This document provides an overview of the musculoskeletal system. It begins by listing the objectives of describing the types and functions of muscles, skeletal muscle tissue, muscle arrangements, muscle structure and function, muscle naming conventions, microscopic muscle anatomy, muscle contraction types, muscle stimulation, muscle fiber anatomy, and the roles of actin, myosin, and ATP in muscle contraction. It then proceeds to define the three main types of muscles - cardiac, skeletal, and smooth muscles - and their characteristics. The document outlines the microscopic structure of skeletal muscle fibers and their organelles. It explains the sliding filament theory of muscle contraction and the roles of actin, myosin, and ATP hydrolysis in the cross-bridge cycling process. Various muscle arrangements

1. THE
MUSCULOSKELETAL
SYSTEM
PBL G5 - CASE 3

2. :OBJECTIVES
❖ Describe the types of muscles with the function and location of each type.
❖ Describe the Skeletal muscles with its tissue types.
❖ Explain the arrangement (location) of the different types of skeletal muscles.
❖ Determine the function and the structure of the skeletal muscles.
❖ Explain “how was the skeletal muscles named?”
❖ Describe the microscopic anatomy of the skeletal muscles.
❖ Figure out the types of muscles contractions.
❖ Determine “what cause the muscle stimulation?”
❖ Describe the tissue fibers and its microscopic anatomy.
❖ Describe the function of Actin and Myosin proteins.
❖ Define the Function of ATP in the skeletal muscles.

4. OBJECTIVE 1:
. - Types of muscles with the function and location of each type
Muscles:
▪ muscles are special types of tissues
of possess the ability of contraction
and relax.
▪ The overall process produce force
for movement.

5. Classification of muscles
Functionally Structurally
Depending
upon striations
• Skeletal muscles
• Cardiac muscles
• Smooth muscles
• Voluntary muscles
• Involuntary
muscles
• Striated muscles
• Non striated
muscles

6. :TYPES OF MUSCLES
1. Cardiac muscles
2. Skeletal muscles
3. Smooth muscles
➢ There are three types of muscles:

7. (Functions of the muscles (In general
◼ Movement.
◼ Maintenance of posture and muscle tone.
◼ Heat production.
◼ Protects the bones and internal organs.

8. TYPES OF MUSCLE MOVEMENTS
1. Adduction
2. Abduction
3. Flexion
4. Extension
5. Rotation
➢ There are many type of muscle
movement, some of them are:

9. OBJECTIVE 2:
. - Describe the Skeletal muscles with its tissue types
• Skeletal Muscle is one of several terms used
to refer to muscle tissue that is under
conscious control.
• Other terms that refer to the same tissue
are Voluntary Muscle & Striated Muscle.

10. Skeletal muscle properties
◼ Fibers are long and cylindrical
◼ Has many nuclei
◼ Has striations
◼ Have alternating dark and light bands
◼ Voluntary

11. OBJECTIVE 3:
- The Arrangements Of Different Types Of Skeletal
.Muscles

12. All skeletal muscle is made up
of fascicles (bundles of fiber),
but fascicle arrangements vary
considerably, resulting in
muscles with different shapes
.and functional capabilities

13. The most common patterns of
-:fascicle arrangement are
1. Circular
2. Parallel
3. Convergent
4. Pennate

14. CIRCULAR .1
◼ The fascicular pattern is circular when the fascicles
are arranged in concentric rings.
◼ Muscles with this arrangement surround external
body openings, which they close by contracting.
◼ The general term used for these kinds of muscles is
“sphincter”.
◼ Examples include the orbicularis muscles
surround the mouth and eyes.

15. CONVERGENT .2
◼ A convergent muscle has a broad origin,
and its fascicles converge toward a single
tendon of insertion. Such a muscle is
triangular or fan shaped like the pectoralis
major muscle of the anterior thorax.

