Lesser tubercle

Abstract: Medial displacement of the tendon of the long biceps brachii muscle was analyzed in a dissection study on autopsy in 77 subjects, 42 men and 35 women. The tendon was found to be medially displaced in five shoulders in five different subjects (6.5%). Medial displacement of the tendon was always found in connection with full-thickness supraspinatus tendon ruptures. It is a common belief that the tendon is always displaced medially to the lesser tubercle riding over the subscapularis tendon. In the present series, this condition was found only in one case; in the other shoulders the tendon had slipped medially to the lesser tubercle under the subscapularis tendon, which was partially internally ruptured. In patients with rotator cuff lesions, medial displacement of the long biceps tendon might be one reason for pain over the front of the shoulder.

Abstract: Purpose: Arthroscopic repair of the subscapularis tendon has become more prevalent in recent years. Tears of the subscapularis insertion can be measured arthroscopically when the size of the average subscapularis tendon insertion is known. This anatomic study was performed to measure the dimensions and describe the anatomy of the subscapularis footprint. Methods: A total of 6 male and 6 female shoulders were dissected down to the insertion of the subscapularis tendon. The insertion was demarcated, the tendon was detached, and the dimensions of the insertion site were measured. Results: The footprint is the insertion of the subscapularis tendon onto the lesser tubercle. The shape of the footprint was characterized as resembling a human ear. The insertion is broad proximally and tapered distally and has a straight medial border that is almost parallel to the longitudinal axis of the humerus. The total average cephalocaudal height of the footprint was 25.8 mm (±3.2 mm). The total average width was 18.1 mm (±1.6 mm). Average male cephalocaudal height was 26.7 mm (range, 22 to 32 mm), and width was 18.3 mm (range, 16 to 21 mm). Average female cephalocaudal height was 24.8 mm (range, 22 to 29 mm), and width was 17.8 mm (range, 15 to 19 mm). Although the male footprint was slightly larger than the female footprint, differences were not statistically significant ( P = .18 and .31 for height and width, respectively). Conclusions: An anatomic study was performed to determine the size of the footprint of the subscapularis tendon. We found that the average cephalocaudal height of the footprint was 25.8 mm, and the average width was 18.1 mm. Clinical Relevance: Subscapularis tears are now more frequently addressed arthroscopically. This anatomic study was performed to characterize the anatomy of the subscapularis footprint so that the surgeon can achieve a more anatomic repair.

Abstract: The insertion of the tendon of subscapularis is accepted as being on the lesser tubercle of the humerus. The transverse humeral ligament (THL) is described as a distinct entity in most textbooks, overlying the long tendon of biceps as it emerges from the capsule of the shoulder joint. In this study, we dissected 85 embalmed shoulders to clarify the anatomy of the THL and variation in the insertion of the tendon of subscapularis. In all specimens no distinct THL could be identified, but in every shoulder a fibrous expansion arose from the posterior lamina of the tendon of pectoralis major overlying the long tendon of biceps. In 86% of shoulders, fibres from the tendon of subscapularis passed over the long tendon of biceps within this fibrous expansion and inserted on to the greater tubercle of the humerus where one would expect to find the THL. In 33% of dissections, fibres from the tendon of subscapularis lay deep to the long tendon of biceps, inserting either into the bicipital groove or on to the greater tubercle. In only 8% of cases did the tendon of subscapularis insert exclusively on to the lesser tubercle. We conclude that the THL does not exist as a separate entity. We suggest that in the majority of cases, the structure overlying the long tendon of biceps as it emerges from the capsule of the shoulder joint consists of tendinous fibres from subscapularis, contained within a fibrous expansion derived from the posterior lamina of the tendon of pectoralis major. In the minority of shoulders, where the tendon of subscapularis inserts exclusively on to the lesser tubercle, we hypothesise that this fibrous expansion acts as a retinaculum preventing the long tendon of biceps from "bowstringing."