Abstract—The deep branch of the radial (posterior interosseous) nerve courses through the radial tunnel between the superficial and the deep layers of the supinator muscle, where it is liable to undergo compression at various sites, giving rise to the radial tunnel syndrome or the posterior interosseous syndrome. For the present study 30 embalmed human cadaveric upper limbs were dissected and the following potential entrapment points were studied: the morphology of the upper (arcade of Frohse) and the lower borders of the supinator muscle, the presence of vascular arcade ( leash of Henry) by radial recurrent artery. The measurements were taken from the proximal border of head of the radius, to the radial nerve bifurcation and the points of entry and exit of the Posterior Interosseous Nerve (PIN) between the two layers of the supinator muscle. Both anterior and posterior approaches were used to expose the course of the PIN. All the measurements were taken from the proximal border of the radial head, which is easily palpable externally. The upper border of the superficial layer of the supinator muscle was found to be tendinous in 70% of the specimens. The radial nerve divided above the humero-radial joint in 83.4%. The vascular plexus was present in 53.3%. The posterior approach made it easier to expose the PIN. These findings will serve as a guide to the surgeons to take minimal possible incision during the surgery.