2. Introduction to Musculoskeletal system
Functions of Muscles
The three basic muscle types
Connective tissues of Muscles
Attachment of muscles
Naming of skeletal muscles
2
3. Muscle tissue is highly cellular, well-vascularized tis
sue.
Responsible for body movement.
There are three kinds of muscle tissue: skeletal
cardiac & smooth muscles. They differ in:
the structure of their cells
their body location
their function
the means by which they are activated to contract
Muscle cells are elongated & are referred to as musc
le fibers.
3
4. Excitability or irritability
- the ability to respond to a stimulus
Contractility
- the ability to shorten
Extensibility
- the ability to stretch
Elasticity
- the ability to resume normal length after bein
g shortened
4
5. Includes: - skeletal muscle
- Smooth muscle
- Cardiac muscle
1. Skeletal muscle
Wrapped by connective tissue
Attach to bones & some to skin
When contracts it causes gross body movements
Have long, cylindrical & multinucleated cells
Voluntarily controlled
5
6. Are Striated, (fibers contain alternating light & da
rk bands)
Long & cylindrical cell.
Diameter of 10-100 m (10x average cell size)
Contains many nuclei, which lie at the cell periphe
ry.
Each muscle fiber enveloped by sarcolema (plas
ma membrane).
Cytoplasm of muscle fiber is referred as sarcoplas
m
6
10. • Each skeletal muscle is a discrete organ with tho
usands of muscle fibers.
• It also contains blood vessels, nerve fibers, & conne
ctive tissues.
• Each muscle fiber (cell) is wrapped by fine sheath
of connective tissue called endomysium.
• Several fibers are gathered side by side into a bun
dle called fascicle.
• Each fascicle is bound by collagen fiber layer called
the perimysium.
• The entire muscle (a group of fascicles) is bound
by a dense fibrous connective tissue layer, called ep
imysium.
10
12. Most muscles have at least two attachments.
Origin
- Attachment of a muscle that remains relatively fixed
during muscular contraction.
- Generally a more proximal or axial location
Insertion
- Attachment of a muscle that moves during muscular
contraction.
- Generally a more distal or appendicular attachment
Direct attachments: when epimysium attach directly t
o periosteum of bone or perichondrium of cartilage.
Indirect attachments: when the epimysium attach to
a tendon or an aponeurosis.
12
13. Muscle fiber can be divided by the strength, spee
d, & endurance of contraction in to three.
Red fibers (slow twitch)
White fibers (fast twitch)
Intermediate fibers
13
14. Relatively fibers are thin so, do not generate much
power .
Named for the abundant myoglobin (oxygen bindi
ng pigment) in their sarcoplasm.
Obtain their energy from aerobic reactions.
Contract slowly, & resistant to fatigue as long as o
xygen is present.
Used in many of the postural muscles of the axial
skeleton.
14
15. Pale because they contain little myoglobin
About twice the diameter of red fibers
Contain more myofibrils & generate more power.
Contract rapidly & tire quickly
Common in the muscle of the upper limbs
Used to lift heavy objects for brief periods
15
16. Size b/n the other two fiber types
Like white fibers they contract quickly
Like red fibers they are oxygen dependent & have
a high myoglobin content & a rich in capillaries.
Less fatigue resistant
Abundant in the muscles of the lower limbs.
Used to move the body for long periods of time in
activities like walking & jogging.
16
17. Lack the courser connective tissue found in skeletal
muscles.
Have small amounts of endomysium
Occur in walls of blood vessels & hollow organs of r
espiratory, urinary, digestive & reproductive tracts.
Organized into sheets of closely apposed fibers.
In most cases their fibers aligned at right angle to e
ach other: longitudinal layer & circular layer.
These two layers contract & squeeze the contents of
the organ.
17
19. Non straited,
Spindle shaped (Fusiform )
Single centrall nucleus.
Range in length from 2 micron in small blood vessel
s to 500 micron in the pregnant uterus.
Actively divide & regenerate
Contractile filaments are not organized into myofib
rils
Contraction occurs more slowly and lasts longer
Involuntarily controlled
19
21. Forms the wall of the heart
Contract spontaneously & display a rhythmic b
eat.
Do not regenerate; repaired by scar formation.
21
22. Involuntary control
Fibers are Striated, short, branched, cylindrical
& interconnected
Fibers have one or two centrally located nuclei
Fibers attached to each other by transverse thickeni
ng of the sarcolemma called intercalated discs (co
mplex cell junction forming end-to-end attachmen
t b/n adjacent cardiac muscle cells) & help them to f
unction as a single unit.
22
25. Modified cardiac muscle cells located in the
atrioventricular (AV) bundle of the heart.
Specialized for conduction
Large, pale cells filled with Glycogen
Form gap junction & desmosomes
25
26. Type of
muscle
Shape of cells Nuclei Control Striation
s
Special features
Skeletal Long and
cylindrical
Many
Peripheral
Voluntary Present hypertrophy and
hyperplasia
Slight
regeneration
Cardiac short,
cylindrical
and
branching
One or two
central
Involunta
ry
Present Hypertrophy
No regeneration
Smooth Fusiform One
Central
Involunta
ry
Absent hypertrophy and
hyperplasia
regenerate
26
27. Muscles can be classified into four functional groups:
Prime movers: a muscle that provides the major
force for producing a specific movement.
Antagonists: muscles that oppose a particular mo
vement.
Synergists: promoting the same movement
Fixators: Serves to stabilize the bone upon which
a prime mover acts.
27
