Orbital Aperture Research Articles

Analysis and treatment of severe trigonocephaly.

A retrospective analysis of seven patients with clinically severe trigonocephaly was performed, including a review of preoperative and postoperative computed tomography scans. A method of analyzing the trigonocephalic deformity was developed. This is based on determination of the angular severity of the forehead (110 +/- 4 degrees) and the length of half of the supraorbital bar (40 +/- 3 mm). This central angle was found to be relatively constant in this population. Using simple trigonometric relationships, a rationale for the alternative method of reconstruction used in these patients is presented. This technique is based on transverse expansion of the supraorbital bar, transposition of the lateral orbital rim, expansion of the temporal fossa, and recontouring the orbital aperture. As a separate consideration and step, the bony interorbital distance is widened.

The evolution of body mass and relative brain size in fossil hominids

Abstract The observation that absolute brain size increased over the past 2 million years is one of the few uncontested facts of hominid evolution. There is, however, less agreement about how the size of the brain evolved relative to that of the body. Relative brain size has proven to be difficult to quantify because fossil hominid crania that offer the endocranial measurements, and postcrania that generally provide the body-mass estimates, can only rarely be attributed to the same individual. If it could be established that some aspect of the cranium is strongly correlated with body mass, then relative brain size could be calculated for each fossil hominid cranium that has a measured endocranial volume. This paper investigates one such cranial feature, the area of the orbital aperture, and its correlation with body mass in a large sample of extant primates. The results demonstrate that orbital area is correlated with body mass atr=0·987. Predictions of body mass on the basis of orbital area measured for fossil hominids suggest that body mass inHomoincreased through time, and that body mass sexual dimorphism was possibly somewhat greater for some fossil hominid species than it is in living humans. Combining these body mass estimates with measures of endocranial volume demonstrates increased relative brain size for bothAustralopithecusand archaicHomo, with the values forAustralopithecusexceeding those of the living hominoids, and archaicHomoexceeding those ofAustralopithecus. The step-like differences among these taxa stand in contrast to the observation that there appears to have been no or only a negligible increase in relative brain size through the subsequent nearly 2 million years of evolution in the genusHomo. The most dramatic changes occur with the appearance of modernHomo sapiensat about 100,000 years ago and include a decrease in body mass and an increase in relative brain size that appears to have been driven by selection for smaller body mass.

Microorbitalism

A simple technique for orbital aperture expansion to facilitate placement of ocular prostheses is described. Both superolateral and inferolateral orbital margins are released by means of a single burr hole craniectomy of the frontosphenoid bone behind the orbital process of the frontal bone. Vertical and horizontal marginal lengthenings are performed by a rotatory displacement of one bone segment alongside the other. The expanded osseous aperture is secured with wire and plate-and-screw fixation following a supraorbital rim craniectomy to allow an adequate fit. The result provides for easier access of ocular prostheses and tissue expanders. The method has been applied to a series of patients with microorbitalism due to unilateral or bilateral congenital anophthalmia over the past 3 years without complication and with excellent results. Three-dimensional re-formatted CT reconstructions of the craniofacial skeleton are shown preoperatively and postoperatively.

Anatomic Considerations in Upper Eyelid Retraction

A series of anatomically correct orbital drawings are created to examine the major integrating factors that determine upper eyelid position on the eye. The principal upper eyelid force planes can be identified as (1) the eyelid vertical retractor plane slightly divergent from the orbital axis, (2) the eyelid protractor plane nearly tangent to the orbital aperture, and (3) the upper eyelid tarsalligamentous plane swinging from within the horizontal orbital rims. These forces are governed by variation in orbital size and shape, globe size and position, and the length-tension characteristics of the eyelid retractors, protractors, and lamellae. Enhanced lateral upper eyelid retraction occurs in part because the eye in primary position looks away from the orbital axis and projects more lateral sclera. When the eye gazes laterally, coincident with the orbital axis, enhanced lateral upper eyelid retraction disappears.

Ocular muscle extorsion and congenital orbital malformation

The pseudo-ectopic macular syndrome with ocular extorsion has been described in France by Weiss. There is a rotation of the four muscular insertions without change of the perpendicular axis between horizontal and vertical muscles. This syndrome is found very often in congenital orbital malformations. We have seen it in Treacher-Collins-Franceschetti syndrome, in craniofacial stenosis (Crouzon disease), in hypertelorism and in orbital dystopy (plagiocephaly). After orbital surgery there is no change in the ocular deviation. According to our opinion this orbital structural abnormality with antimongoloid palpebral apertures is to blame for the displacement of the ocular muscles. Patients with maxillary hypoplasia as in Crouzon's disease or in Treacher-Collins syndrome have an associated antimongoloid slant of the palpebral fissures and overaction of the inferior oblique muscles, resulting in a V pattern. In the same way these antimongoloid palpebral fissures are seen in hypertelorism because the divergence of the orbits is more pronounced in the frontal sector than in the maxillary sector. In plagiocephalies, the orbital aperture is oval with its long axis in the inferior and medial direction. Occasionally this antimongoloid fissure is found in orbital dystopy.

Contour of orbital aperture in representatives of modern and fossil Hominidæ

American Journal of Physical AnthropologyVolume 3, Issue 4 p. 476-488 Article Contour of orbital aperture in representatives of modern and fossil Hominidæ John Cameron, John Cameron Professor of Anatomy, Dalhousie University, Halifax, Nova ScotiaSearch for more papers by this author John Cameron, John Cameron Professor of Anatomy, Dalhousie University, Halifax, Nova ScotiaSearch for more papers by this author First published: October/December 1920 https://doi.org/10.1002/ajpa.1330030405Citations: 8AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume3, Issue4October/December 1920Pages 476-488 RelatedInformation