1. Muscular Tissue
By Dr. Hanan Said Seleem

2. MUSCLE TISSUE
Muscle tissue is responsible for: Body movement as a whole.
According to its function and structure, muscle tissue is classified into three types:

3. MUSCLE TISSUE 1- Skeletal muscle: It is voluntary and striated
It is attached to bone and is responsible for the movement of the axial and peripheral skeleton.
2- Cardiac muscle:
It is involuntary and striated.
It forms the wall of the heart.
3- Smooth muscle:
It is involuntary and non-striated (in which the cells do not exhibit cross striations).
It is present in the body viscera and blood vessels.

4. State which of the following contains skeletal muscle
A) tongue
B) esophagus
C) aorta

5. Connective Tissue Wrappings
Skeletal Muscle Investment
Endomysium
Perimysium
Epimysium
Tendon
Deep Fascia
Muscle Fiber
Skeletal Muscle
art, vein, nerve
Fascicle
Connective Tissue Wrappings

6. Organization of skeletal muscle
Whole muscle
Bundles
Fibers
Fibrils
Filaments.

7. L/M Shape: Nucleus: peripheral, flattened and multinucleated
Long, cylindrical, parallel.
Non-branching except in face and tongue.
Surrounded by sarcolemma and basal lamina.
Nucleus: peripheral, flattened and multinucleated
Sarcoplasm: acidophilic, myofibrils.

8. Longitudinal sections (LS)
Parallel fibers.
Striated.
Peripheral, multiple, flat nuclei.

9. Transverse section (TS)
Rounded fibers
Myofibrils (dots in Cohenheim groups).
Inbetween sarcolemma and basal lamina are satellite stem cells for repair.

11. Types of skeletal muscle fiber
Red (type I)
White (type II)
Intermediate
According to morphology, histochemistry and biochemistry
Sk. Ms. Contain 3 types but white fibers predominate.

12. Type I red fibers Type II white fibers
Central nuclei
Peripheral nuclei
Irregular striations
Regular striations
Fewer myofibrils
Numerous myofibrils
Abundant sarcoplasm
Less abundant
Rich in myoglobin, mitochondria
Poor in myoglobin & mitochondria
Fibers contract slowly over prolonged period & don’t fatigue easily
Fibers contract rapidly over short period & fatigue easily

14. Skeletal muscle Fibers (each is one cell) have striations
Myofibrils are organelles of the cell: these are made up of filaments
Sarcomere
Basic unit of contraction
Myofibrils are long rows of repeating sarcomeres
Boundaries: Z discs (or lines)
This big cylinder is a fiber: 1 cell
-an organelle

15. EM of myofibrils

19. Sliding Filament Model
__relaxed sarcomere__
_partly contracted_
fully contracted
“A” band constant because it is caused by myosin, which doesn’t change length
Sarcomere shortens because actin pulled towards its middle by myosin cross bridges

20. Sarcomere is the distance between:
A) 2 successive A bands
B) 2 successive I bands
C) 2 successive M lines
D) 2 successive Z lines

21. Sarcoplasmic reticulum
It represents a special type of SER that is present in muscle.
The sarcoplasmic reticulum forms a longitudinally arranged tubules around the A band, with cross connections in the region of the H band.
At the A-I junctions the tubules form dilated rings around the myofibrils called terminal cisterna.

22. Transverse tubules (T-tubules)
These are tubular invaginations of sarcolemma into the interior of the muscle fiber.
They form anastomosing network that encircle the boundaries of each sarcomere in every myofibrils at the junctions between A and I bands.
Thus, each sarcomere possesses two sets of T tubules one at each A-I junction.

23. function
facilitate the conduction of waves of depolarization along the sarcolemma.

25. Cardiac muscle fibers L/M: Cylindrical branching anastomosing.
Composed of several cardiac muscle cells.
Size smaller and Striations less than skeletal.
1to 2 central oval pale nucleus.
acidophilic cytoplasm
Rich in myoglobin.
Step-like intercalated disks.

26. Cardiac muscle fibers E/M:. No satellite cells.
Mitochondria (40% of the cytoplasm) and glycogen more than skeletal.
SR: less developed and less regular than skeletal (diad at Z line).

28. SMOOTH MUSCLE Involuntary. Non striated.
Contraction: weak, slow, long duration.
Site: 6 major locations:
inside the eye
walls of vessels
respiratory tubes
digestive tubes
urinary organs
reproductive organs

29. Structure Shape: Fusiform (spindle-shaped )cells.
Nucleus: central single oval.
Cytoplasm: acidophilic.
Surrounded by: basal lamina and reticular network.
Grouped into sheets: often running perpendicular to each other
Peristalsis
No striations (no sarcomeres)
Contractions are slow, sustained and resistant to fatigue

32. Feature Skeletal Muscle Cardiac Muscle Smooth Muscle
Sarcomeres and myofibrils
Yes No
Distinctive features
Long; cylinder-shaped; striations
Branched cells; striations
Fusiform cells with no striations;
Nuclei
Multinucleated; peripheral flattened
One (or two); rounded centrally located
One; centrally located
Sarcoplasmic reticulum
Well-developed with terminal cisterns
Poorly defined; some small terminals
Some smooth endoplasmic reticulum
T tubules
Yes; small, triad formation
Yes; large, diad formation
Cell junctions
Intercalated disks
Nexus (gap junctions)
Contraction
Voluntary
Involuntary; rhythmic and spontaneous
Involuntary; slow forceful;
Regeneration
Yes, via satellite cells
Mitosis
Connective tissue
Epimysium, perimysium, and endomysium
Connective tissue sheaths and endomysium

33. Thank you