16. PARALLEL .3
◼ In a parallel arrangement, the length of
the fascicles runs parallel to the long
axis of the muscle.
◼ Such muscles are either straplike like
the Sartorius muscle of the thigh, or
spindle shaped with an extended belly,
like the biceps brachii muscle of the
arm. However, some scientists classify
spindle-shaped muscles into a separate
class as fusiform muscles.

17. PENNATE .4
◼ In a pennate pattern, the fascicles are short and they attach obliquely to a central
tendon that runs the length of the muscle.

18. -:Pennate muscles come in three forms
◼ Unipennate, in which the fascicles insert into only one side of the tendon, as in
the extensor digitorum longus muscle of the leg.
◼ Bipennate, in which the fascicles insert into the tendon from opposite sides so
the muscle “grain” resembles a feather. The rectus femoris of the thigh is
bipennate.
◼ Multipennate, which looks like many feathers side by side, with all their quills
inserted into one large tendon. The deltoid muscle, which forms the roundness
of the shoulder is multipennate.

19. Unipennate Bipennate Multipennate

21. OBJECTIVE 4:
. -Determine the structure and the function of the skeletal muscles
➢ FIRST: the structure
• Skeletal muscle is called "striated"
because of its appearance consisting
of light and dark bands visible using a
light microscope.
• As shown in the diagram (on the right),
a single skeletal muscle cell is long
and approximately cylindrical in
shape, with many nuclei located at the
edges (periphery) of the cell.

22. OBJECTIVE 4 .. CONT.:
. -Determine the structure and the function of the skeletal muscles
• There are several important functions of the skeletal muscles,
these functions are:
1. Maintenance of posture or muscle
tone.
2. Movement.
3. Guard entrances and exits.
4. Store nutrient reserves.
5. Support soft tissues.
6. Heat production.
➢ SECOND: the function

23. 1. Maintenance of posture or muscle tone:
• We are able to maintain our body position because of tonic
contractions in our skeletal muscles.
- for example, The muscles in our abdominal wall and pelvis contract
to maintain our abdominal organs in position.
• These contractions don’t produce movement yet hold our muscles in
position.

24. 2. Movement: muscle move bones by pulling not pushing.
• The main muscle that contracts to bring about a
movement is called the Prime Mover (agonist).
• The opposite muscle that relaxes as the prime mover contracts is
called the antagonist.
• Synergists - any movement is generally accomplished by more
than one muscle. All of the muscles responsible for the movement
are synergists.

25. Movement .. Cont.
➢ Example, So for a bicep curl
• The prime mover is the biceps.
• The antagonist is the triceps.
• The fixator is the deltoid.
• The synergist is the brachialis.
➢ Levators - muscle that raise a body part.

26. 3. Guard entrances and exits: Encircle openings to digestive and
urinary tracts.
4. Store nutrient reserves: Proteins in muscles can break down.
5. Support soft tissues: Support organs, shield internal tissues.
6. Heat production: contraction of muscles produces most of the
heat required to maintain body temperature.

27. ➢ The skeletal muscles were named depending on some factors:
1. Location.
2. Shape.
3. Size.
4. Direction of the muscle fiber/cell.
5. Action.
OBJECTIVE 5:
”? - Explain “how were the skeletal muscles named

28. 1. location
Frontalis Lateralis
Tibialis
anterior
Fibularis
longus
Frontal
bone. Lateral or on the side.
Front of
tibia near
fibula.

29. 2. Shape
Deltoid Latissimus Trapezius Orbicularis
Triangl
e
Wide Trapezoi
d
circular

30. long
muscle
3. Size
Maximus Minimis Longus Brevis
short
muscle
large
muscle
small
muscle
Ex.: Gluteus
maximus
Gluteus
minims
Adductor
longus
Adductor brevis

31. • the muscle are
perpendicular to the long
axis.
• parallel to the
muscle’s long
axis
Ex.: Tranversus
abdominus
Rectus
abdominis
4. Direction
Rectus (straight) Transvers

32. 5. Action
Abductor
magnus
Extensor
digitorum
Flexor carpi
radials
extends the
fingers
flexes wrist abduct the
thigh

