J3

Glabella Nasion

Orbitale

Subnasion

Maxilla

Vertex

Glabella Nasion

Orbitale

Subnasion

Maxilla

Prominence of occiput

(opisthocranion)

Zygomatic arch Mastoid process Ramus of mandible

Gonion

Supraorbital ridge

Inferior orbital margin (orbitale)

Zygomatic arch Gonion

Body of mandible

Menton

I Head width ,

(bieurion) , Facial width .

Body of mandible

(bizygomatic) I Mandibular | width (bigonial)

Prominence of occiput

(opisthocranion)

Zygomatic arch Mastoid process Ramus of mandible

Gonion

Supraorbital ridge

Inferior orbital margin (orbitale)

Zygomatic arch Gonion

Menton

I Head width ,

(bieurion) , Facial width .

Figure 7.1 Palpable landmarks of craniofacies.

cephalostats used today are much less obstructive and expensive than Broadbent's research instrument, the positioning of the head and the distance between the X-ray unit and the head-holder remain the same. The head is held in the cephalostat, which restrains the head in a precise manner. Adjustable ear rods fit into the external auditory meati, holding the head stable anteroposteriorly and preventing lateral rotation. The central beam of the X-ray is designed to pass through the ear rods. A 5 foot tube-to-film distance and a 52.4 inch tube-to-median plane distance are employed throughout. Further details may be found in the bibliography at the end of this chapter.

A new approach to document the three-dimensional surface of the face consists of multiple camera photography. Computerized programs merge the images into a single three-dimensional surface mesh. In addition to image documentation, this approach allows for identification of soft tissue landmarks, distance measurements between landmarks, and calculation of ratios. Software allowing computer image-driven syndrome identification is being developed.

Results of single measurements will indicate the patient's place within or outside the normal range. Repeated measurements allow calculation of changes and growth. Such changes affect the proportions of the face. In both sexes the vertical profile measurements increase more than horizontal measurements (maximum relative increments occurring earlier in girls than in boys). The upper face seems to grow more rapidly than the lower face up to about the 10th year. After that age, the reverse is apparent. The lower portion of the face, consisting of the mandible, manifests accelerated growth with the result that, at 21 years, the face has the same relative proportions as at three years. Growth is generally completed first in the skull, then in the width of the face, and last in the length and depth of the face. Peak growth occurs between 3-5years, followed by continuous deceleration until the 13th year, and then a distinct adolescent acceleration. There is virtually complete cessation of growth of the craniofacies at age 21 years. However, many nasal dimensions, particularly nasal length, continue to increase. With increasing age, most craniofacial dimensions, with the exception of facial width and nasal length, are reduced. This can be ascribed mostly to soft tissue changes.

Normal growth and development of craniofacial structures also require movement of embryonic muscles during the prenatal period. Lack of movement during the fetal period, for any reason, particularly in the presence of neuromuscular disease, produces a characteristic facial appearance (fetal akinesia sequence)—for example, as seen in Pena Shokeir syndrome.

An approach to measurement of the craniofacies must include comparison with head circumference and height in addition to age. For example, inner and outer canthal distances on the 50th percentile, in the presence of microcephaly, would in fact be abnormal and relatively hyperteloric. Various indices comparing two craniofacial measurements are available in the dental and anthropological literature. Few have been included in this text, but references are found at the end of this chapter.

In addition to detailed individual measurements, an evaluation of the craniofacies requires an impression of the overall gestalt of the face both at rest and during movement such as crying, smiling, and frowning. It is important to remember that the shape of the face and its relative proportions change significantly with age, in both normal and dysmorphic individuals. For this reason, the overall gestalt may be quite different at different times during life. This change should be taken into account when a subject is evaluated.

The terminology used to describe the craniofacies is complex and somewhat confusing. A glossary of terms defining specific landmarks and anomalies is provided at the end of this book.

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