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    SKELETAL MUSCLE HISTOLOGY

    BY

    DR. MUDASSAR ALI ROOMI (MBBS, M. PHIL)

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    Skeletal muscle

    Makes the flesh of animals

    Pink in colour due to presence ofmyoglobin and capillaries.

    Muscle fibers are arranged in fasciculi

    Endomysium= C.T. covering of onemuscle fiber

    Perimysium= C.T. covering of onemuscle fascicle

    Epimysium= C.T. covering of wholemuscle

    Blood vessels penetrate the musclewithin the C.T. septa and form a richcapillary network in the endomysium.Lymphatic vessels and larger bloodvessels are found in the other C.T.layers.

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    CONNECTIVE TISSUE

    IN SKELETAL MUSCLE

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    Skeletal muscle fibers

    shape: cylindrical

    length: 1-40 mm

    Diameter: 10-100 um

    Nuclei: multiple

    (35/mm),

    subsarcolemmal.

    Capillaries are present

    in the endomysium

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    How multinucleated skeletal muscle fibers

    are produced!!

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    sarcomere

    Definition: Sarcomere is the functional unit of

    contraction in skeletal muscle.

    Its length is 2-2.5 um

    Sarcomere is the portion b/w two successive z

    discz.

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    skeletal muscle fibers show cross-striations of alternating light and dark

    bands.

    The darker bands are called A bands (anisotropic or birefringent in

    polarized light)

    the lighter bands are called I bands (isotropic, do not alter polarized light).

    I band is seen to be bisected by a dark transverse line, the Z line (Ger.

    Zwischenscheibe, between the discs).

    A band shows the presence of a lighter zone in its center, the H zone

    Bisecting the H zone is the M line

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    Sarcotubular system

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    Skeletal muscle

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    SKELETAL MUSCLE

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    HOW TO DRAW

    IT!!!!

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    Skeletal muscle

    IDENTIFICATION POINTS:

    1. Well marked Cross

    striations

    2. Cylindrical fibers

    3. Many sub-sarcolemmal flat

    nuclei

    4. endomysium and

    perimysium present

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    Some important definitions

    Hypertrophy: increase in the size of tissue due

    to increase in size of cells.

    Atrophy: decrease in the size of tissue due to

    decrease in the size of cells.

    Hyperplasia: increase in the size of tissue due

    to increase in the number of cells.

    Motor unit: all the muscle fibers supplied by

    one motor neuron.

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