It makes up the part of the throat situated immediately posterior to the nasal cavity, posterior to the mouth and superior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx, the oropharynx and the laryngopharynx. It is also important in vocalization. There are two sets of pharyngeal muscles that act upon the pharynx. These are arranged as an inner layer of longitudinal muscles and an outer circular layer.
The arrangement is to seperate letters which frequently occur consecutively in words, to eliminate jamming of manual typewriters. sue bailey, London UK. The 'qwerty' keyboard was designed for use on typewriters so that frequently used letters were spread apart, avoiding clashing or jamming of the most used 'hammers'.
The QWERTY keyboard was designed in the 1800s for mechanical typewriters and was actually designed to slow typists down to avoid jamming the keys. The AZERTY keyboard is the French version of the standard QWERTY keyboard. AZERTY keyboards differ slightly from the QWERTY keyboard. Another keyboard design, which has letters positioned for speed typing, is the Dvorak keyboard. Unlike the traditional QWERTY keyboard, the Dvorak keyboard is designed so that the middle row of keys includes the most common letters.