[Morphological studies on the distribution of the anterior ethmoidal nerve in Japanese adults and fetuses].

The anterior ethmoidal nerve (a.e.n.) was examined in 10 human adults (40-89 years old) and 5 fetuses (7 months). A.e.n. arises from the naso-ciliary++ nerve, which is the first division of the trigeminal nerve. From this point to the crista galli, a.e.ns. were observed under a dissection microscope in relation to their direction and distribution. The following results were obtained: 1) The number of a.e.n. i. The number of a.e.n. was 1 to 3 (1.45 on average) when they arose from the naso-ciliary nerve in the adults. ii. In the fetuses, the number of a.e.n. was 1 to 2 (1.1 on average). 2) The length of a.e.n. i. The length was 12.0 mm to 24.0 mm (17.3 mm on average) in the adults. ii. In the fetuses, the length was 2.0 mm to 7.0 mm (5.0 mm on average). 3) The anterior ethmoidal branch (e.b.). The anterior ethmoidal branch (e.b.) supplies the mucous membrane of the ethmoidal sinus. i. The number of e.bs. was 20 on the right side and 22 on the left in 8 adult cases. In the upper wall of the ethmoidal sinus, the number of e.bs. was 1.0 on average. In the medial wall of the ethmoidal sinus, the number of e.bs. was also 1.0 on average. In the lateral wall of the ethmoidal sinus, the number of e.bs. was 0.2 on average. ii. The number of e.bs. was 3 on the right side and 2 on the left in 3 fetus cases. In the upper wall of the ethmoidal sinus, the number of e.bs. was 0.2 on average. In the medial wall of the ethmoidal sinus, the number of e.bs. was 0.3 on average. No e.bs. were found in the lateral wall. 4) The anterior ethmoidal foramen. The anterior ethmoidal foramen was examined to determine its positional relation to the angle of the crista galli. i. The angle was 40.0 degrees to 10.0 degrees and 30.0 degrees on average in the adults. ii. In the fetuses, the angle was 50.0 degrees to 20.0 degrees and 43.2 degrees on average.