Morphological Variables

In the past anthropologists have studied the outer ear to make a reliable classification of the dominant and recessive trait of some recurrent morphological characteristics. Studies have been carried out on large groups of individuals of different racial and geographical origin. Another application of the inspection of the outer ear, nowadays superseded by genomic analysis, was sometimes proposed by forensic medicine as a control in the scientific clarification of paternity.8,9

The effort made by anthropologists to describe the morphological variables of the ear as exhaustively as possible is of great value and interest to us. The reader could actually be helped to differentiate some morphological characteristics with a more pronounced hereditary tendency than others acquired later in the patient's life (see the next section). Figure 3.8 reports the first which received particular consideration in the literature as a possible dominant or recessive trait.7 In this description I have excluded any malformations associated with hereditary deafness, renal and vertebral anomalies and chromosome abnormalities such as trisomy 18 syndrome. The frequency of the illustrated characteristics is very variable: for example, according to Lange, in 908 subjects: the curled helix was visible in 60.1%; Darwin's tubercle in 59.8%; the

Folded down helix

Folded down helix

D =

dominant, ID = incomplete dominant, R = recessive

1 =

helix taeniata R

2 =

crus anthelicis tertium R

3 =

uncurled helix R

4 =

arcus cymbalis D

5 =

crus cymbae ID

6 =

scapha ending in the middle region R

7 =

tuberculum supratragicum ID

8 =

incisura prelobularis D

9 =

ear lobe attached to cheek ID

= protuberances, raised areas

Fig. 3.8 Hereditary characteristics as having a possible dominant or recessive trait according to Lange.7

tuberculum supratragicum in 38%; the helix taeniata in 9%; the crus cymbae in 6.8%; the incisura prelobu-laris in 4.7%; the crus anthelicis tertium in 3.4%. Some significant sexual differences were observed, among them the higher frequency of Darwin's tubercle in males and the strikingly higher proportion of curled helix in females (76.8% in females compared with 44.2% in males) ( ). These characteristics are seemingly correlated and Mar-tin3 gives us the following explanation to think about, and perhaps be amused by:

the regression process is more advanced in female ears, i.e. the shape of the female ear has reached a certain stability; instead the shape of the male ear is relatively more like that of the monkey and has less stability.

A further autosomal dominant familial trait, the fistula auris congenita, also known as pitted ear, has been observed in about 1% of Europeans and in 2.5% and 2.6% respectively in samples of the Chinese and Japanese populations (see Fig. 3.18).

Once the possible hereditary origin of the characteristics visible on inspection have been excluded, the practitioner should, however, recognize other signs possibly acquired later in the patient's life. These characteristics have been noted both by anatomists and by anthropologists8-10 (Fig. 3.10). Some of them may be important in the diagnostic process based on inspection of the ear presented in this book (Ch. 4).

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