Oral Cavity Flashcards
Describe the innervation of maxillary and mandibular teeth. What branches of what cranial nerves
are responsible?
The innervation of the maxillary teeth is divided into anterior, middle, and posterior alveolar nn, which are all branches of V2 (maxillary nerve). The mandibular teeth are all innervated by the inferior alveolar nerve, which is a branch V3 (mandibular nerve).
What is the role of the soft palate in swallowing?
The soft palate elevates to close the nasopharynx off from the oral pharynx to prevent passage of food or fluid into the nasal cavity when swallowing.
Between what 2 arches is the palatine tonsil found?
- Palatoglossal arch (anterior)
- Palatopharyngeal arch (posterior)
What nerve provides most of the motor innervation of the soft palate? What muscle is the
exception to this rule?
The motor innervation to the soft palate is provided by the pharyngeal branches of the vagus nerve with the exception of tensor veli palatini, which is innervated by the mandibular branch of the trigeminal nerve (V3).
What vessel is primarily responsible for sublingual absorption of drugs (like nitroglycerin)?
Deep lingual veins.
Trace the pathway of parsympathetic innervation to the submandibular, sublingual and parotid
glands.
Parasympathetic innervation to the submandibular and sublingual glands have cell bodies in the superior salivatory nucleus and the fibers go out through the facial nerve. The facial nerve branches into the chorda tympani within the facial canal. The chorda tympani joins with the lingual nerve (a branch of V3) in the infratemporal and the parasympathetic fibers synapse in the submandibular ganglion. Post-ganglionic fibers either directly enter the sublingual gland or join back up with the lingual nerve to reach the submandibular gland.
The parotid gland gets its parasympathetic innervation from the glossopharyngeal nerve via the lesser petrosal nerve. The pre-ganglionic fibers will travel in the lesser petrosal nerve to the otic ganglion where they will synapse. The post-panglionic fibers with then hitch a ride on the auriculotemporal nerve (branch of V3) to get to the parotid gland.
What bones form the hard palate?
Hard palate = (palatine process of ) Maxillary bone + (horizontal plate of) Palatine bone
What nerve crosses under the submandibular duct in the floor of the mouth?
Lingual nerve
Where would a malignant tumor from the root of the tongue metastatize? Where would a malignant tumor from the tip of the tongue metastasize?
The root of the tongue drains to Deep Cervical lymph nodes. The anterior tip of the tongue drains to Submental lymph nodes.
What is Waldeyer’s ring?
Name for the incomplete ring of tonsils (lymphoid tissue) in the oral and pharyngeal regions. Formed by 4 tonsils: palatine, lingual, pharyngeal, and tubal tonsils.
[pharyngeal and tubal tonsils (tonsils on torus tubarius) = nasopharynx; lingual and palatine = oropharynx]
What nerves mediate the gag reflex? Which is the motor component and which is the sensory component?
Gag reflex, or muscular contraction of pharynx when touching posterior part of the tongue, involves both sensory innervation of IX and motor of X.
Glossopharyngeal n (IX) supplies both general and special sensory for posterior 1/3rd of tongue. The Vagus n supplies all pharyngeal mm, except Stylopharyngeus (IX), with motor inn.
What are the 4 muscles of the soft palate? What is their action and innervation?
Tensor veli palatini (V3 motor branch), Levator veli palatini, palatoglossus, and palatopharyngeus (pharyngeal branch of CN X)
- Tensor veli palatini: tenses soft palate and opens mouth of pharyngotympanic tube during swallowing and yawning
- Levator veli palatini: elevates soft palate
- Palatoglossus: elevates posterior tongue and pulls soft palate onto tongue
- Palatopharyngeus: elevates pharynx and narrows oropharyngeal isthmus
What are the 4 extrinsic muscles of the tongue? What is their action and innervation?
Genioglossus, hyoglossus, styloglossus, and palatoglossus. These extrinsic tongue muscles mainly move the tongue, but they can alter its shape as well.
All but palatoglossus are innervated by Hypoglossal (CN XII). Palatoglossus is also considered a muscle of the soft palate and is innervated by pharyngeal branch of CN X.
What would happen if CN XII were injured? Which muscles would be affected and how would it present?
Hypoglossal innervates all extrinsic tongue mm, except palatoglossus. The remaining 3 are genioglossus, hyoglossus, and styloglossus.
Injury to CN XII would result in paralysis and eventual atrophy of one side of the tongue. The tongue will deviate to the paralyzed side during protrusion b/c of the unopposed action of the unaffected genioglossus on the other side.
