Systematization,description, and territory of arteries that promote vascularization of the midbrain and rhombencephalon in the ostrich (Struthio camelus)

Brain specimens from 30 ostriches were injected with red-dyed latex via the internal carotid arteries (Aa.). The ventral tectal mesencephalic artery (a.), invariably a medium-sized single vessel, was, on the right side, a collateral branch of the caudal branch of the carotid artery (53.4%), a direct branch of the carotid artery (43.3%) and a direct branch of the basilar artery (3.3%) and on the left side, a collateral branch of the caudal branch of the carotid artery (66.7%), a direct branch of the carotid artery (30%), and a direct branch of the basilar artery (3.3%). It vascularized only the ventral half of the optic lobe, with no involvement in cerebellar vascularization on the right (93.3%) and left (80%) sides, extending to the ventrorostral-most cerebellar lobules, which were vascularized on the right (6.7%) and left (20%) sides. The caudal ventral cerebellar arteries were a single vessel on the right (96.7%) and left (93.3%) sides. Its first branch was a common trunk: dorsal spinal—caudal cerebellar on the right (60%) and left (56.6%) sides. Its second branch was the caudal cerebellar artery on the right (76.7%) and left (86.7%) sides. Its third branch was the second component of the caudal cerebellar artery on the right (6.7%) and left (3.3%) sides. The midbrain was vascularized by dorsal and ventral tectal mesencephalic arteries. The cerebellum was vascularized by branches of the caudal ventral cerebellar artery and by the dorsal cerebellar artery.     

Systematization,Description, and Territory of the Middle Cerebral,Rostral, and Cerebroethmoidal Arteries on the Surface of the Brain of the Ostrich (Struthio camelus)

Thirty ostrich specimens were injected with red-dyed latex via the internal carotid arteries (Aa.) The middle cerebral and cerebroethmoidal arteries and their branches were systematized. The middle cerebral artery (a.) was always a single large vessel. On the right side, it had two, three, or one developed medial hemispheric branches in 46.6%, 26.7%, and 26.7% of cases, respectively. On the left side, one (36.7%), two (33.3%), and three (30%) developed medial hemispheric branches were observed. The middle cerebral artery had eight (40%), nine (20%), seven (16.7%), eleven (6.7%) ten (6.7%), twelve (3.3%), six (3.3%), and five (3.3%) developed lateral hemispheric branches on the right side and seven (46.7%), nine (13.3%), eight (13.3%), six (10%), five (10%), and ten (6.7%) on the left. Two (33.3%), four (20%), three (20%), one (16.7%), and five (10%) direct perforating branches of the middle cerebral artery were present on the right, and three (33.3%), two (30%), one (13.4%), six (10%), four (10%), and five (3.3%) were present on the left. The cerebroethmoidal artery, always present as a natural continuation of the rostral terminal branch of the brain's carotid artery and originating from the middle cerebral artery, was a large vessel that projected rostromedially, giving off the rostral cerebral artery shortly after its formation and continuing as the ethmoidal artery. The rostral cerebral artery was a single (90%) and double (10%) vessel on the right and a single (96.7%) and double vessel (3.3%) on the left. The ethmoidal artery was always a medium to large single vessel and was the natural continuation of the cerebroethmoidal artery, immediately after giving off the rostral cerebral artery. Anat Rec, 302:1187–1194, 2019. © 2018 Wiley Periodicals, Inc.     

Contribution to the study of diaphragm innervation in Nelore bovines

The phrenic nerves, in Nelore bovines, divide more frequently (60%) in a dorsal branch and a ventrolateral trunk, in both left and right sides. Another division, in trifurcation, giving off dorsal, lateral and ventral branches occurred in 23.3% of cases in the right side and in 30% left side. The division in ventral branch and dorsolateral trunk was observed in 16.6% of cases in the right side and 10% left side. The dorsal branches, both left and right, were distributed among their corresponding lumbar portions in all the cases verified. In 3% of the muscles studied, the right dorsal branch sent a nervous twig to caudal vena cava, and in 73.3% of the muscles, the left dorsal branch innervated the left lumbar portion and also sent some twigs which, after crossing the middle line, distributed in the right lumbar portion, ventral to esophageal hiatus. The lateral and ventral branches, in both left and right sides, innervated corresponding parts of the muscle. Connections (anastomosis) were observed between left lateral and dorsal branches in 10% of cases, and between dorsal left and right branches in 6.7% of cases.     

