case_images: PMC9918333_01
case_images: Body surface photographs of the neck. . A mass is visible in the left supraclavicular fossa (white arrow).
case_images: cureus-0015-00000033646-i01.jpg
case_images: PMC9918333_01_cureus-0015-00000033646-i01.jpg
case_images: FIG1
case_images: On a repeated physical evaluation, a soft mass was revealed in the left supraclavicular fossa (Figure 1).
case_images: Plain computer tomography and magnetic resonance image.. Plain computer tomography (A) and magnetic resonance image (B) of the neck show the anomalous muscle on the left brachial plexus (white arrow). It is not present on the right side.
case_images: cureus-0015-00000033646-i02.jpg
case_images: PMC9918333_01_cureus-0015-00000033646-i02.jpg
case_images: FIG2
case_images: MRI of the left brachial plexus showed the same pattern (Figure 2).
case_images: Magnetic resonance images of the neck. T1-weighted magnetic resonance images of the neck (A, B, C, D, E, F, G, H) show the anomalous muscle. It originates from the nuchal ligament and stops in the middle one-third of the clavicular head side (white arrow).
case_images: cureus-0015-00000033646-i03.jpg
case_images: PMC9918333_01_cureus-0015-00000033646-i03.jpg
case_images: FIG3
case_images: It originated from the nuchal ligament and stopped in the middle one-third of the upper clavicular side (Figure 3).
case_images: Radiographs after ultrasound-guided neurography of the brachial plexus.. The contrast has moved caudally from the injection site, but the head side and head down positions show a blocked image (A). Upon left upper extremity elevation, which reduced symptoms, contrast migration to the head side is observed (B).
case_images: cureus-0015-00000033646-i04.jpg
case_images: PMC9918333_01_cureus-0015-00000033646-i04.jpg
case_images: FIG4
case_images: When left upper extremity elevation was performed, symptoms were reduced and contrast migration to the head side was observed (Figure 4).