Kielihermo

Kielihermo is a Finnish term that can refer to nerves associated with the tongue. In many Finnish anatomies and clinical texts, kielihermo most often denotes the lingual nerve (n. lingualis), a branch of the mandibular division of the trigeminal nerve (V3). The lingual nerve provides somatic sensory innervation to the anterior two-thirds of the tongue and the floor of the mouth, and it carries taste information from the same region via the chorda tympani, a branch of the facial nerve (VII), which joins the lingual nerve in the region of the tongue.

In other contexts, kielihermo can refer to the hypoglossal nerve (n. hypoglossus), the twelfth cranial nerve, which controls the movements of the tongue. The hypoglossal nerve supplies the intrinsic and most of the extrinsic tongue muscles, enabling articulation and swallowing. Damage to this nerve can result in weakness, atrophy, or tongue deviation toward the affected side upon protrusion.

Anatomically, the lingual nerve arises from V3 and travels anteriorly toward the tongue, often receiving the chorda tympani signal for taste as it nears the tongue. The hypoglossal nerve exits the skull through the hypoglossal canal and courses to the tongue muscles. Clinically, injuries to these nerves can occur during dental or head-and-neck procedures, trauma, or tumor growth, leading to sensory disturbances, altered taste, or impaired tongue movement.

See also: cranial nerves, glossopharyngeal nerve, chorda tympani.