Anatomical Variance of Glenohumeral Ligaments and Their Clinical Significance
B. Jane Freure, Peter Leighton Jones, Melanie Werstine
Literature Review
The major non-contractile structure contributing to glenohumeral stability is the anterior glenohumeral joint capsule, which is reinforced by the superior, middle and inferior ligaments. Each ligament has a different role to play in the stability of the humeral head depending on arm position and degree of rotation (Wilk et al 1997b). Clinicians use stability tests to evaluate and to identify specific anatomic structures. However, it is difficult to conclusively establish clinical findings when there are normal anatomic variations of structures (Wilk et al 1997a).
The glenoid fossa can be envisioned as the face of a clock for the attachments of the glenohumeral ligaments, with twelve and six o’clock representing the most superior and inferior points of the fossa, respectively, and three and nine o’clock being anterior and posterior (O’Brien 1990).
A comprehensive literature review has revealed some variability in the anatomy of the glenohumeral ligaments (Cooper 1993 cites: Andrews et al 1984, DePalma et al 1949, Matthews et al 1985, O’Brien et al 1990). The superior glenohumeral ligaments (SGHL) arise from the upper part of the glenoid margin and adjacent labrum, immediately anterior to the attachment of the long head of biceps. This would be analogous to a position just past 12 o’clock on the previously described clock face. It attaches to the superior surface of the lesser tubercle (Palastanga et al 1998, Wilk et al 1997). The inferior glenohumeral ligament (IGHL) arises from the anterior border of the glenoid margin, below the notch, and from the adjacent anterior border of the labrum. This complex (IGHLC) is comprised of the anterior and posterior bands, as well as the axillary pouch. Specifically, the attachment of the anterior band on the glenoid fossa has been shown to vary from two to four o’clock whereas the posterior attachment ranges from seven to nine o’clock (O’Brien et al 1990). Also, it attaches to the anterior-inferior part of the anatomical neck of the humerus in one of two distinct configurations: a collar-like attachment, in which the entire IGHLC attaches along the inferior articular edge of the humeral head, or a V-shape, with the anterior and posterior bands attaching adjacent to the articular edge and the axillary pouch attaching more distally at the apex of the “V” (O’Brien et al 1990, Palastanga et al 1998). Ferrari (1990) noted significant variability in the presentation of the middle glenohumeral ligament (MGHL). In four percent of the specimens the MGHL presented as a thin thread, eight percent as a large bursal opening and the remainder were defined as definite capsular thickenings. The MGHL arises below the SGHL around the one to two o’clock position on the clock face and attaches to the humerus on the anterior aspect of the lesser tubercle (Ferrari 1990, Palastanga et al 1998, Wilk et al 1997, Watson 1999, O’Brien et al 1990).
The tendon of the long head of the biceps is usually described as arising from the superior aspect of glenoid and blends into the labrum. In the literature, four types of attachments have been distinguished (Vangsness et al 1994): one, the complete labral part of the attachment is posterior; two, in addition to the posterior attachment there is an additional small contribution to the anterior portion; three, it has similarly sized attachments to both the anterior and posterior labrum; four, the majority of the attachment is anterior.
The intent of our dissection was to identify the attachments of the ligaments to the glenoid, comment on their general appearance and fibre orientation and analyze the clinical significance of anatomical variations.
