Page 299 - Atlas of Histology with Functional Correlations

FIGURE 8.1 ■ Diagrammatic representation of the microscopic appearance of

skeletal muscle.

Supplemental micrographic images are available at
www.thePoint.com/Eroschenko13e under Muscle Tissue.

FIGURE 8.2 | Longitudinal and Transverse

Sections of Skeletal (Striated) Muscles: Tongue

In the tongue, skeletal muscle fibers are arranged in bundles that course in
different directions. This image illustrates the tongue muscle fibers in both the

longitudinal (upper region) and transverse (lower region) sections.

Each skeletal muscle fiber (9, transverse section; 11, longitudinal section)
is multinucleated. The nuclei (1, 6) are situated peripherally and below the
sarcolemma of each muscle fiber. (The sarcolemma is not visible in the figure.)

Also, each skeletal muscle fiber shows cross-striations (3) that are visible as
alternating dark A bands (3a) and light I bands (3b). With higher magnification
and transmission electron microscopy, additional details of the cross-striations
are visible (see Figs. 8.5 and 8.6).

Skeletal muscle fibers are aggregated into bundles or fascicles (15),

surrounded by fibers of connective tissue (5) sheath around each muscle fascicle
(15) called the perimysium (12). From each perimysium (12), thin partitions of
connective tissue extend into each muscle fascicle (15) and invest individual
muscle fibers (9, 11) with a connective tissue layer called the endomysium (4,

7). Small blood vessels (8) and capillaries (2, 14) are present in the connective
tissue (5) around each muscle fiber (9, 11).

The skeletal muscle fibers that were sectioned longitudinally (11) show light
and dark cross-striations (3a, 3b). The muscle fibers that were sectioned
transversely (9) exhibit cross sections of myofibrils (13) and peripheral nuclei

(6).

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