LAUSR

Dear Editor, We have recently seen a patient with a complex neurologic presentation, who actually was quite easily understood based on advances in clinical anatomy. A 45-year-old man had wrist and finger extensor paralysis and electromyography (EMG) consistent with a radial nerve lesion distal to the triceps brachii branch due to an inflammatory neuropathy. He had evidence of atrophy and denervation of the inferolateral brachialis (a region previously shown to be supplied through a radial nerve branch) on clinical examination and MRI (Figure 1). Over the past decade, many groups have established in cadavers a relatively consistent anatomic pattern of dual innervation of the brachialis muscle from the musculocutaneous and radial nerves (Bendersky & Bianchi, 2012; Blackburn, Wood, Evans, & Watt, 2007; Frazer, Hobson, & McDonald, 2007; Ip & Chang, 1968; Mahakkanukrauh & Somsarp, 2002; Oh, Won, Lee, & Chung, 2009; Table 1). A recent publication described regions of autologous supply in dually innervated brachialis: with radial nerve branches to the inferior third of the deep (lateral) part of brachialis (Ilayperuma, Uluwitiya, Nanayakkara, & Palahepitiya, 2019). We have previously shown the clinical and MRI features of brachialis involvement in patients with isolated or combined injuries of these nerves (Puffer, Murthy, & Spinner, 2011; Spinner, Pichelmann, & Birch, 2003).