Sorry for the belated blogging, Monday Jess Neil presented a case that turned out to be radial nerve aka Saturday night palsy, but with features concerning for a possible central lesion and the patient was evaluated for a stroke.
Radial Nerve Injury
The radial nerve originates in the axilla as one of the terminal branch of the posterior cord of the brachial plexus, it runs between the medial and lateral head of the triceps (do you even lift bro?) and then enters the anterior compartment of the forearm, running deep to the brachioradialis muscle. Its motor action is extension of the wrist and digits, more proximally it innervates the triceps and thus causes extension at the elbow. The sensory innervation is carried by the superficial branch of the radial nerve, where the posterior interrosseus nerve is responsible for motor. Thus a pure motor palsy (wrist drop, inability to extend the digits) from a distal radial nerve injury is likely to be the PIN branch only, though occasionally more proximal injuries can have little or no sensory deficit.