Muscular system

1. Unit 3
Muscular
System

3. Key Terms
 Origin - the more fixed end or attachment of
muscle
 Insertion - point of attachment that moves when
the muscle contract
 Posture - alignment of body parts
 Myalgia - muscle pain
 Glycogen - polysaccharide that store energy for
muscle contraction
 Myofibril - a bundle of myofilaments that contracts
 Myoglobin - red pigment that store oxygen for
muscle contraction
 Tendon - tissue that connects muscle to bone

4. Type Of Muscle
 The muscles are classified into three types
depending upon the function
1. Skeletal muscle
2. Cardiac muscle
3. Smooth muscle

5. Skeletal Muscle
 Skeletal muscle are in association with
bones forming the skeleton system.
 These muscles form 40 to 50% of body
mass in human beings, about 600 muscles
are identified.
 Skeletal muscles are voluntary and
striated

6. Cardiac Muscle
 Cardiac muscle form the musculature of
heart.
 These muscles are striated and involuntary

7. Smooth Muscle
 The muscle, which are in association with viscera,
are called smooth muscle or visceral muscle.
 Smooth muscles form the main contractile unit of
wall of the various visceral organs and are present
in the following structure.
a) Wall of organ like esophagus, stomach, intestine
b) Duct of digestive gland
c) Trachea, bronchial tube, alveolar duct of
respiratory tract
d) Ureter, urinary bladder and urethra in excretory
system
e) Wall of the blood vessels in circulatory system
f) Mammary gland, uterus, genital duct, prostate
gland and scrotum in reproductive system
g) Iris and ciliary body of the eye

9. Structure Of Muscle
 Muscle mass or tissue is made up of large
number of single muscle cell
 The muscle cells are commonly called
muscle fibers because these are long and
cylinder by appearance
 The muscle fiber are multinucleated and
arranged parallel to one another with
some connective tissue in between

10. Muscle Fiber
 Each muscle cell or muscle fiber is
cylindrical in shape.
 The length of the fiber is 3 cm and it may
vary from 1 to 4 cm depending upon the
length of the muscle.
 The diameter of muscle fiber varies from
10 to 100 microns.

11.  The skeletal muscle is formed by 75% of
water, 20% of protein and 5% of organic
substance other than proteins and some
inorganic substance.
 Muscle proteins are –
1. Myosin
2. Actin
3. Tropomyosin
4. Troponin
5. Actinin
6. Titin
7. Desmin
8. Myogen
9. Myoglobulin

12. Muscle Movement
 Muscles move body parts by contracting
and then relaxing.
 Muscles can pull bones, but they can't
push them back to the original position.
 So they work in pairs of flexors and
extensors. The flexor contracts to bend a
limb at a joint.

13.  Now, lets look at the main 5 types of
muscle movements.
1. Adduction
2. Abduction
3. Flexion
4. Extension
5. Rotation

15. Muscle Tone
 The muscle fiber always maintain a state
of slight contraction with certain degree
of vigor and tension
 This property of muscle is called tone
 All the skeletal muscle show little tone.
 But the antigravity muscles like extensor of
lower limb, trunk muscle and neck muscle
show tone to greater extent

16. Muscle Contraction
 The skeletal muscle gives response to a
stimulus in the form of contraction.
 The contraction can be defined as
internal event of the muscle, which are
manifested by change in either the length
of the muscle fiber or the tension.

17. Type of contraction
 Isotonic contraction - this is a type of
contraction, in which the tension remain the
same where the change occur in the length
of the muscle fiber(Iso = same, Tone = tension)
 Example - flexion of arm
 Isometric contraction - in this type the length
of muscle fiber remain the same and tension
is increased
 Example - pulling any heavy object

19. Maintenance Of Posture
 Several muscle groups, including the
hamstrings and large back muscles, are
critically important in maintaining our
posture.
 These postural muscles, along with others,
when functioning properly, prevent the
forces of gravity.
 Postural muscles also help maintain our
balance while we move.

20. Muscle Groups
 There are more than 600 muscles in the body, which
together account for about 40 percent of a person's
weight.
 Most skeletal muscles have names that describe some
feature of the muscle. Often several criteria are
combined into one name.
 Associating the muscle's characteristics with its name
will help you learn and remember them.
 The following are some terms relating to muscle
features that are used in naming muscles.
 Size: vastus (huge); maximus (large); longus (long);
minimus (small); brevis (short).
 Shape: deltoid (triangular); rhomboid (like a rhombus
with equal and parallel sides); latissimus (wide); teres
(round); trapezius (like a trapezoid, a four-sided figure
with two sides parallel).
 Direction of fibers: rectus (straight); transverse (across);
oblique (diagonally); orbicularis (circular).

21.  Location: pectoralis (chest); gluteus (buttock
or rump); brachii (arm); supra- (above); infra-
(below); sub- (under or beneath); lateralis
(lateral).
 Number of origins: biceps (two heads); triceps
(three heads); quadriceps (four heads).
 Origin and insertion: sternocleidomastoideus
(origin on the sternum and clavicle, insertion
on the mastoid process); brachioradialis
(origin on the brachium or arm, insertion on
the radius).
 Action: abductor (to abduct a structure);
adductor (to adduct a structure); flexor (to
flex a structure); extensor (to extend a
structure); levator (to lift or elevate a
structure); masseter (a chewer).

22. Muscle Of Head

23. Muscle Of Neck

24. Muscle Of Back

25. Muscle Of Upper Limb

26. Muscle Of Chest

27. Muscle Of Abdomen

28. Muscle Of Pelvis

29. Muscle Of Lower Limb

30. Next Class – Unit 4
Nervous System