The coracohumeral ligament originates proximally at the dorsolateral aspect of the coracoid as a fibrous brand extending superiorly over the head of the humerus before it attaches to the greater tuberosity [5, 37]. This ligament then blends in with the superior glenohumeral ligament (SGHL) inferiorly. The SGHL (arthroscopic view, Figs. 9.2 and 9.3) originates just anterior to the insertion of the long head of the biceps at the superior portion of the glenoid. The SGHL is described as originating between the 12 and 2 o’clock positions on the glenoid, just anterior to the insertion of the long head of the biceps, and runs inferiorly and laterally where it then inserts into the humerus at the fovea capitis which lies slightly superior to the lesser tuberosity [8, 45]. As we move counterclockwise around the glenoid, the middle glenohumeral ligament (MGHL, arthroscopic view Fig. 9.4) originates just inferior to the SGHL [5, 8]. It then inserts medial to the lesser tuberosity on the humerus. The MGHL often follows the superior marginal of the subscapularis tendon; however, it has also been described as the most variable ligament of the labral structures of the shoulder [5, 8]. Anatomically, the MGHL may appear to be flush to the SGHL, as a distinct structure that arises from the inferior aspect of the SGHL as described above, or may not even be clearly identified. The inferior segment of the capsule, the inferior glenohumeral ligament has been identified as the broad inferior glenohumeral ligament and is further broken down into an anterior band which originates from the 3 to 5 o’clock position, posterior band which originates from the 7 to 9 o’clock position which inserts onto the posterior articular margin of the humerus, and the axillary pouch in between [5, 8, 35].

The labrum of the glenoid circumferentially surrounds the outer portion of the glenoid and is the point of insertion of all the glenohumeral ligamentous structures described above. It acts to deepen the socket on average 9 mm in the superior-inferior dimension and 5 mm in the anteroposterior plane which acts to add stability to the joint [35]. The only caveat to these insertions is in regard to the IGHL which has two insertion sites. One insertion is into the anteroinferior aspect of the labrum with a second insertion into the anterior neck of the glenoid [8]. An additional structure that inserts into the superior aspect of the glenoid, just superior to the SGHL, is the long head of the biceps tendon . The biceps tendon originates distally at the radial tuberosity. It course up the humeral shaft in the bicipital groove located between the great and lesser tuberosities. The tendon finally inserts into the superior glenoid and is held in place by the coracohumeral ligament superiorly (arthroscopic view, Fig. 9.5) and the superior glenohumeral ligament inferiorly [46, 48]. This anatomic description has been termed the biceps pulley for the long head of the biceps.

The glenoid is a pear-shaped shallow socket with a wider inferior half [35, 37]. This structure is tilted anteriorly therefore making the joint more susceptible to anterior dislocation [37]. Specifically, the physical features of the glenoid bone are often variable but have been reported as 39 mm (±3.7 mm; range 30–48 mm) in the superior-inferior dimension, 29 mm (±3.1 mm; range 21–35 mm) in the anteroposterior dimension of the lower half, and 23 mm (±2.7 mm; range 18–30 mm) in the anteroposterior dimension of the upper half with the fossa slightly inclined and retroverted [8, 35]. The variation of the size and angle of the glenoid is part of what makes pathology of this bone challenging to treat.