FASCIA, MUSCLES, TENDONS. Skeletal Muscle Structure Origin: Origin: Proximal attachment Insertion:...
Transcript of FASCIA, MUSCLES, TENDONS. Skeletal Muscle Structure Origin: Origin: Proximal attachment Insertion:...
Skeletal Muscle StructureSkeletal Muscle Structure
Origin:Origin:Proximal attachmentProximal attachment
Insertion:Insertion:Distal attachmentDistal attachment
Tendons: Tendons: Peritendineum Peritendineum
Aponeurosis Aponeurosis
Skeletal Muscle HierarchySkeletal Muscle Hierarchy
Myofilament:Myofilament:Thick filamentsThick filaments
Myosin Myosin
Thin filamentsThin filamentsActin Actin
Myofibril:Myofibril:Bundle of myofilamentsBundle of myofilaments
Segmentally arranged into sarcomeresSegmentally arranged into sarcomeres
Skeletal Muscle HierarchySkeletal Muscle Hierarchy
MyofiberMyofiber
Made up of many myofibrilsMade up of many myofibrils
Multinucleated in skeletal musclesMultinucleated in skeletal muscles
= muscle cell= muscle cell FascicleFascicle
Bundle of myofibersBundle of myofibers Muscle Muscle
Composed of several to several hundred Composed of several to several hundred fasciclesfascicles
Connective TissuesConnective Tissues
Endomysium:Endomysium:Surrounds a myofiber Surrounds a myofiber
Perimysium:Perimysium:Surrounds a fascicleSurrounds a fascicle
Connective TissuesConnective Tissues
Epimysium:Epimysium:Covers entire muscleCovers entire muscleBlends in with deep fasciaBlends in with deep fascia
Connective tissue supports provide Connective tissue supports provide physical support and a pathway for nerves physical support and a pathway for nerves and vessels.and vessels.
MyofilamentsMyofilaments
Actin myofilaments (F-actin):Actin myofilaments (F-actin):Polymers of G-actinPolymers of G-actin
Tropomyosin Tropomyosin
TroponinTroponin Myosin filaments:Myosin filaments:
ATPaseATPase
SarcomeresSarcomeres
Z-line (Z-actin):Z-line (Z-actin):Composed of Z-actinComposed of Z-actinMarks ends of Z-actinMarks ends of Z-actin
I bands:I bands:Part of a sarcomere composed entirely of Part of a sarcomere composed entirely of actinactin
SarcomeresSarcomeres
A band:A band:Part of a sarcomere composed of both Part of a sarcomere composed of both
actin and myosinactin and myosin
H band:H band:Part of a sarcomere composed entirely of Part of a sarcomere composed entirely of
myosinmyosin
Sliding Filament TheorySliding Filament Theory
During a contraction:During a contraction:I band and H band shortenI band and H band shorten
A band remains the same lengthA band remains the same length
Sliding occurs when ATPase heads of Sliding occurs when ATPase heads of myosin attach to actin via troponin and myosin attach to actin via troponin and swivel.swivel.
MyofiberMyofiber
Sarcoplasmic reticulum:Sarcoplasmic reticulum:Equivalent to endoplasmic reticulum of Equivalent to endoplasmic reticulum of
most most cells.cells.T-tubules:T-tubules:
Tubular extensions of the muscle fiber Tubular extensions of the muscle fiber membrane that extend down into the membrane that extend down into the cytoplasm (saracoplasm).cytoplasm (saracoplasm).
Conduct action potential from cell Conduct action potential from cell membrane membrane surface to interior.surface to interior.
MyofiberMyofiber
Cisternae:Cisternae:Saccular extensions of the sarcoplasmic Saccular extensions of the sarcoplasmic reticulum that release calcium ions in reticulum that release calcium ions in
response to action potential.response to action potential.
Calcium ions trigger sliding of myosin and Calcium ions trigger sliding of myosin and actin filaments, resulting in a contraction.actin filaments, resulting in a contraction.
Myofiber TypeMyofiber Type
The myofiber type (red or white) depends The myofiber type (red or white) depends on innervation.on innervation.
All myofibers in a motor unit are of the All myofibers in a motor unit are of the same type.same type.
