| Popis: |
SUMMARY A description is given of a modification of M. splenius capitis, best developed in the Apodiformes. In this order, the muscle originates on the opposite side of the midline from its insertion; the right and left muscles cross each other by means of interdigitating slips. This arrangement is termed the “cruciform origin”. A cruciform origin of simpler structure is also found in the Aegothelidae and Turnicidae, and similar tendencies on a smaller scale have been discerned in most orders. It is suggested that the cruciform origin in its extreme form increases the capacity for rapid and extensive head turning. The evolution and possible taxonomic significance of the cruciform origin are discussed, and problems for further investigation are suggested. |
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