By:M. Thiru murugan Unit XIV Type, structure and functions of muscle Origin, Insertion, and action of muscles Muscle: Muscle is a soft tissue and it is one of the 4 basic tissues, along with nervous tissue, epithelium, and connective tissue. Muscles helps in movement, support and protection of internal organs. Muscle cells or myocytes contain protein filaments  called myofilaments actin & myosin that producing a contraction that changes both the length and the shape of the cell. Types of Muscles: There are 3 types of muscles: skeletal, cardiac & smooth muscle Skeletal muscle or “voluntary muscle” or striated Muscles is attached to bone, helps in movement & in maintaining posture. Smooth muscle or “involuntary muscle” or non striated muscles is found within the walls of organs and structures Cardiac muscle is also an "involuntary muscle" found only in the heart. Structure of Skeletal muscle: Skeletal muscle consist plasma membrane is called sarcolemma, the cytoplasm is called sarcoplasm & specialized sarcoplasmic reticulum that play important role in regulation of Calcium. Cells contain many nucleus peripherally It consist of number of elongated cells called muscle fibers or muscle cell , that consist of myofibrils (elongated protein molecules). These Muscle fibers are arranged in bundle called fasciculi Each muscle fibers covered by endomysium, each fasciculi covered by perimysium & the whole muscle is covered by epimysium. Neuromuscular junction (NMJ) or myoneural junction is a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. Properties of skeletal muscle: Excitability: this refers to muscle tissue being able to react to nervous stimulation. Extensibility: this refers to the ability of muscle tissue to lengthen when contracting Elasticity: this refers to the ability of muscle tissue to return to its normal resting length once it has been stretched. Contractility: this refers to the capacity of a muscle to contract or shorten forcibly when stimulated by nerves and hormones Muscle contraction: Muscle use the movement of actin against myosin to create contraction. In skeletal muscle, contraction is stimulated by electrical impulses transmitted by the nerves Cardiac and smooth muscle contractions are stimulated by internal pacemaker cells which regularly contract, and propagate contractions to other muscle cells they are in contact with. All skeletal muscle and many smooth muscle contractions are facilitated by the neurotransmitter acetylcholine. Types of muscle contraction: Isotonic contractions maintain constant force or tone in the muscle as the muscle length changes Isometric contractions changes in force without changing the length of the muscle Muscle tone is defined as the tension in a muscle at rest. Function of skeletal muscles Body movement (Locomotion) Maintenance of posture Respiration Constriction of organs and vess

1. By:
M. Thiru murugan
The Muscular System

2. Unit XIV
a) Type, structure and functions of muscle
b) Origin, Insertion, and action of muscles

3. Muscle:
Muscle is a soft tissue and it is one of the 4 basic tissues, along
with nervous tissue, epithelium, and connective tissue.
Muscles helps in movement, support and protection of internal
organs.
Muscle cells or myocytes contain protein filaments called
myofilaments actin & myosin that producing a contraction that
changes both the length and the shape of the cell.
Types of Muscles:
There are 3 types of muscles: skeletal, cardiac & smooth muscle

4. • Skeletal muscle or “voluntary muscle” or striated Muscles is
attached to bone, helps in movement & in maintaining posture.
• Smooth muscle or “involuntary muscle” or non striated muscles
is found within the walls of organs and structures
• Cardiac muscle is also an "involuntary muscle" found only in the
heart.

5. Structure of Skeletal muscle:
• Skeletal muscle consist plasma membrane is called
sarcolemma, the cytoplasm is called sarcoplasm & specialized
sarcoplasmic reticulum that play important role in regulation
of Calcium.
• Cells contain many nucleus peripherally
• It consist of number of elongated cells called muscle fibers or
muscle cell , that consist of myofibrils (elongated protein
molecules).
• These Muscle fibers are arranged in bundle called fasciculi
• Each muscle fibers covered by endomysium, each fasciculi
covered by perimysium & the whole muscle is covered by
epimysium.

7. •Neuromuscular junction
(NMJ) or myoneural junction
is a chemical synapse between
a motor neuron and a muscle
fiber.
•It allows the motor neuron to
transmit a signal to the muscle
fiber, causing muscle
contraction.

8. Properties of skeletal muscle:
Excitability: this refers to muscle tissue being able to react
to nervous stimulation.
Extensibility: this refers to the ability of muscle tissue to
lengthen when contracting
Elasticity: this refers to the ability of muscle tissue to return
to its normal resting length once it has been stretched.
Contractility: this refers to the capacity of a muscle to
contract or shorten forcibly when stimulated by nerves and
hormones

9. Muscle contraction:
Muscle use the movement of actin against myosin to
create contraction.
In skeletal muscle, contraction is stimulated by electrical
impulses transmitted by the nerves
Cardiac and smooth muscle contractions are stimulated by
internal pacemaker cells which regularly contract, and
propagate contractions to other muscle cells they are in
contact with.
All skeletal muscle and many smooth muscle contractions are
facilitated by the neurotransmitter acetylcholine.

