P.M. Mwachaka

Anatomic position of the asterion in Kenyans for posterolateral surgical approaches to cranial cavity.

The asterion, defined as the junction between lambdoid, parietomastoid, and occipitomastoid sutures, has been used as a landmark in posterolateral approaches to the posterior fossa. Its reliability however has been put into question due to its population‐specific variability in position, using external palpable landmarks and its relation to the transverse–sigmoid sinus complex. This study aimed at determining the anatomic position of the asterion in a Kenyan population. Measurements from the asterion to the root of zygoma and the tip of mastoid process, respectively were taken on both left and right sides of 90 (51 male, 39 female) human skulls. The relation of the asterion to the transverse–sigmoid sinus junction was also determined. The distances on the right and left sides from the asterion to the root of the zygoma were 58.85 ± 2.50 mm and 58.44 ± 2.12 mm, respectively. The asterion was 47.89 ± 3.72 mm above the tip of mastoid process on the right side and 47.62 ± 2.87 mm on the left side. This point was significantly higher in males (48.36 ± 2.72 mm) than in females (46.62 ± 3.37 mm) with a P‐value of 0.041. Regarding its position from the transverse–sigmoid sinus junction, it was at the junction in 72 cases, below it in 17 cases (average 3.68 mm) and only one case had the asterion above this junction (2.57 mm). The asterion therefore can reliably be ascertained using the parameters from the root of the zygoma and the tip of the mastoid process. The safest approach would be posteroinferior to the asterion so as to avoid lacerating the transverse–sigmoid sinus complex. Clin. Anat. 23:30–33, 2010.

Locating the Arcuate Line of Douglas: Is It of Surgical Relevance?

Ventral hernia formation is a common complication of rectus abdominis musculocutaneous flap harvest. The site and extent of harvest of the flap are known contributing factors. Therefore, an accurate location of the arcuate line of Douglas, which marks the lower extent of the posterior wall of the rectus sheath, may be relevant before harvesting the flap. This study is aimed at determining the position of the arcuate line in relation to anatomical landmarks of the anterior abdominal wall. Arcuate lines were examined in 80 (44 male, 36 female) subjects, aged between 18 and 70 years, during autopsies and dissection. The position of the arcuate line was determined in relation to the umbilicus, pubic symphysis, and intersections of rectus abdominis muscle. Sixty four (80.4%) cases had the arcuate line. In most cases (52), this line was located in the upper half of a line between the umbilicus and the pubic symphysis. Most males (93%) had the arcuate line, while more than a third of females did not have it. In all these cases, the line occurred bilaterally as a single arcade, constantly at the most distal intersection of the rectus abdominis muscle. Consequently, the arcuate line is most reliably marked superficially by the distal tendinous intersection of the rectus abdominis muscle. Harvesting of the muscle cranial to this point will minimize defects in the anterior abdominal wall that may lead to hernia formation. Clin. Anat. 23:84–86, 2010.

Anatomic Position of the Pterion among Kenyans for Lateral Skull Approaches

La pterion es un punto de confluencia sutural visto en la norma lateral del craneo, donde se unen los huesos frontal, parietal, temporal y esfenoides. La posicion del pterion exhibe variaciones en la poblacion. La ubicacion de este punto es importante en abordajes quirurgicos a las fosas craneales anterior y la media. Mediciones especificas se han realizado en ambos lados de 90 craneos humanos Kenyanos (51 varones, 39 mujeres). Las distancias desde el centro de pterion a la sutura frontocigomatica fue de 38,88+3,49 mm en el lado derecho y 38,24+3,47 mm en el lado izquierdo. El pterion fue ubicado 30,35+3,40 mm y 30,34+4,34 mm por encima del punto medio del arco cigomatico en los lados derecho e izquierdo, respectivamente. Los hombres presentaron un pterion estadisticamente significativo superior en comparacion con las mujeres, siendo de 39,31+3,28 mm y 37,35+2,97 mm por encima del punto medio del cigoma, respectivamente. La sutura frontocigomatica y el punto medio del cigoma pueden ser utilizados como referencia fiables para localizar a el pterion. Esta informacion puede ser util en la planificacion previa a la cirugia, sobre todo cuando los equipos dispositivos de neuronavegacion son escasos.

