To present an overview of the anatomy, imaging techniques and a range of pathologies that can affect the hypoglossal canal.

Normal Anatomy The hypoglossal canal is the bony canal in which the hypoglossal nerve (Cranial Nerve XII) exits the posterior cranial fossa. CN XII provides somatic motor innervation to the intrisic and extrinsic muscles of the tongue and has 4 anatomical segments: intra-axial cisternal skull base (hypoglossal canal) extracranial. Pathology Various pathological processes can affect the nerve along its course. This can result in unilateral tongue atrophy and tongue deviation (hypoglossal nerve palsy) in the patient. Imaging In the hypoglossal canal, CT provides bony detail...

Normal Anatomy The origins of the hypoglossal nerve are from the hypoglossal nuclei, which extends through the medulla oblongata in a paramedian location (intra-axial segment).1The roots of the hypoglossal nerve lie posterolateral to the verteberal artery within the premedullary cistern (cisternal segment). The roots then merge together to form the hypoglossal nerve, exiting the hypoglossal canal of the occipital bone (skull base segment). Just medial to the lower border of the jugular foramen is an elevation, is the jugular tubercle. Arising from the concave inferolateral...

This educational exhibit has provided an overview of the imaging of the hypoglossal canal.The nerve is best visualised on the post Gadolinium T2 as compared to the cisternographic sequences. The pattern of change of the margins of the hypoglossal canal given an indication of the rate of growth of the lesion. Slow growing lesions such as a Schwannoma produce smooth expansion. More aggressive lesions such as metastases or infection may produce aggressive osteolysis or marrow infiltration. Denervation patterns in the tongue muscles are a clue...

M. Thu, Princess Alexandra Hospital, Brisbane, Australia N. Waters, Royal Brisbane and Women's Hospital, Brisbane, Australia M. Gandhi, Department of Radiology, Princess Alexandra Hospital & Queensland X-Ray, Brisbane, Australia J. Sommerville, Department of Radiology, Princess Alexandra Hospital, Brisbane, Australia.

1. Thompson EO, Smoker WR. Hypoglossal nerve palsy: a segmental approach. Radiographics. 1994;14(5):939-58. 2.Osborn AG, Brinton WR, Smith WH. Radiology of the jugular tubercles. AJR Am J Roentgenol. 1978;131(6):1037-40. 3.Yousry I, Moriggl B, Schmid UD, Wiesman M, Fesl G, Bruckmann H, et al. Detailed anatomy of the intracranial segment of the hypoglossal nerve: neurovascular relationships and landmarks on magnetic resonance imaging sequences. J Neurosurg. 2002;96(6):1113-22. 4.Russo CP, Smoker WR, Weissman JL. MR appearance of trigeminal and hypoglossal motor denervation. AJNR Am J Neuroradiol. 1997;18(7):1375-83.