Lateral or Frontal Plane
• Transverse or Horizontal
Plane
6. Manual of
Structural Kinesiology Foundations of Structural Kinesiology 1-9
Axes of rotation
• For movement to occur in a plane, it
must turn or rotate about an axis as
referred to previously
• The axes are named in relation to their
orientation
9. 1-12
Axes of rotation
• Vertical, long or
longitudinal axis
– Runs straight down through top
of head & is at a right angle to
transverse plane of motion
– Runs superior/ inferior
– Commonly includes internal
rotation, external rotation
movements
10. 2-14
Muscle Nomenclature
• Muscles are usually named due to
– visual appearance
– anatomical location
– function
• Shape –
• Size –
• Number of divisions –
• Direction of its fibers –
13. 2-17
Shape of Muscles & Fiber Arrangement
• Muscles have different shapes & fiber
arrangement
• Shape & fiber arrangement affects
– muscle’s ability to exert force
– range through which it can effectively exert
force onto the bones
14. 2-18
Shape of Muscles & Fiber Arrangement
• Cross section diameter
• Muscle’s ability to shorten
15. 2-19
Shape of Muscles & Fiber Arrangement
• 2 major types of fiber arrangements
– each is further subdivided according to
shape
• Parallel muscles
– Fibers run parallel to the tendon
– produce a greater range of movement than
similar sized muscles with pennate
arrangement
16. 2-20
Fiber Arrangement - Parallel
• Categorized into
following shapes
– Flat
– Fusiform
– Strap
– Convergent
– Sphincter or
circular
17. 2-21
Fiber Arrangement - Parallel
• Flat muscles
– usually thin & broad, originating from
broad, fibrous, sheet-like aponeuroses
– allows them to spread their forces over
a broad area
19. 2-23
Fiber Arrangement - Parallel
• Fusiform muscles
– spindle-shaped with a central belly that
tapers to tendons on each end
– allows them to focus their power onto
small, bony targets
20. 2-24
Fiber Arrangement - Parallel
• Strap muscles
– more uniform in diameter with
essentially all fibers arranged in a
long parallel manner
– enables a focusing of power onto
small, bony targets
– Ex. sartorius
21. 2-25
Fiber Arrangement - Parallel
• Radiate/Convergent muscles
– also described sometimes as being
triangular, fan-shaped or convergent
– have combined arrangement of flat &
fusiform
– originate on broad aponeuroses &
converge onto a tendon
22. 2-26
Fiber Arrangement - Parallel
• Sphincter or circular muscles
– technically endless strap muscles
– surround openings & function to
close them upon contraction
23. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-27
Fiber Arrangement - Pennate
• Pennate muscles
– have shorter fibers
– arranged obliquely to their tendons in a
manner similar to a feather
– arrangement increases the cross sectional
area of the muscle, thereby increasing the
force capacity
24. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-28
Fiber Arrangement - Pennate
• Categorized based upon the exact
arrangement between fibers & tendon
– Unipennate
– Bipennate
– Multipennate
25. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-29
Fiber Arrangement - Pennate
–Unipennate muscles
• fibers run obliquely from a tendon
on one side only
26. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-30
Fiber Arrangement - Pennate
–Bipennate muscle
• fibers run obliquely on both sides
from a central tendon
27. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-31
Fiber Arrangement - Pennate
–Multipennate muscles
• have several tendons with fibers
running diagonally between them
–Bipennate & unipennate produce
strongest contraction
28. 2-32
Muscle Tissue Properties
• Skeletal muscle tissue has 4 properties
related to its ability to produce force &
movement about joints
– Irritability or excitability
– Contractility
– Extensibility/Plasticity
– Elasticity
32. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-36
Muscle Terminology
• Any of the muscles in the group can be
said to cause the action, even though it
is usually an effort of the entire group
• A muscle may cause more than one
action either at the same joint or a
different joint depending upon the
characteristics of the joints crossed by
the muscle
33. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-37
Muscle Terminology
• Innervation - segment of nervous
system defined as being responsible for
providing a stimulus to muscle fibers
within a specific muscle or portion of a
muscle
– A muscle may be innervated by more than
one nerve & a particular nerve may
innervate more than one muscle or portion
of a muscle
34. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-38
Types of muscle contraction
• Isometric contraction
– tension is developed within
muscle but joint angles remain
constant
35. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-39
Types of muscle contraction
Muscle Contraction
(under tension)
Isometric Isotonic
EccentricConcentric
36. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-40
Types of muscle contraction
• Isotonic contractions involve muscle
developing tension to either cause or
control joint movement
– dynamic contractions
– Tension remains the same as the muscle
length changes
