Aponeurotic expansion of the supraspinatus tendon

The aponeurotic expansion of the supraspinatus tendon is an anatomical variant that is usually seen incidentally on imaging.

Epidemiology

This structure can be seen in ~33% (range 19-49%) of shoulder joints imaged on MRI ^1,3,4.

Gross anatomy

The aponeurotic expansion of the supraspinatus tendon represents a tendon-like structure arising from the supraspinatus tendon coursing in a vertical direction, along and parallel to the anterior aspect of the long head of the biceps at the level of the bicipital groove ^1,2. It inserts distally, attaching to the pectoralis major tendon next to its humeral insertion ^1,2.

Classification

A classification was proposed by Moser et al. ¹:

• type 0: absence of definite structure

• type 1: thin flat (most common ³)

• type 2a: oval; <50 % of the long head biceps tendon section

• type 2b: oval; >50 % of the long head biceps tendon section

Clinical importance

It can be easily mistaken for a bifid long head of biceps tendon and more importantly, an interstitial tear of long head of biceps tendon. Hence, the correct identification becomes important to prevent unnecessary intervention ^1,2.

History and etymology

This structure was first described by Scottish anatomist and surgeon Charles Gordon Brodie (1860-1933) in 1890 ^1,4,5,6.