Infraspinatus fascia

The infraspinatus fascia is a fibrous sheet that covers the infraspinatus muscle within the infraspinous fossa of the scapula. Medially, it firmly attaches to the margins of the infraspinous fossa. Laterally, it seamlessly blends with the deltoid fascia and the fascia overlying the teres minor muscle.

This fascia is characterized by distinct fascial bundles, including a medial band, superior-lateral and inferior-lateral bands, and a retinacular sheet that lies deep to the deltoid but superficial to both the infraspinatus and teres minor muscles. Significantly, the posterior deltoid muscle inserts directly into the infraspinatus fascia, and transverse fascial connections exist between these two structures, highlighting their biomechanical integration in the posterior shoulder.

The infraspinatus fascia maintains continuity superiorly with the supraspinatus fascia at the spinoglenoid notch, forming a crucial fascial envelope relevant for the passage of the suprascapular nerve and vessels. Inferiorly and laterally, it connects with the fascia of the axillary region, integrating with the broader fascial network of the upper limb.