Can you name the key structures/layers in this transverse longitudinal image of the radial wrist?

Below are the major structures of interest labeled in this transverse wrist ultrasound image. 

What is your diagnosis?

This is de Quervain’s tenosynovitis.

Image 4: Case courtesy of Mohammad A. ElBeialy, Radiopaedia.org, rID: 54740, author’s own annotations

What are the major structures in this transverse radial wrist ultrasound and where is the pathology?

De Quervain’s tenosynovitis involves inflammation of the first dorsal compartment of the wrist. The first dorsal compartment houses the abductor pollicis longus and extensor pollicis brevis tendons. In the image, you can see a ring of hypoechoic fluid around the tendons, signifying inflammation. Note the sRN is difficult to identify in this still image and thus not labeled. 

• Pearl: Test for de Quervain’s tenosynovitis using Finkelstein’s test