Objective. Circulus arteriosus/circle of Willis (CW) is a polygonal anastomotic channel at the base of the brain which unites the internal carotid and vertebrobasilar system. It maintains the steady and constant supply to the brain. The variations of CW are seen often. The Aim of the present work is to find out the percentage of normal pattern of CW, and the frequency of variations of the CW and to study the morphological and morphometric aspects of all components of CW. Methods. Circulus arteriosus of 150 formalin preserved brains were dissected. Dimensions of all the components forming circles were measured. Variations of all the segments were noted and well photographed. The variations such as aplasia, hypoplasia, duplication, fenestrations, and difference in dimensions with opposite segments were noted. The data collected in the study was analyzed. Results. Twenty-one different types of CW were found in the present study. Normal and complete CW was found in 60%. CW with gross morphological variations was seen in 40%. Maximum variations were seen in the PCoA followed by the ACoA in 50% and 40%, respectively. Conclusion. As it confirms high percentage of variations, all surgical interventions should be preceded by angiography. Awareness of these anatomical variations is important in neurovascular procedures.

Objective:Although posterior communicating artery (PCoA) is a smaller branch of the internal carotid artery, it gives the main contribution in the formation of circle of Willis (CW) by communicating with the internal carotid arterial system and the vertebro-basilar arterial system. The size of PCoA varies frequently. The present work aims to study the PCoA regarding its morphology, morphometry, and symmetry.Materials and Methods:This study was conducted on 170 human cadaveric brains. Brains were dissected carefully and delicately to expose all components of CW, especially PCoA. Morphological variations of PCoA were noted along with its morphometry and symmetry.Results:Morphological variations of PCoA were aplasia (3.52%), hypoplasia (25.29%), fenestration (0.58%), and persistent fetal pattern (16.47%). In the present study, we found the five different types of terminations of PCoA. Type I termination was the most common type, seen in 92.94% of cases, Type II termination was seen in 1.17%, Type III and Type IV terminations both were seen in 0.58%, and Type V was seen in 1.17%. The mean length of PCoA was 15.9 mm and 15.3 mm on the right and left sides, respectively. The mean diameter of PCoA was 2.1 mm and 1.9 mm on the right and left sides, respectively. Symmetry of PCoA was seen in 65.29% and asymmetric PCoA was seen in 34.70% of cases.Conclusion:The present study provides the complete description of PCoA regarding its morphology, symmetry, and morphometry. Awareness of these anatomical variations is important in neurovascular procedures.

Objectives:The chordae tendinae (CT) are strong, fibrous connections between the valve leaflets and the papillary muscles. Dysfunction of the papillary muscles and chordae is frequent. Mitral valve replacement with preservation of CT and papillary muscles may preserve postoperative left ventricular function better than conventional mitral valve replacement in patients with chronic mitral regurgitation.Methods:The study was carried out on 116 human cadaveric hearts. The heart was opened through the atrioventricular valve to view the constituents of the complex. Origin, attachments, insertions, distribution, branching pattern and gross structure of CT were observed and studied in detail.Results:In the present study more than 21 terminologies of CT were defined by classifying it into six different types. Classification is done according to the origin, attachments, insertion, distribution, branching pattern and gross structure. Terminologies defined are as follows. Apical pillar chordae, Basal pillar chordae, True chordae, False chordae, Interpillar chordae, Pillar wall chordae, Cusp chordae, Cleft chordae, Commissural chordae, First order chordae, Second order chordae, Free zone chordae, Marginal chordae, Rough zone chordae, Straight chordae, Branched-fan shaped chordae, Spiral chordae, Irregular-web chordae, Tendinous chordae, Muscular chordae, Membranous chordae. Basal pillar chordae are found in 9.48%. Mean number of chordae taking origin from apical half of a single papillary muscle or single head of papillary muscle was 9.09 with the range of 3-18. Mean number of the marginal chordae attached to a single cusp was 22.63 ranging from 11 to 35. Strut chordae showed interesting insertion with broad aponeurosis in 38.79% and large muscular flaps in 13.79%. Chordae muscularis were found in 14% and membranous chordae were found in 6%.Conclusions:This knowledge may prove useful for cardiologists and cardiac surgeons.

