Page:American Anthropologist NS vol. 22.djvu/249

 THE FOSSA PHARYNGEA IN AMERICAN INDIAN

CRANIA

BY LOUIS R. SULLIVAN

THE fossa pharyngea, fovea bursae, or medio-basial fossa is a small oval depression in the ventral surface of the basilar part of the occipital bone. The major axis lies in the antero- posterior direction in the median line. It varies in depth from 2 millimeters to 7 millimeters. The width is approximately 4 milli- meters on the average while the length varies from 5 to n milli- meters.

The function or purpose of the fossa is not altogether clear. Anatomical text-books dismiss it with a sentence. Thompson 1 writing in Cunningham says: "An oval pit, the fovea bursae or pharyngeal fossa, is sometimes seen in front of the tuberculum pharyngeum. This marks the site of the bursa pharyngea. . . . The origin and morphological significance of this pouch are not yet solved." Romiti 2 and Agostino 3 claim that the fossa pharyngea is produced by a pharyngeal diverticulum either abnormal or acces- sory. This is in agreement with the opinion stated above. Perna 4 concludes that the fossa pharyngea can be explained as a survival of that part of the median basilar canal which passes below the perichondrium on the ventral surface of the basilar portion of the occipital bone. The basilar part of the occipital bone ossifies like a vertebra and the fossa is the result of the non-ossification of the hypochordal bow element due to the position of the notochordal element in this region. I am not in a position to state the relative merits of the two opinions nor am I altogether certain that they are necessarily contradictory.

1 Arthur Thompson and David Waterson in Cunningham's Text-book of Anatomy. New York, 1917.

2 Romiti, 1891.

8 Agostino, 1901. 4 Perna, 1906.

237

�� �