Abstract
Background The suprascapular notch (SN) represents the point along the route of the suprascapular nerve (SSN) with the greatest potential risk for injury and compression. Thus, factors reducing the area of the notch have been postulated for suprascapular neuropathy development. Methods Thirty-one fresh-frozen shoulders were dissected. The contents of the SN were described according to four types as classified by Polguj et al and the middle-transverse diameter of the notch was measured. Also, the presence of an ossified superior transverse scapular ligament (STSL) was identified. Results The ligament was partially ossified in 8 specimens (25.8%), fully ossified in 6 (19.35%), and not ossified in the remaining 17 (54.85%). The mean middle-transverse diameter of the SN was 9.06 mm (standard deviation [SD] = 3.45). The corresponding for type-I notches was 8.64 mm (SD = 3.34), 8.86 mm (SD = 3.12) was for type-II, and 14.5 mm (SD = 1.02) was for type III. Middle-transverse diameter was shorter when an ossified ligament was present (mean = 5.10 mm, SD = 0.88 mm), comparing with a partially ossified ligament (mean =7.67 mm, SD = 2.24 mm) and a nonossified one (mean = 11.12 mm, SD = 2.92 mm). No statistically significant evidence was found that the middle-transverse diameter depends on the number of the elements, passing below the STSL. Conclusion Our results suggest that SSN compression could be more likely to occur when both suprascapular vessels pass through the notch. Compression of the nerve may also occur when an ossified transverse scapular ligament is present, resulting to significant reduction of the notch's area.
Highlights
The suprascapular nerve (SSN) is a mixed peripheral nerve that originates from the superior trunk of the brachial plexus and innervates the supraspinatus and infraspinatus muscles, its sensory components supply the acromioclavicular and glenohumeral joints, and there have been described lateral and medial subacromial branches coming from it.[1,2,3,4] It typically stems from the fifth and sixth cervical nerves, a contribution from the fourth cervical nerve has been identified
The ligament was partially ossified in 8 specimens (25.8%), fully ossified in 6 (19.35%), and not ossified in the remaining 17 (54.85%)
Our results suggest that SSN compression could be more likely to occur when both suprascapular vessels pass through the notch
Summary
The suprascapular nerve (SSN) is a mixed peripheral nerve that originates from the superior trunk of the brachial plexus and innervates the supraspinatus and infraspinatus muscles, its sensory components supply the acromioclavicular and glenohumeral joints, and there have been described lateral and medial subacromial branches coming from it.[1,2,3,4] It typically stems from the fifth and sixth cervical nerves, a contribution from the fourth cervical nerve has been identified. It enters the supraspinous fossa through the suprascapular notch (SN), running under the superior transverse scapular ligament (STSL), passes deep to the supraspinatus muscle and after passing through the spinoglenoid notch, it reaches the infraspinous fossa. STSL may be ossified, converting so the SN into an osseous foramen, causing stenosis of the notch and possible compression of the nerve. The presence of an ossified superior transverse scapular ligament (STSL) was identified
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