Chapter 17Chapter 17

MusculatureMusculature

SystemSystem

The Musculature SystemThe Musculature System

The Musculature SystemThe Musculature System Includes 3 types of Muscle:Includes 3 types of Muscle:

Striated, Smooth & Striated, Smooth & CardiacCardiac

Function of the Muscles:Function of the Muscles: Provide means of Provide means of

MovementMovement Keeps blood pumpingKeeps blood pumping Moves food thru Digestive Moves food thru Digestive

SystemSystem Skeletal Muscle usually in Skeletal Muscle usually in

Antagonistic PairsAntagonistic Pairs FlexorFlexor (bicep) (bicep) Extensor Extensor (tricep)(tricep)

The The Musculature Musculature

SystemSystem

Skeletal Skeletal StriatedStriated VoluntaryVoluntary

Organ Organ SmoothSmooth InvoluntarInvoluntar

yy

HeartHeart CardiacCardiac InvoluntarInvoluntar

yy

3 Types of Muscle Tissue

Skeletal, Smooth and Cardiac

How Muscles WorkHow Muscles Work Muscles can only Muscles can only contractcontract & &

get shorterget shorter They cannot push things, they They cannot push things, they

only pull. only pull. They are attached to two They are attached to two

different bones and cause different bones and cause them to bend at the jointthem to bend at the joint

OriginOrigin – place the muscle – place the muscle attaches or begins (proximal)attaches or begins (proximal)

InsertionInsertion – place on the other – place on the other side of joint muscle attaches side of joint muscle attaches (distal side)(distal side)

They work in Antagonistic PairsThey work in Antagonistic Pairs Flexors Flexors – cause the joint to – cause the joint to

bend – bicepbend – bicep ExtensorExtensor – causes the joint to – causes the joint to

extend ( straighten out) - tricepextend ( straighten out) - tricep

Muscles are attached to bones Muscles are attached to bones w/ w/ tendonstendons

Origin

Insertion

Smooth & Cardiac MuscleSmooth & Cardiac Muscle Smooth MuscleSmooth Muscle – usually are not voluntarily controlled. Found in the – usually are not voluntarily controlled. Found in the

walls of hollow organs of the digestive tract & blood vessels. walls of hollow organs of the digestive tract & blood vessels. They assist in the movement of food thru the digestive system They assist in the movement of food thru the digestive system

((peristalsisperistalsis) and movement of blood thru the circulatory system. ) and movement of blood thru the circulatory system. Cardiac MuscleCardiac Muscle – found only in the heart. Similar to both Striated & – found only in the heart. Similar to both Striated &

Smooth Muscle tissue. Involuntarily controlled by brain.Smooth Muscle tissue. Involuntarily controlled by brain.

Skeletal Muscle StructureSkeletal Muscle Structure Skeletal Skeletal musclesmuscles are made up of are made up of bundlesbundles of of muscle fibersmuscle fibers which in turn which in turn

are made of are made of myofibralsmyofibrals (multi-nucleated muscle cells). (multi-nucleated muscle cells). Each myofibral is made of Each myofibral is made of

thin thin filamentsfilaments called called ActinActin and thick filaments called and thick filaments called MyosinMyosin.. Muscle Muscle Bundle Bundle Fibers Fibers Myofibrils Myofibrils Filaments Filaments Actin & Myosin Actin & Myosin Each fiber is divided into functional units called sarcomeresEach fiber is divided into functional units called sarcomeres

tendon

Muscle

BundleBundle

Fiber

Myofibril

Filaments

Sarcomere

Skeletal Muscle Skeletal Muscle SarcomereSarcomere

SarcomereSarcomere is divided is divided into various zones. into various zones.

Each Sarcomere is Each Sarcomere is separated by separated by Z discsZ discs

Light colored bands Light colored bands are are I bands I bands

Dark colored bands Dark colored bands are are A bandsA bands

Middle of the dark Middle of the dark A band is A band is H zoneH zone

Middle of H zone is Middle of H zone is the the M line M line

MyosinActin

Muscle contraction begins Muscle contraction begins after a nerve stimulates the after a nerve stimulates the muscle fiber.muscle fiber.

Skeletal Muscle Skeletal Muscle ContractionContraction

MyosinActin

Muscle contraction begins Muscle contraction begins after a nerve stimulates the after a nerve stimulates the muscle fiber.muscle fiber. Impulse causes Impulse causes ActinActin filaments to slide over (like filaments to slide over (like a ratchet) the a ratchet) the Myosin Myosin filaments.filaments. This shortens the length of This shortens the length of the the sarcomere.sarcomere. Once contracted, the H Once contracted, the H zone closes up.zone closes up.This shortening isn’t much This shortening isn’t much until you add up the until you add up the thousands of sarcomeres in thousands of sarcomeres in each muscle bundle. each muscle bundle.

Need-to-Know Skeletal MusclesNeed-to-Know Skeletal MusclesKnow these muscles: Masseter, Trapezius, Deltoid, Pectoralis, Latissimus dorsi,

intercostals, Rectus abdominis, External obliques, Biceps brachii, Triceps, Gluteus, Rectus femoris, Biceps femoris, gastronemius