10. Types of muscle contraction:
Isotonic contractions maintain constant force or tone
in the muscle as the muscle length changes
Isometric contractions changes in force without
changing the length of the muscle
Muscle tone is defined as the tension in a muscle at
rest.

11. Function of skeletal muscles
Body movement
(Locomotion)
Maintenance of posture
Respiration
Constriction of organs
and vessels
Peristalsis of intestinal
tract
Diaphragm and
intercostal contractions
Communication (Verbal
and Facial)
 Vasoconstriction of blood
vessels & pupils
Production of body heat
(Thermogenesis)

12. Cardiac muscle
Cardiac muscle forms the contractile
walls of the heart.
The cells known as cardiomyocytes,
also appear striated under the
microscope.
Cardiomyocytes are single cells
typically with a single centrally
located nucleus.
They contract on their own intrinsic
rhythms without any external
stimulation.

13. Contraction of
Cardiac muscle
The heart also contains specialized
“pacemaker” cells.
These contract and expand in
response to electrical impulses
from the CNS.
Pacemaker cells generate
electrical impulses to contract
and relax.
The pacemaker cells control heart
rate and determine how fast the
heart pumps blood.
Function of
Cardiac muscle
Rapid, involuntary
contraction and relaxation
of the cardiac muscle are
vital for pumping blood
throughout the
cardiovascular system.
It maintain Bp within
blood vessels

14. Smooth muscle
Smooth muscle is responsible for involuntary movements in
the internal organs.
It forms the contractile parts of the digestive, urinary, and
reproductive systems as well as the airways and arteries.
Smooth Muscle Structure:
Each cell is spindle shaped with a single nucleus and no visible
striations
Smooth muscle tissue, does not have clearly defined striations
visible on the cells. This is because smooth muscle cells are
organized in a different way than other muscle cells.

15. Location of smooth
muscle
Walls of blood vessels, Walls
of stomach, Ureters,
Intestines, Gastrointestinal
Tract, Respiratory Tract,
Reproductive tracts (both
genders), Bladder, Uterus,
Sphincter, Trachea & Bile
duct
Functions of Smooth Muscle:
 Maintain Circulation
 Movement of food, absorb nutrients,
Smooth muscle composes all sphincters in
the GIT,
 In the bladder helps to push out urine &
prevent refluxes of urine.
 shrinking the size of the pupil & dilates the
pupil.
 Several parts of the respiratory system
have smooth muscle that helps in
breathing
 Both male and female reproductive
systems include smooth muscles involving
in many functions

16. Cranial muscles:
Occipitofrontalis:
Frontal muscle & occipital
muscle
Functions or Action:
Raises the eye brows, transverse
wrinkles of forehead & surprise
look of face

17. Facial muscles:
Function or Action:
It involve facial expressions
like sadness, Grinning (smile
broadly), doubt, impatience,
frowning(disapprove), surprise,
anger, grief & contempt

18. Masticatory muscles:
Masseter, Temporalis, Lateral
pterygoid & Medial pterygoid
The muscles of mastication are a
group of muscles responsible for
the chewing movement of the mandible
at the temporomandibular (TMJ) joint
They enhance the process of eating,
they assist in grinding food

19. Muscles of the neck:
• Platysma, Omohyoid, Sternohyoid,
SCM (sternocleidomastoid), Levator
scapulae, Scalenes & Trapezius
• Function or Action:
• Platysma - involving in facial
expression, SCM – tilt the head &
rotate the face

20. Muscles of chest wall:
4 muscles: the pectoralis major,
pectoralis minor, serratus anterior and
subclavius.
Function or action:
Rotates & flex the upper limb and
draws the scapula

21. Muscles of thoracic cavity:
It includes the external intercostal ,
internal intercostal , innermost
intercostal muscles and transversus
thoracis.
These muscles are primarily
responsible for changing the volume of
the thoracic cavity during respiration

22. Muscles of back:
Trapezius, Latissimus Dorsi,
levator scapulae, Rhomboid Major
& Rhomboid Minor
Function: trapezius elevates the
scapula and rotates, Latissimus
Dorsi Extends, adducts & rotates
the upper limb, levator scapulae
Elevates the scapula, Rhomboid
Major & Minor Retracts and
rotates the scapula.