• Isotonic contractions are either
concentric or eccentric on basis of
whether shortening or lengthening
occurs
37. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-41
Types of muscle contraction
• Movement may occur at any given joint
without any muscle contraction
whatsoever
– referred to as passive
– solely due to external forces such as those
applied by another person, object, or
resistance or the force of gravity in the
presence of muscle relaxation
38. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-42
Types of muscle contraction
• Concentric contractions
involve muscle
developing tension as it
shortens
• Eccentric contractions
involve the muscle
lengthening under
tension
39. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-43
Types of muscle contraction
• Concentric contraction
– muscle develops tension as it
shortens
41. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-45
Types of muscle contraction
• Eccentric contraction (muscle
action)
– muscle lengthens under tension
42. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-46
Types of muscle contraction
• Eccentric contraction (muscle
action)
43. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-47
Types of muscle contraction
• Eccentric contraction (muscle
action)
44. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-48
Types of muscle contraction
• Eccentric contraction (muscle action)
– Some refer to this as a muscle action
instead of a contraction since the muscle is
lengthening as opposed to shortening
• Various exercises may use any one or
all of these contraction types for muscle
development
45. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-49
Types of muscle contraction
• Isokinetics - a type of dynamic exercise
using concentric and/or eccentric muscle
contractions
– speed (or velocity) of movement is constant
– muscular contraction (ideally maximum
contraction) occurs throughout movement
– Ex. Biodex, Cybex, Lido
46. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-50
Role of Muscles
• Agonist muscles
– cause joint motion through a specified
plane of motion when contracting
concentrically
– known as primary or prime movers, or
muscles most involved
47. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-51
Role of Muscles
• Agonist muscles
– Primary or prime movers, or muscles most
involved
• Some agonist muscles, because of their relative location,
size, length, or force generation capacity, are able to
contribute significantly more to the joint movement than
other agonists
– Assisters or assistant movers
• Agonist muscles that contribute significantly less to the
joint motion
– Consensus among all authorities regarding which
muscles are primary movers and which are weak
assistants does not exist in every case
48. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-52
Role of Muscles
• Antagonist muscles
– located on opposite side of joint from agonist
– have the opposite concentric action
– known as contralateral muscles
49. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-53
Role of Muscles
• Stabilizers
– surround joint or body part
– contract to fixate or stabilize the area to enable
another limb or body segment to exert force &
move
– known as fixators
– essential in establishing a relatively firm base for
the more distal joints to work from when carrying
out movements
– Ex. biceps curl
• muscles of scapula & glenohumeral joint must contract in
order to maintain shoulder complex & humerus in a
relatively static position so that the biceps brachii can
more effectively perform curls
51. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-55
Role of Muscles
• Helping synergists
– have an action in common but also have actions
antagonistic to each other
– help another muscle move the joint in the desired
manner and simultaneously prevent undesired
actions
– Ex. Anterior & posterior deltoid
• Anterior deltoid acts as an agonist in glenohumeral
flexion, while posterior deltoid acts as an extensor
• Helping each other, they work in synergy with middle
deltoid to accomplish abduction
52. Manual of
Structural Kinesiology Neuromuscular Fundamentals 2-56
Role of Muscles
• True synergists
– contract to prevent an undesired joint action of
agonist and have no direct effect on agonist action
– Ex. Finger flexors are provided true synergy by
wrist extensors when grasping an object
• Finger flexors originating on forearm and humerus are
agonists in both wrist flexion & finger flexion
• Wrist extensors contract to prevent wrist flexion by finger
flexors
• This allows finger flexors to utilize more of their force
flexing the fingers
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Structural Kinesiology Neuromuscular Fundamentals 2-57
Role of Muscles
• Neutralizers
– counteract or neutralize the action of another
muscle to prevent undesirable movements such
as inappropriate muscle substitutions
– referred to as neutralizing
– contract to resist specific actions of other muscles
– Ex. when only supination action of biceps brachii
is desired, the triceps brachii contracts to
neutralize the flexion action of the biceps brachii