This document provides an overview of the muscular system and different types of muscles. It begins by outlining the learning objectives of understanding muscle types, attachments, shapes, arrangements, innervation, and roles. It then defines muscles and describes the three main types: skeletal, smooth, and cardiac. Skeletal muscles are striated and voluntary, attaching to bones and enabling movement. Smooth muscles are involuntary muscles that line organs. Cardiac muscle is striated and involuntary, found only in the heart. The document proceeds to detail skeletal muscle structure, arrangement, attachments, actions, and nerve supply.

1. Prof. Laila M. Aboul Mahasen Morsy
Anatomy Department, Faculty of Medicine ,
Al-Azhar University & King Abdulaziz University

2. After this lecture, student should be able to:
 Know the different types of muscles.
 Know the attachment of skeletal muscles
( origins and insertions).
 Describe the shapes and arrangement of muscle
fibres.
 Describe the major muscles of the body.
 Know the nerve supply of the muscles.
 Understand the mechanism of action of the
muscles (agonism, antagonism & synergism).
 Understand the role of muscles in muscle tone
and muscle dysfunction (paralysis).Prof. Laila M. Aboul Mahasen
Morsy

3. Definition :
It concerns with the study of different muscles of
the body, which produce contractions that move
the body parts including the internal organs.
The Muscular System
Types of Muscle Fibers
Prof. Laila M. Aboul Mahasen Morsy

4. Types of Muscle Fibers
Skeletal muscle
Smooth muscle
Cardiac muscle
Striated muscle
Prof. Laila M. Aboul Mahasen Morsy

5. CardiacSmoothStriated
Skeletal
Type of
Muscle
Longitudinal branched
muscle fibre
Longitudinal and
transverse striations
with intercalated discs
Spindle shaped muscle
fibre
No striations .
Longitudinal and parallel
Longitudinal and
transverse striations
Muscle fibres
Striations
One nucleusOne nucleusMulti-nucleatedNucleus
InvoluntaryInvoluntaryVoluntaryMode of action
Muscles of heartMuscles of visceraSkeletal musclesExample
Prof. Laila M. Aboul Mahasen Morsy

6. Prof. Laila M. Aboul Mahasen Morsy

7. I. Smooth muscles
• The fibers are fusiform and non-striated
• They are involuntary
• They line the walls of hollow organs, e.g. walls of blood vessels, digestive & urinary
tracts
Prof. Laila M. Aboul Mahasen Morsy

8. II. Cardiac muscle
•The fibers have a striated pattern
•They are involuntary
•Constitutes the wall of the heart and
causes its rhythmic contraction
Prof. Laila M. Aboul Mahasen Morsy

9. III. Skeletal muscle
• They have a striated pattern
• They are Voluntary
• These muscles are attached to the skeleton and cause its movement
Prof. Laila M. Aboul Mahasen Morsy

10. Functions of Muscles
Functions of skeletal muscles
1. They produce different movements of the
body by their contractions , which
approximate the bones of the skeleton on
which they are attached
2. Their contractions pump venous blood to
the heart
3. They share in the heat production of the
body
4. Maintain posture and body position
Functions of smooth muscles :
Guard entrances and exits :
They encircle openings to digestive and urinary
tracts. Control swallowing, defecation and urination
Function of Cardiac
muscle
It is responsible for its
rhythmic contraction
Prof. Laila M. Aboul Mahasen Morsy

11. SKELETAL MUSCLES
• 1. Structure
• 2. Arrangement of muscle fibres
• 3. Attachment of skeletal muscles
• 4. Action of skeletal muscle
• 5. Nerve supply of skeletal muscles
Prof. Laila M. Aboul Mahasen Morsy

12. Structure of skeletal muscle
•The skeletal muscles consist of muscle cells (muscle fibers)
•The individual muscle fibers are grouped together to form fascicles
•The muscle fibers are surrounded by 3 connective tissue layers:
1. Endomysium: surrounds an individual muscle fiber
2. Perimysium: surrounds a group of muscle fibers to form a
fascicle
3. Epimysium: encircles all the fascicles of a muscle
Prof. Laila M. Aboul Mahasen Morsy

13. Arrangement of Muscle Fibers
I. Parallel: the fibers run parallel to each other
They take different shapes:
a. Flat like : e.g. platysma
b. Strap-like : e.g. sartorius
c. Strap-like with tendinous intersections :
e.g. rectus abdominis
d. Quadrate : e.g. pronator quadratus
e. Rhomboid : e.g. rhomboideus major
Sartorius m.Rectus abdominis m.Rhomboideus major m.
Pronator
quadratus m.
Platysma muscle
Prof. Laila M. Aboul Mahasen Morsy

