Medial vestibular nucleus

The medial vestibular nucleus, located medially in the brainstem near the sulcus limitans in the floor of the fourth ventricle (rhomboid fossa), is one of the four nuclei comprising the vestibular nuclear complex. This complex resides in the floor of the fourth ventricle at the junction of the pons and medulla oblongata.

The medial vestibular nucleus has a critical role in coordinating head and neck movements as well as stabilizing gaze during motion. Its efferent fibers run bidirectionally within the medial longitudinal fasiculus. Ascending fibers from the nucleus connect to the oculomotor (cranial nerve III), trochlear (cranial nerve IV), and abducens (cranial nerve VI) nuclei. These connections enable control over the extraocular muscles, facilitating the vestibulo-ocular reflex (VOR)—a mechanism that stabilizes gaze by generating reflexive eye movements during head and body motion.

Descending fibers from the medial vestibular nucleus travel through the medial longitudinal fasciculus and contribute to the medial vestibulospinal tract. This tract descends to the cervical spinal cord, primarily targeting motor neurons involved in controlling the muscles of the neck and upper torso.

By integrating inputs and outputs between the medial vestibular nucleus, extraocular motor nuclei, and the cervical spinal cord, this system ensures that head and neck movements are coordinated with eye movements. This integration is essential for maintaining stable gaze on objects of interest, supporting balance, and enabling precise spatial orientation.