The prevalence of the extensor digitorum communis tendon and its insertion variants: A systematic review and meta‐analysis

The tendons of the Extensor Digitorum Communis (EDC) are frequently injured in hand trauma. Dislocation and spontaneous rupture can also occur during the course of wrist osteoarthritis and rheumatoid arthritis. The EDC exhibits many variations including splitting of its individual slips to the medial four fingers or their absence. The aim of this systematic review is to assemble evidence about the prevalence of the EDC and its variants on the dorsum of the hand. Twenty‐four cadaveric studies met the inclusion criteria, providing data from a total of 2,005 hands. Meta‐analysis yielded the following results: (a) for EDC‐II (Index), the pooled prevalence estimates (PPEs) were 99.8, 98, 1.8, and 0.2% for the total, single, double, and triple slips, respectively; (b) for EDC‐III (Middle), the PPEs were 100, 67.7, 24.2, 6, and 0.42% for the total, single, double, triple, and quadruple slips, respectively; (c) for EDC‐IV (Ring), the PPEs were 100, 58.6, 29.1, 7.1, and 1.3% for the total, single, double, triple, and quadruple slips, respectively; (d) for EDC‐V (Little), the PPEs were 63.2, 58.5, 10.4, 0.94, and 25% for the total, single, double, triple, and common 4th–5th slips, respectively. There were no significant differences in relation to hand side. Many EDC slip variants demonstrated some interaction with ancestry. A sound knowledge of EDC variants and their prevalences is paramount for assessing and treating hand injuries and disorders. Clin. Anat. 27:1284–1290, 2014. © 2014 Wiley Periodicals, Inc.     

320排螺旋CT三维重建大脑前动脉的临床影像解剖学研究

目的　观测大脑前动脉的起源、走行及分支分布规律，期为脑血管疾病的诊疗提供影像学依据。 方法　随机收集100例无血管疾病的脑部多层螺旋CTA影像资料，利用其自带工作站进行图像后处理，观察大脑前动脉的影像解剖学结构。 结果　（1）测得大脑前动脉各段的数值，大脑前动脉A1段长度、内径及A1-A2夹角左右侧有统计学差异；（2）大脑前动脉走形变异率20%（20/100），其中左侧A1段优势征9%，右侧A1段优势征5%，左侧A1段缺如1%，双侧大脑前动脉发育不良1%，左侧A4、A5段代偿供血1%，右侧A1段优势征合并同侧A2~A5段狭窄（由左侧A2~A5段代偿供血）1%，A4、A5共干1%，双侧A1段畸形1%；（3）大脑前动脉单干型71%，双干型29%。 结论　多层螺旋CTA能清晰立体地显示大脑前动脉的全长和主要分支及其解剖变异；大脑前动脉的变异复杂，左右差异显著，可为临床病变的早期诊断和治疗提供可靠依据。     

An investigation of the origin, location and variations of the renal arteries in human fetuses and their clinical relevance

