kinesiology lab assignment 2

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Principles of Kinesiology
Lecture 02
Professor Berthet

Apparel
Technical
Design

Anatomical and
Physiological

Fundamentals of
Human Motion

The Musculoskeletal
System:The Musculature
System and its Movement

&
The Neuromuscular Basis of

Human Movement
(Ch. 3 & 4)

The Musculoskeletal System

! Extensibility and Elasticity:
enable the muscle to be
stretched and return to normal
length.

” Tendons are continuations of

muscle’s connective tissue and
also possess these properties.

” Contractility: is the ability to shorten
and produce tension.

Architecture of the Skeletal Muscle

Muscle Fiber

! Muscle Fiber: Consists
of myofibrils held
together by cell
membranes that can
propagate nerve
impulses.

• Muscle
• Muscle Fiber Bundle

• Muscle Fiber

Muscle

Muscle Fiber Bundle

Muscle Fiber: Myofibrils

! Myofibrils are arranged in
parallel formation.

!Made up of alternating
dark & light bands that
give muscle fiber their
striated appearance.

• Muscle
• Muscle Fiber Bundle

• Muscle Fiber
• Myofibrils

Actin: when
stimulated slides
over myosin.

Cross-bridges:
projections (heads)
of myosin attach to
actin.

Functional contractile
unit of skeletal
muscle.

Muscle Fiber:
Myofiliments

Myosin

“motor protein” perform cross-linking

Architecture of the Skeletal Muscle

Fast Twitch Muscles

! Fast twitch fibers are large,
pale, and have less blood
supply than slow twitch
fibers.

“Suitable for intense
responses over a short
period of time

Slow Twitch Muscles

! Slow twitch fibers are small,
red, and have a rich blood
supply, and greater myoglobin
(binds O2).

! Highly efficient, do not
fatigue easily.

“Suitable for long duration,
posture and endurance
events.

Structural
Classification of
Muscles by Fiber
Arrangement

! Longitudinal: long, strap like
muscle with fibers in parallel
to its long axis.

Structural Classification of
Muscles by Fiber Arrangement

! Quadrilateral: four sided and
usually flat.

! Consist of parallel fibers.

Structural Classification of
Muscles by Fiber Arrangement

! Triangular: fibers radiate from
a narrow attachment at one
end to a broad attachment at
the other.

” Pectoralis major

Structural
Classification of
Muscles by Fiber
Arrangement

! Fusiform or Spindle-Shaped:
rounded muscle that tapers at
either end.

Structural Classification of
Muscles by Fiber Arrangement

! Pennate: a series of short,
parallel, feather like fibers
extends diagonally from the
side of a long tendon.

Structural Classification
of Muscles by Fiber
Arrangement

! Bipennate: A long central
tendon with fibers extending
diagonally in pairs from either
side of the tendon.

Structural
Classification of
Muscles by Fiber
Arrangement

! Multipennate:
Several tendons are
present, with fibers
running diagonally
between them.

! Middle deltoid

A

B

C

D

E

F

Longitudinal

Triangular

PCS
! Force a muscle can exert is

proportional to its
physiological cross section
(PCS).

! A broad, thick, longitudinal
muscle exerts more force than
a thin one.

! A pennate muscle of the same
thickness as a longitudinal
muscle can exert greater
force.

” The oblique (slanted)
arrangement of fiber allows for
a larger number of fibers than in
comparable sizes of other
classifications.

Muscle Movement
! When tension by the muscle is

sufficient to overcome a resistance
and move the body segment.

! The muscle shortens.

! When a muscle slowly lengthens as it
gives in to an external force that is
greater than the contractile force it is
exerting.

! Muscle is acting as a “brake”.

Fig 3.5c

Muscle Movement
! Movers, or Agonists: directly

responsible for producing a
movement.

” Prime movers: large impact on
movement

” Assistant movers: only help when
needed

! This distinction between the various
muscles that contribute to a
movement is not always clearly
defined.

! ers, or Agonists:

Muscle Movement
! Synergists: cooperative muscle function

“Stabilizing, Fixator, & Support Muscles

“Neutralizers – prevent undesired action

Muscle Movement

! Antagonists: have an
effect opposite to that
of movers (agonist).

! 1st: Antagonists must
relax to permit
movement.

! 2nd: Acts as a brake at
completion of
movement.

Movement
! Ballistic Movements: initiated by

vigorous contraction and
completed by momentum.

