Medical Terminology IMuscular System

Chapter 15

Functions

• Types of Muscles

• Structures

• Types

Functions

• Movement

• Create Heat

• Provide support

Types of Muscles

• Skeletal Muscle- called Striated voluntary muscles

• Cardiac Muscle- called mixed it contains both voluntary and involuntary muscle fiber

• Nonstriated Muscles- called involuntary muscles or smooth muscles found in the intestines, blood vessels

New York, 1837. Chromolithograph. National Library of Medicine.Jean Baptiste Sarlandière(1787-1838)[author]J. Bisbee[artist]

Structure

• Contractile cells- made up of myofilaments– Myosin protein that makes up the filaments– Sarcomere- basic contractile unit

seperated by “Z” lines• Thick and thin filaments slide past each other

and catch like “barbs” of a thistle

Muscle Tissue

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Contraction

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Structure Continued…

• All or none principle- the fibers must contract completely when they are stimulated

Structure

• Origin point immobile point where it attaches to bone tendon that attaches muscle to bone.

• Body of the muscle (belly) greatest amount of contractile fibers are found

• Insertion- muscle attaches to the bone and creates joint movement

Muscle Actions

• Prime Movers- muscle that creates the greatest amount of movement….most muscle action is carried out by groups of muscles– Synergist- muscles that help the prime

movers move the body– Antagonistic- muscles that move opposite

of the prime movers

Muscle Actions

• Tonic Contractions- muscles that stay contracted to provide good posture

• Can be trained to improve posture– Sit up straight– Stand up straight– Maintain muscle control through contractile exercises

» Crunches and pelvic floor exercises

Poor posture causes problems with your back and disease…..

Muscle Fatigue

• Muscles have built in energy called glycogen– The more you exercise the more glycogen

you store increases endurance slows the fatigue process

– When you burn Glycogen you release acid into muscles (lactic acid)

– To remove lactic acid you need to exercise more

Motor Unit

• Motor neurons are specialized nerve cells that stimulate muscles to shorten and produce movement

• Motor units are nerve/ muscle connects – Different types of motor units require

different levels of stimulation to cause contraction

Fast Twitch

• All people have both fast and slow twitch muscle fibers…..sprinters have more fast twitch muscle fiber and fewer slow twitch tissues

• Isotonic contractions- muscle contractions that produce movement

• Isometric contractions- muscle contractions that do not produce movement muscle tension increases.

Exercise and Muscles

Exercise is essential for proper muscle growth and motor development

•Atrophy- muscles become smaller due to lack of use or disease

•Hypertrophy- increase in muscle size due to exercise

Muscle movements

• Flexion

• Extension

Muscle movements

• Abduction

• Adduction

• Rotation

Muscle movements

• Supination

• Pronation

Muscle movements

• Dorsiflexion

• Plantar Flexion

Muscular Disorders

• Injuries– Strain- overexertion or trauma to muscles

causing over stretching or tearing of muscle fiber

– Cramps- painful contraction of muscle fiber

Muscular Disorders

• Poliomyelitis- a viral infection of the motor neurons causes paralysis

• Muscular Dystrophy- rapid progressive weakness and atrophy of muscles

Activities

• Vocabulary Flashcards

Assessment 15.06

Give the word for each definition, break it down into its parts, and give an example of a medical term using it.

1. Sheaths enveloping muscles2. Muscle3. Soles of the feet4. Lack of strength5. Back6. Smooth muscle lining the intestinal tract7. Development, nourishment8. Toward9. Away from10.Skeletal muscle connected to bone

Assessment 15.07 – Case StudyClinical information:• The patient was a 48 year-old woman who presented with a 10 cm

proximal, anterior intramuscular mass in her left thigh. Magnetic resonance imaging (MRI) studies suggested a "fatty tumor".  The patient was prepped for sugery and the mass was sent to the pathology department for evaluation and diagnosis. A resection yielded the following specimen.

Gross pathology of the case:• The tumor was a soft mass and the surface was covered by some tan

tissue fragments that were grossly consistent with skeletal muscle. The cut surface was translucent and gelatinous. Neither necrosis nor hemorrhage was present.

• Cellular myxoma, also known as low-grade myxoid neoplasm with recurrent potential, is a term that has been used recently to describe a family of myxomatous neoplasm with features in between intramuscular myxoma and low-grade myxofibrosarcoma. Although these tumors may recur, they do not metastasize. During the short available period of follow up in two of the recent studies, the rate of recurrence of these tumors is low.

Mirela Stancu, M.D.1 and Kar-Ming Fung, M.D., Ph.D.2 Last update on July 30, 2003.1 Department of Pathology, Roger William Medical Center-University Medical Group, Providence, Rode Island and 2 Department of Pathology, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma.