The anatomical variations of the hyoid–larynx complex

Abstract

Introduction Pressure on the neck in cases of hanging or strangulation could lead to fracturing of the hyoid bone and/or the calcified laryngeal cartilages. During forensic examination by the pathologist and radiologist, these fractures have to be discerned from anatomical variations. Therefore, proper understanding of the complex embryonic development of the hyoid bone and larynx is essential to interpret the etiology of variations within this complex. The aim of our research is to combine embryological knowledge with forensic practice concerning the hyoid–larynx complex. Methods Serial sections of 34 human embryos were used to examine the development of the hyoid–larynx complex. Every structure was manually annotated in order to create 3-dimensional (3D) reconstructions. A total of 284 excised hyoid–larynx complexes were radiologically examined for anatomical variations by the use of standardized X-ray. Results Of the 284 radiologically examined cases, 38% showed single or combined variations in the hyoid and/or larynx. Often noted were variable degrees of existing accessory bones or cartilages present in the tract of the obliterated pharyngeal arch cartilages, the existence of a median process of the corpus and hyperplastic, hypoplastic or aplastic parts of the hyoid or larynx. Conclusions The hyoid–larynx complex derives in part from the pharyngeal arch cartilages, but the development appeared to differ from current knowledge in embryology books and literature. Therefore we are now able to explain the etiology of hitherto inexplicable variations such as the existence of a median process of the hyoid bone corpus. Anatomical variations often occur and mistakes in distinguishing a fracture from for example an accessory bone is of great impact in this field. Therefore we emphasize the importance of using solid embryological background knowledge during forensic examination of a hyoid or larynx.