2009年1月12日 星期一

[生物] typing LB042~045 惠珍/ Done

LB042-045惠珍 Done on Jan 12’09

According to Schultz(1958), the arch circumscribed by the upper teeth, schematically represented in Fig 2.12, does not differ basically in man and the other Hominoidea. Nor is the basic plan of the molars and incisors different in any significant way. One derivation in the shape of man’s denture is the conspicuous absence of the enlarged canines which are so prominent in most males od most other primate forms. Owning to the great evenness in height and width of all teeth in man, the denture forms an unbroken palisade around the oral cavity. This structural peculiarity is the essential prerequisite for the production of spirant sounds such as f, v, s, sh, th, and others.

The position of the epiglotiss with respect to the soft palate has been the subject of much discussion in connection with the development of speech. From sagittal sections such as those shown in Fig 2.7-2.11, we see hat in man the epiglottis is located much lower than in lost other primates. One the other hand, the epiglottis seems to be in close contact with the soft palate in the lower species and at least in close proximity in the Pongidae. Negus(1929), Kelemen(1938 and 1948), DuBrul(1958), and many others have concluded from this that only man was capable of conducting the glottis-produced sounds through the oral cavity, whereas other primates had the sounds directed through their nasal cavity. Stack and Schneider (1960) have pointed out that these conclusions may not be warranted, and that the basic anatomical facts have easily disarranged in the process of fixation, and organs odten become displaced in the course of anatomical dissections.

(3) Intrinsic Anatomy of the Larynx

Each species of the Hominoidea has a differently shaped larynx with a great many variations and specializations in the individual mechanism that are inherent in this intricate apparatus. The most recent survey of all comparative investigations of primate larynges was contributed by Starck and Schneider (1960), who may be consulted for further details. We can only report on a few of the more obviously voice-related differenced.

The complex construction and the irregular shape of the larynx make it impossible to find comparable anatomic preparations or diagrams in any literature. Therefore, our pictorial material here is confined to reproducing the few schemata shown in Fig . 2013 and 2014, which illustrate some of the variability encountered in comparing the voice box of higher primates.

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