Download Muscles

Introduction to Muscles
What are the functions of
muscles?
Muscle are the machines converting
chemical energy to mechanical
energy!
Control openings
Tone/posture
Movements
http://dennismitchell.wordpress.com/2007/04/26/beer-muscles/
Heat production
Electricity
production?!?
Introduction to Muscles
What is the difference between
muscle vs. muscles?
Muscle is a tissue and there are
three types…
Skeletal
Cardiac
Smooth
Muscles (organs) fall in 2 main
categories and a third minor group…
Somatic, visceral & branchiomeric
(somatic subtype)
Introduction to Muscles
What are the 4 common
characteristics of muscle tissue?
All muscle tissue has 4 common characteristics:
Excitability
Respond to stimuli with electric current
Contractility
Ability to shorten when stimulated
Extensibility
Can be stretched up to 3 times contracted length
Elasticity
Recoils to resting length after tension released
Introduction to Muscles
What are the series elastic
components?
The connective tissue of the
bone is continuous with the
connective tissue of skeletal
muscles clear down to the
package around muscle fibers…
Deep Fascia ~ epimysium
Perimysium
Endomysium
Purpose(s)?
Introduction to Muscles
What other components do
muscles have?
Vessels necessary for
transporting blood to and from
muscle tissue travel through the
connective tissue.
Nerves necessary for conducting
electrical signals to initiate
muscle contraction also travel
through the connective tissue
Introduction to Muscles
What other components do
muscles have?
Contractile components…
Muscles (whole) are comprised
of:
Fasciculi, which are…
Many individual muscle cells
(muscle fibers)…
Each with a cell membrane
(sarcolemma), cytoplasm
(sarcoplasm), organelles and
myofibrils…
made of myofilaments
See Fig. 10.2
Introduction to Muscles
What are the
components at
the cellular level?
The molecular
machinery
consists of myosin
(thick) and actin
(thin)
myofilaments.
Crossbridges form
and stored energy
in mysosin heads
is used to change
conformation
resulting in actin
sliding
Introduction to Muscles
Another View…
Introduction to Muscles
How do limbs/structures move
in 2 (or more) directions?
Myofibrils CAN NOT exert a force in
two directions!!!
So in this sense relaxation is
passive. It depends on:
1) Series-Elastic components
(elasticity)
2) Antagonist muscle(s)
3) Gravity
http://www.dailyhaha.com/_pics/big_muscles.htm
However, relaxation
DOES require energy!
Where and Why?
?Rigor mortis?
Introduction to Muscles
How do limbs/structures move
in 2 (or more) directions?
Skeletal muscles often work in
pairs (or groups).
If they generate force in same
direction = Synergists
Opposite directions = Antagonists
Force is generally applied across
the joint that will facilitate
movement
Immovable portion = Origin
Moved part = Insertion
Introduction to Muscles
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter10/anima
tion__function_of_the_neuromuscular_junction__quiz_1_.
html
How do we get a whole
muscle response based
on individual muscle
fibers?
Muscle fibers contract in
an “All-or-none” fashion.
To control force of a whole
muscle contraction, you
must control the NUMBER
of muscle fibers
contracting.
Each motor neuron and the
muscle fibers it innervates is
called a motor unit
Axial Muscles
What muscles are identified as
axial?
T3… those of tongue, trunk and
tail
Notice the complementary
orientation of the abdominal
fasciculi
External
Internal
Transverse
Axial Muscles
What muscles are identified as
axial?
They exhibit metamerism
(primitive trait). This is a
consequence of embryonic
development from mesodermal
segments or somites.
Myomeres and myosepta
Absent in anurans and amniotes,
but spinal nerves are segmental
Axial Muscles
How are myomeres of fishes
organized?
Dorsal and ventral bundles are
separated by a sheet of
connective tissue the horizontal
septum
Myomeres dorsal to this septum
are epaxials and those ventral are
hypaxials.
Myomeres are arranged as
“cones” that extend caudad.
Generate great force that is
maximal at tail
Where would you look for
epibranchials and
hypobranchials?
Axial Muscles
How are myomeres of tetrapods
organized?
