The spinal rami of the lumbar artery were observed in two hundreds lumbar ganglion areas corresponding to the first to the fourth lumbar nerves in 25 Japanese in relation to their origin, divergence, direction and distribution.
Following results were obtained:
1) By observing ramus spinalis in relation to the origin and distribution, four branches were identified:
(1) The basivertebral artery was found in 199 out of 200 (99.5%), (2) The superior branch in 200 out of 200 (100%), (3) The middle branch in 63 out of 200 (31.5%), (4) The inferior branch in 164 out of 200 (82.0%).
2) The superior branch was the chief artery reaching the lumbar ganglion, anterior root, posterior root and spinal cord. In 146 cases out of 200, it formed the common stem with the basivertebral artery. Its origin was classified into the following five types according to its relationship with the basivertebral artery:
Type I: Both the superior branch and the basivertebral artery originate from the lumbar. artery as an independent branches (25.5%). This type is subclassified as follows;
Type A: The superior branch originates from a point more central than that of the basivertebral artery (13.7%).
Type B: Both the superior branch and the basivertebral artery originate from a point at the same level (31.4%)
Type C: The superior branch originates from a point more peripheral than that of the basivertebral artery (54.9%).
Type II: The superior branch forms the common stem with the basivertebral artery and both branches diverge almost equally (28.5%).
Type III: The superior branch forms the common stem with the basivertebral artery. Thereafter, the basivertebral artery becomes the main stem, from which the superior branch emerges (42.5%).
Type IV: The superior branch forms the common stem with the basivertebral artery. Thereafter, the superior branch becomes the main stem, from which the basivertebral artery emerges (2.0%).
Type V: anomalous type (1.5%)
3) The distribution of the superior branch to the lumbar ganglion was classified into the following three types:
Type I: At the region of the ganglionic ampulla, the superior branch penetrates deeply into the confluent area of the anterior and posterior roots (70.3%).
Type II: The superior branch tends to run a long way on the surface of the lumbar ganglion, then along the confluent area of the anterior and posterior roots finally perforating the dura mater (18.5%).
Type III: At the region of the ganglionic ampulla, the periphery of the superior branch subdivides arborescently and reaches the surface of the lumbar ganglion (11.2%).
4) The middle branch originates in most cases directly from the lumbar arterial trunk as an independent branch and proceeds directly toward the lumbar ganglionic surface (7-3.2%).
5) The inferior branch originates mostly from the dorsal branch of the lumbar artery and proceeds directly to the lumbar ganglionic surface (64.7%).
6) Among the superior, middle and inferior branches, 51 cases out of 200, or 25.5%, showed anastomosis at the lumbar ganglionic surface. As modes of anastomosis, the following two types were observed:
(1) One is the mode where the two branches are connected to each other by a communicating branch.
(2) T he other is the mode where the two branches from a V-shaped anastomosis.
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