. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Hitman Skull* VOL. in. Human Skull. ments of the others are, however, met with imbedded in the flesh beneath the skin. The hyo-branchial apparatus.—The osseous framework to which in the human subject the name of os hyoides has been appropriated, from the trivial circumstance that in the simple con- dition under which it presents itself in man it resembles the Greek letter v, is found in the lower Vertebrata to be permanently composed of very numerous pieces, which are made sub- servient to respiration, and from their siz
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Hitman Skull* VOL. in. Human Skull. ments of the others are, however, met with imbedded in the flesh beneath the skin. The hyo-branchial apparatus.—The osseous framework to which in the human subject the name of os hyoides has been appropriated, from the trivial circumstance that in the simple con- dition under which it presents itself in man it resembles the Greek letter v, is found in the lower Vertebrata to be permanently composed of very numerous pieces, which are made sub- servient to respiration, and from their size and number render the whole apparatus, which they assist in forming, really worthy of the name of an anterior thorax. The hyoid svstern of bones may indeed be regarded as being in some respects vicarious in function with the true thorax, the former belonging especially to the aquatic, the other to the aerial mode of respiration; whilst, therefore, as in Fishes, the gills form the only means of breathing, and the branchial arches exist in their full state of developement, the hyo-branchial ap- paratus is complete and preponde- rates in importance over the thorax ; but, in proportion as pulmonary respiration is established, as we ascend the scale of animal existence, the thoracic system of bones as- sumes the principal duties con- nected with the inspiration and expiration of air, and the os hyoides dwindles into a very rudimentary condition. The above circum- stances however, interesting as they are when a mere comparison is instituted between the hyoid bones of various animals as to their com- position when in the adult state, assume additional importance when we reflect that all the higher Ver- tebrata possess in the earlier stages 3 it. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Todd, Robert Bent
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