Fig. 3

Convergence theory of cardiac cephalalgia. Adapted from Foreman [58]. Adapted with permission from John Wiley and Sons. Figure legend: Sympathetic cardiac afferents converge in the spinothalamic tract (STT) neurons in the T1-T5 and C5-C6 segments with somatic fibers from the chest and upper arm respectively. Vagal afferents primarily terminate in the nucleus tractus solitarius and then project to the STT neurons located in C1-C2 segments. These segments also receive nociceptive information from the neck and could also receive nociceptive input from the trigeminal region through the trigeminocervical complex. However, C1-C2 segments do not receive significant stimuli from sympathetic afferents