Abstract:

Objective　To observe and measure the clinical anatomical parameters of atlas lateral mass nutrient foramen, so as to provide a reference for the reduction of vascular injury risk by atlas lateral mass screw fixation.　Methods    Thirty-eight normal dry human atlas specimens were randomly selected to observe the shape, number, location and symmetry of the nutrient foramen in the lateral mass of atlas (defined as those with a diameter greater than or equal to 1.0 mm). The maximum transverse diameter, longitudinal diameter, depth, and the distance between the outer edge of the nutrient foramen and the inner edge of the transverse perforation hole were measured.　Results　 In 38 cases, 95% of atlas had nutrient foramen, 42% were round, 8% were transverse ellipse, 45% were longitudinal ellipse, and 5% had no nutrient foramen. About 79% of the sides were symmetrical, and about 16% of the sides were asymmetrical. The maximum transverse diameter of the nutrient foramen was (2.16±0.86) mm, the maximum longitudinal diameter was (2.82±1.03) mm, and the maximum depth of the nutrient foramen was (1.75±0.71) mm. The outer diameter of the nourishing hole was between the inner diameter of the transverse hole. The distance was (8.61±1.46) mm, and there was no significant difference between the left and right sides of each measurement index.  Conclusion　There are nourishing holes on the left and right sides of 95% of the atlas. The position is located in the middle of the lateral mass of the atlas, which is in the channel of the pedicle screw. When atlas is fixed, the diameter of the screw can be referenced is (8.61±1.46) mm. The screw channel is located at the inner edge of the atlas lateral mass (1.73±0.7) mm.

Key words: Atlas;   , Nutrient foramen;    , Pedicle screw;    , Anatomical measurement