Illustration of an idealized cervical spine showing the variable course of cervical medial branches relative to bony landmarks, demonstrating the variability noted in consecutive cadaver dissections. A, Lateral view. Each line represents the nerve course of one cadaver specimen. The variable courses of the third occipital nerve (TON) (i.e., the C3 superficial medial branch) and the C3-C7 medial branches are shown. Note how the variable courses of the TON ( blue ) and the C3 deep medial branches ( black ) overlap with each other. Also note that the C5 medial branches course along the middle aspect of the C5 articular pillar, but the other medial branches are located progressively higher on their respective articular pillar as the level progresses further away from the C5 level. Note that the C8 medial branch is illustrated in a lateral view, but not relevant for C8 MB block, which is performed from an adjusted AP view. B, Anteroposterior view. Each dot represents the cross section of one cadaver specimen’s nerve course. The variations in location of the TON are shown as larger open circles, whereas the lower cervical medial branches are shown as smaller solid dots.