The external ear: more attention to detail may aid syndrome diagnosis and contribute answers to embryological questions.

The human pinna has a complex shape and yet the basic components of normal structure are remarkably constant between individuals. It is precocious in its appearance during embryogenesis and it has been subject to many developmental and surgical studies, yet questions remain as to its primary embryogenesis and the causes of its malformations. Unfortunately, the vast majority of clinical reports of syndromes and of individuals with dysmorphic signs provide limited and inadequate description of the external ear. Given the intricate pattern of the pinna, and hence its potential for morphological variation, we think that more attention to the specific description of ear anomalies may lead to a better appreciation of the etiology and embryology of the malformations. Furthermore, in some cases correlation with specific syndromes may provide an aid to diagnosis. Towards those ends this paper reviews some of the controversy concerning the embryology of the pinna, and discusses a number of the better-defined anomalies of the external ear. Although it has been suggested that anomalies of the insertion and orientation of intrinsic muscles of the pinna may be responsible for variations in external ear morphology, we think it likely that in many cases the anomalous insertions may be secondary.