We investigated the origin, localizations and anatomic variations of the renal artery (RA) in human fetuses with the aim of determining the distribution of these variations according to lateralization and gender. In total, 90 fetuses of spontaneous abortion (45 males, 45 females) with no congenital malformations were included to the study. The abdominal aorta and its branches were dissected after latex solution colored with red ink had been injected into the vessels from the thoracic aorta. In all, 180 RA dissections were performed bilaterally in 90 cases and the anatomic variations were photographed. Right and left RAs were found to originate from the following levels according to the columna vertebralis, respectively: 3.8% and 1.9% lower T12, 67.3% and 25.0% upper L1, 9.6% and 28.8% mid L1, 15.3% and 40.3 lower L1, 3.8% and 3.8% upper 1/3 part of L2 vertebra. The right RA originated from the lateral part and anterolateral wall of the abdominal aorta in 73.0% and 26.9% of cases while the lateral and anterolateral wall origin percentages of left RA were 90.3% and 9.6%, respectively. The origin site of the right RA from the abdominal aorta was superior to, at the same level with, and inferior to that of the left RA in 53.8%, 34.6% and 11.5% of the cases, respectively. There were no variations in 75% of the cases whereas the remaining 25% had several variation patterns. The presented morphological results are as follows: A single hilar artery in 75% of the cases, double hilar arteries in 11.1%, an inferior polar artery in 10.5%, and a superior polar artery in 3.3% of specimens studied. Anatomical variations were observed more frequently among male fetuses and on the right side. Knowledge of RA variations is important for surgeons in performing many procedures and may help to avoid clinical complications, especially, during radiological examination and/or surgical approaches in the abdominal region.     

Ascending vermian artery, branch of the V4 segment of the vertebral artery

A previously undescribed anatomical variant is reported here, that of vermian arteries (vAs) branched from the vertebral arteries (VAs) and replacing the medial branches of the posterior inferior cerebellar arteries (PICAs) that, in turn, were leaving the basilar artery. Both vAs left the VAs in the foramen magnum. The left vA initially looped in front of the spinal root of the accessory nerve (Sp11) and then looped inferiorly on the dorsal side of the spinal cord, in the vertebral canal and continued ascending on the dorsal surface of the medulla oblongata. The right vA looped dorsally to the Sp11 above the foramen magnum, and also ascended dorsally to the medulla. Both vAs were distributed to the vermis. On both sides, the PICAs looped above the glossopharyngeal nerves and the jugular foramina and continued as only lateral terminal branches of a normal PICA that descended in countercurrent on the outer side of the variant vAs. Such anatomical variation is relevant for surgery and microsurgery on both sides of the foramen magnum and in the posterior cerebral fossa.     

Dog kidney: Anatomical relationships between intrarenal arteries and kidney collecting system

The detailed findings of canine intrarenal anatomy (collecting system and arteries) are presented. Ninety‐five three‐dimensional endocasts of the kidney collecting system together with the intrarenal arteries were prepared using standard injection–corrosion techniques and were studied. A single renal artery was observed in 88.4% of the casts. The renal artery divided into a dorsal and a ventral branch. Using the branching pattern of the ventral and dorsal divisions of the renal artery, the vessels were classified in type I or type II. Type I presented a cranial and a caudal artery, whereas type II presented a mesorenal and a caudal artery. Cranial branches of dorsal and ventral arteries supplied the cranial pole in 90.5% of the specimens. Caudal branches of the dorsal and the ventral divisions of the renal artery irrigated both the caudal pole and the mid‐zone of the kidney in 95.8% and 98.9% of the cases, respectively. In all casts, caudal branches of both dorsal and ventral arteries supplied the caudal pole. Therefore, the caudal branches of the ventral and dorsal divisions of the renal artery are of utmost importance in the kidney arterial supply. Although many results of renal and intrarenal anatomy in dogs may not be completely transposed to humans, the anatomical relationship between arteries and the collecting system in the cranial pole of the dog kidney is similar to those in man. This fact supports the use of the dog as an animal model for urologic procedures at the cranial pole. Anat Rec, 290:1017–1022, 2007. © 2007 Wiley‐Liss, Inc.     