Variations in the pattern of formation of the abdominis rectus muscle sheath among Kenyans

El patron de formacion de la vaina del musculo recto abdominal humano muestra variaciones, no esta claro si estas variaciones son poblacion-especificas. Este estudio tiene como objetivo describir el patron de formacion de la vaina del musculo recto del abdomen en una poblacion seleccionada de Kenia. La formacion de la vaina del musculo recto del abdomen se analizo en 80 sujetos (47 hombres, 33 mujeres) durante autopsias y diseccion de cadaveres. La pared anterior de la vaina del musculo recto en todos los casos era aponeurotica y firmemente unida al musculo recto abdominal. La pared posterior de la vaina del musculo recto era aponeurotica en 71 (88,5%) casos, las paredes restantes eran musculoaponeuroticas y solo se observaron en varones. En todos los casos, la aponeurosis del musculo oblicuo interno del abdomen se dividio en dos laminas, una lamina profunda que se fusionaba con la aponeurosis del musculo transverso del abdomen en el borde lateral del musculo recto del abdomen y una lamina superficial que se fusionaba con la aponeurosis del musculo oblicuo externo del abdomen a mitad del recorrido entre los bordes medial y lateral del musculo recto del abdomen. El patron de formacion de la vaina del musculo recto del abdomen, entre los kenianos muestra algunas variaciones que no han sido reportadas en trabajos anteriores. El conocimiento de estas variaciones es importante en cirugia ya que esta vaina es seccionada en abordajes abdominales.

Features of atherosclerosis in the tunica adventitia of coronary and carotid arteries in a black kenyan population.

Introduction. Histologic changes which occur in the tunica adventitia during initiation, progression, and complications of atherosclerosis are seldom reported. This study aimed at describing the features of atherosclerosis in the tunica adventitia of two of the commonly afflicted arteries, namely, left anterior descending coronary and common carotid in black Kenyans. Materials and Methods. Specimens from 108 individuals [76 males and 32 females, mean age 34.6] were processed for paraffin embedding. Seven micron thick sections were stained with Masons trichrome and Haematoxylin/Eosin and examined with a light microscope. Results. Features of atherosclerosis were present in the tunica adventitia of 14.8% of left anterior descending arteries and 11.1% of common carotid arteries. Increase in adventitial thickness was associated with increased density of vasa vasora in 8.3% of both arteries. In the left anterior descending and common carotid arteries, 6.5% and 3.7% of cases, respectively, the tunica adventitia thickened without intimal hyperplasia. Conclusion. Features of atherosclerosis occur in the tunica adventitia of coronary and carotid arteries in over 10% of the black Kenyans studied. These features often precede the intimo medial changes. Tunica adventitia should therefore be prioritized in evaluation for atherosclerosis, in individuals at risk. This may enhance early detection and intervention.

Vasa Vasora in the Tunica Media of Goat Aorta

El objetivo de este estudio fue describir la distribucion de vasa vasora en la tunica media de diversas partes de la aorta de cabra, ya que esto influye en las propiedades fisicas y la aparicion de enfermedades. Las muestras se obtuvieron de 16 cabras machos adultos sanos (Capra hircus) desde la porcion ascendente del arco aortico, segmentos toracicos descendentes y de la parte abdominal de la aorta. Las muestras se fijaron en solucion de formol al 10%, y fueron sometidas a procesamiento de rutina para inclusion en parafina. Secciones de siete micras de grosor se tineron con reaccion tricromica de Masson. Vasa vasora estan presentes en la tunica media de todos los segmentos de la aorta. En los segmentos proximales, que localizan con islas de musculo que se encuentra en la mitad de la adventicia. Su densidad disminuye en sentido caudal, pero aun estan presentes en la tunica media, incluso en la parte abdominal de la aorta, donde el espesor es inferior a 0,5 mm y laminas elasticas menos de 29. Vasa vasora en la tunica media de la aorta de la cabra penetran en el medio luminal y estan presentes incluso en segmentos relativamente delgados. Esta medida, que puede mejorar la salud vascular, sugiere que la pared aortica de la cabra es muy activa, una caracteristica probablemente relacionada con la funcion de la bomba auxiliar de las islas del musculo en la pared aortica.