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Inferior Glenohumeral Ligament

The IGHL originates on the inferior half of the glenoid neck or anterior inferior labrum, and it inserts inferior to the MGHL on the lesser tuberosity. Various descriptions have been used to define this large, ligamentous structure that undergoes reciprocal tightening and loosening, depending on the position of the arm.

Some have used the terms superior band, anterior axillary pouch, and posterior axillary pouch to describe the three regions of this ligament; others have described its anatomy as resembling a hammock, with a thick anterior band and a thin posterior band, surrounding the axillary pouch.

The axillary pouch runs from the inferior one-third of the humeral head to the inferior two-third of the anterior glenoid. In external rotation, the IGHL complex moves in the anterior direction, whereas with internal rotation, the complex moves in the posterior direction .

In a cadaveric study by Steinbeck et al.It is the IGHL was a clearly defined structure in 72% of the specimens and only a thickening of the inferior joint capsule in 21%. The superior band was the thickest, with an average size of 2.8 mm, whereas the posterior portion was thinner (mean thickness, 1.7 mm). In addition, that study revealed that the IGHL is thicker at the glenoid origin (mean thickness, 2.3 mm) than at the humeral insertion (mean thickness, 1.6 mm).The length and width of the anterior band have been reported to average of 37 and 13 mm, respectively. Histologically, the collagen fibers are predominantly radial fibers that are linked to each other by circular elements.

The IGHL complex functions as the primary restraint to anterior, posterior, and inferior GH translation with the arm at 45 to 90 degrees of abduction and external rotation. The anterior band and axillary pouch are anterior stabilizers, resisting anterior and inferior translation at 45 to 90 degrees degrees of abduction and external rotation, whereas the posterior band resists posterior translation of the humeral head in shoulder flexion and internal rotation.

At the neutral position (0 degrees of abduction, 30 degrees of horizontal extension), the anterior band of the IGHL becomes the primary stabilizer. Sectioning of the anterior band of the IGHL and the anterior half of the axillary pouch resulted in significant increases in anterior, posterior, and total translation at -30 and 0 degrees of flexion and extension, respectively.

The posterior capsule of the GH joint lies proximal to the superior portion of the posterior band of the IGHL. It is the thinnest part of the capsule, being approximately 1 mm in width. It often is blamed for poor results after surgery for posterior instability, and it functions to limit posterior translation of the humeral head with the arm in forward flexion, adduction, and internal rotation .

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