Articular surface of humeral head

The articular surface of the humeral head is covered by cartilage and thinner at the periphery and thicker in the center (average thickness of 1.24 mm).

There is a posteriorly bare area of the humeral head between the posterior insertion of the joint capsule and synovial membrane and the adjacent articular cartilage. This should not be confused with a Hill-Sachs impaction injury.

There is another acquired bare area between the supraspinatus insertion in the greater tuberosity and the adjacent articular cartilage. This might lead to overestimation of a partial articular surface supraspinatus tear, but this bare area is increased in undersurface supraspinatus tears and cartilage lesions.

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