Innervation and Clinical Significance of the Styloglossus Muscle

Anatomy and Function

The extracranial hypoglossal nerve travels caudally within the carotid space and courses anteriorly inferior to the hyoid, as described by the American College of Radiology 1, 2
The hypoglossal nerve innervates all intrinsic tongue muscles and three extrinsic tongue muscles, with the exception of the palatoglossus muscle, according to the American College of Radiology 1, 3

Hypoglossal nerve palsy affects all muscles it innervates, including the styloglossus, resulting in dysarthria and deviation of the tongue to the side of the lesion upon protrusion, as reported by the American College of Radiology 1
MRI is the preferred imaging modality for evaluating hypoglossal nerve pathology, with CT providing complementary information on bony structures, as recommended by the American College of Radiology 2, 3

The hypoglossal nerve, which is the primary motor nerve of the tongue, provides somatic motor innervation to the intrinsic and extrinsic muscles of the tongue, and its nucleus arises in the dorsal medulla, according to the American College of Radiology 4
The hypoglossal nerve travels caudally within the carotid space and then courses anteriorly inferior to the hyoid, providing innervation to the infrahyoid strap muscles via the ansa cervicalis, as stated by the American College of Radiology 4, 5

Hypoglossal nerve palsy presents with dysarthria and deviation of the tongue to the side of the lesion upon protrusion, with common causes including neoplasms, brainstem infarct, demyelinating disease, vascular lesions, and infectious processes, according to the American College of Radiology 4, 5