Original article
The subscapular and subcoracoid bursae: descriptive and functional anatomy

https://doi.org/10.1016/j.jse.2004.02.001Get rights and content

Abstract

The subscapularis and subcoracoid bursae, as well as the subscapularis muscle, were studied in 42 fresh cadaveric shoulders. Fibrous bands were found in the medial part of the muscle; they were intercalated with the distal tendon-like bands. The superior distal fibrous band was always found to be thicker than the others. Strong fibrous attachments of the subscapularis muscle were found along the lateral border of the scapula as well as along the medial third of the bony crests in the subscapular fossa. Between the crests, the muscle bundles were directly attached to the bone. In the lateral part of the scapula, the subscapularis muscle had only weak connective links with the bone. The subscapularis bursa was found in all cases as a pouch strongly attached to the scapular neck and the adjacent part of the joint capsule. The top of the bursa was linked to the coracoid process by a fibrous attachment called the suspensory ligament. The subcoracoid bursa had only weak connective links with the coracoid process. In 28% of cases, the subscapularis and subcoracoid bursae merged into a unique wide bursa. The subscapular bursa had two types of links with the muscle: (1) weak connective links with the superficial muscle bundles and (2) at least 2 fibrous arcs joining the lateral tendon-like bands, the bursa, and bony crests of the subscapularis fossa. These arcs allow the bursa to follow the course of the muscle exactly. During movements of the glenohumeral joint, the subscapularis muscle sustains huge changes of orientation, particularly the upper part of the muscle that coils around the coracoid process. The strong superior fibrous band enables the muscle to maintain contact with the coracoid process. It is the function of the subscapularis and subcoracoid bursae to manage the friction of the superficial fibers against the scapular neck, the humeral head, and the coracoid process.

Section snippets

Material and methods

Forty-two shoulders were studied in twenty-one fresh cadavers (age range, 46–98 years, mean age, 80 years). The absence of scar and a normal range of motion were confirmed. The upper limb was harvested by detaching the scapula from the chest. The deltoid and the conjoined tendon were detached from the scapula; at this time, shoulders with full-thickness rotator cuff tears were rejected. The excursion of the subscapularis muscle was studied during passive mobilization of the glenohumeral joint

Results

With the arm at rest, the subscapularis was slightly curved around the humeral head, and the muscle bundles were parallel each together. During external rotation, the muscle bundles moved horizontally, the mean extent of the humeral attachment was 4.3 cm (extremes of 3 to 5.2 cm), and the muscle turned around the convexity of the humeral head. In abduction and external rotation, the direction of the muscle bundles changed dramatically. The humeral insertion passed from vertical and anterior to

Discussion

The distal tendon-like bands described by Klapper et al,6 in association with the intercalated proximal bands evidenced in the present results, create the same fibrous organization as in the middle deltoid as published by Gagey and Hue.5 This organization is known to increase the strength of the muscle instead of the range of excursion.

The fibrous arcs and the suspensory ligament have not been described previously; their functional importance will be discussed further.

The limited size of this

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