Synovial Recesses
The shoulder joint contains numerous synovial recesses that permit communication between the glenohumeral joint and subscapularis bursa. [1] They are consistently found within the anterior capsule of the shoulder joint and exhibit considerable variation in size, location, number and frequency [Table 13]. [8-9,18,40] Such variation is “…dependent on both topographic variations of the glenohumeral ligaments and the distance between the insertion of the joint capsule on the neck of the scapula and the joint surface”. [40]
Table 13 – Anatomical variation in the synovial recesses found within the anterior capsule of the shoulder joint [9]
| Description | Description | % Prevalence |
| Type I | One recess above the middle glenohumeral ligament |
6.7% – Cadaveric study [18] 30.2% - Cadaveric study [8] Not specified – Cadaveric study [9] 38.5% - Cadaveric study [40] |
| Type II | One recess below the middle glenohumeral ligament |
2.7% – Cadaveric study [18] 2.04% – Cadaveric study [8] 0% - Cadaveric study [40] |
| Type III | One recess above and below the middle glenohumeral ligament |
89.3% – Cadaveric study [18] 46.6% – Cadaveric study [8] Not specified – Cadaveric study [9] 46.2% – Cadaveric study [40] |
| Type IV | One large recess with absent middle glenohumeral ligament |
1 case – Cadaveric study [18] 9.03% – Cadaveric study [8] 5.8% – Cadaveric study [40] |
| Type V | Two small synovial folds |
0% – Cadaveric study [18] 5.1% – Cadaveric study [8] 0% – Cadaveric study [40] |
| Type VI | No recesses present |
0% – Cadaveric study [18] 11.4% – Cadaveric study [8] 9.6% – Cadaveric study [40] |
In a cadaveric study, Matthews et al [9] reported the width of the middle glenohumeral ligament to be reduced in Type III recesses as compared to Type I recesses.
In addition to the recesses already mentioned, other recesses are commonly found throughout the shoulder joint:
- Posterior recess/ posterior capsular reflection - This recess is situated posterior to the glenoid and the reflection of the posterior capsule. [10] It gives the appearance of “…a deep fold of tissue posterior to the labrum”. [6]
- Inferior recess / axillary pouch - This is a large pouch allowing visualisation of the inferior capsular attachment to the humeral head. [6] In pathological states, the pouch may be closed. [6]
- Subscapularis recess - This variable-sized recess is situated medial to the subscapularis tendon. [6] It often contains loose bodies. [6]
- Superior sublabral recess - It is situated “…between the superior glenoid rim and the anterior half of the superior labrum but does not extend posterior to the long head of biceps.” [41]