33. • Tendon: cord-like extension of connective tissue beyond the muscle,
serving to attach it to the bone.
• Epimysium: connective tissue ensheathing the entire muscle.
• Perimysium: connective tissue surrounding a fascicle.
• Fascicle: a discrete bundle of muscle cells
• Endomysium: thin connective tissue investing each muscle cell
• Myofibril: a muscle cell .
OBJECTIVE 6:
. - Describe the microscopic anatomy of the skeletal muscles

35. • Sarcolemma: plasma membrane of the muscle cell.
• Myofibril: a long, filamentous organelle found within a
muscle cells that has a banded appearance.
• Sarcomere: contractile unit of a muscle.
• Myofilament: actin or myosin-containing structure.

38. ◼ Huda’s Part
OBJECTIVE 7:
. - Figure out the types of muscles contractions

39. OBJECTIVE 8:
”? - Determine “what cause the muscle stimulation
1. To contract, skeletal muscle cells must be stimulated by nerve impulses.
2. One motor neuron (nerve cell) may stimulate a few muscle cells or hundreds of them, depending on the
particular muscle and the work it does.
3. One neuron and all the skeletal muscle cells it stimulates is called a motor unit.
4. When a long thread like extension of the neuron, called the nerve fiber or axon, reaches the muscle, it branches
into a number of axon terminals, each of which forms junctions with the sarcolemma of a different muscle cell.
5. These junctions, called neuromuscular (literally, “nerve muscle”) junctions, contain vesicles filled with a chemical
referred to as a neurotransmitter.
6. The specific neurotransmitter that stimulates skeletal muscle cells is acetylcholine.
7. Although the nerve endings and the muscle cells membranes are very close, the never touch. The gap between
them, the synaptic cleft, is filled with tissue fluid.

40. SKELETAL MUSCLES FIBERS
➢ Skeletal muscle fibers are long
and narrow cells that often span
the entire length of muscle
OBJECTIVE 9:
. - Describe the tissue fibers and its microscopic anatomy

41. MUSCLE FIBER ANATOMY
◼ Sarcolemma - cell membrane.
◼ Surrounds the sarcoplasm.
◼ Myoglobin - an abundance of oxygen binding protein.
◼ Punctuated by opening - transverse tubules (T-tubules)
Narrow tubes that extend into the sarcoplasm at right angles to the surface.
Filled with extracellular fluid.

43. ◼ Myofibrils- cylindrical structures within muscle fiber
are bundles of protein filaments ( Myofilaments)
◼ Two types of Myofilaments:
1. Actin filaments (thin filaments)
2. Myosin filaments (thick filaments)

44. TYPES OF SKELETAL MUSCLE FIBERS
◼ Red – Slow
(Type l fibers “slow twitch fibers”)
◼ Red – Fast
(Type lla fibers “fast oxidative fibers”)
◼ White – Fast
(Type llb fibers “fast glycolytic fibers”)

45. TYPE L
• Type l or slow twitch fibers, red in color due to the presence
of large volumes of myoglobin ,oxygen and high numbers of
Mitochondria .
• They are suited to endurance activity using the aerobic
energy system which relies on oxygen from the blood for the
supply of energy.
• They are smaller and develop less force than fast twitch
fibers.
• Athletes such as marathon runners have high number of this
type of fiber, partly through genetics , partly through
training.

46. TYPE LLA
• Type 2a or fast oxidative fibers and are a hybrid of type 1 and 2 fibers.
• These fibers contain a large number of mitochondria and myoglobin, so they are red.
• They manufacture and split ATP at a fast rate by utilizing both aerobic(oxygen
dependent) and anaerobic (no oxygen used) metabolism and so produce fast, strong
muscle contractions.
• They are more prone to fatigue than type 1 fibers.

