Inferior glenohumeral ligament

The inferior glenohumeral ligament (IGHL) is actually defined as a complex of anterior and posterior bands of the articular capsule as well as an axillary pouch that is reinforced by the fasciculus obliquus on the glenoid side. As opposed to the other glenohumeral ligaments, its origin is inseparable from the base of the labrum :

• The anterior band originates along the inferior two thirds of the anterior glenoid labrum ( two o’clock to four o’clock positions). When redundant, it may overlap the anterior edge of the glenoid cartilage. 
• The axillary pouch or recess has a U-shaped appearance on MRA or CTA when the inferior glenohumeral ligament is normal.
• The posterior band arises from the inferior glenoid rim at the seven o’clock to nine o’clock position. Both the anterior and posterior bands of the inferior glenohumeral ligament insert along the inferior aspect of the surgical neck of the humerus. 

The inferior glenohumeral ligament (IGHL) is the most important glenohumeral ligament in terms of stability, stabilizing  the glenohumeral joint when the arm is abducted to approximately 90°.

Source: Normal Shoulder MRI and MR Arthrography: Anatomy and Technique. Llopis E, Montesinos P, Guedez MT, Aguilella L, Cerezal L. Semin Musculoskelet Radiol. 2015 Jul;19(3):212-30. doi: 10.1055/s-0035-1549316. Epub 2015 May 28. Review.PMID: 26021583