Dark (red) FibersDark (red) Fibers
Fatigue resistantFatigue resistantContract slowly (slow twitch)Contract slowly (slow twitch)Rely on oxidative phosphorylationRely on oxidative phosphorylationHave a large number of mitochondriaHave a large number of mitochondriaHave a high concentration of myoglobinHave a high concentration of myoglobinHave a low concentration of ATPaseHave a low concentration of ATPase
Light (white) FibersLight (white) Fibers
Fatigue easilyFatigue easilyContract rapidly (fast twitch)Contract rapidly (fast twitch)Rely on glycolysisRely on glycolysisHave a small number of mitochondriaHave a small number of mitochondriaHave a low concentration of myoglobinHave a low concentration of myoglobinHave a high concentration of ATPaseHave a high concentration of ATPase
Neuromuscular JunctionsNeuromuscular Junctions
Components:Components:Presynaptic membrane:Presynaptic membrane:
Terminal end of motor neuron.Terminal end of motor neuron.
Synaptic cleftSynaptic cleft
Postsynaptic membrane:Postsynaptic membrane:Sarcolemma (cell membrane of myofiber)Sarcolemma (cell membrane of myofiber)
Motor UnitMotor Unit
Consists of a motor neuron and all the Consists of a motor neuron and all the myofibers it innervatesmyofibers it innervates
Units for fine control have fewer fibersUnits for fine control have fewer fibers
Units for gross control have many fibersUnits for gross control have many fibers
Muscle ClassificationMuscle Classification
Fiber arrangementFiber arrangementShapeShapeOrigin and insertionOrigin and insertionFunctionFunction
Fiber ArrangementFiber Arrangement Straight:Straight:
Example: rectus abdominisExample: rectus abdominis Fusiform:Fusiform:
Example: biceps brachiiExample: biceps brachii Unipennate:Unipennate:
Example: palmar interosseous musclesExample: palmar interosseous muscles Bipennate:Bipennate:
Example: dorsal interosseous musclesExample: dorsal interosseous muscles Multipennate:Multipennate:
Example: deltoid muscleExample: deltoid muscle
Muscle Origin/InsertionMuscle Origin/Insertion
CoracobrachialisCoracobrachialis
SternocleidomastoidSternocleidomastoid
ContractionContraction
Definition:Definition:A contraction is a muscle’s response to a A contraction is a muscle’s response to a stimulus.stimulus.
Types of contraction:Types of contraction:Isotonic (the length of the muscle Isotonic (the length of the muscle
changes)changes)Concentric (length decreases)Concentric (length decreases)Eccentric (length increases)Eccentric (length increases)
Isometric (the length of the muscle stays Isometric (the length of the muscle stays the the same)same)
Types of ActionTypes of Action
Agonist (prime mover):Agonist (prime mover):A muscle that primarily carries out the A muscle that primarily carries out the
desired action.desired action.Antagonist:Antagonist:
A muscle that opposes the agonist.A muscle that opposes the agonist.Synergist:Synergist:
A muscle that eliminates the unwanted A muscle that eliminates the unwanted action of the agonist.action of the agonist.
Types of ActionTypes of Action
Fixator:Fixator:A muscle that stabilizes the origin of A muscle that stabilizes the origin of
another another muscle.muscle.Note: a single muscle can be all the above Note: a single muscle can be all the above
at one time or another.at one time or another.
InsufficiencyInsufficiency
Refers to the inability of a multijoint muscle Refers to the inability of a multijoint muscle to maximally contract simultaneously over to maximally contract simultaneously over all joints crossed.all joints crossed.
Active:Active:Refers to the agonistRefers to the agonist
Passive:Passive:Refers to the antagonistRefers to the antagonist
Smooth MuscleSmooth Muscle
Synonyms:Synonyms:VisceralVisceralInvoluntaryInvoluntary
Found in:Found in:Walls of visceral tubes (intestines, etc.)Walls of visceral tubes (intestines, etc.)Associated with hair folliclesAssociated with hair folliclesAround glandular structuresAround glandular structuresIn walls of blood vesselsIn walls of blood vessels
Smooth Muscle CharacteristicsSmooth Muscle Characteristics
Bundles of sheets of individual cells.Bundles of sheets of individual cells.Not striated (smooth).Not striated (smooth).Cells are primarily elongated and tapered.Cells are primarily elongated and tapered.Mononucleated.Mononucleated.
Smooth Muscle CharacteristicsSmooth Muscle Characteristics
Nuclei are centrally located in each cell.Nuclei are centrally located in each cell.Does not conduct action potential.Does not conduct action potential.Cells connected by gap junctions.Cells connected by gap junctions.Not under voluntary control.Not under voluntary control.
Cardiac Muscle TissueCardiac Muscle Tissue
Found only in walls of heart.Found only in walls of heart.Characteristics:Characteristics:
Striated (sarcomeres)Striated (sarcomeres)
Mononucleated cells:Mononucleated cells:May branchMay branch
Intercalated discs:Intercalated discs:Sites of transfer of stimulus between Sites of transfer of stimulus between
adjacent adjacent cells.cells.