Muscle are the machines converting chemical energy to mechanical energy!

Muscle are the machines converting chemical energy to mechanical energy!

Tone/posture

Heat production

Control openings

Movements

What are the functions of muscles?

http://dennismitchell.wordpress.com/2007/04/26/beer-muscles/

Introduction to Muscles

Electricity production?!?

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

Contractility

Extensibility

Elasticity

Respond to stimuli with electric current

Ability to shorten when stimulated

Can be stretched up to 3 times contracted length

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

made of myofilaments

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…

Introduction to Muscles

See Fig. 10.2

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

However, relaxation DOES require energy!

Where and Why?

?Rigor mortis?

http://www.dailyhaha.com/_pics/big_muscles.htm

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 = OriginMoved part = Insertion

Introduction to Muscles

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

Introduction to Muscleshttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__function_of_the_neuromuscular_junction__quiz_1_.html

Axial MusclesWhat muscles are identified as axial?

T3… those of tongue, trunk and tail

Notice the complementary orientation of the abdominal fasciculi

External

Internal

Transverse

Axial MusclesWhat 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

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

Axial MusclesWhat 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 MusclesWhat are the epaxial muscles of the trunk?

4 categories…

Intervertebrals

Longissimus

Spinales

Iliocostales

Cause extension or lateral flexion of the trunk. How?

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

Axial MusclesWhat 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 MusclesWhat 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)

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)

Appendicular Muscles

Would you expect blastemas of the median dorsal fins to arise from hypaxial or epaxial myomeres?

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

Appendicular Muscles

Pectoralis and Supracoracoideus

In birds the pectoralis are the primary adductors and the supracoracoideus are the abductors

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

Appendicular Muscles

Which of the above would you expect to insert on the ulna?

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

Appendicular Muscles