Patient cannnot extend wrist, which is innervated by radial nerve

Patient has been on crutches, which would affect axillary nerve --> this affects deltoid muscle, which does arm abduction 15-100º (so it can normally move arm above shoulder)

The only location in the given diagram to effect all of these nerves would be location "C"

Note: normally, arm movement above the horizontal is associated with serratus anterior muscle/long thoracic nerve. However, none of the diagram locations allow for inclusion of SALT. Since the patient has been on crutches for weeks, it suggests axillary nerve involvement --> deltoid is affected

https://www.youtube.com/watch?v=Zlozkdj6wjU

Posterior cord Lesions are called: Radial Plus Palsy.

Cuz Posterior cord has BOTH Radial Nerve & Axillary nerve & cuz they are the 2 terminal branches that come off the posterior cord, so Sx include: triceps & wrist weakness, limitations finger extension indicate injury to radial nerve is located above innervation of triceps Injury of radial nerve occurs in axilla / above weakness of wrist, finger extension Axillary N. injury : weakness of abduction (paralysis of deltoid muscle), sensory shoulder loss. Axillary nerve also innervate teres minor muscle.

Hope this helps

Can someone please explain why the answer to this is injury to the posterior cord rather than the radial nerve?