Download Muscle Notes - Polk School District

Muscular System
Human A & P

There are 3 types of muscle tissue:
◦ A. Skeletal
◦ B. Smooth
◦ C. Cardiac
◦ The essential function of a muscle is
contraction, or shortening, and are responsible
for essentially all of the body’s ability to move.






They attach to bones.
They are huge, cigar-shaped,
multinucleated cells.
The largest type (up to 30 cm).
Striated (stripes in the fibers)
Voluntary (conscious control—except
reflexes)
Contract rapidly and with great force, but
also tire easily and require reset after
short periods of activity.
Skeletal Muscle Description




Thousands of skeletal muscle fibers are
bundled together by connective tissue, which
provides strength and structure to the muscle
as a whole.
Each individual fiber is enclosed in an
endomysium.
Several fibers are bundled together into a
fascicle and covered with a coarse
perimysium.
Several fasciles are bound together and
covered by an epimysium, which covers the
entire muscle.
Skeletal Muscle Structure
Skeletal muscle fibers blend or taper into
tendons or aponeuroses. Aponeuroses
attach indirectly to bones, carilage, or
connective tissue coverings.
 Tendons anchor muscle to bone, but also
provide durability and conserve space.
They are tough collagenic fibers, so they
can cross rough bony projections without
tearing like muscles would.

Tendons and Aponeuroses
Tendon pictures and diagrams
Apopneuroses
Smooth muscle has no striations.
It is involuntary (cannot consciously
control it).
 They are found mainly in the walls of
hollow visceral (internal) organs, such as
the stomach, urinary bladder, and
repertory passages.
 They propel substances along a definite
tract or pathway within the body, such as
moving food through the digestive tract
and emptying bowels and bladder.


Smooth Muscle Description
Smooth muscle is spindle shaped with a
single nucleus and are surrounded by a
small endomysium.
 They are arranged in layers, usually 2,
one is circular, the other longitudinal. The
2 layers alternately contract and relax as
they change the size and shape of the
organ.
 The movement is slow and sustained.

Smooth Muscle Structure
Smooth Muscle
Cardiac muscle is found only in the heart.
It forms the bulk of the heart walls.
It is striated and involuntary.
The cardiac fibers are cushioned by small
amounts of soft connective tissue
(endomysium) and arranged in spiral
bundles (figure 8 shaped).
 Cardiac fibers are branching cells joined
by special junctions called intercalated
discs.




Cardiac Muscle
Cardiac Muscle Fibers

When the heart contracts, its internal
chambers become smaller, forcing the
blood into the large arteries leaving the
heart. Cardiac muscle usually contracts at
a fairly steady rate set by the heart’s “inhouse” pacemaker.
How the heart muscle works
1.
 2.
 3.
 4.

Produce Movement
Maintaining Posture
Stabilizing Joints
Generating Heat
Muscle Functions
Microscopic Anatomy of Skeletal
Muscle