The lower cranial nerves: IX, X, XI, XII

Abstract

The lower cranial nerves innervate the pharynx and larynx by the glossopharyngeal (CN IX) and vagus (CN X) (mixed) nerves, and provide motor innervation of the muscles of the neck by the accessory nerve (CN XI) and the tongue by the hypoglossal nerve (CN XII). The symptomatology provoked by an anomaly is often discrete and rarely in the forefront. As with all cranial nerves, the context and clinical examinations, in case of suspicion of impairment of the lower cranial nerves, are determinant in guiding the imaging. In fact, the impairment may be located in the brain stem, in the peribulbar cisterns, in the foramens or even in the deep spaces of the face. The clinical localization of the probable seat of the lesion helps in choosing the adapted protocol in MRI and eventually completes it with a CT-scan. In the bulb, the intra-axial pathology is dominated by brain ischemia (in particular, with Wallenberg syndrome) and multiple sclerosis. Cisternal pathology is tumoral with two tumors, schwannoma and meningioma. The occurrence is much lower than in the cochleovestibular nerves as well as the leptomeningeal nerves (infectious, inflammatory or tumoral). Finally, foramen pathology is tumoral with, outside of the usual schwannomas and meningiomas, paragangliomas. For radiologists, fairly hesitant to explore these lower cranial pairs, it is necessary to be familiar with (or relearn) the anatomy, master the exploratory technique and be aware of the diagnostic possibilities.

BCL11A frameshift mutation associated with dyspraxia and hypotonia affecting the fine, gross, oral, and speech motor systems

“…BCL11A is a known interactor of COUP‐TF1 and COUP‐TF1 knockout in mice results in malformations of the glossopharyngeal ganglion (Avram et al, 2000, 2002; Qiu et al, 1997). In humans the glossopharyngeal nerve and ganglion are responsible for motor (stylopharyngeal) and sensory innervation of the upper pharynx, and parasympathetic innervation of the parotid gland (Sarrazin, Toulgoat, & Benoudiba, 2013). Hence, the hypothesis of BCL11A mediating a dysfunction of the glossopharyngeal nerve could, at least partially, explain the oro‐praxic and phonological deficits and excessive drooling present in the described patients.…”

Swallowing‐related outcomes associated with late lower cranial neuropathy in long‐term oropharyngeal cancer survivors: cross‐sectional survey analysis

“…Patients with oropharyngeal cancer (OPC) receive local treatments, radiotherapy (RT), and/or surgery, to this functionally critical region that can cause chronic dysphagia with adverse impact on swallowing-related quality of life (QOL). [1][2][3][4][5][6] Dysphagia is one of the most impactful and prevalent functional toxicities reported in approximately 30%-50% of survivors. [7][8][9][10] Prior analysis of this OPC survivorship found that, among 22 symptoms queried, the severity of dysphagia symptoms most strongly associated with decisional regret about cancer treatment.…”

El verdadero origen aparente de los nervios glosofaríngeo, vago y accesorio

“…Otros autores estiman que emerge entre la oliva inferior y el pedúnculo cerebeloso inferior (13,14); incluso se cita que emerge del surco lateral de la médula, caudal al nervio facial (15). También se señala que tiene su origen en la parte superior del surco colateral posterior (16,17), o que se ubica en el surco retro-olivar (5,6,18,19) o surco post-olivar (20). Asimismo, se afirma, sin dar mayores detalles, que emerge detrás de la oliva (21).…”

“…Nervio vago: está conformado por 10 a 15 raíces procedentes de la medula oblonga, por detrás de la oliva (21,22) o lateral a ella (14,23,24) e incluso en el tercio superior de su cara lateral (10,11). Chatain & Bustamante (12) le dan una ubicación más específica a este nervio al señalar que emerge con 16 filetes radiculares del surco dorsolateral de la médula oblongada, por debajo del nervio glosofaríngeo, mientras que otros autores describen que las fibras del vago emergen del surco retro-olivar (5,6,18,19) o fisura post-olivar (7,9). También se señala que la emergencia de este ocurre por el surco colateral del bulbo (16,17), entre los nervios glosofaríngeo y accesorio (16); Pansky (15) lo ubica en el surco lateral de la médula y Escobar & Pimienta (25) indican que se origina de la médula oblongada, sin especificar el sitio exacto.…”

“…Nervio accesorio: hace su aparición mediante 4 a 6 raíces (22) por detrás de la oliva (2,4,5,8,9,21,22), pero no se especifica el lugar preciso de su aparición. También se describe sin mayores detalles que sus raíces craneales emergen por la parte lateral de las olivas (14,23,26), en sus dos tercios inferiores (10); Sarrazin et al (18) lo ubican en el surco retro-olivar (18). Algunos autores hacen una descripción un poco más detallada, pues señalan que se hace visible por el surco posterolateral (2,3) o dorsolateral de la médula oblongada, con 4 a 5 filetes radiculares que emergen a continuación de las raíces del vago (12); para Spalteholz (27), emerge con 3 a 6 filetes nerviosos por un surco que recorre el bulbo por detrás de la oliva bulbar, inmediatamente por debajo del nervio vago.…”