Horizontal septum has gone away
since most tetrapods have lost
hypaxial segmentation
Some tetrapods have retained the
“-paxials” such as urodeles.
How would this facilitate
locomotion?
Axial Muscles
What adaptations facilitate
terrestrial tetrapod locomotion?
Increased vertebral mobility
(dorsoventral) and unified muscle
arrangement (sheets rather than
myomeres) allows a variety of
motions… for example “humping”
or galloping
Axial Muscles
What are the epaxial
muscles of the trunk?
4 categories…
Intervertebrals
Longissimus
Spinales
Iliocostales
Cause extension or lateral
flexion of the trunk.
How?
Axial Muscles
What are the hypaxial
muscles of the trunk?
4 categories…
Subvertebrals
Obliques
Transverse
Rectus abdominis
What motion would
these likely cause?
http://www.yorku.ca/earmstro/journey/images/extobliques.jpeg
Axial Muscles
What is special about the
mammalian diaphragm?
Central tendon
surrounded by a muscular
sheet.
Attaches sternally,
costally and vertebrally
Axial Muscles
What are the functions of
the hypobranchial
muscles?
Assist in depressing the
mandible/lower jaw
Expand the pharyngeal
and branchial chambers
For what purpose(s)?
Axial Muscles
What are the functions of
the hypobranchial
muscles in tetrapods?
Assist in depressing the
mandible/lower jaw
Moving the hyoid and
laryngeal cartilages
Moving the tongue (bats
and people)
Appendicular Muscles
What is the significance of
appendicular muscles?
These muscles insert (as opposed
to originate) on the girdles, fins
and limbs…
They can arise from blastemas
within the body wall originating
off axial skeleton or fascia are
Extrinisic
Those arising from blastemas
within the limb and originating
on the limb are Intrinsic
Appendicular Muscles
What role do appendicular
muscles play in fishes?
Since most fish move by lateral
undulations, the musculature of
the appendicular skeleton is
minimal.
Fin fold is invaded by muscle
buds from adjacent myomeres.
Dorsal blastemas form extensors
(elevators)
Ventral blastemas form flexors
(depressors)
Would you expect blastemas of the
median dorsal fins to arise from
hypaxial or epaxial myomeres?
Appendicular Muscles
What are the extrinsic muscles of the
pectoral girdle and forelimbs?
A consistent muscle among taxa is the
Latissimus dorsi
It is more developed in taxa relying
heavily on limbs for movement and
spread from hypaxial region to insert on
spinous processes
Pharyngeal arches contribute to
trapezius muscles.
Cleidomastoideus and cleido-occipitalis
actually move the head.
Appendicular Muscles
What are the extrinsic
muscles of the pectoral
girdle and forelimbs on the
ventral surface?
Pectoralis and
Supracoracoideus
In birds the pectoralis are the
primary adductors and the
supracoracoideus are the
abductors
Pectoralis and Supracoracoideus
In birds the pectoralis are the
primary adductors and the
supracoracoideus are the
abductors
Appendicular Muscles
What are the intrinsic
muscles of the
forelimbs?
The dorsal group is
comprised of the
Deltoideus, Teres major,
Teres minor,
Subscapularis and long
head of the Triceps
Extensors of the hands
and digits
Which of the above would you
expect to insert on the ulna?
Appendicular Muscles
What are the intrinsic
muscles of the
forelimbs?
The ventral group is
comprised of the Biceps
brachii, Brachialis
Flexors of the hands and
digits
Appendicular Muscles
What are the muscles of the pelvic
girdle and hindlimbs?
Not much for pelvic girdle… Why?
Iliopsoas group and the gluteal
group arise from pelvic region and
insert on what?
Quadratus femoris
Adductor group
“Hamstrings”
Extensors and flexors of the foot
and digits
Appendicular Muscles
Branchiomeric muscles.
Arising from the
pharyngeal arches are
several muscles including
the masseter, temporalis
and the pterygoids
Digastric muscles
Tensor tympani
Platysma
Stapedius
Appendicular Muscles
Appendicular Muscles
Appendicular Muscles
Appendicular Muscles