Infraspinatus - Muscle Physiology & Functional Anatomy

Anatomy

Origin:

• Infraspinous fossa of the (medial) scapula
  

Insertion:

• Middle facet of greater tubercle of the (posterior) humerus

Major Arteries:

• Suprascapular artery

• Circumflex scapular artery

Neural Innervation:

• Subscapular nerve

Trigger Points:

Physiology

Concentric Functions:

• External rotation, transverse abduction & transverse extension of the humerus

Eccentric Function:

• Decelerates shoulder internal rotation

Isometric Function:

• Assists in posterior stabilization of the shoulder joint

Related Muscles

• Supraspinatus

• Subscapularis

• Teres Minor

Antagonists:

• Deltoids
• Pectoralis Major
• More depending on motion

Exercises:

• Rotator Cuff Exercises

More Images of the Infraspinatus Muscle

More Information about the Infraspinatus Muscle

Infraspinatus is derived from the Latin words 'infra' meaning beneath and 'spina' meaning spine.  The infraspinatus muscle which is assisted by the teres minor is the second most commonly injured rotator cuff muscle.  behind the supraspinatus.

The infraspinatus works along with the other rotator cuff muscles to produce dynamic caudal glide in the glenoid fossa which helps prevent impingement.

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