Neurology | Descending Tracts: Corticobulbar Tract

Video Description

Official Ninja Nerd Website: https://ninjanerd.org Ninja Nerds! In this lecture, Professor Zach Murphy provides a detailed exploration of the corticobulbar tract, one of the key descending motor pathways responsible for controlling the voluntary movements of the muscles of the face, head, and neck. We begin by tracing the origin of this tract in the primary motor cortex, specifically in the lateral portion of the precentral gyrus, where upper motor neurons for cranial nerve motor nuclei reside. These axons descend through the corona radiata and genu of the internal capsule before entering the brainstem. The lecture then explains how corticobulbar fibers synapse bilaterally (with a few exceptions) on the motor nuclei of cranial nerves in the midbrain, pons, and medulla. This includes connections to cranial nerves III, IV, V, VI, VII, IX, X, XI, and XII, collectively coordinating functions such as eye movements, mastication, facial expression, swallowing, phonation, and tongue movements. Importantly, specific nuclei, such as the lower face portion of the facial nerve nucleus and the hypoglossal nucleus, receive contralateral input only, which is clinically significant in differentiating upper versus lower motor neuron lesions. We conclude by discussing the functional importance of the corticobulbar tract in integrating voluntary control with reflexive and automatic motor patterns mediated by the brainstem. This sets the stage for understanding clinical presentations such as dysarthria, facial weakness, and tongue deviation, and how these can be used to localize lesions along the pathway. Enjoy the lecture and support us below! 🌐 Official Links Website: https://www.ninjanerd.org Podcast: https://podcast.ninjanerd.org Store: https://merch.ninjanerd.org 📱 Social Media https://www.tiktok.com/@ninjanerdlectures https://www.instagram.com/ninjanerdlectures https://www.facebook.com/ninjanerdlectures https://x.com/ninjanerdsci/ https://www.linkedin.com/company/ninja-nerd/ 💬 Join Our Community Discord: https://discord.gg/3srTG4dngW #ninjanerd #CorticobulbarTract #DescendingTracts