Arterial supply of, and arterial preponderance in, the human interventricular septum.

Purpose of the study: To determine the pattern of arterial supply of, and eventual arterial preponderance in, the human interventricular septum (IVS). Material and methods: 100 human heart specimens (84 cadaveric specimens and 16 corrosion casts) were studied macroanatomically. In 20 cases, the coronary arteries were injected with barium sulphate and red gelatin. The intramural courses of septal arteries were exposed in 38 cases. Radiographs of the IVS were made in 8 cases. The IVS was divided into superior and inferior parts; each part was subdivided into anterior, middle, and posterior sections; additionally, there was an apical section. In order to determine the nature of the arterial supply, the extramural portions of the septal branches were first dissected and evaluated; then, the intramural courses were traced. Results: The septal branches derived from arteries distributed in the coronary and interventricular sulci of the heart. The strongest of the septal arteries, the anterior descending septal artery (ADSA) or main septal artery, originated from the anterior interventricular artery (AIA) and was found in 72 cases. Its stem exhibited an average length of 16 mm and then bifurcated into superior and inferior or trifurcated into superior, inferior and deep (left) branches. These branches supplied the middle superior and middle inferior sections of the IVS. The moderator band and anterior papillary muscle of the right ventricle received twigs from the inferior branch of the ADSA and from the fourth or fifth anterior septal arteries. The small left superior septal artery, which originated from the AIA but was not always present, supplied the anterior superior section of the IVS. The right superior septal artery, which derived from the initial part of the right coronary artery (RCA), nourished the middle superior section of the IVS (in cases in which the latter was not supplied by branches from the ADSA). The posterior septal arteries (including branches of the atrioventricular node artery) arose from the posterior interventricular artery (PIA) and supplied the superior and inferior posterior sections of the IVS. Apical branches derived from the terminal AIA and supplied the apical section. The most conspicious peculiarity was a stout right superior septal artery (RSSA), which in some instances supplied more than just the middle superior section of the IVS, reaching the moderator band and right anterior papillary muscle. Another peculiarity was the ectopic origin of one of the posterior septal arteries from the right marginal artery or even the stem of the RCA (frequency: 18 cases). Evaluation: In 92 cases a preponderance of the left coronary artery was evident because the anterior septal branches were frequent and large (among them the stout and long ADSA). A balanced type of arterial supply was found in 5 cases when the RSSA appeared to be as strong as the ADSA. A preponderance of the right coronary artery was found in 3 cases when the proximal RCA released a stout and long ("dominant") RSSA without the existence of a main septa

Unusual bone formation in the anterior rim of foramen magnum: cause, effect and treatment

A rare case of proatlas segmental abnormality resulting in a bony mass in the anterior rim of the foramen magnum is studied. Case report of a 19-year-old female showed a progressive weakness of all four limbs for about 3 years. When admitted she could not perform any useful activities by herself. Investigations revealed an unusual bone growth in the region of the anterior rim of foramen magnum that resulted in severe cord compression. The abnormal bone formation involved the lower end of clivus, the tip of the odontoid process and the posterior arch of the atlas. Dynamic imaging did not reveal any clear evidence of instability. Following transoral decompression and posterior fixation, the patient showed dramatic and lasting clinical recovery. Conclusions were drawn as follows. Anomalies of the most caudal part of the occipital sclerotomes due to the failure of proatlas segmentation can be the cause of an abnormal bone mass in the anterior rim of foramen magnum. Transoral decompression, followed by posterior atlantoaxial fixation, results in neurological recovery and provides lasting cure from the problem