Arterial arrangement of the cervical spinal cord in rabbit

The aim of this study was to describe the arterial arrangement of the cervical spinal cord in rabbit because it has been used widely to examine the pathophysiology of spinal cord injury. The study was carried out on 20 adult New Zealand White rabbits. We prepared corrosion casts of the arterial system of the cervical spinal cord. Batson's corrosion casting kit no. 17 was used as a casting medium. The origin of the ventral spinal artery from the right vertebral artery was found on average in 40 % of cases. The origin from the left vertebral artery was found on average in 35 % of cases. The ventral spinal artery raised from the anastomosis of two ventral spinal arteries on average in 25 % of cases. The presence of spinal arteries entering the ventral spinal artery in the cervical region was observed in 46.2 % of cases on the right side and in 53.8 % of cases on the left side. On the dorsal surface we found two irregular dorsal spinal arteries receiving dorsal branches of spinal arteries or they were absent. Until the cervical spinal cord arterial arrangement in species of laboratory animals is described in detail, it will be very difficult to determine the appropriate species for experiments in this field. Variations in arterial arrangement can produce biased or erroneous results in studies.     

应用MRA研究大脑前动脉A1段发育与交通动脉开放之间的关系

目的　探讨大脑前动脉A1段发育与前后交通动脉开放情况之间的关系。方法 回顾性分析了107例3.0T磁共振血管成像（MRA）无脑血管病的检查者和体检者。观察双侧大脑前动脉A1段发育、前交通动脉和双侧后交通动脉开放情况,测量双侧大脑前动脉A1段、前交通动脉及后交通动脉的管径,分析二者的相关性。  结果　①右侧大脑前动脉A1段发育不良占22.43%（24/107）,缺如占0.93%（1/107）,左侧大脑前动脉A1段发育不良占16.82%（18/107）,缺如占1.87%（2/107）。②前交通动脉开放占47.66%（51/107）。③单侧或双侧后交通动脉开放共有39例,其中双侧同时开放占21例,仅左侧开放占7例,仅右侧开放占11例。④大脑前动脉A1段发育不良与交通动脉开放相关（r=0.654,P＜0.01）。  结论 大脑前动脉A1段发育不良可引起交通动脉代偿性开放。     

The human anterior tympanic artery. A nutrient artery of the middle ear with highly variable origin

The variability of the origin of the anterior tympanic artery was investigated in 104 individuals of both sexes. A surprising laterality was found: thus, while the left anterior tympanic artery originated as a singular vessel from either the maxillary or the superficial temporal artery with almost equal frequencies (44.7 and 45.9%, respectively), the right anterior tympanic artery predominantly branched off from the maxillary artery (77.8% of cases). Besides the origin from either the maxillary artery or the superficial temporal artery, also anterior tympanic arteries branching off from the external carotid artery were found to occur (4% on the left and 1% on the right side). Although in the majority of individuals, a singular anterior tympanic artery occurred within the infratemporal fossa, duplications of the anterior tympanic artery were found to be present: in one case on the right and in 8 cases on their left side. In 1 female individual, a triplet of left anterior tympanic arteries was found to supply the tympanic cavity. Also in these cases, the anterior tympanic artery arose from either the external carotid, the superficial temporal or the maxillary artery. In singular cases, even several other branches of the maxillary artery, viz. the deep auricular, middle, and accessory meningeal, as well as the posterior deep temporal, inferior alveolar and masseteric arteries were found to form common trunks with the anterior tympanic artery.     

Double renal arteries originating from the aorta

From a study of renal vascularization, we present 54 cases of double renal arteries supplying one kidney and originating from the aorta. Of the 54 cases, 42 were unilateral, showing a left predominance (25 cases), three of them with triple renal arteries on the opposite side. In six cases we encountered bilateral double renal arteries. Most often, the supplementary renal artery originated from the lateral side of the aorta (58%). Examination of the renal approach showed that in 28 cases the supplementary renal artery entered the kidney through the hilum (proper supplementary renal artery), in 16 cases it was inferior polar, in five cases it was superior polar and in five cases the supplementary renal artery terminated in two branches, equal in caliber, one polar and the other hilar, thus showing a combined character, identical with the manner of termination of the main renal artery. In most of the samples the supplementary renal artery ended with a bifurcation inside the kidney, either into the renal sinus (proper supplementary renal artery) or inside the renal parenchyma (polar supplementary renal artery). The course of the double renal arteries showed multiple variations: retro-ureteral passage of the supplementary renal artery (6 cases), right supplementary renal artery passing anterior to the inferior vena cava (5 cases), crossed course of the double renal arteries (5 cases). Double renal arteries may coexist with other uro-vascular variations, such as: double renal veins on the same side (4 cases) or on the opposite side (3 cases), double ureter on the same side (2 cases) or on the opposite side (1 case), persistence of the fetal renal lobulation on the adult kidney (3 cases) and genital artery originating from the supplementary renal artery (3 cases).     

