Individual Readiness Assurance Test (iRAT) 4 Head and Neck Practice Test

This question targets how parasympathetic signals reach the submandibular and sublingual glands and which nerve carries those preganglionic fibers to the submandibular ganglion.

Parasympathetic fibers to these glands originate in the superior salivatory nucleus and travel with the facial nerve. A branch called the chorda tympani leaves the facial nerve and joins the lingual nerve. The preganglionic fibers synapse in the submandibular ganglion, and the postganglionic fibers then hitchhike along branches of the lingual nerve to reach the submandibular and sublingual glands. This route makes sense because the submandibular and sublingual glands are innervated by parasympathetic fibers associated with the facial nerve via the chorda tympani.

In contrast, the glossopharyngeal nerve supplies parasympathetic input to the parotid gland (via the otic ganglion), the vagus supplies parasympathetic functions in the thorax and abdomen, and the hypoglossal nerve is motor to tongue muscles with no parasympathetic component to these glands.