The proboscis in human cyclopia: an anatomical study in two dimensions.

A 2-dimensional anatomical study has been undertaken of the proboscis and its contribution to the roof of the median orbit in human cyclopia. The cyclops material consists of 4 sectioned fetal heads and a dried cyclops skull. The skeleton of the proboscis is formed by the nasal capsule. The base of the proboscis lies in the floor of the anterior cranial fossa filling an extended ethmoidal notch and contributing to the roof of the median orbit anterior to the fused lesser wings of sphenoid. The cavity of the proboscis is lined with squamous epithelium, respiratory and olfactory mucosa. Olfactory fibres pass from the proboscis into the extradural space of the ethmoidal notch forming a collection of tissue similar to the inferior layer of the normal olfactory bulb. The data indicate that the proboscis represents the anterosuperior part of the normal nasal cavity developed in the absence of median components. It is suggested that the cyclops face constitutes a model for the study of the development of the normal face.