Arches & Vaults - The Architecture of the Oral Cavity

Published: May 26, 2023

Zohara Nguyen, CCC-SLP, QOM

Neo-Health Services Director of Education & Training.
'Orofacial Myology: From Basics to Habituation' Course Instructor

Orofacial Myologists often use building and construction terms to explain the oral structures in the mouth and how they function. We often say “the palate is the roof of the mouth” or “the palate is the floor of the nasal cavity”. Then we even weave in more sophisticated architectural terms to further explain our ideas, “narrow V-shaped arches” and “high vaulted-palate”. Hard palates remind me of the vaulted cathedral ceilings I’ve been in awe of during my travels. Using these architectural descriptors helps us to decode the form of the palate, how it may have formed that way and what functions it could be helping or hindering.

I like to split my observations of the palate into three descriptions:

The Dental Arch (a.k.a Maxillary Arch)

I firstly follow the curve of the maxillary teeth and figure if the arch is a nice U-shape, or more V-shaped, and whether this arch appears narrow or broad. Identifying the shape is helpful for our purposes as orofacial myologists because the tongue has to be able to fit inside of the dental arch not just for tongue rest posture, but during speech and swallowing the lateral edges of the tongue need to brace inside of the dental arch for stability. Narrow dental arches are often seen in people with a low tongue rest posture and/or sucking habits - anything that creates disharmony between the buccal, labial, and lingual intraoral forces.

The Palatal Arch

Sometimes a dental arch can be a beautiful, wide U-shape; however, on closer inspection the palatal arch may be a different shape from the dental arch. The palatal arch may be narrower and even be a V-shape compared to the broader dental arch. Discrepancies such as these make me query if the teeth have been straightened for the dental arch to have a beautiful form, while the palatal arch still echoes the remnants of the underlying dysfunction. Perhaps an oral habit such as thumb sucking or mouth breathing has contributed. We should question if there are oral habits and if potential barriers to therapy are still active.

The Palatal Vault

We can also observe the height of the hard palate. Ideally the center of the palate should be broad and more "domed" than "vaulted" in shape, so the tongue can contact the palate, stripping off food during the oral phase of the swallow. A high palatal vault can look like a thumb print inside of the middle of the palate - forming a crevice that often throws a shadow upon observation. A high palatal vault can also indicate dysfunction during development or due to habits including pacifier use, thumb sucking, mouth breathing, and possibly put the individual at risk of sleep disordered breathing. A high palatal vault is commonly observed alongside a narrow palatal arch. People with high palatal vaults may not be able to rest or contact the dorsum of the tongue to the middle of their palate due to the height. In my clinical observations, some people with steep palatal vaults suction the bolus into the vault but are not always successful at propelling the bolus on the first swallow, and may need numerous swallows or to dislodge the bolus manually.