Muscular system 2

Macroanatomy of the Muscular System

EHS unit 3 day 2

Goals

• Describe the anatomy of muscles in the body.• Analyze muscle tone, contraction (on a macro

level) and muscle naming.

Review from yesterday…

• Muscle cells are called ________ and contain myofibrils called _______ and _______ that create contractions.

• 3 electrolytes (ions) that are important in muscle reaction??

• Muscle fatigue occurs when???

Putting it all together…

• Each skeletal muscle has many, many X100 Myocytes (each filled with myofibrils). – Many Myocytes are bound together in fasciae.

Each bundle is called a fascicle. – The middle of the muscle is called the belly. – Each end is anchored to bone by tendons. – Many fascicles are bound together by more

connective tissue to create our muscles.

Muscle Tone

• This is the passive, partial contraction of the muscles to resist stretching.– Help maintain posture. – Declines during REM sleep

All or None Rule

• This is the principle or fact that each myofiber can either fully contract or not contract. There is no partial contractions. – Effort is regulated by HOW MANY of the fibers are

excited to contract.

Muscles doing their Jobs

• A Prime Mover is the main muscle that performs a particular movement. – The antagonist is what does the opposite of the

prime mover. – Muscles that work with the prime mover to refine

a movement are called synergists.

Analyzing Muscle Movements

• When we discuss the prime overs, – We label the point of INSERTION (attachment to

the bone that moves– We label the point of ORIGIN (attachment to the

bone that is static)• The job title of a muscle may vary depending

on the movement: – Ex: may be prime mover for one motion, synergist

for the next, and antagonist in the next.

Naming Muscles

• Muscle names can be long and confusing. But, general rules apply. – Muscles are named for: • Location• Size• Shape• Direction of fibers• Number or origins• Location of attachment points. • Action