Background: Middle cerebral artery (MCA) is the larger terminal branch of the internal carotid artery. It travels through the Sylvian fissure on the insula. Objective: MCA supplies a large area of distribution than the other two cerebral arteries. Though it is so, there are very few articles in the literature describing MCA. Aim of the present work is to study the MCA regarding its origin, course, termination, branching pattern, morphometry and symmetry. Materials and Methods: 340 MCAs from 170 formalin preserved brains were dissected. Morphology, morphometry and symmetry of MCAs, were studied in detail and well photographed. The data collected in the study was analyzed. Results: Accessory MCA was found in seven specimens (2.05%). Duplicated MCA was seen in three specimens (0.88%). Aneurysm was found in three specimens (0.88%). MCA with bifurcated, trifurcated, quadrifurcated and single trunk termination was seen in 220 (64.70%), 42 (12.35%), 8 (2.35%), and in 70 (20.58%) specimens respectively. Bifurcated pattern as upper prominent trunk (type A), lower prominent trunk (type B) and both equal prominent trunks (type C) were seen in 63 (28.63%), 129 (58.63%), and 28 (12.72%) specimens respectively. Asymmetry was seen in 102 specimens (60%). Mean length and diameter of the MCA was 25.5-27.8 mm and 3 mm respectively. Conclusion: Awareness of these anatomical variations in branching patterns is important in neurovascular procedures. As very few Anatomical studies on MCA are there in the literature, this type of research work should be done by a number of scientists from a different region of the world in large scale.

Singapore Med J 2013; 54(1) : 44 O r i g i n a l A r tic le INTRODUCTIONA large proportion of the human population suffers from valvular heart diseases, leading to increased morbidity and mortality. These valvular diseases are most common on the left side. Dysfunction of the papillary muscles and chordae is also frequent. Both papillary muscle rupture and dysfunction can lead to mitral valve prolapse. Many operative procedures involving the papillary muscle, such as resection, repositioning and realignment, are carried out to restore its normal physiological function. Therefore, knowledge of the variations in the normal anatomy of the papillary muscles of the heart is crucial. METHODSA total of 116 formalin-preserved hearts of human cadavers were used in the study. The cadavers from whom the hearts were removed were of unknown age and unknown cause of death. The approximate age of the cadavers was 40-60 years. Hearts with gross morphological variations and those with diseased, fibrosed valves were excluded from the study.First, the hearts were washed and the cavity of the left ventricle was opened by taking a longitudinal incision along the left border, extending from the left auricle to the apex of the heart. The blood clots were removed and the chamber was washed with water in order to visualise the papillary muscles. The number, shape, position and pattern of the papillary muscles were noted and recorded. The method used in this study was comparable to that in the study of papillary muscles of the tricuspid valve complex by Skwarek et al, (1) who based their classification of the papillary muscles on that set out earlier by Grochowski,which was enriched with different papillary muscle types not described previously. Skwarek et al had used the concepts of 'multi-apical'and 'multi-segmental' papillary muscles.(1) In this study, papillary muscles that had a single base or a single apex were considered to be classical papillary muscles. Those with a single base and divided apex were categorised as multi-apical or multi-bellied, while papillary muscles with separate bases were considered multi-segmental or groups of papillary muscles. RESULTSThe number of papillary muscles found in the series was highly variable. Instead of the usual two papillary muscles, many groups of papillary muscles were found. The classical picture of papillary muscles -the presence of two papillary muscles in the left ventricle -was found in only four (3.44%) specimens (Fig. 1a).Two groups of papillary muscles were seen in 50 (43.11%) specimens (Fig. 1b), three groups in 37 (31.90 %) specimens (Fig. 1c), and four groups in 25 (21.55%) specimens (Fig. 1d). The variations in the number of papillary muscles are shown in Table I.Various shapes of papillary muscles were observed as wellconical ( Fig. 2a), broad-apexed (Fig. 2b), pyramidal ( Fig. 2c) and fan-shaped (Fig. 2d). The frequency of occurrence of these four