1. Muscle Histology

3. Cross Section of a Skeletal Muscle
Blue = epimysium
Green = perimysium
Yellow = endomysium surrounding muscle fiber

4. Skeletal Muscle Cross Section Slide
Pointer is on the perimysium surrounding a muscle fascicle
Skeletal Muscle Cross Section Slide
Epimysium would be here surrounding the entire muscle organ (but it is not visible on the slide)

5. Skeletal Muscle Cross Section Slide
Muscle fascicles can be a variety of shapes!

6. Skeletal Muscle Cross Section Slide
Pointer is on the perimysium surrounding a muscle fascicle
black arrows are pointing at individual skeletal muscle fibers

7. Multinucleated Skeletal Muscle Fibers
The small purple dots are the nuclei of a skeletal muscle fiber. Notice that each fiber has more than 1 nucleus?

9. Skeletal Muscle Long Section
Each bracket is on one Skeletal Muscle Fiber (cell)

10. Skeletal Muscle: Striations
Skeletal muscle fibers are clearly striated with dark A-bands and light I-bands

11. Skeletal Muscle Long Section: Multinucleated
Skeletal muscle fibers are multinucleated (they have more than 1 nucleus per cell)

12. Cardiac Muscle
Intercalated discs
Striations
Nuclei

13. black arrows are pointing at intercalated discs (only found on cardiac muscle)

14. Smooth Muscle
Nuclei
Smooth muscle cells
Smooth muscle cells have a spindle shape and only one nucleus per cell with NO striations!

15. Motor Unit = a somatic motor neuron + skeletal muscle fibers it synapses with

16. Motor Unit Slide Green = Neuromuscular Junction
Yellow = Axon of a somatic motor neuron
White = skeletal muscle fiber

17. Motor Unit Slide Pointer is on the axon of a somatic motor neuron
Green arrow is on a neuromuscular junction

18. Motor Unit