Periarticular neural elements in the shoulder joint

Due to its unconstrained nature, the glenohumeral joint must necessarily ha ve several mechanisms to regulate its position in space. The neural mechani sms associated with this positioning have not been fully evaluated anatomic ally. In this study, three fresh-frozen human cadaveric adult shoulders wer e dissected. Specimens were excised from the proximal biceps insertion, the superior, middle, and inferior glenohumeral ligaments, and the capsule sup erior to the glenohumeral ligaments. In two specimens, a portion of glenoid labrum was analyzed using a modified gold chloride staining method and lig ht microscopy. A portion of mid-biceps tendon was used as a control. In the superior glenohumeral ligament, 45% of sections contained neural ele ments consisting of Golgi's, Ruffini's, and Pacini's corpuscles as well as free nerve endings. The predominant types were Ruffini's and Golgi's. The m iddle glenohumeral ligament sections revealed all four receptor types in 42 %, with the most common elements being Pacini's and Ruffini's receptors. Th e inferior glenohumeral ligament specimens contained the four receptor type s in 48% of sections, with Ruffini's, Pacini's, and Golgi's types equally d istributed. The shoulder capsule specimens revealed Ruffini's and Pacini's receptors in 47.5% of sections. Only free nerve endings were identified in the biceps tendon and glenoid labral tissue. These findings suggest that th e pattern of neural elements does not appear to be random in nature and may have some correlation with the specific functions of some of the glenohume ral ligaments.