23. Muscles of abdomen:
Transversus abdominis
Rectus abdominis
External oblique muscles
Internal oblique muscles
Function or Action: movement of
the trunk, maintain intra
abdominal pressure, protection of
internal organs, helping in
respiration

24. Diaphragm:
• The diaphragm, located below the
lungs, is the major muscle of
respiration.
• It is a large, dome-shaped muscle that
contracts rhythmically and continually
• Upon inhalation, the diaphragm
contracts and flattens and the chest
cavity enlarges
• It separates the thoracic and abdominal
cavities

25. Muscles of pelvic floor:
The levator ani is situated on
either side of the pelvis.
(pubococcygeus, the iliococcygeus,
puborectalis)
The coccygeus muscle completes
the pelvic floor, which is also called
the pelvic diaphragm.
Function or Action: support &
protect pelvic organs and maintain
intra pelvis pressure

26. Muscle of upper arm:
 The upper arm muscles are – in
anterior compartment (biceps
brachii, brachialis,
coracobrachialis, deltoid) & the
posterior compartment (teres major
and teres minor, triceps brachii).
 Function or Action: flexes the arm
at the elbow and at the shoulder,
Flexion at the elbow, flexion and
internal rotation of the arm,
extension of arm at elbow

27. Muscles of fore arm:
The superficial muscles in the
anterior compartment are the flexor
carpi ulnaris, flexor carpi
radialis, palmaris longus, flexor
digitorum superficialis &
pronator teres
Function or Action: Pronation of
the forearm, Flexion and abduction
at the wrist, Flexes the
metacarpophalangeal joints and
interphalangeal joints

28. Muscles of fore arm:
 There are three muscles in
the deep anterior forearm:
flexor digitorum profundus,
flexor pollicis longus, and
pronator quadratus.
 Function or Action: Flexes
the interphalangeal joint and
metacarpophalangeal joint,
Pronates the forearm

29. Muscles of hand and Fingers:
• Adductor pollicis, palmaris brevis,
interossei, lumbricals, thenar (includes
Abductor Pollicis Brevis, Flexor Pollicis
Brevis, Opponens Pollicis) & hypothenar
muscles(includes Opponens Digiti Minimi,
Abductor Digiti Minimi, Flexor Digiti
Minimi Brevis)
• Functions: fine movements of the thumb ,
medially rotating and flexing the metacarpal,
Abducts the thumb, Flexes the
metacarpophalangeal (MCP) joint, rotates the
metacarpal, Abducts the little finger, Flexes
the MCP joint of the little finger

30. Muscles of the gluteal region:
Superficial: group of large muscles
that abduct and extend the femur.
Includes the gluteus maximus,
gluteus medius & gluteus minimus
Deep lateral rotators: group of
smaller muscles that mainly act to
laterally rotate the femur. Includes
the quadratus femoris, piriformis,
gemellus superior, gemellus inferior
and obturator internus

31. Muscle of the thigh:
It includes 3 sections: anterior, medial
and posterior
Anterior thigh: the pectineus,
sartorius & quadriceps femoris (rectis
femoris, vastus medialis, vastus lateralis,
vastus intermedius. In addition to these,
the end of the iliopsoas muscle passes
into the anterior compartment.
Function: Extend the leg at the knee
joint & flex the hip

32. Muscle of the Medial thigh:
• Gracilis, obturator externus,
adductor brevis, adductor longus
& adductor magnus.
• Function: Flexes the thigh,
Adduction of the thigh, lateral
rotation of the thigh, flexion of the
leg at the knee

33. Muscle of the posterior thigh:
 The muscles in the posterior compartment
of the thigh are collectively known as
the hamstrings. They consist of the biceps
femoris, semitendinosus &
semimembranosus,
 Function: Extend at the hip, and flex at the
knee, lateral rotation of leg

34. Muscle of the leg:
• It includes 3 sections: anterior,
lateral and posterior
• Anterior leg: tibialis anterior,
extensor digitorum longus,
extensor hallucis longus and
fibularis(peroneus) tertius.
Function:
• Dorsiflex and invert the foot at the
ankle joint. The extensor digitorum
longus and extensor hallucis longus
also extend the toes

35. Muscles in the lateral
Compartment of the Leg:
 2 muscles in the lateral
compartment of the leg
the fibularis longus and
fibularis brevis (also known
as peroneal longus and
peroneal brevis)
 Function: Eversion - turning
the sole of the foot outwards.

36. Muscles in the posterior Compartment of
the Leg:
 It consists 7 muscles, organized into two
layers - 3 superficial and 4 deep muscles
 Superficial - Gastrocnemius, plantaris
& soleus
 Deep - Popliteus, Flexor hallucis longus,
Flexor digitorum longus & Tibialis
posterior
 Action of muscles in this area plantarflex,
knee flexion, invert the foot

37. Muscle of the foot:
The foot has two surfaces: Dorsal
Surface (upper part of the foot) &
Plantar Surface (sole of the foot)
Many of the extrinsic muscles
attach to the foot, there are only two
intrinsic muscles located in this
compartment – the extensor
digitorum brevis & extensor
hallucis brevis
Assisting some of the extrinsic
muscles in their actions