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The alveolar ridge, sometimes referred as the alveolar margin or process, is a modestly raised prominence of both the upper and lower jaw bones located just behind the teeth in human beings. It is so-named because the small jaw ridges are actually the edges of the cavity sockets, or alveoli, that house the roots of teeth. Although subtle and somewhat difficult to discern, they can be felt as an irregular and bumpy surface by the tongue tracing the hard palate near the inner base of teeth.
Medically termed processus alveolaris, this area is the thickest and most spongy, relative to the rest of the jaw bones. There are a total of eight cavities with corresponding ridges, varying in size and shape according to the teeth they contain. Usually, the most prominent ridges are those for the forward incisors; they are called the alveolar point. Collectively, the alveolar ridge is also commonly described as the alveolar arch.
Anatomically, the most important feature of the alveolar ridge is developmental. At birth, most of the jaw bones consist entirely of the alveolar process with teeth sockets reaching almost as deeply as the base of the eye sockets. In adults, ossification or the hardening of bone tissue and the increased growth of the mouth and nasal cavities result in the gum ridges’ diminished prominence. Following the permanent loss of a tooth, its corresponding alveolar ridge is absorbed by the surrounding bone and disappears nearly completely.
The most important function of this seemingly insignificant feature of a mouth’s interior is phonetics. Along with the voice box or larynx, the tongue and nasal passageways, the alveolar ridge plays a critical role in the articulation of human speech. This is particularly true of consonants which are expressed when the tongue makes contact with the upper roof of the mouth. Sometimes also called dental consonants, alveolar consonants include the most common in human languages — [T], [K] and [N]. The latter is called an alveolar “nasal” consonant.
“Approximant” consonants include [L] and [R]. The susurant voicing of [S] and [Z] are termed alveolar “fricative” consonants. “Plosive” consonants like [T] are characterized by a burst of exhalation. Consonants are also categorized by whether they are “voiceless” and in [T] or hardened to its “voiced” counterpart [D]. Additionally, they are also categorized by whether it is “apical,” requiring only the tip of the tongue to make contact, or “laminal,” requiring greater surface area of the tongue to contact the alveolar ridge.
Other less common consonants include the “affricate” such as the sound combination expressed by double consonants like [TS] or [DZ]. The rolled [R] used in Spanish is called an alveolar “trill” consonant. “Ejective” and “implosive” are other kinds of alveolar consonants. The very rare alveolar “click” consonant is heard in some African languages.
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