compa lecture5 muscular system slides

8/6/2019 Compa Lecture5 Muscular System Slides

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The Muscular System



Muscle Characteristics• The ability to contract• Contraction results in movement• Contraction occurs due to sliding filaments• Muscles contract due to nerve activity• Muscles can be under voluntary or involuntary

control



Muscle Actions• Propulsion of materials through tubes• Animate the skeleton• Control entry & exit of materials

• Control hair or feathers for insulation• Thermogenesis•

Create low voltage electrical fields



Muscle Classification• Red muscle & white

muscle• Somatic & visceral

locations

•

o untary nvo untarycontrol• Three histological types

– Skeletal – Cardiac – Smooth

http://www.calhoun.cc.al.us/distance/Internet/Natural/Healthlinks/ems/paramedic%20student%20page/Vol.%201%20Ch.%208a_files/slide0018_image005.jpg



Skeletal Muscle Characteristics• Striated & multinucleated• Somatic muscle under voluntary control• Quick response time due to nerve stimulation of

independently contracting muscle fibers• Results in body movement, posture and balance

http://www.colorado.edu/intphys/Class/IPHY3430-200/image/12-1.jpg



Smooth Muscle Characteristics• Non-striated & mononucleated•

Under involuntary control• Relatively slow response time due to stimulation

produced by pacemaker potentials & hormones

secretions




Cardiac Muscle Characteristics• Striated, branched & mononucleated• Under involuntary control• Quick response time due to pacemaker produced action

potentials• Intercalated discs connecting fibers produce simultaneous

• Results in heart beats and the movement of blood




Muscle

Anatomy



Muscle Anatomy



Muscle AnatomyOriginOrigin

HeadHead

GasterGaster

(belly)(belly)

SlipSlip



Muscle Anatomy• Tendons are fibrous connective tissues that

are continuous with the periosteum of thebone

•

en ons connect musc e to one, cart age orother connective tissues• Aponeuroses are thin, flat sheet like tendons• Facia are sheets of connective tissues that

encapsulate and bind body parts together



Motor Unit



Muscle Origins• All muscle originates from the mesodermal germ layer•

Mesenchyme - a loose assembly of embryonic cellsthat give rise to smooth muscle in the blood vessels &some viscera

-mesoderm that embrace the gut and produce thesmooth muscle of the alimentary canal & itsderivatives

• Paraxial mesoderm - mesoderm that forms next to theneural tube along the axis of the body, giving rise tothe skeletal muscles



Muscle Origins



Muscle Actions• Since muscles can only contract, there is an opposite

reaction to pull them back to their original position• In most cases, especially with skeletal muscle, this

opposite reaction is brought about by opposingmuscles or muscle groups

•

Synergists are muscles or muscle groups that performthe same or similar actions on the same bone(s) orbody region

– tensor facia latae, gluteus• Antagonists are muscles or muscle groups that performopposite actions on the same bone or body region

– tensor fascia latae, adductor longus



Muscle Actions• Fixators are muscles that act to hold a body

part rigid, e.g. muscles of the abdomen, back& shoulders

between articulating bones – biceps brachii, rectus abdominis

• Extensors are muscles which increase the anglebetween articulating bones

– triceps brachii, quadriceps



Muscle Actions• Protractors are muscles that cause the

projection of a part – Lateral pterygoid

•

Retractors are musc es t at return a part roma protracted position – Masseter

• Rotators are muscles that cause a limb tomove 360 o about its axis



Muscle Actions• Supinators are rotators that move the palm or sole

upwards – Supinator

• Pronators are rotators that move the palm or soledownwards

–

• Sphincters are muscles that constrict to close anopening

– cardiac sphincter, anal sphincter•

Dilators are muscles that constrict to widen an openingor orifice – ciliary muscles



Muscle Actions

compa lecture5 muscular system slides

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