14. IV. Circular: the fibers are arranged in concentric rings
e.g. orbicularis oris
III. Triangular (convergent): the fibers converge into a tendon
e.g. Pectoralis major
II. Fusiform
e.g. biceps brachii
Prof. Laila M. Aboul Mahasen Morsy

15. V. Oblique (pennate):
The fibers run & attached obliquely to a longitudinal tendon
They take the following shapes:
•Unipennate: resembling ½ of a feather, e.g. extensor
digitorum longus
•Bipennate: resembling a complete feather, e.g. rectus
femoris
•Multipennate: resembling 3 or more feathers joined at their
bases, e.g. deltoid
Prof. Laila M. Aboul Mahasen Morsy

16. Different forms of the internal structure of skeletal muscle.
On contraction, the
muscle fibers, shorten
by 1/3 to ½ of their
resting length.
Prof. Laila M. Aboul Mahasen Morsy

17. Prof. Laila M. Aboul Mahasen Morsy

18. Attachment
Attachment of Skeletal
Muscle
Attachment of Skeletal Muscles
Belly : is the fleshy part of the muscle
muscle
Each muscle has 2 bony attachments :
Prof. Laila M. Aboul Mahasen Morsy

19. Attachment of Skeletal Muscle
• A skeletal muscle usually connects a bone
to another bone , usually across a joint
• When a muscle contracts one attachment
usually remains stationary while the other
moves .
• Each muscle has 2 bony attachments:
1. Origin of a muscle is usually the less
mobile and more proximal attachment
2. Insertion of a muscle: is usually the
mobile attachment
Origin
Insertion
Prof. Laila M. Aboul Mahasen Morsy

20. Attachment of Skeletal Muscle
1. Tendon: a condensed
fibrous tissue, e.g.
gastrocnemius m.
2. Aponeurosis: flat tendon,
e.g. external oblique
3. Raphe: median tendon,
e.g. mylohoid muscle
4. Muscle fibers
themselves, e.g.
orbicularis oculi
The muscle insertion may take one of the following forms:
Prof. Laila M. Aboul Mahasen Morsy

21. Different types of muscle action
• 1 . Prime mover
• 2 . Antagonist
• 3 . Synergist
• 4 . Fixator
 All movements are the result of the coordinated action of
many muscles. A muscle may work in the following 4 ways:
Prof. Laila M. Aboul Mahasen Morsy

22.  A muscle is a prime mover when
it is the chief muscle or member
of a chief group of muscles
responsible for a particular
movement .
 e.g. quadriceps femoris is a
prime mover in the movement of
extending the knee joint.
Prime mover
Prof. Laila M. Aboul Mahasen Morsy

23. Antagonist
• Any muscle that opposes the action of the prime mover is an
antagonist.
• E.g. , biceps brachii opposes the action of triceps brachii when
the elbow joint is extended. Before a prime mover can contract,
the antagonist muscle must be equally relaxed .
Prime mover
Biceps :
Antagonist
Prime mover
Triceps :
Antagonist
Extension of elbow
Flexion of elbow
Prof. Laila M. Aboul Mahasen Morsy

24. Synergist
• Synergist are other muscles that work together with the prime
mover to produce a common action .
• When the prime mover crosses 2 or more joints , synergists
prevent undesired action at the intermediate joints .
Prof. Laila M. Aboul Mahasen Morsy

25. Fixator
• A fixator contracts isometrically (i.e., contraction increases the
tone but does not produce movement) to stabilize the origin of
the prime mover so that it can act efficiently e.g., the muscles
attaching the shoulder girdle to the trunk contract as fixators to
allow the deltoid to act on the shoulder joint.
Muscles around shoulder girdle fixing the
scapula so that movement of abduction
can take place at the shoulder jointProf. Laila M. Aboul Mahasen

26. Nerve Supply of Skeletal Muscle
• The nerve trunk to a
muscle is a mixed nerve,
about 60% is motor and
40% is sensory, and it also
contains some sympathetic
autonomic fibers.
• The nerve enters the
muscle at about the
midpoint on its deep
surface, the place of
entrance is known as the
motor point or unit
(neuromuscular junction)
.
Prof. Laila M. Aboul Mahasen Morsy

27. The skeletal muscles are:
A. Striated and involuntary.
B. Striated and voluntary.
C. Non-striated and voluntary.
D. Non-striated and involuntary
Prof. Laila M. Aboul Mahasen

28. Prof. Laila M. Aboul Mahasen Morsy