Double origin of the posterior inferior cerebellar artery with juxta-proximal fenestration of caudal component

We demonstrate the first case of double origin of the posterior inferior cerebellar artery (PICA) with juxta-proximal fenestration of the caudal component, which was misunderstood as triple origin, combined with an unruptured middle cerebral artery aneurysm. The caudal component of the PICA originated from the atlanto-occipital portion and it was fenestrated shortly after origin. The cranial component originated from the intracranial vertebral artery and converged with the superior branch of the caudal component, and then met the inferior branch of the caudal component distally.     

A Golgi study on the afferent fibers to the habenular ganglion in the red stingray, Dasyatis akajei.

Afferent fibers to the habenular ganglion (HG) were derived mainly from the stria medullaris thalami (SM), which was roughly divided into a dorsal and ventral bundle. In the left ganglion seen at the level of the rostrocaudal middle, the dorsal bundle gave off collaterals to the lateral habenular nucleus (LH) and dorsal subnucleus of the medial habenular nucleus (MH), while the ventral bundle innervated the intermediate and ventral subnuclei of the MH. On the other hand, in the right ganglion at the level of the rostrocaudal middle, the dorsal subnucleus of the MH was innervated by collaterals from the dorsal bundle of the SM, whereas in the intermediate and ventral subnucleus fibers from the ventral bundle were seen. In the left ganglion at the caudal level, the dorsal and ventral bundle extended medially and joined the same bundle of the opposite side to constitute a dorsal and intermediate component of the habenular commissure, respectively. A third component of the HC, a ventral component, was seen to run between the fasciculus retroflexus of both sides. As in the case of the rostral level, the dorsal bundle of the SM emitted collaterals to the LH and dorsal subnucleus of the MH, while the intermediate and ventral subnuclei of the MH were projected upon by collaterals from the ventral bundle of the SM. At the caudal level of the right ganglion, the dorsal bundle gave off collaterals to the dorsal subnucleus of the MH. In contrast, the LH and the intermediate and ventral subnuclei of the MH were innervated by fibers from the ventral bundle. With regard to terminal patterns of the SM, fibers to the MH gave off many short fine branchlets forming the glomerular structures, whereas those to the LH branched out into numerous terminals to form a dense fiber plexus. Thus, the afferent fibers to the HG in the red stingray exhibited a striking left-right asymmetry.     

The morphology and the surgical importance of the gonadal arteries originating from the renal artery

