Spinal Trigeminal Nucleus

Authors

Affiliations

Nathaniel Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Somatotopic maps of the spinal trigeminal nucleus (See Blumenfeld figure 12.9¹)

Overview

The spinal trigeminal nucleus is a sensory afferent nucleus of the CN V Trigeminal Nerve which lies in the lateral medulla and whose principal function is to relay pain and temperature sensations from the oral cavity and face².

Anatomy

The spinal trigeminal nucleus is found in the lateral medulla of the brain stem^1,2, but extends from the midpons to the cervical cord (C2-C4)³. The extension of the spinal trigeminal nucleus into the cervical cord can be considered the rostral extension of the dorsal horn¹.

• “Root fibers entering the spinal trigeminal tract and nucleus have a definite topographical organization caused by medial rotation of the sensory root as it enters the pons”³
• “Fibers of the ophthalmic division are most ventral, fibers of the mandibular division are most dorsal, and those of the maxillary division are intermediate and descend less far caudally than the other divisions”³

Note

“This topographic anatomy of the spinotrigeminal pathway may explain the onion peel representation of the face in the descending spinotrigeminal tract”³

Three parts

“The spinal trigeminal nucleus consists of three parts: (1) a pars oralis, (2) a pars interpolaris, and (3) a pars caudalis”³

It is subdivided into three segments representing topographical regions of the face in an inverted fashion; the forehead is represented ventrally (distally), and the oral region is represented dorsally (proximally). Lesions of the SN cause important clinical syndromes owing to the crucial utility in the daily life of the orofacial region²

Pars Oralis

The pars oralis receives impulses predominantly from internal structures of the nose and mouth.

Pars Interpolaris

The pars interpolaris is related mainly to cutaneous facial regions

Pars Caudalis

pars caudalis has large receptive field over the forehead, cheek, and jaw.

Function

“The spinal trigeminal tract and nucleus relays the sensory modalities of pain and temperature”³

Mechanism of Pain referral from the cervical spine to the head⁴: Nociceptive afferents of the trigeminal and upper three cervical spinal nerves converge onto second-order neurons in the trigeminocervical nucleus in the upper cervical spinal cord. This convergence mediates the referral of pain signals from the neck to regions of the head innervated by cervical nerves or the trigeminal nerve⁴.

References

1.

Blumenfeld H. Neuroanatomy Through Clinical Cases. 3rd ed. Oxford university press; 2022.

2.

Patel NM, Jozsa F, M Das J. Neuroanatomy, Spinal Trigeminal Nucleus. In: StatPearls. StatPearls Publishing; 2023. Accessed January 10, 2024. http://www.ncbi.nlm.nih.gov/books/NBK539729/

3.

Joo W, Yoshioka F, Funaki T, Mizokami K, Rhoton AL. Microsurgical anatomy of the trigeminal nerve. Clinical Anatomy. 2014;27(1):61-88. doi:10.1002/ca.22330

4.

Bogduk N, Govind J. Cervicogenic headache: An assessment of the evidence on clinical diagnosis, invasive tests, and treatment. The Lancet Neurology. 2009;8(10):959-968. doi:10.1016/S1474-4422(09)70209-1