The muscular system is a complex network of tissues and organs responsible for movement, stability, and heat generation in the human body. Comprising more than 600 individual muscles, it enables various functions, including locomotion, posture maintenance, breathing, and circulation assistance. Muscles are composed of muscle fibers, which are elongated cells capable of contracting and relaxing to generate force. Skeletal muscles, attached to bones via tendons, facilitate voluntary movements, such as walking and lifting objects, under conscious control. Smooth muscles, found in organs like the digestive tract and blood vessels, perform involuntary functions like peristalsis and regulating blood flow. Cardiac muscle, exclusively present in the heart, sustains its rhythmic contractions to pump blood throughout the body. The muscular system works in coordination with the skeletal, nervous, and circulatory systems to ensure efficient movement and overall bodily function. Regular exercise and proper nutrition are essential for maintaining muscular health and strength throughout life.

1. MUSCULAR
SYSTEM
Nicos Rivera
Jenny ann Bicera
Ashley Ramirez
Monarica Alvarez

2. Muscular System
The muscular system consist
of all the muscles of the
body. These make up
approximately 42%of total
body weight, and are
composed of long, slender
cells known as fibers. The
fibers vary in lengths and
color from white to deep red.

3. Function of the muscles
 Movement
 Maintenance of posture and muscle tone
 Heat production
 Protects the bone and internal organ

4. Muscle classification
 Functionally
• Voluntarily
• Involuntarily
 Structurally
• Striated
• Smooth

5. Anterior view

6. Posterior view

7. TRIVIA
• How many muscles are there in the human body?
Answer: 640 Muscles
The muscles make up about 40 % of the body mass.
• What is the longest muscle in the body?
Answer: The Sartorius
The Sartorius runs from the outside of the hip, down and across
to the inside of the knee. It twists and pulls the thigh outwards.

8. TRIVIA!!!
• What is the smallest muscle in the body?
Answer: The Stapedius
The Stapedius is located deep in the ear. It is only 5mm long and
thinner than cotton thread. It is involved in hearing.
• What is the biggest muscle in the body?
Answer: The Gluteus Maximus
The Gluteus Maximus is located in the buttock. It pulls the leg
backwards powerfully for walking and running.

9. The 3 types of muscles
Skeletal muscle
cardiac muscle smooth muscle

10. TYPES OF
MUSCLES

11. intestines
SMOOTH MUSCLE
• Fibers are thin and spindle shaped.
• Contracts slowly.
• They fatigue, but very slowly.
• They contract slower than skeletal
muscles.

12. SMOOTH MUSCLE
• These muscles line the insides of organs such as the
bladder, stomach and intestines. Smooth muscles play an
important role in many body systems such as the
reproductive system, urinary system and respiratory
system. They do essential jobs like move waste and expand
the lungs when we breathe.

13. SMOOTH MUSCLE
• Found in the circulatory system
Lining of the blood vessels
Helps in the circulation of the blood.
• Found in the digestive system
Esophagus, stomach, intestine
Controls digestion

14. SMOOTH MUSCLE
• Found in the respiratory system
Controls breathing
• Found in the urinary system
Urinary bladder
Controls urination

15. HEART
CARDIAC MUSCLE
• Found ONLY in the heart.
• Cells are branched and appear fused
with one another.
• Healthy cardiac muscle never fatigue.
• Made from cells called cardiocytes.

16. CARDIAC MUSCLE
• These muscle line the heart walls. They help the
heart pump blood that travels through the
cardiovascular system.
• It performs coordinated contractions.
• Contains more mitochondria than skeletal muscle
cells.

17. CARDIAC MUSCLE
The heart wall is composed
of three layers.
a. Epicardium
b. Myocardium
c. Endocardium
heart

18. SKELETAL MUSCLE
• Fibers are long and cylindrical.
• Are attached to skeleton by tendons.
• Causes movement of bones at the joints.
• They fatigue
Limbs

19. SKELETAL MUSCLE
Limbs

20. SKELETAL MUSCLE
• These muscles work with the bones, tendons and
ligaments. Tendons attach skeletal muscles to bones
all over the body. Together they support the weight
of the body and help the body move.

21. FUNCTION OF SKELETAL MUSCLE
1. Produce movement.
2. Maintain posture and body position.
3. Support soft tissues.
4. Guards entrances and exits.
5. Maintain body temperature.

22. FUNCTION OF SKELETAL MUSCLE
1. Movement – muscle move bones by pulling
not pushing.
a. Synergists – any movement is generally
accomplished by more than one muscle.
All of the muscles responsible for the
movement are synergists.
b. The one that is most responsible for the
movement is the Prime Mover (agonist).

23. FUNCTION OF SKELETAL MUSCLE
c. Antagonists – muscles and muscle groups usually
work in pairs
– example the biceps flex your arm and its partner
the triceps extend your arm. The two muscles are
antagonists, i.e. cause opposite actions.
– when one contracts the other relaxes.
d. Levators – muscle that raise a body part.

24. FUNCTION OF SKELETAL MUSCLE

25. FUNCTION OF SKELETAL MUSCLE
• Maintenance of posture or muscle tone
We are able to maintain our body position because
of tonic contractions in our skeletal muscles. These
contractions don’t produce movement yet hold our
muscles in position.

26. FUNCTION OF SKELETAL MUSCLE
• Heat production – contraction of muscles
produces most of the heat required to maintain
body temperature.

27. Structure of Skeletal Muscle
• Composed of striated muscle cells (=muscle fibers) and
connective tissue.
• Most muscles attach to 2 bones that have a moveable
joint between them.
The attachment to the bone that does not move is
the origin.
The attachment to the bone that moves is the
insertion.

28. Structure of Skeletal Muscle
• Tendons anchor muscle firmly to bones. Tendons are
made of dense fibrous connective tissue.
• Ligaments connect bone to bone at a joint.

29. Structure of Skeletal Muscle
• Bursae – small fluid filled
sacs that lie between
some tendons and the
bones beneath them.
They are made of
connective tissue and are
lined with synovial
membrane that secretes
synovial fluid.

30. Structure of Skeletal Muscle
• The membrane that surrounds the
muscle cell is called the sarcolemma.
• Muscle cells are filled with 2 types of
fine threadlike proteins:
MYLOFILAMENTS
myosin (thick)
actin (thin).
• The myofilaments are arranged in the
cells in small units called sarcomeres.

31. Structure of Skeletal Muscle
Neuromuscular junction
• Spot where the axon of a motor nerve nears the muscle
fiber.
• The axon terminal does not touch the muscle but comes
close. The space between the axon and the muscle cell
is called the synapse.
• Within the terminal end of the axon are small sacs filled
with a neurotransmitter called acetylcholine.

32. Movement of Muscles
Origin: the attachment of the
muscle to the bone that
remains stationary
Insertion: the attachment of
the muscle to the bone that
moves
Belly: the fleshy part of the
muscle between the tendons
of origin and/or insertion

33. Movement of Muscles
• These muscles move when the brain
sends messages to the muscle
• Always work in pairs
• 2 movements of skeletal muscle
Contraction (shorten)
Extension (lengthen)

34. Categories of skeletal muscle actions
Categories Actions
Extensor Increases the angle at a joint
Flexor Decreases the angle at a joint
Abductor Moves limb away from midline of body
Adductor Moves limb toward midline of body
Levator Moves insertion upward
Depressor Moves insertion downward
Rotator Rotates a bone along its axis
Sphincter Constricts an opening

35. Movement of Muscles

36. NICOS RIVERA
ASHLEY RAMIREZ
MONARICA ALVAREZ
JENNY ANN BICERA