Subscapularis Muscle – Anatomy Breakdown Video & Clinical Guide

Jul 10

The Subscapularis is the largest and strongest of the four rotator cuff muscles, but it often flies under the radar until there’s dysfunction or pain. In this video, we’ll break down its origin, insertion, function, innervation, and clinical relevance. Perfect for students, clinicians, trainers, and anyone wanting to understand shoulder anatomy with real-world clinical context.
Watch the full video below and read on for detailed insights.

Quick Hits

The Subscapularis is a broad, triangular muscle located on the anterior (costal) surface of the scapula, filling the subscapular fossa and forming the anterior wall of the rotator cuff.

Origin: Subscapular fossa of the scapula.
Insertion: Lesser tubercle of the humerus.
Innervation: Upper and lower subscapular nerves (C5, C6, C7).
Actions: Primary internal rotation of the humerus. It also assists in adduction and stabilizes the humeral head within the glenoid fossa.

The Subscapularis is the main internal rotator of the shoulder joint and plays a crucial role in anterior shoulder stability.

Clinical Relevance

Clinically, Subscapularis pathology is often overlooked compared to supraspinatus or infraspinatus, tears but it is equally important—especially in patients with anterior shoulder pain or instability.

Partial or full-thickness tears can lead to loss of internal rotation strength and altered glenohumeral mechanics. These tears are harder to diagnose clinically but should be suspected with weakness in lift-off or bear hug tests.

Rehabilitation includes internal rotation strengthening, isometric holds, and closed-chain stabilization exercises. Emphasis on restoring scapular control and balanced rotator cuff activation is key to long-term success.