This document provides an overview of the musculoskeletal system and the three types of muscle tissue: skeletal, smooth, and cardiac. It discusses the structure, function, and characteristics of each muscle type. The key points are: - Skeletal muscle is striated, voluntary, and attaches to bones to allow movement. It contains many nuclei and is found wrapped in connective tissue. - Smooth muscle is involuntary, non-striated, and forms hollow organ walls. It is spindle-shaped with a single nucleus. - Cardiac muscle is striated, involuntary, and branched. It forms the heart wall and beats rhythmically.

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Dr Chimdessa T.(MD)

2.  Introduction to Musculoskeletal system
 Functions of Muscles
 The three basic muscle types
 Connective tissues of Muscles
 Attachment of muscles
 Naming of skeletal muscles
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3.  Muscle tissue is highly cellular, well-vascularized tis
sue.
 Responsible for body movement.
 There are three kinds of muscle tissue: skeletal
cardiac & smooth muscles. They differ in:
 the structure of their cells
 their body location
 their function
 the means by which they are activated to contract
 Muscle cells are elongated & are referred to as musc
le fibers.
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4.  Excitability or irritability
- the ability to respond to a stimulus
 Contractility
- the ability to shorten
 Extensibility
- the ability to stretch
 Elasticity
- the ability to resume normal length after bein
g shortened
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5. Includes: - skeletal muscle
- Smooth muscle
- Cardiac muscle
1. Skeletal muscle
 Wrapped by connective tissue
 Attach to bones & some to skin
 When contracts it causes gross body movements
 Have long, cylindrical & multinucleated cells
 Voluntarily controlled
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6.  Are Striated, (fibers contain alternating light & da
rk bands)
 Long & cylindrical cell.
 Diameter of 10-100 m (10x average cell size)
 Contains many nuclei, which lie at the cell periphe
ry.
 Each muscle fiber enveloped by sarcolema (plas
ma membrane).
 Cytoplasm of muscle fiber is referred as sarcoplas
m
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9.  Produces movement
 Maintains posture
 Stabilizes joints
 Generates heat
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10. • Each skeletal muscle is a discrete organ with tho
usands of muscle fibers.
• It also contains blood vessels, nerve fibers, & conne
ctive tissues.
• Each muscle fiber (cell) is wrapped by fine sheath
of connective tissue called endomysium.
• Several fibers are gathered side by side into a bun
dle called fascicle.
• Each fascicle is bound by collagen fiber layer called
the perimysium.
• The entire muscle (a group of fascicles) is bound
by a dense fibrous connective tissue layer, called ep
imysium.
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12.  Most muscles have at least two attachments.
Origin
- Attachment of a muscle that remains relatively fixed
during muscular contraction.
- Generally a more proximal or axial location
Insertion
- Attachment of a muscle that moves during muscular
contraction.
- Generally a more distal or appendicular attachment
Direct attachments: when epimysium attach directly t
o periosteum of bone or perichondrium of cartilage.
Indirect attachments: when the epimysium attach to
a tendon or an aponeurosis.
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13.  Muscle fiber can be divided by the strength, spee
d, & endurance of contraction in to three.
 Red fibers (slow twitch)
 White fibers (fast twitch)
 Intermediate fibers
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14.  Relatively fibers are thin so, do not generate much
power .
 Named for the abundant myoglobin (oxygen bindi
ng pigment) in their sarcoplasm.
 Obtain their energy from aerobic reactions.
 Contract slowly, & resistant to fatigue as long as o
xygen is present.
 Used in many of the postural muscles of the axial
skeleton.
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15.  Pale because they contain little myoglobin
 About twice the diameter of red fibers
 Contain more myofibrils & generate more power.
 Contract rapidly & tire quickly
 Common in the muscle of the upper limbs
 Used to lift heavy objects for brief periods
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16.  Size b/n the other two fiber types
 Like white fibers they contract quickly
 Like red fibers they are oxygen dependent & have
a high myoglobin content & a rich in capillaries.
 Less fatigue resistant
 Abundant in the muscles of the lower limbs.
 Used to move the body for long periods of time in
activities like walking & jogging.
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17.  Lack the courser connective tissue found in skeletal
muscles.
 Have small amounts of endomysium
 Occur in walls of blood vessels & hollow organs of r
espiratory, urinary, digestive & reproductive tracts.
 Organized into sheets of closely apposed fibers.
 In most cases their fibers aligned at right angle to e
ach other: longitudinal layer & circular layer.
 These two layers contract & squeeze the contents of
the organ.
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19.  Non straited,
 Spindle shaped (Fusiform )
 Single centrall nucleus.
 Range in length from 2 micron in small blood vessel
s to 500 micron in the pregnant uterus.
 Actively divide & regenerate
 Contractile filaments are not organized into myofib
rils
 Contraction occurs more slowly and lasts longer
 Involuntarily controlled
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21.  Forms the wall of the heart
 Contract spontaneously & display a rhythmic b
eat.
 Do not regenerate; repaired by scar formation.
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22.  Involuntary control
 Fibers are Striated, short, branched, cylindrical
& interconnected
 Fibers have one or two centrally located nuclei
 Fibers attached to each other by transverse thickeni
ng of the sarcolemma called intercalated discs (co
mplex cell junction forming end-to-end attachmen
t b/n adjacent cardiac muscle cells) & help them to f
unction as a single unit.
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25.  Modified cardiac muscle cells located in the
atrioventricular (AV) bundle of the heart.
 Specialized for conduction
 Large, pale cells filled with Glycogen
 Form gap junction & desmosomes
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26. Type of
muscle
Shape of cells Nuclei Control Striation
s
Special features
Skeletal Long and
cylindrical
Many
Peripheral
Voluntary Present  hypertrophy and
hyperplasia
 Slight
regeneration
Cardiac short,
cylindrical
and
branching
One or two
central
Involunta
ry
Present  Hypertrophy
 No regeneration
Smooth Fusiform One
Central
Involunta
ry
Absent  hypertrophy and
hyperplasia
 regenerate
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27. Muscles can be classified into four functional groups:
 Prime movers: a muscle that provides the major
force for producing a specific movement.
 Antagonists: muscles that oppose a particular mo
vement.
 Synergists: promoting the same movement
 Fixators: Serves to stabilize the bone upon which
a prime mover acts.
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28. Shape: Rhomboideus (rhomboid), Trapezius (trapez
oid)
Location: Pectoralis (chest or pectus),
Intercostal (b/n ribs)
Attachment: Sternocleidomastoid (sternum, clavicle
& mastoid process)
Size: Maximus (largest), minimus (smallest),
Longus (long), Brevis (short)
Number of origins: Biceps, Triceps, Quadriceps
Orientation of fibers: Rectus (straight), Transverse,
Oblique
Relative position: Medial, Lateral, Internal & External
Action : Adductor, Flexor, Extensor, Levator
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