The craniofacial proportions and laryngeal position in monkeys and man of different ages (a morphometric study based on CT-scans and radiographs).

Using CT-scans and radiographs, sagittal planes through the head and neck of men and monkeys at different ages were analyzed morphometrically for their craniofacial proportions and laryngeal position. In monkeys, a continuous prognathic growth of the splanchnocranium was found within the first 3 years. The neurocranial growth, however, was markedly reduced. The larynx of monkeys showed only a slight descensus with age. In contrast to this, the growth of the splanchnocranium in man did not change the craniofacial proportions significantly. The larynx, however, descended markedly within the first two years of life. In adults, the final position of the larynx was nearly 3 vertebral bodies further caudally than in the newborn. The differences in the postnatal position of the larynx, which is essential for the development of speech, are explained by differences in the growth pattern of human and monkey skulls.