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