! Throwing, striking, & kicking

! Termination of ballistic action:

1. By contracting antagonist muscles.
” Forehand drive in tennis

2. By passive resistance of ligaments or other
tissues at limits of motion.
” Throwing motion

3. By the interference of an obstacle
” Chopping wood

Methods of Studying Muscles
! Conjecture & Reasoning: Using

knowledge of location and
attachments, and nature of joints,
one can deduce a muscle’s
action.

! Dissection: meaningful basis for
the visualization of muscle’s
potential movements.

! Inspection & Palpation: valuable
method for superficial muscles.

! Models: used for demonstration.

! Muscle Stimulation: contraction of
individual muscles.

Methods of Studying Muscles
! Electromyography (EMG): based

on the fact that contracting muscles
generate electrical impulses.

! Reveals both intensity
& duration of muscle
activity.

Histology

Connective tissue

Bones

Cartilage

Tendens

Ligaments

Histology
Neural Tissue

Motor Neurons

Sensory Neurons

Connector Neurons

Histology

Muscular Tissue

Muscles

The Nervous
System

I. Central nervous system (CNS)

A. Brain

B. Spinal cord

-The bodies master control unit

The Nervous
System

II. Peripheral nervous system (PNS)

A. Cranial nerves (12 pairs)

B. Spinal nerves (31 pairs)

– The bodies link to the outside world

The Nervous System

III. Autonomic nervous system

A. Sympathetic

-“fight or flight”

B. Parasympathetic

– calming

The Cerebral Cortex

Motor Cortex Sensory Cortex

Motor Neuron

! A single nerve cell consists
of a cell body and one or
more projections.

” Dendrites: Carry impulses
toward cell body.

” Axons: Carry impulses away
from cell body.

receives signal

sends signal

The Neuron

Spinal Chord
(ventral view)

Spinal Chord
(areal view)

Motor Neurons
! Motor neutron axons extend from spinal chord to muscle

! Neuromuscular junctions

Sensory Neurons
! Sensory Neurons:

Situated in a dorsal root
ganglion just outside the
spinal cord.

! Neuron may terminate in
spinal cord or brain.

! A long peripheral fiber
comes from a receptor.

Connector Neurons

! Connector Neurons:
Exist completely within
the CNS.

! Serve as connecting
links from sensory to
motor neurons.

! May be a single neuron

OR

! An intricate system of neurons, whereby a sensory impulse may be
relayed to many motor neurons.

Connector Neuron

Connector Neuron

Nerves
!Nerves: A bundle of

fibers, enclosed
within a connective
tissue sheath, for
transmission of
impulses.

Nerves
! A typical spinal nerve consists of:

” Motor, outgoing (efferent) fibers

” Sensory, incoming (afferent) fibers

! Each spinal nerve is attached to spinal cord by an anterior (motor)
root and a posterior (sensory) root

Synapse
! Synapse: connection

between neurons.

! Is a proximity of the
membrane of an axon to
the membrane of a
dendrite or cell body.

! The more often a
synapse is used the
faster a signal will pass
through it

! Substance diffuses the synapse and produces an action
potential in the postsynaptic neuron (the next neuron).

Muscle Fiber to Motor Neurons
! Muscles contract with various gradations of strength.

“Number of motor units that are activated.

“Frequency of stimulation.

Reflex Movement
! A specific pattern of response without volition (will) from the cerebrum.

! Stimulus – receptor organ – sensory neuron – motor neuron – muscle (response)

! Connector neurons often used.

No brain activity involved

Central Nervous System (CNS)

Brain and Spinal Cord

Integrates information it receives
and coordinates and influences the
activity of all parts of the body of
bilaterally symmetric animals

-All multicellular animals except
sponges and radially symmetric
animals such as jellyfish

Contains the majority of the
nervous system.

Central Nervous System (CNS)
1. Cerebral cortex: where consciousness

occurs, initiation of voluntary movement.

2. Basal ganglia: responsible for homeostasis,
coordination & some learned acts of posture.

Central Nervous System (CNS)

3. Cerebellum “little brain”: key role in sensory integration,
regulates timing & intensity of muscle contraction.

Central Nervous System (CNS)

4. Brain stem: arousal and monitoring of physiological
parameters, key facilitory and inhibitory centers.

Central Nervous System (CNS)

5. Spinal cord: contains cell bodies of lower motor neurons,
common pathway between CNS & PNS, final point for
integration and control.

Central Nervous System (CNS)

What is this
Electron Scanning Microscope (ESM) Image of?

Explain the mechanisms at work in this illustration

What’s missing?

Would would be the result of missing this?