Variation archive

754 published articles

• Encyclopedia entry9 August 2026

  Superior Ulnar Collateral Artery

  The superior ulnar collateral may arise together with the profunda brachii (22%) or from a trunk common to several other branches of the axillary and brachial arteries. When absent, the inferior ulnar collateral takes its place. This artery frequently supplies the nutrient artery to the humerus, and provides a branch to the triceps and to the elbow joint. A case was reported where the radial recurrent artery was absent, but was replaced by the anterior ulnar recurrent, which crossed over and ascended on the outer (lateral) side of the elbow joint.

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• Encyclopedia entry9 August 2026

  Vesicodeferential Artery

  This artery has been well studied and has been found to arise from the umbilical in 94% of cases. It may also arise from the prostatic and from the pudendal. This artery, which supplies the trigone of the bladder, occurred in 48 of 66 bodies. It may also give rise to a superior vesical artery. Although Levi considered this artery to be absolutely constant, Dubreuil-Chambardel found it arising from a common trunk with the superior vesical. It may arise from the internal pudendal or from the trunk of the pudendal/inferior sciatic.

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• Encyclopedia entry9 August 2026

  Superior Renal Polar Arteries

  Superior renal polar arteries are usually single. They arise as separate branches from the aorta in 7% of cases, or as branches of the renal artery in 12% of cases. There may be two or three unilaterally or bilaterally with different aortic or renal sources. They often arise from an inferior suprarenal or from a branch of an inferior suprarenal, i.e., an adipose renal capsular branch to the kidney. Superior renal polar arteries can also arise from the inferior phrenic or from the superior mesenteric artery.

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• Encyclopedia entry9 August 2026

  Inferior Renal Polar Arteries

  Inferior renal polar arteries are usually single and arise from the aorta (95.5% of cases), or the renal artery (1.4% of cases). They have also been reported arising from a suprarenal, common iliac, or superior mesenteric artery. They may have a high aortic origin, and hence may cross the lower renal arteries to supply the inferior pole of the kidney. The inferior polar arteries are sometimes doubled, with one arising from the aorta and the other from the renal, or the pair from either source. They may or may not be accompanied by a vein.

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• Encyclopedia entry9 August 2026

  Artery of the Penis

  The penile artery (artery of the penis) may have anastomoses between the two sides. The penile artery may anastomose, immediately after its division, by a large anastomosis with the artery of the opposite side. The penile artery of one side may have a bilateral distribution. Anatomical and angiographical studies have demonstrated variation in the number and subdivisions of the cavernosal arteries. Helweg, et al., reported that the penile shaft was evaluated to detect arterial anatomical variations. In 8 patients (21%) there were unilateral variations in 6 and bilateral in 2.

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• Encyclopedia entry9 August 2026

  Variations in Branches of the Superior Mesenteric Artery

  Several variations in the branches of the superior mesenteric artery have been recorded. Inconstant branches have been noted. These are the dorsal pancreatic (21% of cases studied), inferior pancreatic, right hepatic (accessory or replacing, 14%), common hepatic, and accessory middle colic. In some cases, the inferior mesenteric, splenic, gastroduodenal, right gastroepiploic, or even the cystic artery arise from the superior mesenteric.

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• Encyclopedia entry9 August 2026

  Superior Vesical Artery

  The number of superior vesical arteries varies from one to five. They commonly arise from the umbilical artery, but were also found arising from the uterine (6 of 66 sides), the vesicodeferential (6 of 66 sides), and the obturator (6 of 132 sides). A large anastomosis between the superior and inferior vesical arteries was found in 60 of 70 specimens. Parsons and Keith reported on 58 observations of the superior vesical artery as part of the program of the Committee of Collective Investigation of the Anatomical Society of Great Britain and Ireland.

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• Encyclopedia entry9 August 2026

  Accessory Meningeal Artery

  An accessory meningeal artery is present in about 96% of individuals. It originates from either the middle meningeal or maxillary artery with almost equal frequency. When the maxillary passes behind the lateral pterygoid muscle, the accessory meningeal arises from the maxillary artery; when the maxillary passes in front of the lateral pterygoid muscle, the accessory meningeal arises from the middle meningeal artery. The accessory meningeal artery may be doubled.

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• Encyclopedia entry9 August 2026

  Masseteric Artery

  The masseteric artery is frequently absent (Poynter, 25%; Livini, 60%; Dall'Acqua, 25%). Reference Poynter, C.W.M. (1922) Congenital Anomalies of the Arteries and Veins of the Human Body with Bibliography. The University Studies of the University of Nebraska, Lincoln 22:1-106.

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• Encyclopedia entry9 August 2026

  Thymic Artery

  The thymic artery usually arises from the anterior mediastinal branch of the internal thoracic, but it may also arise as a sizable branch of the ascending aorta or aortic arch, or from the brachiocephalic, common carotid, inferior thyroid, pericardiacophrenic, or internal thoracic directly.

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• Encyclopedia entry9 August 2026

  Supreme (Superior) Thoracic Artery

  The supreme (superior) thoracic is occasionally missing (10%, Poynter). In 10% of cases the supreme thoracic provided a branch to the second intercostal space. It may replace the pectoral branch of the thoracoacromial and may itself arise as a branch of the thoracoacromial artery (2.5%, Poynter). When absent, it is represented by the lateral thoracic (0.5%) or by the thoracoacromial (2.5%).

