Test your knowledge: morphology of the scapula

Question:

Do you recognize the red delineated structure in the picture below? What is the most important pathology related to this structure?

(Image by: en.wikipedia.org)

Answer:

This is the suprascapular notch and it is related to an entrapment syndrome called: suprascapular notch syndrome. 

Originated from segments C5-C6 (superior trunk) a nerve is formed, called the suprascapular nerve. It passes inferiorly under the trapezius muscle towards the superior edge of the scapula, where it passes the suprascapular notch. After this the nerve turn obliquely and laterally towards the supraspinatus muscle and then split into an inferior trunk to the infraspinatus muscle. Both very important cuff muscles.

As cause of an entrapment of the nerve (paralabral ganglion cyst, bony ossification of the transverse ligament) a weakness and atrophy in the supraspinatus and infraspinatus could be observed. So radiographic evaluation is a diagnostic option (Xray but also ultrasonographic evaluation) for preventing a complete paralysis of these muscles.

Other causes of entrapment of this nerve are:

- Major or repetitive trauma (afractured scapula, rotator tear) causes an entrapment of the suprascapular nerve.

- Parsonage Turner Syndrome. An uncommong condition of neuralgic amyotrophy (may be due to an infection/virusses).