Muscle Histology

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

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)

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

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

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?

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

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

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

Cardiac Muscle Intercalated discs Striations Nuclei

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

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

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

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

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

Motor Unit