Muscular System Responsible for movement Main function is contraction and shortening.

Muscular SystemMuscular System

Responsible for movementResponsible for movement

Main function is contraction Main function is contraction and shorteningand shortening

Muscle SystemMuscle System

A. General InformationA. General Information– 1. 3 muscle types1. 3 muscle types

a. Skeletala. Skeletal

b. Cardiacb. Cardiac

c. Smoothc. Smooth

– 2. Differ based on cell structure, body 2. Differ based on cell structure, body location, and how they are stimulated to location, and how they are stimulated to contractcontract

Muscle System – General FunctionMuscle System – General Function

B. General FunctionB. General Function– 3. Contract due to electrochemical 3. Contract due to electrochemical

impulsesimpulses– 4. 3 general functions 4. 3 general functions (we will cover (we will cover

each of these individually)each of these individually)a. Motiona. Motion

b. Heat productionb. Heat production

c. Posture and body supportc. Posture and body support

Muscle System – General FunctionMuscle System – General Function

B. General Function (cont)B. General Function (cont)– 4. (cont)4. (cont)

a. Motiona. Motion– i. General movement of the bodyi. General movement of the body

Examples: walking, running, writing, Examples: walking, running, writing, swimming, etc.swimming, etc.

– ii. Breathing and moving of body parts, without ii. Breathing and moving of body parts, without actually moving, are caused by skeletal muscleactually moving, are caused by skeletal muscle

– iii. Blood flow and food flow through the iii. Blood flow and food flow through the associated systems is caused by smooth muscleassociated systems is caused by smooth muscle

Muscle System – General FunctionMuscle System – General Function

B. General Function (cont)B. General Function (cont)– 4. (cont)4. (cont)

b. Heat productionb. Heat production– i. Muscle metabolism helps to support the internal i. Muscle metabolism helps to support the internal

temperature temperature – ii. Muscles make up 40% of the body weight and ii. Muscles make up 40% of the body weight and

are continuously active creating heatare continuously active creating heat– iii. Shivering is a response to the body needing to iii. Shivering is a response to the body needing to

warm upwarm up

Muscle System – General FunctionMuscle System – General Function

B. General Function (cont)B. General Function (cont)– 4. (cont)4. (cont)

c. Posture and body supportc. Posture and body support– i. Skeletal muscle gives form and supporti. Skeletal muscle gives form and support– ii. Some muscles work in opposition to gravityii. Some muscles work in opposition to gravity– iii. Oppositional muscles (to gravity) work without iii. Oppositional muscles (to gravity) work without

our control, that is why we get the head nodding our control, that is why we get the head nodding when I am particularly boring!when I am particularly boring!

Muscle System – General FunctionMuscle System – General Function

C. Basic Characteristic PropertiesC. Basic Characteristic Properties1. Irritability1. Irritability

– Receives and responds to nerve stimulusReceives and responds to nerve stimulus

2. Contractility2. Contractility– Responds to stimulus by contrationResponds to stimulus by contration

3. Extensibility3. Extensibility– Opposing muscles will stretch or lengthen muscle Opposing muscles will stretch or lengthen muscle

fibers after the stimulus stopsfibers after the stimulus stops

4. Elasticity 4. Elasticity – Tends to return to original lengthTends to return to original length

Muscle System – General FunctionMuscle System – General Function

D. Basic Characteristic of Smooth D. Basic Characteristic of Smooth and Skeletal Musclesand Skeletal Muscles

1. Skeletal and smooth muscles are 1. Skeletal and smooth muscles are elongatedelongated

Called muscle fibersCalled muscle fibers

2. Contraction is dependant on the type of 2. Contraction is dependant on the type of myofilamentmyofilament

Myo- and mys- and sarco- prefixes mean the term Myo- and mys- and sarco- prefixes mean the term is dealing with musclesis dealing with muscles

Muscle System - SkeletalMuscle System - SkeletalE. Skeletal Muscle CharacteristicsE. Skeletal Muscle Characteristics– 1. The muscles are usually:1. The muscles are usually:

a. long and narrowa. long and narrowb. span a jointb. span a jointc. are attached by tendons to bonesc. are attached by tendons to bones

– 2. The origin of a muscle is the more 2. The origin of a muscle is the more fixed or stationary attachmentfixed or stationary attachment

a. Generally the proximal attachmenta. Generally the proximal attachment

– 3. The insertion is the more movable end 3. The insertion is the more movable end a. Generally the distal attachmenta. Generally the distal attachment

Skeletal Muscle FibersSkeletal Muscle Fibers

Muscle System - SkeletalMuscle System - SkeletalE. Skeletal Muscle CharacteristicsE. Skeletal Muscle Characteristics– 4. The belly or gaster is the fleshy or thickened 4. The belly or gaster is the fleshy or thickened

portionportiona. Usually on the bone proximal to the bone being a. Usually on the bone proximal to the bone being movedmoved

