Lecture 4 Flashcards by jihwan yoo

Myology

Study of muscle

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Muscle cells (fibers)

Only cell in the body that have property of contractility,.

Allows them to shorten and develop tension

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3 types of muscle

Skeletal, smooth, cardiac

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Skeletal muscle

Attaches to and moves the skeleton
Striped pattern
Voluntary control
75% water, 20% protein, inorganic salts, pigment, fat, carbs

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Smooth muscle

founding the walls of hollow organs and blood vessels.
Not aligned, creating smooth appearance
Involuntary control
Syncytium

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Syncytium

Connection between cells allows them to contract together

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Cardiac muscle

Heart wall contractile tissue
Has characteristics of both smooth muscle and skeletal muscle
Striped
involuntary control
syncytium

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6 criteria used to name muscles

Shape
Action
Location
division
Size relationship
direction of the fibers

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Shape

Deltoid, trapezius, rhomboid

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Action

Flexor, extensor, adductor, pronator

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Location,

anterior, intercostals, pectoralis major

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Division

Bicep, tri cep, quad ricep

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Size

Include the term Brevis (Short) , Longus (long)

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Direction of the fibers

Transverse (sideways) Rectus ( updown)

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Fasciculi

Bundle of muscle fibers

May run parallel to long axis muscle. Insert diagonally into a tendon running the length of the muscle.

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Unipennate:

All fascicule insert on one side of a tendon

-semimembranosus

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Bipennate-

fascicule insert on both sides of tendon

Multipennate

Convergence of several tendons- deltoid.

Longitudinal (strap)

Fascicule run parallel to the long axis of the muscle

Radiate

Fan our from a single attachment - pec major

Primary mover

A muscle whose contraction is primarily responsible for a particular movement

Antagonist

Oppose one another upon contraction

Located on opposite side of a joint

Fixator/stabilizer-

Muscle that immobilize a bone or joint near the organ of the prime mover so prime mover can act more efficiently

Gross Anatomy

Origin = less movable end of a muscle, proximal
Insertion = more movable end of a muscle, distal
Belly = Widest portion of a muscle, between its origin and insertion

Connective tissue 3 Layers:

Epimysium = whole muscle Perimysium = bundle of muscle fiber Endo mysium= a single muscle fiber

Myofibrils

Within muscle fiber, there are many myofibrils. consist of large array of contractile protein Striped

Sarcomere

Repeated area of a contractile protein, every section

Two major contractile proteins

Actin = (thin filament) | Myosin( thick filament)

Motor unit

Functional unit of a muscle consists of a motor neurone and all the muscle fiber that motor neurone innervates at spinal cord

Axon

Motor neurone extends from spinal cord to the target muscle which may be a few millimetres away or a few feet away

All-or none law

Once motor neuron receives a strong enough stimulus, an action potential is generated. All or none at all

Motor units can be slassfied in 2 ways

Slow twitch & fast twitch

3 types of metabolic characteristics

Slow twitch oxidative (SO) Fast twitch oxidative-glycolytic (FOG) Fast twitch glycolytic (FG)

Endurance athlete vs power athletes

Endurance athelte= more slow twitch | Power athlete = more fast twitch

Concentric

Muscle is shortening

Eccentric

Muscle is lengthening

Isometric

Muscle is stationary

Muscle Force-Velocity Relationship

when Maximally activated, faster a muscle shorten = less for it produces Faster it lengthens, more force it produces

Power =

= force x velocity

Angle of muscle pull

MUScle act on bones about the joint to form a lever system . Must be at 90 degrees or stabilizing component of the force increases.

3 factors that affects the expression of strength by a muscle

1. The initial length of the muscle fibers 2. speed of shortening 3. Angle of the muscle

Sarcopenia

Age-related loss of skeletal muscle mass, strength, and function.