Why is it called nucleus ambiguus?

The nucleus ambiguus is the common nucleus of the efferent fibers for glossopharyngeal (CN IX) and vagus (CN X) nerves. The name ‘ambiguus’ originates from its difficult-to-find location and variation in different species. Its location is in the reticular formation in the medulla oblongata.

What is solitary nucleus?

The nucleus of the solitary tract (solitary nucleus, nucleus tractus solitarii [NTS]), located in the dorsomedial medulla, is the first relay station for general visceral and taste afferents carried by the cranial nerves and has a critical role in the initiation and integration of a wide variety of reflexes controlling …

Is nucleus ambiguus parasympathetic?

As well as motor neurons, the nucleus ambiguus contains preganglionic parasympathetic neurons which innervate postganglionic parasympathetic neurons in the heart. It receives upper motor neuron innervation directly via the corticobulbar tract.

Where is hypoglossal nucleus?

The hypoglossal nucleus lies caudal in the floor of the fourth ventricle, part of the calamus scriptorius. Its fibers traverse the medulla from back to front, thus circling around and in front of the inferior olivary nucleus and emerging from the medulla in the preolivary sulcus, between the pyramid and inferior olive.

What is the Stylopharyngeus?

The stylopharyngeus muscle is a long, slender and tapered longitudinal pharyngeal muscle that runs between the styloid process of the temporal bone and the pharynx and functions during the pharyngeal phase of swallowing.

What is tractus?

Medical Definition of tractus solitarius : a descending tract of nerve fibers that is situated near the dorsal surface of the medulla oblongata, mediates especially the sense of taste, and includes fibers from the facial, glossopharyngeal, and vagus nerves.

What would happen if a person’s right hypoglossal nerve is not functioning?

If there are problems with the hypoglossal nerve, the tongue may become paralyzed. To test the nerve’s function, a patient would be asked to stick out their tongue. If paralysis were present, the tongue would point in the direction of the affected side.

What is the origin of Styloglossus muscle?

The styloglossus muscle is an extrinsic muscle of the tongue, and its origin in the styloid process of the temporal bone is well documented.

What is the function of the nucleus ambiguus?

The nucleus ambiguus (literally “ambiguous nucleus”) is a group of large motor neurons, situated deep in the medullary reticular formation named by Jacob Clarke. The nucleus ambiguus contains the cell bodies of neurons that innervate the muscles of the soft palate, pharynx, and larynx which are associated with speech and swallowing.

Are there motor neurons in the nucleus ambiguus?

The vagus also supplies the upper part of the esophagus, and other parts of the pharynx and larynx . As well as motor neurons, the nucleus ambiguus in its “external formation” contains cholinergic preganglionic parasympathetic neurons for the heart. These neurons are cardioinhibitory.

How are vagal visceral reflexes related to nucleus ambiguus?

Functional development of vagal visceral reflexes has been correlated with maturation of nucleus ambiguus neurons.

Where does the nucleus ambiguus receive corticobulbar fibers from?

The nucleus ambiguus receives corticobulbar fibers from both hemispheres and is the efferent innervation to the stylopharyngeus muscle, which contributes toward the elevation of the pharynx and larynx.