– 5. The tendon spans the joint between the 5. The tendon spans the joint between the bonesbones

– 6. Tendons in the wrist and ankle are protected 6. Tendons in the wrist and ankle are protected by a tendon sheathby a tendon sheath

a. Lubricate the tendons with synovial fluid, although a. Lubricate the tendons with synovial fluid, although the tendon is covered by a retinaculumthe tendon is covered by a retinaculum

Muscle System - SkeletalMuscle System - SkeletalE. Skeletal Muscle CharacteristicsE. Skeletal Muscle Characteristics– 7. Made up of skeletal muscle fibers7. Made up of skeletal muscle fibers– 8. Attach to the skeleton8. Attach to the skeleton– 9. Are cigar shaped9. Are cigar shaped– 10. Multinucleated cells10. Multinucleated cells– 11. Largest muscle fibers11. Largest muscle fibers

a. Some up to 30cm long (almost a foot!)a. Some up to 30cm long (almost a foot!)

– 12. Striated muscle12. Striated muscle– 13. Voluntary muscle (can control)13. Voluntary muscle (can control)

a. Mostly reflexivea. Mostly reflexive

Muscle System - SkeletalMuscle System - SkeletalE. Skeletal Muscle CharacteristicsE. Skeletal Muscle Characteristics– 14. Contracts with great force14. Contracts with great force– 15. Become tired easily and must rest15. Become tired easily and must rest– 16. Muscles that contract together are called 16. Muscles that contract together are called

synergisticsynergistica. Muscles of the upper arm (biceps and brachialis) a. Muscles of the upper arm (biceps and brachialis) contract to contract to flexflex the elbow the elbow

– 17. Muscles that contract opposite to each 17. Muscles that contract opposite to each other are called other are called antagonisticantagonistic

a. The triceps muscle contracts to a. The triceps muscle contracts to extendextend the elbow the elbow

Muscle System - SkeletalMuscle System - SkeletalE. Skeletal Muscle CharacteristicsE. Skeletal Muscle Characteristics– 18. Architecture (just a few) of the Origin or 18. Architecture (just a few) of the Origin or

Insertion (a.k.a. Tendon Shapes)Insertion (a.k.a. Tendon Shapes)a. Parallel or fusiforma. Parallel or fusiform

– i. Have Fibers that run parallel to each other i. Have Fibers that run parallel to each other – ii. Are sometimes called Strap Musclesii. Are sometimes called Strap Muscles– iii. These are long musclesiii. These are long muscles– iv. Have good endurance, but are not strongiv. Have good endurance, but are not strong

ex. Sartorius and Sternocleidomastoid ex. Sartorius and Sternocleidomastoid musclesmuscles

Muscle System - SkeletalMuscle System - Skeletal

E. Skeletal Muscle Characteristics E. Skeletal Muscle Characteristics (cont)(cont)– 18. Architecture (just a few) of the 18. Architecture (just a few) of the

Origin or Insertion (a.k.a. Tendon Origin or Insertion (a.k.a. Tendon Shapes) [cont]Shapes) [cont]

b. Convergentb. Convergent– i. The origin is wider than the point of insertioni. The origin is wider than the point of insertion– ii. Fibers converge at the insertion point to ii. Fibers converge at the insertion point to

maximize contractionmaximize contraction– iii. Sometimes called Triangular Musclesiii. Sometimes called Triangular Muscles

ex. Pectoralis Majorex. Pectoralis Major

Muscle System - SkeletalMuscle System - Skeletal

E. Skeletal Muscle Characteristics E. Skeletal Muscle Characteristics (cont)(cont)– 18. Architecture (just a few) of the Origin 18. Architecture (just a few) of the Origin

or Insertion (a.k.a. Tendon Shapes) [cont]or Insertion (a.k.a. Tendon Shapes) [cont]c. Pennatec. Pennate

– i. Many fibers per unit area, are strong, provide i. Many fibers per unit area, are strong, provide dexterity and tire quicklydexterity and tire quickly

3types 3types (we will go into more detail for each)(we will go into more detail for each)(indent) Unipennate(indent) Unipennate(indent) Bipennate(indent) Bipennate(undent) Multipennate(undent) Multipennate

Muscle System - SkeletalMuscle System - Skeletalc. Pennate (cont)c. Pennate (cont)– 3 types (cont)3 types (cont)

Unipennate (cont)Unipennate (cont)– Muscle fibers are arranged in a diagonal direction Muscle fibers are arranged in a diagonal direction

into the tendoninto the tendon

Allows for great strengthAllows for great strength

Examples: Lunbricals, Externsor Digitorum Examples: Lunbricals, Externsor Digitorum LongusLongus

Bipennate (cont)Bipennate (cont)– Muscle fibers are concentrated into two rowsMuscle fibers are concentrated into two rows– Facing in opposite diagonal directions into the Facing in opposite diagonal directions into the

central tendon (looks like a feather)central tendon (looks like a feather)

