The rotator interval is important in shoulder stability and movement. The rotator interval is enclosed in the triangular area bordered by the subscapularis anteroinferiorly, supraspinatus posterosuperiorly, and the coracoid process medially. The rotator interval contains the long head of the biceps tendon, coracohumeral ligament, superior glenohumeral ligament (SGHL), and the middle glenohumeral ligament (MGHL). The rotator interval contains multiple static stabilizers of the shoulder, and its integrity is important for anterior and inferior stability of the shoulder, especially when the shoulder is adducted. Furthermore, external rotation of the shoulder is altered with rotator interval pathology. For surgical intervention to have success, an intimate understanding of the rotator interval structures is necessary. Rotator Interval Anatomy The rotator interval of the shoulder is the area defined by the subscapularis anteroinferiorly, the supraspinatus posterosuperiorly, and the coracoid process medially. The long head of the biceps tendon traversing in the bicipital groove exits the joint just lateral to the insertion of the subscapularis tendon on the lesser tuberosity (Fig. 1a). The coracohumeral ligament originates from the proximal third of the dorsolateral aspect of the base of the coracoid process and runs on the bursal side of the SGHL, inserting mostly on the greater tuberosity and to a lesser extent on the lesser tuberosity (Ferrari 1990; Burkhart et al. 1993; Jost et al. 2000; Fig. 1a). The superior glenohumeral ligament (SGHL) originates from the glenoid labrum, frequently with the long head of the biceps tendon (Jost et al. 2000; Fig. 1b). The SGHL fibers insert mainly into the lesser tuberosity and also form a band around the biceps tendon and insert into the greater tuberosity contributing to the roof of biceps sling (Ferrari 1990; Burkhart et al. 1993; Jost et al. 2000; Werner et al. 2000; Kask et al. 2010; Fig. 2). During its course, the SGHL borders the biceps anteriorly (Figs. 1b, 2, 3a–d). The MGHL commonly originates in the anterosuperior aspect of the labrum or the supraglenoid tubercle (SGT). The MGHL then inserts onto the inferior aspect of the lesser tuberosity (Ferrari 1990; Jost et al. 2000; Pouliart and Gagey 2005; Kask et al. 2010; Felli et al. 2012). As it enters the shoulder joint in the bicipital groove, the long head of the biceps tendon has a sling formed around it consisting of the supraspinatus, subscapularis, SGHL, and coracohumeral ligament (Fig. 3). The medial aspect of the sling consists of from deep to superficial the SGHL, coracohumeral ligament, and subscapularis tendon, respectively. The lateral aspect of the sling from deep to superficial consists of the SGHL, deep coracohumeral ligament, supraspinatus tendon, and superficial *Email: johnpeggers@gmail.com Sports Injuries DOI 10.1007/978-3-642-36801-1_10-1 # Springer-Verlag Berlin Heidelberg 2013