47. TYPE LLB
• Type 2b or fast glycolytic fibers they are white color due to the low level of
myoglobin and also contain few mitochondria
• The produce ATP at a slow rate by only anaerobic metabolism and break it down very
quickly , this result in short, fast bursts of power and rapid fatigue.
• This type of fiber can be turned into type 2a fibers by resistance training , it’s a good
change
• This fibers can be found in large quantities in the muscles of the arms

49. :An individual’s muscle fiber type is determined by three factors
1. Genetics: you’re genetically programed to have a certain
percentage of each muscle fiber on your parents’ genes.
2. Hormone levels within the blood: the amount of hormone in
the blood will effect the fiber type and how big are they.
3. Training undertaken: there is no evidence as yet to show that
fiber type can be changed, however there is evidence to show
that fibers adapt to the type of training they are exposed to.

50. Muscles
∙ Muscles are composed of bundles of single large
cells called muscle fibers.
∙ Each muscle fiber contains many myofibrils.
∙ Myofibril is made up of thick and thin filament.
∙ The thin filament is made up of actin protein.
∙ The thick filament is made up of myosin protein.
OBJECTIVE 10:
. - Describe the function of Actin and Myosin proteins

51. Actin protein
∙ Actin is the most abundant protein in most eukaryotic cells.
∙ The thin filament is made up of actin protein and are 7-8 nm thick.
∙ There are kidney shaped polypeptide subunits of actin called globular
actin or G-actin.
∙ G-actin bears the active sites to which myosin heads attach during
contraction.
∙ G actin monomers are polymerized into long actin filament called
fibrous or F-actin.
∙ Actin filament also consist of troponin and tropomyosin.

52. Function of actin
∙ Actin along with myosin helps in muscle
contraction in sliding movement.
∙ They give mechanical support to cell and
helps in signal transduction.

53. Myosin protein
• Myosin are said to be motor proteins.
• The thick filament composed of only myosin protein.
• They work along actin protein and are fueled by ATP for muscle
contraction.
• Each myosin protein molecule consist of six polypeptides.
• They are arranged in such a way that each myosin posses a head
and two globular tails.
• Each thick filament consist of 300 myosin molecules join
together with their tail in the center and head facing outward.

54. Function of actin and myosin in sliding filament model:
∙ During muscle contraction, each sarcomere shortens bringing Z-disc closer.
∙ There is no change in width of A but I band and H band disappears.
∙ These changes are explained by the actin and myosin filaments sliding past one
another.
∙ The actin filaments move into the A band and H zone.
∙ The binding of myosin to actin filaments, allows myosin to function as a motor
that drives filament sliding.
∙ Muscle contraction thus results from an interaction between the actin and
myosin filaments.

56. ATP and Muscle Contraction:
Muscles contract in a repeated pattern of binding and releasing between the two thin
and thick strands of the sarcomere. ATP is critical to prepare myosin for binding and
to "recharge" the myosin
OBJECTIVE 10:
. - Define the Function of ATP in the skeletal muscles

57. The Cross-Bridge Muscle Contraction Cycle
• ATP first binds to myosin, moving it to a high-energy state.
• The ATP is hydrolysed into ADP and inorganic phosphate (Pi) by
the enzyme ATPase.
• The energy released during ATP hydrolysis changes the angle of
the myosin head into a "cocked" position, ready to bind to actin if
the sites are available.
• ADP and Pi remain attached; myosin is in its high-energy
configuration.

59. • Martini, Frederic H.; Timmons, Michael J.; Tallitsch, Robert B. (2008). Human Anatomy (6 ed.). Benjamin
Cummings. pp. 251–252. ISBN 978-0-321-50042-7.
• Costanzo, Linda S. (2002). Physiology (2nd ed.). Philadelphia: Saunders. p. 23. ISBN 0-7216-9549-3.
• http://cephalicvein.com/tag/muscular-system-of-human-body-pdf/
• https://www.slideshare.net/mobile/angellacx/the-muscular-system-powerpoint-presentation
• https://youtu.be/4t2X2IvGyUE
• https://youtu.be/j3EpMyqyv0E
• http://study.com/academy/lesson/major-skeletal-muscle-functions.html
• https://youtu.be/j3EpMyqyv0E .. by doc rent Allen hartung oaks community college
REFERENCES

60. Thank You