The dorsal motor nucleus of vagus is primarily responsible for?

The dorsal motor nucleus of the vagus nerve is indeed primarily responsible for providing parasympathetic innervation to the gastrointestinal (GI) tract. This nucleus is located in the medulla oblongata and is an essential part of the autonomic nervous system. Specifically, it plays a crucial role in regulating functions such as digestion, including controlling the peristaltic movement of the intestines and the secretion of digestive enzymes.

The vagus nerve, which is the tenth cranial nerve, carries fibers from the dorsal motor nucleus to various organs, including the stomach and intestines. This innervation facilitates various involuntary functions, allowing for the proper digestion and absorption of nutrients. The ability of the vagus nerve to modulate gut activity is integral to maintaining homeostasis within the digestive system.

The other choices, while related to different cranial nerve functions, do not pertain to the primary responsibilities of the dorsal motor nucleus. Muscles of facial expression are primarily controlled by the facial nerve, salivation and tear production are functions of the facial and glossopharyngeal nerves, respectively, and the control of vocal cords is managed mainly by the recurrent laryngeal branch of the vagus nerve but does not originate from the dorsal motor nucleus.