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PALATE

BIG PICTURE

The palate consists of a hard and soft palate, which separates the oral and nasal cavities. The muscles that act upon the soft palate are innervated by CN X, with the exception of the tensor veli palatini (CN V-3). The difference in innervation reflects the embryologic origins of the branchial arches.

HARD PALATE

The hard palate consists of the palatine process of the maxillary bone and the horizontal plate of the palatine bone. The incisive canal is in the anterior midline and transmits the following (Figure 24-1B):

  • Innervation. Nasopalatine and greater palatine nerves (CN V-2); provides general sensory innervation.

  • Vascular supply. Sphenopalatine and greater palatine arteries (arise from the maxillary artery within the infratemporal fossa).

Figure 24-1:

A. Open mouth showing the palatal arches. B. Anterior view of the innervation of the palate. C. Posterior view of the palate.

SOFT PALATE

The soft palate forms the soft, posterior segment of the palate and consists of muscle fibers sheathed within a mucous membrane (Figure 24-1A–C).

  • Uvula. A projection from the posterior midline of the soft palate; helps close the nasopharynx during swallowing.

  • Palatoglossal and palatopharyngeal folds. The soft palate is continuous with the palatoglossal and palatopharyngeal muscles/folds.

  • Palatine tonsil. A collection of lymphoid tissue between the palatoglossal and palatopharyngeal folds; aids the immune system in combating pathogens entering the oral cavity.

  • Functions. The soft palate acts like a flap valve by moving posteriorly against the pharynx, and separating the oropharynx from the nasopharynx during swallowing. This movement ensures food moves down into the esophagus when swallowing, rather than up into the nasal cavity.

  • Vascular supply. Lesser palatine artery (maxillary artery), ascending palatine artery (facial artery), and palatine branch of the ascending pharyngeal artery.

  • Innervation. Sensory innervation is from the lesser palatine nerves (CN V-2).

  • Soft palate muscles. The muscles of the soft palate are as follows:

    • Tensor veli palatini muscle. Courses from the pterygoid plate of the sphenoid bone, hooks around the hamulus, and inserts in the soft palate; tenses the soft palate and is innervated by CN V-3.

    • Levator veli palatini muscle. Originates along the cartilaginous portion of the auditory tube and inserts into the superior aspect of the soft palate; elevates the soft palate and is innervated by CN X.

    • Palatoglossus muscle. Attaches between the soft palate and the tongue and is innervated by CN X; depresses soft palate.

Image not available. Lesion of CN X. To test the function of CN X, the physician will ask the patient to open his mouth wide to determine if the palate deviates to one side or the other during a yawning motion. A lesion of CN X causes paralysis of the ipsilateral levator veli palatini muscle, resulting in the uvula being ...

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