Using dissection and plastic injection followed by corrosion as study methods, we describe 16 cases of gonadal arteries originating from the renal artery. Among them, in 12 cases (75%), we assessed this variation on a single gonadal artery while two gonadal arteries appeared in four cases (25%). In 13 cases (81.25%) the gonadal arteries were located on the left side and in only three cases (18.75%) they were on the right. In seven cases (43.75%), an unique gonadal artery that originated from a single renal artery, in three cases (18.75%) the gonadal artery started from the artery of the inferior segment that started from the anterior branch of the renal artery, in other three cases (18.75%), from the trunk of the renal artery, prior to its terminal ramification and in one case (6.25%), from the artery of the superior segment that started from the anterior branch of the renal artery. In five cases (31.25%), a single gonadal artery started from a supplementary renal artery, in four cases (25%), from double renal arteries (three from the inferior and one from the superior one) and in a single case, from triple renal arteries (from the inferior one). All the four cases (25%) of double gonadal arteries were located on the left. Within them, in two cases, the two gonadal arteries started from the renal artery (unique or supplementary) and in the other two cases, the lateral gonadal artery originated from the renal artery (unique or supplementary) and the medial one from the aorta. This vascular variation shows a significant importance for renal surgery, in partial or total nephrectomy or in the renal transplant as long as it may lead to the compromise of the gonadal blood supply, mostly when the gonadal artery with renal origin is unique, without a second one with aortic or other arterial origin. A gonadal artery with origin from an inferior polar renal artery may be injured during the percutaneous treatment of the syndrome of pielo-ureteral junction, so it becomes a major contraindication. Also, this anatomical variation enhances the importance of the arteriography or Doppler ultrasound examination of the renal hylum. Sometimes, the gonadal artery may pass posterior to the proximal ureter that can be disturbed in traject, leading to hydronephrosis.     

Intravenous thrombolytic treatment for acute myocardial infarction. Effects of early intervention and early examination

Intravenous thrombolytic treatment (streptokinase or anisoylated plasminogen streptokinase activator complex (APSAC) was given to 50 consecutive patients within 3 hours after onset of symptoms of acute myocardial infarction. Left heart catheterisation with coronary angiography and simultaneous double view left ventriculography were performed approximately 4 hours after start of thrombolytic treatment. This examination showed that the acute infarct-related coronary artery was open in 36 patients (72%) and closed in 14 patients (28%). A higher left ventricular ejection fraction was found among patients with open, than among patients with closed infarct-related artery (58.8% vs. 48.4%, p = 0.05). The group with open artery also had a lower score of regional left ventricular dysfunction (1.7 vs. 2.4, p less than 0.05, on a scale from 0-3). Single, double and triple vessel coronary heart disease was found in 22, 14 and 13 patients respectively. Mean age was lower in the group with single vessel disease as compared to double and triple vessel disease (48.4 years vs. 53.4 and 55.4 years, p less than 0.05 and p less than 0.005). Independently of whether the infarct-related artery was open or closed, there tended to be an inverse correlation between number of diseased vessels and preservation of left ventricular function (statistical significance only for single vessel versus triple vessel disease with respect to score of regional left ventricular dysfunction, 1.8 vs. 2.4, p less than 0.05). These findings suggest that early thrombolytic treatment within 3 hours of onset of symptoms may preserve myocardial tissue during the evolution of acute infarction. Furthermore, a presumably better collateralisation from adjacent coronary arteries without stenoses may be important for myocardial preservation. Finally, early angiographic examination can be performed safely and is a good support for determination of further treatment, which in the actual patients was coronary bypass surgery in 8 cases, transluminal angioplasty, PTCA, in 20 cases, and medical treatment alone in 22 cases.     

Morphology of coronary vessels in coronary heart disease. An analysis of 930 coronary angiograms

Coronary anatomy was analyzed in 930 patients who underwent coronary arteriography because of coronary artery disease. There was a slight predominance of single vessel disease, whereas double and triple vessel disease were equally distributed. A left main (LM) lesion was found in 5.2%, with an additional right coronary artery lesion in 3.3%. The left anterior descending (LAD) artery was involved most frequently, followed by the right coronary artery (RCA) and left circumflex (Cx). The LAD demonstrated more often a proximal stenosis than the RCA and Cx. If the LM is associated with a RCA-stenosis then the LAD and Cx are involved more commonly, suggesting a more advanced disease in all major vessels. The analysis of ventricular function revealed a significant deterioration according to the number of diseased vessels. If the LM is associated with a RCA lesion, then the hemodynamics are similar to a 3-vessel disease, whereas isolated LM lesions are associated with good ventricular function according to the lesser degree of coronary sclerosis. The deterioration of the hemodynamics in correlation with coronary vessel involvement is significant, however due to the large standard deviations conclusions for the individual patient can not be drawn.     

