Nociceptive trigeminal afferents innervating craniofacial area, e.g., facial skin and cranial meninges, project to a broad region in the medullary and upper cervical dorsal horn designated as the trigeminocervical complex. Lamina I neurons in the trigeminocervical complex integrate and relay peripheral inputs, thus playing a key role in both cranial nociception and primary headache syndromes. (Luz et al, 2019)
Neurons in the trigeminocervical complex are the major relay neurons for nociceptive afferent input from the meninges and cervical structures; therefore, they are the neural substrates of head pain. (Bartsch & Goadsby)
The upper cervical nerves provide innervation to the posterior scalp, while the periauricular region and posterior fossa are territories with shared innervation. Afferent fibers that innervate the head and neck send nociceptive input to the trigeminocervical complex, which then projects to additional pain processing areas in the brainstem, thalamus, hypothalamus, and cortex. (Robertson & Benarroch, 2023)
The Trigeminocervical complex integrates external auditory, somatosensory, and central impulses. (Boedts, 2020)
Luz LL, Fernandes EC, Dora F, Lukoyanov NV, Szucs P, Safronov BV. Trigeminal Aδ- and C-afferent supply of lamina I neurons in the trigeminocervical complex. Pain. 2019 Nov;160(11):2612-2623. doi: 10.1097/j.pain.0000000000001659. PMID: 31356449.
Bartsch T, Goadsby PJ. The trigeminocervical complex and migraine: current concepts and synthesis. Curr Pain Headache Rep. 2003 Oct;7(5):371-6. doi: 10.1007/s11916-003-0036-y. PMID: 12946290.
Robertson CE, Benarroch EE. The anatomy of head pain. Handb Clin Neurol. 2023;198:41-60. doi: 10.1016/B978-0-12-823356-6.00001-9. PMID: 38043970.
Boedts MJO. Tympanic Resonance Hypothesis. Front Neurol. 2020 Jan 30;11:14. doi: 10.3389/fneur.2020.00014. PMID: 32117001; PMCID: PMC7008469.