““myo = muscle”myo = muscle”

The Muscular SystemThe Muscular System

Muscular SystemMuscular System

• There are over 600 skeletal muscles There are over 600 skeletal muscles • They make up 40-50% of our body weightThey make up 40-50% of our body weight• Muscles play a crucial role in Muscles play a crucial role in

communicationcommunication• No other animal has more complex facial No other animal has more complex facial

muscles than humans havemuscles than humans have• The smallest muscle in the body is the The smallest muscle in the body is the

stapedius and controls the stapes (stirrup stapedius and controls the stapes (stirrup bone in the ear)bone in the ear)

• The largest muscle in the body???The largest muscle in the body???• Gluteus maximus!Gluteus maximus!

Skeletal Muscle CellsSkeletal Muscle Cells• Muscle cells are called Muscle cells are called

muscle fibersmuscle fibers• Layers of connective tissue Layers of connective tissue

group muscles fibers group muscles fibers together and give them together and give them strengthstrength

• The The epimysiumepimysium, , perimysiumperimysium, and , and endomysiumendomysium, are , are continuous with each continuous with each other. other.

• Perimysium holds muscle Perimysium holds muscle cells together to form a cells together to form a fasciclefascicle..

• FasciaFascia is tough connective is tough connective tissue that covers muscle tissue that covers muscle organ including the organ including the epimysiumepimysium

Levels of Organization of a Levels of Organization of a MuscleMuscle

MuscleMuscle Fascicles Fascicles Muscle Fibers (cells) Muscle Fibers (cells) MyofibrilsMyofibrils Thick/Thin Thick/Thin filamentsfilaments

Shape, Size and Shape, Size and ArrangementArrangement

• Skeletal muscles are considered organsSkeletal muscles are considered organs• Their arrangement and shape are suited to their functionTheir arrangement and shape are suited to their function

Parallel Convergent Pennate Bipennate Sphincter

• During contraction one bones usually stays stationaryDuring contraction one bones usually stays stationary• Skeletal muscles can only contractSkeletal muscles can only contract• OriginOrigin is point of attachment that doesn’t move is point of attachment that doesn’t move• InsertionInsertion is point that does move with contraction is point that does move with contraction

Origin and Insertion Origin and Insertion PointsPoints

Muscle ActionsMuscle Actions

Agonist Agonist – Also called the prime moverAlso called the prime mover– Contracts to produce Contracts to produce

movementmovement

AntagonistAntagonist– Performs opposing action of Performs opposing action of

agonistagonist– Relaxes during contractionRelaxes during contraction

SynergistSynergist– Contract at same time of Contract at same time of

agonistagonist– Makes prime movers action Makes prime movers action

more efficientmore efficient

Fixator musclesFixator muscles– Stabilize jointsStabilize joints– Help maintain posture during Help maintain posture during

movementmovement

Lever SystemsLever Systems

First class leversFirst class levers– Work like seesawsWork like seesaws

Second class leversSecond class levers– Work like wheelbarrowWork like wheelbarrow

Third class leversThird class levers– Flexing of forearm at elbowFlexing of forearm at elbow– Most common type in bodyMost common type in body

Major Muscles of the Major Muscles of the BodyBody

How Muscles are NamedHow Muscles are Named

LocationLocation– Brachialis(arm) & gluteus(buttocks)Brachialis(arm) & gluteus(buttocks)

ActionAction– Adductor brevisAdductor brevis

Direction of fibersDirection of fibers– Rectus abdominisRectus abdominis

ShapeShape– DeltoidDeltoid (triangular) (triangular)

Number of heads/divisionsNumber of heads/divisions– Biceps, triceps, quadricepsBiceps, triceps, quadriceps

Origin and Insertion Origin and Insertion – SternocleidomastoidSternocleidomastoid (sternum, clavicle, mastoid) (sternum, clavicle, mastoid)

Relative Size of muscleRelative Size of muscle– Gluteus maximus, medius and minimusGluteus maximus, medius and minimus

Quick ReviewQuick Review• Connective tissue that covers individual muscle fibers?Connective tissue that covers individual muscle fibers?

– EndomysiumEndomysium• Connective tissue that surrounds and connects fascicles?Connective tissue that surrounds and connects fascicles?

– PerimysiumPerimysium• Covers the muscle as a whole?Covers the muscle as a whole?

– Epimysium or fasciaEpimysium or fascia• Which term includes all the rest- thin filament, muscle fiber, & myofibril?Which term includes all the rest- thin filament, muscle fiber, & myofibril?

– fasciclefascicle• This connects muscle to bone.This connects muscle to bone.

– TendonTendon• Name three fiber arrangements?Name three fiber arrangements?

– Parallel, convergent, pennate, bipennate, sphincterParallel, convergent, pennate, bipennate, sphincter• Point of attachment that does not move with contraction?Point of attachment that does not move with contraction?

– OriginOrigin• Does move with attachment?Does move with attachment?

– InsertionInsertion• Muscle that directly performs a movement?Muscle that directly performs a movement?

– AgonistAgonist• What is the most common type of lever system found in the body?What is the most common type of lever system found in the body?

– 33rdrd class class• Name two ways muscles are named and give examples.Name two ways muscles are named and give examples.

– Points of insertions-biceps, Shape deltoid, direction of fibers-rectus abdominis, functions-Points of insertions-biceps, Shape deltoid, direction of fibers-rectus abdominis, functions-adductor group, location- medialus, lateralis, intermediusadductor group, location- medialus, lateralis, intermedius