Sex variations in the structure of human atrioventricular annuli.

Atrioventricular annuli are important in haemodynamic flexibility, competence, and support for tricuspid and mitral valves. The anatomical features of the annuli, such as circumference, organisation of connective tissue fibres, myocardium, and cellularity, may predispose to annular insufficiency and valvular incompetence. These pathologies occur more commonly in females, although the anatomical basis for this disparity is unclear. Sex variation in the structure of the annuli is important in providing a morphological basis for the patterns of these diseases. This study therefore aimed to determine the sex variations in the structure of human atrioventricular annuli. One hundred and one hearts (48 males, 53 females) obtained from the Department of Human Anatomy of the University of Nairobi were studied. Annular circumferences were measured using a flexible ruler and corrected for heart weight. Results were analysed using SPSS version 17.0 and sex differences determined using student's t-test. A p-value of less than 0.05 was considered significant. For light microscopy, specimens were harvested within 48 hours post-mortem, processed, sectioned, and stained with Masson's trichrome and Weigert's elastic stain with van Gieson counterstaining. Females had significantly larger annular circumferences than males after correcting for heart weight (p ≤ 0.05). Histologically, myocardium was consistently present in all male annuli while this was absent in females except in one specimen. The annuli were more elastic and cellular in males especially in the annulo-myocardial and annulo-valvular zones, respectively. The corrected larger annular circumference in females may limit heart valve coaptation during cardiac cycle and may be a risk factor for valvular insufficiency. The predominance of myocardium, annular cellularity, and elasticity may be more protective against heart valve incompetence in males than in females.

The suprascapular notch: its morphology and distance from the glenoid cavity in a Kenyan population.

The morphology of the suprascapular notch has been associated with suprascapular entrapment neuropathy, as well as injury to the suprascapular nerve in arthroscopic shoulder procedures. This study aimed to describe the morphology and morphometry of the suprascapular notch. The suprascapular notch in 138 scapulae was classified into six types based on the description by Rengachary. The suprascapular notch was present in 135 (97.8%) scapulae. Type III notch, a symmetrical U shaped notch with nearly parallel lateral margins, was the most prevalent type, appearing in 40 (29%) scapulae. The mean distance from the notch to the supraglenoid tubercle was 28.7 ± 3.8 mm. This varied with the type of notch, being longest in type IV (30.1 ± 1.8 mm) and shortest in type III (27.3 ± 2.3 mm). The mean distance between the posterior rim of the glenoid cavity and the medial wall of the spinoglenoid notch at the base of the scapular spine was found to be 15.8 ± 2.2 mm. Type III notch was the most prevalent, as found in other populations. In a significant number of cases the defined safe zone may not be adequate to eliminate the risk of nerve injury during arthroscopic shoulder procedures, even more so with type I and II notches.

Morphometry and variations of bony ponticles of the atlas vertebrae (C1) in kenyans / Morfometría y variaciones de puentes óseos de la vértebra atlas (C1) en kenianos

Atlas bridges, the bony outgrowths over the third segment of the vertebral artery are associated with compression of the artery and nerves. There are limited studies comparing morphometry of the complete atlas bridges and that of the ipsilateral transverse foramen. Bilateral and gender differences in the morphometry of the complete bridges remain relatively unexplored. One hundred and two atlas vertebrae (49 male and 53 female) obtained from the Osteology Department of the National Museums of Kenya were used for this study. The presence of complete posterior atlas bridge (retroarticular canal) and lateral bridge (supratransverse foramen) was noted. Measurements were taken for the diameters of foramina, and the ipsilateral transverse foramina and their areas calculated. Complete posterior bridges occurred in 14.6 percent and 13.6 percent on the right and left sides respectively. The lateral bridge was found in 3.9 percent of the cases on the right side only. The complete posterior bridges had a cross-sectional area of 23.44mm2 on the right and 24.98mm2 on the left side. The lateral bridges had a mean cross-sectional area of 27.30mm2. The right and left transverse foramina had mean crosssectional area of 36.30mm2 and 37.20mm2 respectively, which was significantly larger than that of the ipsilateral complete and posterior bridges. The smaller dimensions of the complete atlas bridges compared to the ipsilateral transverse foramen suggest that they may predispose to vertebrobasilar insufficiency, Barre-Lieou and cervicogenic syndromes due to compression of the contents in the foramina.

Puentes del atlas, sobrecrecimientos óseos en el tercer segmento de la arteria vertebral se asocian con la compresión de la arteria y los nervios. Hay pocos estudios que comparan la morfometría de los puentes completos del atlas y el foramen transversal ipsilateral. Diferencias bilaterales y de género en la morfometría de los puentes completos permanecen relativamente inexplorados. Ciento dos vértebras atlas (49 hombres y 53 mujeres) obtenidos del Departamento de Osteología de los Museos Nacionales de Kenya se utilizaron para este estudio. Fueron identificados la presencia de puentes completos posteriores del atlas (canal retroarticular) y puentes laterales (foramen supratransverso). Se realizaron las mediciones de los diámetros del foramen y los forámenes transversos ipsilaterales, y se calcularon sus áreas. Puentes completos posteriores se observaron en el 14,6 por ciento y 13,6 por ciento de los lados derecho e izquierdo, respectivamente. El puente lateral se encontró en el 3,9 por ciento de los casos en el lado derecho solamente. Los puentes completos posteriores tuvieron un área transversal de 23,44mm2 en el lado derecho y 24,98mm2 en el lado izquierdo. Los puentes laterales tuvieron un área media de sección transversal de 27,30mm2. En los lados derecho e izquierdo se encontrron forámenes transversos con un área promedio de sección transversal de 36,30mm2 y 37,20mm2 respectivamente, lo que fue significativamente mayor que el de los puentes completos ipsilaterales y posteriores. Las dimensiones más pequeñas de los puentes atlas completos en comparación con los forámenes transversos ipsilaterales sugieren que pueden predisponer a la insuficiencia vertebrobasilar, síndromes de Barre-Lieou y cervical debido a la compresión de los contenidos en los forámenes.

