Skeletal muscle is composed of bundles of muscle fibers wrapped in connective tissue sheaths. Each muscle fiber contains myofibrils which are made of repeating contractile units called sarcomeres. Sarcomeres contain thick myosin filaments interdigitating with thin actin filaments. During muscle contraction, cross bridges extending from the myosin filaments attach to the actin filaments, causing the sarcomere to shorten and the muscle fiber to contract.

1. Presents…

2. *SKELETAL MUSCLE….

3. *
The outer most covering by connective tissue is called
EPIMYSIUM {give shape and surrounds muscles}
The bundles of fibers wrapped in a connective tissue
sheath are called as FASCILES AND they are surrounded
by PERIMYSIUM

4. Each skeletal muscle consist of elongated fiber called as
MUSCLE FIBER.
It is a complete cell with cytoplasm called as sarcoplasm
and bounded by an outer membranecalled sarcolemma
It has many nuclei
Each muscle fiber
Consist of many Small
fibers called
MYOFIBRILS.

6. *
MYOFIBRILS
Contain special part SARCOMERE, found in straight line.
Actual unit of contraction.
Each sarcomere is separated from each sarcomere by aline
called Z-LINE

7. Between 2 Z-lines zones arepresent
1. DARK ZONE
2. LIGHT ZONE
These zones are responsible for the striation on
skeletal muscle.
Myofibril Consist
of many Small
parts called As
MICRO
FILAMENTS.

8. *

9. Dark band is called as A-band
Light band is called I-band
Between 2dark A bands a clear line is present called
H-line
In the centre of light I-band a black line is present called as
Z-line
The region between 2Z-lines isSARCOMERE

10. MICROFILAMENTS:
They are of two types
THICK FILAMENTS THIN FILAMENTS
MYOSIN ACTIN
The thick contractile
fliament in muscle cell
The thin contractile
fliament in muscle
cell

12. Thick filaments have cross bridges which are
thick and swollen along the ends called as
BULBOUSHEADS.
During contraction these cross bridges
connect with the actin filament.