Transcript Ch 7 Muscular System

Ch 7 Muscular System
Gross anatomy first!
Pages 171-194
Muscles include:
 Cardiac
 Smooth
 SKELETAL!
This will be our
focus for this test
Muscles contract, pulling
one bone closer to another
(typically they do not move
equally in response to the
contraction)
Anatomy of a muscle
 ORIGIN
(head) –movement is
minimal/stationary
X
 INSERTION
– greatest movement
 BELLY – fat middle portion
Often times:
Origin is proximal to the insertion,
especially in the limbs
 Insertion moves towards the origin
 Most muscles are arranged in opposing
pairs at joints
 Roles of opposing pairs may change for
different movements

Analogy: a screen door
Spring attached to the doorframe = origin
 End attached to swinging door = insertion

origin
insertion
Levers diagram
Grouping Muscles
AGONIST
ANTAGONIST
A muscle producing a
certain movement
A muscle acting in
opposition to an agonist
Group of muscles
producing a certain
movement = synergists
If one from group plays a
major role = prime mover
Muscles that hold one bone
in place while another bone
is moved = fixators
Examples
AGONIST
(SYNERGISTS)
FLEXORS
ABDUCTORS
ANTAGONISTS
EXTENSORS
ADDUCTORS
There are seven methods of naming
muscles (see handout)
 Direction
 Size
 Shape
 Action
 Location
 Origin
and insertion
 Number of origins