Download Muscle - Yengage

INTRODUCTION TO
MUSCLE TISSUE
Learning objectives
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Definition
Structure
Properties
Classification
Functions.
Muscle
Definition: collection of specialised cells
with impt properties – contractility
Elasticity
Muscle – Muscle fibers
blood vessels
connective tissue
nerve fibers
Properties of muscle
Special property = contractility
Plasmalemma = sarcolemma
Cytoplasma = sarcoplasm
Endoplasmic reticulum = sarcoplasmic
reticulum
tissue ?
group of cells morphologically similar &
physiologically identical.
Muscle cells or myocyte –
Features
1.Shape : long , narrow , cylinderical fibres
2. Fibres run parallel to axis of muscle .
3. Composed of smaller of thicker & thinner
filaments
4. Made up of myoproteins = Actin , myosin
,tropomyosin , troponin
Three kinds of muscle
•Striated
•Smooth
•Cardiac
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Skeletal muscle / Voluntary/Striated
Straight
Unbranched
They acts on the joint
Reveals cross striations
Structural Syncitium
•It is under the control of our will – voluntary
• Nuclei towards periphery.
• Light & dark band present -striped muscle
• Parts of voluntary muscle
• Fleshy belly
• Fibrous extension = tendon or aponeurosis
Classification of voluntary muscles
1.According to color= Red & White
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Red
More primitive
Less cross striations
More sarcoplasm
Contraction is slow
Found in deep
muscles
• Ex: extensors
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White
More recent
More striations
Less sarcoplasm
Contraction is rapid
Found in Superficial
muscles
• Ex: muscles for eye
movement
2.Types of insertion of muscles
3. According to the direction of the
muscle fibers
a. Parallel
b. Pennate
c. Spiral
d. Cruciate
a).Parallel muscles
• The muscle fibers are parallel to line of
pull
• The fibers are long
• Functions:
• Range of movement
• ↓ Power of action
Sub divisions of parallel muscles
a).Strap muscles
b).Quadrate muscles
c).Fusiform muscles
• Strap muscles
Ex: Sartorius
Rectus abdominis
• Quadrate
Quadratus lumborum
• Fusiform muscle
Biceps brachii
b) Pennate muscles
• Fibers are oblique to line of pull
b.1 Unipennate
Flexor pollicis longus
Extensor digitorum longus
Peroneus tertius
b.2 Bipennate
Rectus femoris
Dorsal interossei of hand & foot
b.3 Multipennate
• A series of bipennate muscles lie side
by side in one plane
Acromial fibers of deltoid
B 4 Circumpennate
• The muscle is cylindrical
• Oblique fibers converge into central
tendon from all sides
Tibialis anterior
c) Spiral muscle
• Muscles are twisted in arrangements
close to their insertion
ex- Pectoralis major & latissimus dorsi
• Cruciate muscle
• Muscle fibers are arranged in sup and
deep planes crossing like “X”
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Action of muscles
Prime mover
Antagonists
Fixation muscles
Synergists
TENDON: skeletal muscle & bundles of
fibres is surrounded by connective tissue , at
the end of muscle & is continued as tendon .
Aponeurosis ?
Antagonistic muscle
Definition : muscle on contraction brings
opposite movements at the same joint
example–
a) contraction of biceps flexes the elbow joint
whereas triceps brings expense elbow joint .
b) Abductor draw the bone away from body
Adductors brings bone towards the body
c) sphinctor – constricts an opening
d) dilator - dialates opening
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Structure of voluntary muscle
Coverings
Epimysium
Perimysium
Endomysium
Each fasiculus is covered by
endomysium
muscle
Fasciculus
Muscle fibers
Myofibris
Myofilaments of actin &
mysoin
E M structure of skeletal muscle
1)Myofibrils composed of
myosin (thick filaments) ,
actin & other proteins (thin filament)
2).Dark bands – A band
3).Lightband – I band
4). Center of A band – light – H band .
•H band is again bisect by M line .
•Each I band has dark line the Z disc
the portion of myofibril b/w two Z
discs – sarcomere.
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Sarcolemma
Sarcoplasm
Myofibrils
Myofilaments
• Smooth muscle
• Not under control of conscious mind
• The action is sluggish
• Smooth muscle
• Two types of smooth muscles
• Multi unit muscle
Contraction does not arise
spontaneously
• Ex: Muscles of iris and those of the wall
of large arteries
• Single unit muscle
• Contraction is spontaneous
• Action is myogenic
• Ex: are muscles of stomach, intestines,
uterus, ureter and some of the small
blood vessels
• Cardiac muscle
• Source of development : all from
secondary mesoderma in origin .
Ciliary muscle of eye & iris
----- ectodermal in origin .
• Skeletal muscle – somatopleuric
mesoderm
• Cardiac muscle
splanchnopleuric
• Smooth muscle
mesoderm.
Functions muscle tissue
•To provide movement of
skeleton & other organs .
•Contraction
•Storage of glycogen
Muscle contracts & relaxes but never expands
 largest muscle – gluteus maximus
 longest muscle – sartorious
Smallest muscle – stapedius of
middle ear