Example: Rectus FemorisExample: Rectus Femoris

Muscle System - SkeletalMuscle System - Skeletalc. Pennate (cont)c. Pennate (cont)– 3 types (cont)3 types (cont)

MultipennateMultipennate– Multiple rows of diagonal fibers with a branching Multiple rows of diagonal fibers with a branching

central tendon (two or more)central tendon (two or more)

Example: Deltoid (three sections, Example: Deltoid (three sections, [anterior/posterior/middle])[anterior/posterior/middle])

Muscle System - SkeletalMuscle System - Skeletal

E. Skeletal Muscle Characteristics E. Skeletal Muscle Characteristics (cont)(cont)– 18. Architecture (just a few) of the 18. Architecture (just a few) of the

Origin or Insertion (a.k.a. Tendon Origin or Insertion (a.k.a. Tendon Shapes) [cont]Shapes) [cont]

d. Circular d. Circular – i. Appear circular in shapei. Appear circular in shape– ii. Surround a body openingii. Surround a body opening

act as a sphincteract as a sphincter

Tendon/Muscle ShapesTendon/Muscle Shapes

Parallel MusclesParallel Muscles

Parallel and PennateParallel and Pennate

Circular MusclesCircular Muscles

Muscle System – Skeletal FibersMuscle System – Skeletal Fibers

F. Skeletal Muscle FibersF. Skeletal Muscle Fibers– 1. Anatomy of a skeletal muscle fiber1. Anatomy of a skeletal muscle fiber

a. Fibers are bundled together by connective a. Fibers are bundled together by connective tissuetissue

b. Each single fiber is bundled by a b. Each single fiber is bundled by a connective tissue sheath called connective tissue sheath called endomysiumendomysium

– i. The i. The endomysiumendomysium package is called a bundle package is called a bundle

Muscle System – Skeletal FibersMuscle System – Skeletal Fibers

F. Skeletal Muscle FibersF. Skeletal Muscle Fibers– 1. Anatomy of a skeletal muscle fiber (cont.)1. Anatomy of a skeletal muscle fiber (cont.)

c. Several muscle bundles are wrapped by a coarse c. Several muscle bundles are wrapped by a coarse fibrous membrane called fibrous membrane called perimysiumperimysium

d. The wrapped fiber bundles are called a d. The wrapped fiber bundles are called a fasiclefasicle

e. Many e. Many fasiclesfasicles are bundled together in a tissue are bundled together in a tissue called called epimysiumepimysium

f. f. EpimysiaEpimysia are blended together to form are blended together to form tendonstendons or or aponeurosesaponeuroses (which attach muscles indirectly to (which attach muscles indirectly to bones)bones)

Skeletal Muscle EpimysiumSkeletal Muscle Epimysium

Muscle System - SmoothMuscle System - SmoothG. Smooth Muscle CharacteristicsG. Smooth Muscle Characteristics– 1. No striations1. No striations– 2. Involuntary movement (can’t control)2. Involuntary movement (can’t control)– 3. Found in the walls of hollow organs3. Found in the walls of hollow organs

a. Examples: stomach, urinary bladder, a. Examples: stomach, urinary bladder, bronchial tubes, etc.bronchial tubes, etc.

– 4. Overall description:4. Overall description:a. Viscerala. Visceralb. Nonstriatedb. Nonstriatedc. Involuntary c. Involuntary

Muscle System - SmoothMuscle System - Smooth

G. Smooth Muscle CharacteristicsG. Smooth Muscle Characteristics– 5. Cells are spindle shaped5. Cells are spindle shaped– 6. Have a single nucleus6. Have a single nucleus– 7. Arranged in sheets or layers7. Arranged in sheets or layers– 8. Usually one layer is circular, the other 8. Usually one layer is circular, the other

is arranged longitudinallyis arranged longitudinally– 9. They contract opposite or 9. They contract opposite or

antagonistically, changing the shape of antagonistically, changing the shape of the organthe organ

Smooth Muscle FibersSmooth Muscle Fibers

Muscle System - CardiacMuscle System - CardiacH. Cardiac Muscle CharacteristicsH. Cardiac Muscle Characteristics– 1. Found only in the heart1. Found only in the heart– 2. It is striated and involuntary2. It is striated and involuntary– 3. Cushioned by small amounts of 3. Cushioned by small amounts of

connective tissueconnective tissue– 4. Arranged in spiral shapes4. Arranged in spiral shapes– 5. Connected by intercalated discs, 5. Connected by intercalated discs,

sends chemicals to allow for controlled sends chemicals to allow for controlled contractionscontractions

– 6. Usually contracts at a steady rate6. Usually contracts at a steady rate

Cardiac Muscle FibersCardiac Muscle Fibers