Nucleus of hypoglossal nerve

The nucleus of hypoglossal nerve consists of neuronal cell bodies situated near the midline beneath the fourth ventricle floor's lower part. It functions as a general somatic efferent nucleus, crucial for innervating tongue muscles, thus controlling its movement and shape.

Afferent Connections:

The nucleus of hypoglossal nerve receives input from corticonuclear fibers originating from both cerebral hemispheres. Notably, cells that supply the genioglossus muscle receive corticonuclear fibers only from the contralateral hemisphere.

Efferent Connections:

Efferent neurons from the nucleus of hypoglossal nerve exit the medulla oblongata's ventral surface, between the pyramid and olive. These neurons travel through the hypoglossal nerve, passing the hypoglossal canal to reach the tongue and innervate intrinsic and extrinsic muscles, except for the palatoglossus muscle, which is innervated by the vagus nerve.

Clinical Relevance:

A stroke affecting the medial medulla oblongata can cause a lower motor neuron lesion of the hypoglossal nucleus. This leads to atrophy or fasciculations of the tongue muscles on the lesion side. When protruding the tongue, it deviates toward the lesion side, illustrating the principle that the "tongue points to the lesion."