The Muscular System

Myology is the study of the muscles

There are 3 different types of muscles

Skeletal Muscle -

Voluntary

Striated

Skeletal muscle fiber is also a skeletal muscle cell

85% is fiber, 15% striated

Cardiac Muscle -

Only in heart (duh)

Involuntary

Striated

Made of cardiocytes - fusiform shaped

Smooth Muscle -

Involuntary

Nonstriated - cytoskeletal is not striped

Made of fusiform cells called myocytes

Functions of Muscle:
Movement - can contract and change
Stability - keeps the bones together
Communication - facial expressions (smile, speak)
Control of body openings - voluntary
Heat production - keep body 98.6 degrees, muscle contractions (shiver - skeletal muscle)

Properties of Muscle:
Excitability - can work with electrical signals
Conductivity - can conduct electricity
Contractibility - ability to shorten
Extensibility - some ability to stretch
Elasticity - ability to return to original state

General Anatomy of Skeletal Muscles:
Made of muscle fibers, connective tissue, nervous tissue, and blood vessels.
Connective tissues:
Endomysium - single layer collagen that surrounds the inside like a cell wall
Perimysium and fascicles - end of each muscle cell, divided by perimysium
Epimysium - holds all the fascicles together in a muscle
Deep fascia
Superficial fascia - hypodermis

Fascicles and Muscle Shapes:
Determines strength and direction of tension

Fusiform muscles - fascicles nonparallel
-Biceps brachii
-Gastrocnemious

Parallel muscles
-Rectus abdominus
-Sartorius (allows us to cross our legs)

Convergent muscles
-Pectoralis major

Pennate muscles
-Unipennate (semimembraneous)
-Bipennate (rectus femoris)
-Multipennate (deltoid)

Circular muscles
-Orbicularis oris