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• Encyclopedia entry9 August 2026

  Thyrocervial Trunk Arteries

  Present in 83% of cases, there is in addition, an inconstant pattern of branching in this trunk. The most frequent variations include the following: a) the inferior thyroid has a common stem (of varying length, 0.1 to 3.8 cm) for the suprascapular and transverse cervical arteries (30%), or both of the latter arise independently from the thyrocervical trunk (28%), b) the trunk may bifurcate into an inferior thyroid with a suprascapular branch (15%), or with a transverse cervical branch (8%); the additional branch has a different source, c) a simple trifurcation of the thyrocervical trunk was fo…

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• Encyclopedia entry9 August 2026

  Inferior Phrenic Artery

  Variations in the origin of the phrenic arteries are numerous and supplementary phrenic vessels are common. The inferior phrenic arteries arise from a common trunk (55%, Poynter) from the aorta or the celiac trunk in 18-30% of cases, or as independent branches from these same sources in 62%. Other sources may be the hepatic, left gastric, renal, suprarenal, or superior mesenteric arteries in about 8% of cases. When independent, the right and left phrenics usually arise asymmetrically. Occasionally, the inferior phrenic may supply an "accessory" renal artery and suprarenal branches.

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• Encyclopedia entry9 August 2026

  Iliolumbar Artery

  This artery is usually the first branch of the posterior division of the internal iliac artery. It may be absent, reduced in size, or partially replaced by one of the lumbars. It occasionally gives rise to a lateral superior sacral artery. It has been seen as a branch of the lumbars, middle sacral, and the lateral sacral. In the report of the Committee of Collective Investigation by Parsons and Keith (1897), the data for iliolumbar artery was reported from 57 observations.

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• Encyclopedia entry9 August 2026

  Uterine Artery

  The uterine artery usually arises from the internal iliac but may also arise in common with the vaginal artery or with the middle rectal. The artery may be doubled or composed of multiple parts. It occasionally supplies branches that may be designated as superior vesical, inferior vesical, ureteral and vaginal arteries. Parsons and Keith reporting for the Committe of Collective Investigation of the Anatomical Society of Great Britian and Ireland had 18 observations on the uterine artery.

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• Encyclopedia entry9 August 2026

  Persistent Embryologic Arteries (Hyaloid, Hypoglossal, Stapedial, and Trigeminal)

  Occasionally, arteries that are found during embryologic development, that usually disappear, persist. The primitive trigeminal artery is the most common persistent carotid-basilar anastomic channel observed in adult life and has been reported as an incidental finding in 0.1 to 0.6% of consecutive cerebral angiograms or autopsy cases. See also text and references given for the Ophthalmic, Hyaloid, and Lacrymal arteries and for the Anterior Inferior Cerebellar , the Posterior inferior Cerebellar arteries , the internal carotid and the vertebral arteries .

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• Encyclopedia entry9 August 2026

  Portal Vein

  The portal vein is rarely variable. It often receives the left gastric vein, and may also receive an accessory splenic, inferior phrenic branch, pancreaticoduodenal, a pulmonary vein or right gastroepiploic vein. The hepatoduodenal ligament constitutes the anterior margin of the foramen of Winslow and enclosed the common bile duct, hepatic artery, and portal vein. Usually, the the hepatic artery is located to the left of the common bile duct, and the portal vein is situated posterior and between these two structures (Marois, et al.).

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• Encyclopedia entry9 August 2026

  Heart

  Congenital cardiac anomalies are seen in 0.6% of live births and in 2.0% of stillbirths. Common cardiac anomalies are: a) atresia or stenosis of the pulmonary trunk or aorta, b) defective closure of septal openings, c) defective closure of the ductus arteriosus, d) reverse rotation of the heart and, e) mirror imaging. Situs inversus are examples of d and e. Incomplete closure of the foramen ovale, "probe patency," is common (~25% of adult hearts) and may be regarded as a normal variant rather than an abnormality. The foramen is closed physiologically but patent anatomically.

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• Encyclopedia entry9 August 2026

  Inferior Vesical Artery

  The inferior vesical may arise in common with the middle rectal, or from a common trunk with the internal pudendal and superior gluteal or as a branch from the internal pudendal. It is usually a single branch. Anastomoses between the inferior vesical and uterine arteries were found in 60-70% of subjects reported. In the report of the Committee of Collective Investigation of the Anatomical Society of Great Britian and Ireland, Parsons and Keith reported on 58 observations of the inferior vesical artery.

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• Encyclopedia entry9 August 2026

  Lateral Sacral Artery

  Usually the second branch of the posterior division of the internal iliac, these vessels show great irregularity in development, according to Poynter. They represent two separate vessels, a superior and an inferior vessel. They are frequently associated with the superior gluteal artery in early development, a condition that is reflected in adult statistics (in 92% of cases, Parsons). Poynter found the lateral sacral single in 55%, doubled in 45%, and arising from the hypogastric (internal iliac) in 22%. These vessels from both sides may arise in common.

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