Abstract:
This study aimed to investigate the anatomical relations of suprascapular nerve
that may cause nerve entrapment in Thais. It was done by carefully dissecting the bilateral
limbs of cadaveric specimens to explore and scrutinize the relationship of the thorough
course of the suprascapular nerve and its related structures. The dimension of superior
transverse scapular, anterior coracoscapular and spinoglenoid ligaments was measured.
A photograph of the suprascapular notch was taken and the area of suprascapular foramen
was estimated. The anterior coracoscapular ligament was randomly taken out and
processed under a standard histological technique for further microscopic study. One
hundred and thirty-four limbs from 67 cadaveric specimens (34 male and 33 female, with
an average age of 68.06 years) and 238 bony scapulae specimens were used in this study.
On the bony structure aspect, the morphology of the suprascapular notch and the area of
the suprascapular foramen were varied in size and shape. The results showed that a small
V-shaped notch was the most risky type, corresponding to the triangular area of the
suprascapular foramen, which yielded the least area and was most likely to cause nerve
entrapment neuropathy. For related ligaments, the superior transverse scapular ligament
which stretched out between the banks of the suprascapular notch was a single band and
occasionally ossified, so could affect the nerve entrapment. Considering the relationship
between the structures, the accompanying suprascapular artery traversed underneath the
superior transverse scapular ligament together with the nerve could cause nerve
entrapment, particularly if it coincided with the small V-shaped notch. Additionally, the
existence of the anterior coracoscapular ligament located below the superior transverse
scapular ligament and narrowed suprascapular foramen was another cause of nerve
compression. Furthermore, the spinoglenoid ligament partly attached to the capsule of the
shoulder joint could be an irritative cause of suprascapular nerve entrapment during joint
motion.
In conclusion, the results suggested that there were several factors likely to cause
suprascapular nerve compression, due to its long course. The anatomic variation of the
related structures along the nerve course can be predisposing causes of suprascapular
nerve entrapment. This thesis therefore provides fundamental knowledge for further
clinical diagnosis and treatment for suprascapular nerve entrapment syndrome.