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The Shoulder Joint
Muscles of the Shoulder Joint
Chapter 5
Anterior Shoulder Muscles
• Coracobrachialis
• Pectoralis Major
• Subscapularis
Coracobrachialis
• O: Coracoid process
• I: Anteromedial
surface of midshaft of
humerus
• Actions:
– Flexion
– Adduction of the
shoulder
– Horizontal Adduction
Pectoralis Major
• Origin:
– Medial two-thirds of clavicle
– Sternum
• Insertion: intertubercular groove
• Actions
– Upper fibers (Clavicular)
• Internal rotation
• Horizontal Adduction
• Flexion
• Adduction
– Lower fibers (Sternal)
• Internal Rotation
• Horizontal adduction
• Extension
• Adduction
Subscapularis
• O: Subscapular fossa
• I: Lesser tubercle and
crest of humerus
• Actions:
– Internal Rotation
– Adduction
– Extension
• Stabilization
• Anterior Rotator Cuff
Muscle.
Superior Shoulder Muscles
• Deltoid
• Supraspinatus
Deltoid
• Origin
– Lateral 1/3 of clavicle
(Anterior fibers)
– Acromion process (Middle fibers)
– Spine of scapula
(Posterior fibers)
• Insertion – deltoid tuberosity
Actions
Anterior – Abduction, Flexion, Horizontal adduction, & Internal
rotation.
Middle – Abduction
Posterior – Abduction, Extension, Horizontal abduction, & External
rotation
Supraspinatus
• O: Supraspinous
fossa
• I: Greater tubercle
• Action:
– Abduction
• Stabilization
• Superior Rotator Cuff
Muscle.
• Most injuired rotator
cuff muscle
Inferior Shoulder Muscles
• Latissimus Dorsi
• Teres Major
Latissimus Dorsi
• O: Spinous process of
lower 6 thorasic and all
lumbar and sacral
vertebrae; iliac crest
• I: Intertubercular groove
• Actions:
–
–
–
–
Adduction
Extension
Internal Rotation
Horizontal Abduction
Teres Major
• O: Inferior angle of
scapula
• I: Intertubercular groove
• Actions:
– Extension
– Adduction
– Internal rotation
• “Lats little helper”
Posterior Shoulder Muscles
• Infraspinatus
• Teres Minor
Infraspinatus
• O: Infraspinous fossa
• I: Greater tubercle
• Actions:
– External rotation
– Horizontal abduction
– Extension
• Stabilization
• Posterior Rotator Cuff Muscle
• Second most commonly
injured rotator cuff muscle
Teres Minor
• O: Upper 2/3 of lateral
border of scapula
• I: Greater tubercle
• Actions:
– External rotation
– Horizontal abduction
– Extension
• Stabilization
• Posterior Rotator Cuff
Muscle
Study guide
• List the muscles for
• Name the muscles
Horizontal Adduction
for Horizontal
Abduction
Practice
• List the muscles that
do flexion of the
shoulder
• List the muscles that
do extension of the
shoulder
Practice
• List the muscles that
do adduction of the
shoulder
List the muscles that do
abduction of the
shoulder
Practice
• List the muscles that
do internal rotation
of the shoulder
• List the muscles that
do external rotation
of the shoulder
Name the muscle.
Coracobrachialis
Name the action
Adduction of
the shoulder
Name the muscle.
Pectoralis Major
Name the muscle.
Subscapularis
Name the action
Internal
rotation of the
shoulder
Name the muscle.
Deltoid
Name the action
Abduction of
shoulder
Name the muscle.
Infraspinatus
Name the action
External
rotation
Name the muscle.
Name the action
Teres Major
Adduction of
scapula
Name the muscle.
Teres Minor
Name the action if the humerus move directly to the posterior
Extension of the shoulder
Name the muscle.
Supraspinatus
Name the action
Abduction of the shoulder
Coracobrachialis
Subscapularis
Pect. Major
Deltoid
Supraspinatus
Teres Major
Infraspinatus
Teres Minor