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Chapter 6
The Muscular System:
Pathology
Muscular System: Pathology
Relatively few pathologies afflict the
muscular system. It’s rich blood supply ensures
that skeletal muscle is resistant to infection.
However, if destroyed, skeletal muscle tissue
regenerates poorly. Smooth muscle
regenerates better than skeletal muscle.
Cardiac muscle barely regenerates, if at all.
Muscular System: Pathology
The muscular system, like all organ
systems, is subject to atrophy. If you don’t use
your muscles, you will lose muscle strength
and tone. On the other hand, with regular use
the muscular system will continue to function
well for decades.
Muscular System: Pathology
Cramping
Most common causes:
• Muscle Fatigue
• Dehydration
• Insufficient electrolytes (potassium, calcium)
1. Water and electrolytes are lost through sweat
2. Osmotic pressure forces water out of muscle
cells
3. Ca2+ ion concentration remains greater inside
the muscle cell, so calcium does not release
troponin binding sites and myosin is bound to
actin
• Hyperflexion
• Complication of pregnancy
Muscular System: Pathology
Strains, Sprains, Tears
Strains - less serious than
sprain; a stretched or
partially torn muscle
Sprains - forcible wrenching
or twisting of a joint that
stretches or tears its
ligaments but does not
dislocate the bones. (NOT
Muscular!!)
Tears – a really bad strain
Swelling and redness resulting from a
partially torn triceps muscle
Muscular System: Pathology
Muscular Dystrophy
• A group of congenital
muscle-destroying diseases
that affect specific muscle
groups
• Most common is Duchenne
muscular dystrophy,
affecting exclusively young
boys.
• Muscle enlarge due to fat
and connective tissue
deposits, while muscle
tissue atrophies.