Download Upper body

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Retraction of the scapulas (shoulder blades) is bringing them together—kind of like
adduction for other joints. Protraction of the shoulder blades is like abduction for
other joints.
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The pec minor assists in drawing the shoulder forward and downward. It also helps
to stabilize the shoulder girdle.
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This muscle is also known as the “boxer’s muscle” because the serratus anterior helps
with horizontal arm movement like punching and pushing during horizontal
adduction.
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The trapezius is such a big muscle with a big origin and more than one insertion,
which allows it to do multiple actions including opposite ones—elevation and
depression. It is sometimes divided into 4 areas. The superior part of the trapezius
(Trap 1) does elevation, the middle part (Trap 2 & 3) does retraction, and the inferior
part (Trap 4) does depression as well as upward rotation.
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Is this a left or right scapula??
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This is a triaxial joint. So what movements can occur at this joint?
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The deltoid is a superficial muscle and is a common site for injections and shots.
Once the arm has been abducted to the horizontal level from the anatomical
position, all 3 portions of the muscle are considered abductors of the joint. The
anterior deltoid also helps with horizontal adduction, while the posterior deltoid
helps with horizontal abduction.
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There are 4 rotator cuff muscles that are important for stabilizing the shoulder joint.
The supraspinatus is a very deep muscle and when it gets torn the pain is deep in the
shoulder and gets worse as you try and abduct your arm. It is considered the primary
initiator of abduction until approximately 30 degrees of abduction, when the deltoid
muscle takes over as the major abductor.
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Subscapularis is another rotator cuff muscle. Remember the subscapular fossa is on
the anterior part of the scapula. So the subscapularis crosses all the way across the
subscapular fossa and inserts on to the lesser tuberosity of the humerus.
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The latissimus dorsi is also known as the “swimmer’s muscle” because it is important
in bringing the arm down (shoulder extension) during the power stroke.
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Remember the infraspinous fossa is located on the posterior side of the scapula,
below the spine. So the infraspinatus originates from the infraspinous fossa and
inserts on to the greater tuberosity. The teres minor is located more lateral and
inferior to the infraspinatus.
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Supraspinatus is located superior, Infraspinatus and teres minor are located posterior,
and the subscapularis is located anterior on the scapula and they all go and insert on
to the humerus.
**The rotator cuff muscles not only generate the force needed by contracting
concentrically to throw something, but also apply a braking action through an
eccentric contraction to prevent the upper extremity from leaving the body.**
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The biceps long head originates on the superior part of the glenoid cavity of the
scapula.
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The triceps long head originates on the inferior part of the glenoid cavity of the
scapula.
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