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Infraspinatus – Functional Anatomy

The anatomy of the infraspinatus is a bit more complicated than typically explained. A more detailed understanding is helpful for effective neuromuscular massage. The trigger point locations, which produce different patterns, are in different bellies.

Overview of Anatomy


Overview

The infraspinatus is a flat rotator cuff muscle located in the infraspinous fossa of the scapula.

Origin:

  • infraspinous fossa

Insertion

  • posterior greater tubercle of the humerus

Function

  • stabilize the humeral head, externally rotate the humerus

Innervation

  • C4-C6, Brachial Plexus, Suprascapular nerve

Attachment Details

The infraspinous fascia is a complex structure that covers the entire muscle. Anchoring sections of the infraspinatus is one of its many features.

  • The central belly originates from the interior surface of the scapula. It thickens as it travels laterally, Eventually, until it forms a thick tendon that wraps around to the anterior greater tubercle.

Attachment Details

  • The superior belly originates from the inferior edge of the spine of the scapula and inserts into the tendon of the central belly before it reaches the humerus

Attachment Details

  • The inferior belly originates from the caudal border of the scapula and inserts with the tendon of the teres minor.

Rotator Cuff Involvement

Functional Considerations

The infraspinatus is one of the rotator cuff muscles. These muscles stabilize the head of the humerus by strapping it tightly into the socket.

The infraspinatus tendon actually wraps around the side and connects to the greater tubercle. This configuration stabilizes the humerus from becoming anterior displaced.

Anomalies, Etc.

This study reports that physiological variations as rare.

Wikipedia entry for Infraspinatus

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Tony Preston has a practice in Atlanta, Georgia, where he sees clients. He has written materials and instructed classes since the mid-90s. This includes anatomy, trigger points, cranial, and neuromuscular.

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