Anatomical relationships of the suprascapular and spinoglenoid notches and the scapular bony landmarks in adult Kenyans: a dry bone study

Abstract

Background: The suprascapular nerve, derived from the upper trunk of the brachial plexus passes through the suprascapular notch into the supraspinous fossa where it supplies the supraspinatus and then through the spinoglenoid notch to gain entry into the infraspinous fossa where it innervates the infraspinatus muscle. The nerve may be compressed at either of these two notches or injured in operations around the shoulder. Knowledge of the location of the nerve in these notches in relation to fixed bony landmarks around the shoulder is important in avoiding iatrogenic injury to the nerve or to locate it for release when it is compressed or for anaesthetic blockade.

Objective: To determine the distances between the suprascapular and spinoglenoid notches and fixed bony landmarks in the shoulder i.e the acromion, the supraglenoid tubercle, the posterior edge of the glenoid rim and the tip of the coracoid process.

Methods: The distances were measured using digital vernier callipers on dried unpaired adult scapulae that were grossly not deformed. The mean, minimum, maximum and standard deviation of the measurements was obtained.

Results: Average distance to the suprascapular notch from the supraglenoid tubercle, anterolateral edge of the acromion and the tip of the coracoid process were 31.2mm, 65.6mm and 45.7mm respectively. Average distance to the spinoglenoid from the posterior glenoid rim was 16.3mm.

Conclusion: Comparison with other populations shows variability in these distances. In order not to imperil the suprascapular nerve in the suprascapular incisure, a safe distance of less than 25.5mm from the supraglenoid tubercle should be observed. In the spinoglenoid notch, a safe distance of less than 13.1mm from the edge of the posterior glenoid rim should be maintained.

Keywords: Suprascapular nerve, Suprascapular notch, Spinoglenoid notch, Acromion, Coracoid process