An anomalous cleido-occipitalis muscle is an uncommon anatomical variant found in the posterior cervical triangle. To the best of our knowledge, the presence of an intra-muscular lipoma within this muscle has not been reported previously. We present a case report of this condition with Ultrasound (US) and Magnetic Resonance Imaging (MRI) correlation, which presented as posterior triangle neck mass mimicking cervical lymphadenopathy. We also present a succinct summary of published literature pertaining to anomalous neck muscles.