Bilateral high division of sciatic nerve

Sciatic nerve is the thickest nerve in the body formed by the sacral plexus from L4 to S3 in the lesser pelvis. It emerges through the greater sciatic foramen below the piriformis and enter the gluteal region. Then the nerve passes on the back of the thigh and at the level of superior angle of popliteal fossa it terminates by dividing into tibial and common peroneal nerve. The knowledge of anatomical variations in the division of nerve is important for various surgical and anaesthetic procedures. During routine dissection in the department of anatomy, Mysore Medical College & Research Institute, Mysore, a rare bilateral high division of sciatic nerve was observed in a female cadaver aged about 40 years. In the present case there was bilateral high division of sciatic nerve. The nerve was seen dividing into two branches before it emerges through the greater sciatic foramen. The tibial nerve was entering the gluteal region below the piriformis muscle and common peroneal nerve was entering by piercing the piriformis. The knowledge of this variation is important as the nerve may get compressed with surrounding anatomical structures resulting in non discogenic sciatica. The awareness of variations is important for surgeons during various procedures like fracture, posterior dislocation of hip joint and hip joint replacement. The anatomical variations are important during deep intramuscular injections in gluteal region and also for anaesthetists during sciatic nerve block

Morphometric features of asterion in adult human skulls

Background: Asterion is the meeting point of temporal, occipital and parietal bones on the posterolateral surface of skull and surgically an important point of reference for approaching the posterior cranial fossa structures. However surgeons have been skeptical about its reliability due to population based differences in its morphology, distance with other external landmarks and also to sigmoid and transverse sinuses.Methods: In this study 50 (27 male & 23 female) adult skulls were investigated to determine the type of asterion, its distance from important bony landmarks and also the nearby venous sinuses were measured.Results: Our study revealed that type II (absence of sutural bones) was commoner than type I (presence of sutural bones) asterion. The asterion was 4.82 ± 0.58 cm from tip of the mastoid process on the right side and 4.70 ± 0.70 cm on the left. It was greater in males than in females, p value being statistically significant (P = 0.00 & P = 0.02 for right & left sides respectively). The distance of asterion from supramastoid crest was 4.22 ± 0.73 cm on the right and 4.23+/-0.58 cm on the left. The distance in males was more than in females. The P value 0.00 was statistically significant on the right side. Regarding the position of the asterion in relation to transverse sinus, it was on the transverse sinus in 62% cases, below it in 32% and above in 6%.Conclusions: The data obtained shows that the asterion is located either at the level or below the level of the transverse sinus in majority of the cases. This information is useful to neurosurgeons to reduce the risk during posterior cranial fossa surgeries. This work will also be useful to anthropologists, forensic science experts for determination of sex of the skull along with other parameters.

Prevalence of anatomical variations of cystic artery in South Indian cadavers

Background: The knowledge of variations in the origin and course of cystic artery is important for the surgeons as uncontrolled bleeding from the cystic artery and its branches can be fatal during cholecystectomy. Intra operative bleeding can result in an increase in the risk of intra operative injury to vital vascular and biliary structures. Keeping in view the clinical significance and applied importance of the cystic artery anatomy and to add some more knowledge to the existing ones, the present study was undertaken, to know in detail the level of origin, length, and variations in the course and relation of the cystic artery.Methods: The present study was performed on 100 human liver specimens with intact gallbladder and extrahepatic duct system, obtained after dissection from the cadavers in the Department of Anatomy and from post-mortem cases from the Department of Forensic Medicine, Mysore Medical College and Research Institute, Mysore, over a period of 18 months.Results: Most common source of origin of the cystic artery was the right hepatic artery in 92 cases (92%) followed by aberrant right hepatic artery in 4 cases (4%) and the least common sources observed were the left hepatic artery in 1 case (1%) and the gastroduodenal artery in 1 case (1%).Mean length of the cystic artery was 17.6 mm and ranged between 3.7 mm to 42 mm. Out of the 100 dissected specimens, in 65 (65%) the cystic artery was found inside the Calot’s triangle and in 35 (35%) outside the triangle.Conclusion: This study provides details of the normal as well as the variant anatomy of the cystic artery, knowledge of which is very essential for the surgeons to minimize the risk of injury to the blood vessels and the biliary apparatus during cholecystectomy.