Tracking the glossopharyngeal nerve pathway through anatomical references in cross-sectional imaging techniques: a pictorial review

Abstract

The glossopharyngeal nerve (GPN) is a rarely considered cranial nerve in imaging interpretation, mainly because clinical signs may remain unnoticed, but also due to its complex anatomy and inconspicuousness in conventional cross-sectional imaging. In this pictorial review, we aim to conduct a comprehensive review of the GPN anatomy from its origin in the central nervous system to peripheral target organs. Because the nerve cannot be visualised with conventional imaging examinations for most of its course, we will focus on the most relevant anatomical references along the entire GPN pathway, which will be divided into the brain stem, cisternal, cranial base (to which we will add the parasympathetic pathway leaving the main trunk of the GPN at the cranial base) and cervical segments. For that purpose, we will take advantage of cadaveric slices and dissections, our own developed drawings and schemes, and computed tomography (CT) and magnetic resonance imaging (MRI) cross-sectional images from our hospital’s radiological information system and picture and archiving communication system.Teaching Points• The glossopharyngeal nerve is one of the most hidden cranial nerves.• It conveys sensory, visceral, taste, parasympathetic and motor information.• Radiologists’ knowledge must go beyond the limitations of conventional imaging techniques.• The nerve’s pathway involves the brain stem, cisternal, skull base and cervical segments.• Systematising anatomical references will help with nerve pathway tracking.

Characterization of sensory neuronal subtypes innervating mouse tongue

“…Therefore, knowledge of lingual nociceptive mechanisms is critical to be able to treat these patients safely and effectively. The majority of lingual sensory innervation is conveyed via TG afferents in the lingual nerve terminating in the anterior two-thirds of the tissue, whereas the posterior one-third is innervated by the glossopharyngeal nerve [ 17 – 19 ]. The lingual nerve arises from the mandibular division of the trigeminal nerve and its cell bodies lie in the V3 branch of the trigeminal ganglion (TG).…”

18F-FDG-PET/CT in radiation therapy-induced parotid gland inflammation

“…The glossopharyngeal nerve provides parasympathetic innervation to the parotid gland, as well as sensory innervation to the posterior one-third of the tongue and pharynx. Photon RT and/or chemotherapy-induced damage of the parotid gland can impact glossopharyngeal nerve function and indirectly lead to deleterious effects on adjacent structures in the head and neck region (García Santos et al, 2018 ). Thus, determining the FDG uptake in the parotid gland is of clinical importance in investigating potential previously underappreciated side effects of radiotherapy in HNC cancer patients.…”

Cranial nerve schwannoma – A pictorial essay

“…The nerve traverses the cerebello medullary cistern in close association with flocculus of the cerebellum and anterior and superior to the vagus nerve. [ 19 ] The nerve exits the cranium via the pars nervosa which is anterior aspect of the jugular foramen, enters the carotid space, lies between the internal carotid artery and internal jugular vein and then it descends in front of the internal carotid artery. [ 19 ] Glossopharyngeal nerve schwannoma [ Figure 12 ] can involve the cerebello-medullary cistern, jugular foramen or suprahyoid carotid space.…”