On the fenestration of the vertebral and basilar arteries]

The fenestration of the vertebral and basilar arteries was investigated macroscopically in 370 human cases. Altogether 43 fenestrations were found in 32 (8.6%) out of 370 cases. The fenestrations could be divided in three groups according to the position where the fenestration appeared. Group I was the fenestration observed along the vertebral artery (Fig. 1), and 7 such fenestrations were found in 6 (1.6%) out of 370 cases; 3 fenestrations among them were located on the right side, 2 were located on the left side and 1 was found on the bilateral vertebral arteries. In 4 out of 7 fenestrations in this group, the hypoglossal nerve was found passing through the fenestration. Group II was the fenestration observed along the basilar artery (Fig. 2), and 26 fenestrations of this type were found in 20 (5.4%) out of 370 cases: 23 fenestrations (88.5%) were located at the caudal half, 3 (11.5%) were located on the rostral half of the basilar artery (Fig. 5). A close relation was indicated between the side on which the fenestration appeared in the basilar artery and the largeness in caliber of the vertebral artery of either side. Group III was the fenestration observed at the lateral area of the vertebral and basilar arteries (Fig. 3), and 10 fenestrations of this type were found in 9 (2.4%) out of 370 cases; all the fenestrations were located on the right side. In this group, the hypoglossal nerve was observed passing through the fenestratin in 4 out of the 10 fenestrations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Variations of the Circle of Willis at the End of the Human Embryonic Period

Variations of the circle of Willis (CW) influence blood supply to the brain and adjacent structures in adults. We examined the formation of the CW in 20 human embryo samples at the end of the embryonic period using 3‐D reconstructions of serial histological sections. The CW was closed in all samples, and did not form in a single plane, but was composed of multiple stair‐like planes. The artery acutely curved at the caudal part of the CW, namely, at the inlet of the basilar artery and bifurcation of the P1 segment of the posterior cerebral artery (PCA), reflecting flexure of the mesencephalon and diencephalon at this stage. Variations were observed in 17 of 20 samples—only anterior parts (anterior communicating artery [Acom] and anterior cerebral artery [ACA]) in 10 samples, only posterior parts (posterior communicating artery [Pcom]) in one sample, and both anterior and posterior parts in six samples. Variations included the Acom formed as partially duplicated in three samples, duplicated in four, plexiform in three, and no channel as a result of a single azygos ACA in one. The ACA formed as duplicated in two, median ACA in two, and right hypoplasia in one. The Pcom formed in hypoplasia of either side in six samples. Variations observed in this study are similar to those observed in fetuses, neonates, and adults. The P1 segment of PCA was very large in all samples. The present observations indicate that variations in the CW are present from the initiation of CW formation. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.     

A schematic diagram showing the various components of the embryonic aortic arch complex in the retroesophageal right subclavian artery

A retroesophageal right subclavian artery, arising from the arch of the aorta as the terminal branch and passing dorsal to the esophagus, was found in five (1.2%) of 428 bodies donated for student dissection at Kumamoto University between 1993 and 2008. The presence of a retroesophageal right subclavian artery has been generally explained to be caused by the persistence of the normally eliminated part of the right dorsal aorta caudal to the seventh intersegmental artery and the disappearance of the normally patent right fourth aortic arch and the part of the right dorsal aorta cranial to the seventh intersegmental artery during the developmental process. However, the parts which remain or disappear are different in each case. With the aim of determining the portions eliminated or persisting and thereby gaining an understanding of the developmental process of the retroesophageal right subclavian artery in each instance, we made schematic diagrams showing the various components of the embryonic aortic arch complex as the prototype just before the anomaly occurred. Based on these diagrams, we conclude that immediately preceding the disappearance of the distal part of the right dorsal aorta and the dorsal part of the right sixth aortic arch, the third intersegmental artery was situated opposite to the fourth aortic arch and the seventh intersegmental artery was situated cranial to the point of junction of the right and left dorsal aortae.