Muscle
Tissue & Organization
Sports Medicine
Unit 3
MUSCULAR SYSTEM
Muscle Functions
 Body Movement
 Maintenance of Posture
 Temperature Regulation – muscle contraction
generates 85% of the body’s heat
 Storage and Movement of Materials
 Support
Characteristics of Muscle
Tissue
 Excitability- receive and respond to stimuli
 Contractility- ability to shorten and thicken
 Extensibility- ability to stretch
 Elasticity- ability to return to its original shape after
contraction or extension
Types of Muscle
Types of Muscle
Skeletal
Muscle
Smooth Muscle
Cardiac Muscle
Location
Attached to
bone
On hollow organs,
glands and blood
vessels
Heart
Function
Move the
whole body
Heart
Compression of tubes
contraction to
& ducts
propel blood
Nucleus
Multiple,
peripheral
Single, central
Central & single
Control
voluntary
involuntary
involuntary
Striations
yes
no
yes
Cell Shape
Cylindrical
Spindle-shaped
Branched
Microscopic
Anatomy of
Skeletal Muscle
 Each muscle- has thousands of muscle fibers in a
bundle running from origin to insertion bound
together by connective tissue through which run
blood vessels and nerves.
 Each muscle fiber - contains many nuclei, an
extensive endoplasmic reticulum or sarcoplasmic
reticulum, many thick and thin myofibrils running
lengthwise the entire length of the fiber, and many
mitochondria for energy
Sacromere
Sacromere -The basic functional unit of
the muscle fiber consists of the array of
thick and thin filaments between two Z
disks.
Thick filaments - with myosin (protein)
molecules
Thin filaments - with actin (protein)
molecules plus smaller amounts of
troponin and tropomysin (also proteins).
Striations -of dark A bands and light I
bands.
A bands- are bisected by the H zone with
the M line or band running through the
center of this H zone.
I bands- are bisected by the Z disk or
line.
Muscle Contraction
 As the muscle contracts - the
width of the I bands and H
zones decrease causing the Z
disks to come closer together,
but there is no change in the
width of the A band because
the thick filaments do not
move.
 As the muscle relaxes or
stretches - the width of the I
bands separate as the thin
filaments move apart but the
thick filaments still do not
move.
Skeletal Fiber Organization
 Circular Muscles
 Convergent Muscles
 Parallel Muscles
 Pennate Muscles
Circular Muscles
 Fibers arranged concentrically around an opening
 Functions as a sphincter to close a passageway or
opening
 Example: Orbicularis oris (around mouth)
Convergent Muscles
 Triangular muscle with common attachment site
 Direction of pull of muscle can be changed
 Does not pull as hard as equal-sized parallel muscle
 Example: pectoralis major
Parallel Muscles
 Fascicles are parallel to the long axis of the muscle
 Body of muscle increases in diameter with contraction
 High endurance, but not very strong
 Example: rectus abdominis or sartorius
Pennate Muscles
 Muscle body has one or more tendons
 Fascicles at oblique angle to tendon
 Pulls harder than a parallel muscle of equal size
 Unipennate: all muscle fibers on the same side of the
tendon (example: extensor digitorum)
 Bipennate: muscle fibers on both sides of the tendon
(example: Interosseous)
 Multipennate: tendon branches within the muscle
(example: deltoid)
Skeletal Muscles
 Origin - Attachment to the more stationary bone by tendon
closest to the body or muscle head or proximal (head)
 Insertion - attachment to the more moveable bone by tendon
at the distal end
 During movement, the origin remains stationary and the
insertion moves.
 The force producing the bending is always a pull of
contraction. Reversing the direction is produced by the
contraction of a different set of muscles.
 As one group of muscles contracts, the other group
stretches and then they reverse actions.
Naming of Skeletal Muscles
 Muscles are named according to a variety of features:

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Muscle action
Specific body region
Muscle attachments
Orientation of muscle fibers
Muscle shape and size
Muscle heads/tendons of origin
Naming of Skeletal Muscles
 Muscle Action:
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Adductor
Abductor
Flexor
Extensor
Naming of Skeletal Muscles
 Specific Body Regions:
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Oris (mouth)
Cervicis (neck)
Brachial (arm)
Carpi (wrist)
Pollicis (thumb)
Gluteal (buttocks)
Femoris (thigh)
Hallus (great toe)
 Anterior (toward front)
 Posterior (toward back)
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Superior
Inferior
Superficialis (superficial)
Profundus (deep)
Naming of Skeletal Muscles
 Muscle Attachments
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Sternum and clavical (cleido)
Between the ribs (intercostal)
Subscapular fossa (Subscapularis)
Fibula (fibularis longus)
Zygomatic bone (zygomaticus major)
Naming of Skeletal Muscle
 Orientation of muscle fibers
 Rectus (straight)
 Oblique (angled)
 Orbicularis (circular)
Naming of Skeletal Muscles
 Muscle shape and size
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Deltoid (triangular)
Quadratus (rectangular)
Trapezius (trapezoidal)
Longus (long)
Brevis (short)
Major (larger of two muscles)
Minor (smaller of two muscles)
Maximus (largest)
Medius (medium sized)
Minimus (smallest)
Naming of Skeletal Muscles
 Muscle heads/tendons of origin
 Biceps (two heads)
 Triceps (three heads)
 Quadriceps (four heads)
Front
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