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.

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.

Variations in the pattern of formation of the abdominis rectus muscle sheath among Kenyans / Variaciones en el patrón de formación de la vaina del músculo recto abdominal en kenianos

The pattern of formation of the human rectus sheath exhibits variations, it is not clear if these variations are population specific. This study aimed at describing the pattern of formation of the rectus sheath in a select Kenyan population. Formation of the rectus sheath was analyzed in eighty subjects (47 male, 33 female) during autopsies and cadaveric dissection. The anterior wall of the rectus sheath in all cases was aponeurotic and firmly attached to rectus abdominis muscle. The posterior wall of the rectus sheath was aponeurotic in 71 (88.5 percent) cases, the rest were musculoaponeurotic and only seen in males. In all cases the aponeurosis of internal oblique abdominis split into two lamina; a deep lamina that fused with the aponeurosis of transverses abdominis at the lateral border of rectus abdominis and a superficial lamina that fused with aponeurosis of external oblique abdominis mid-way between the medial and lateral borders of rectus abdominis muscle. The pattern of formation of the rectus sheath among Kenyans shows some variations which have not been reported by previous workers. Knowledge of these variations is important in surgery as this sheath is always incised when making most aabdominal incisions.

El patrón de formación de la vaina del músculo recto abdominal humano muestra variaciones, no está claro si estas variaciones son población-específicas. Este estudio tiene como objetivo describir el patrón de formación de la vaina del músculo recto del abdomen en una población seleccionada de Kenia. La formación de la vaina del músculo recto del abdomen se analizó en 80 sujetos (47 hombres, 33 mujeres) durante autopsias y disección de cadáveres. La pared anterior de la vaina del músculo recto en todos los casos era aponeurótica y firmemente unida al músculo recto abdominal. La pared posterior de la vaina del músculo recto era aponeurótica en 71 (88,5 por ciento) casos, las paredes restantes eran musculoaponeuróticas y sólo se observaron en varones. En todos los casos, la aponeurosis del músculo oblicuo interno del abdomen se dividió en dos láminas, una lámina profunda que se fusionaba con la aponeurosis del músculo transverso del abdomen en el borde lateral del músculo recto del abdomen y una lámina superficial que se fusionaba con la aponeurosis del músculo oblicuo externo del abdomen a mitad del recorrido entre los bordes medial y lateral del músculo recto del abdomen. El patrón de formación de la vaina del músculo 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 cirugía ya que esta vaina es seccionada en abordajes abdominales.

Sex variation in occurrence of myocardium in human mitral valve cusps / Variación del sexo en la aparición del miocardio en cúspides de la válvula mitral humana

Mitral valve cusps consist mainly of connective tissue and myocardium. Connective tissue fibres within the cusps have been demonstrated to exhibit sex variations in organisation. Mitral prolapse, a disease attributed to defects within the cusps occurs more commonly in females. Sex variations in valvular myocardium however remain to be studied. Possible variations in its organisation may enhance understanding of sex differences in prevalence of mitral prolapse. The aim of this study was to determine anatomical variations of mitral valvular myocardium by sex; by mean a comparative cross-sectional study. A total of 48 (27 male and 21 female) adult heart specimens obtained during autopsy at Nairobi City and Chiromo mortuaries after ethical approval were used. Valvular cusps were then harvested. Four ¡ millimetre sections were made at the area of maximum width for both anterior and posterior cusps. These were processed for paraffin-embedding and sectioning and stained with Masson's trichrome and Weigert's resorcin fuchsin with Van Gieson counterstain to demonstrate cardiac muscle, collagen and elastic fibres. Both anterior and posterior cusps demonstrated three histological laminae, that is, atrialis, fibrosa and ventricularis. Only lamina atrialis contained cardiac muscle. This lamina in males was characterised by a transversely oriented subendothelial myocardial strip while that in females contained compact longitudinal elastic fibres but no muscle. The presence of cardiac muscle in the lamina atrialis may be relatively protective against mitral valve prolapse in males compared to females.

Las cúspides de la valva mitral están constituidas principalmente por tejido conectivo y miocardio. Se ha demostrado que las fibras del tejido conectivo de las cúspides presentan diferencias en la organización según sexo. El prolapso mitral, una enfermedad atribuida a defectos en las cúspides es más frecuente en las mujeres. Las variaciones de sexo en el miocardio valvular sin embargo aún no se han estudiado. Las posibles variaciones en su organización puede mejorar la comprensión de las diferencias de sexo en la prevalencia de prolapso mitral. El objetivo de este estudio fue determinar las variaciones anatómicas del miocardio valvar mitral por sexo, por medio un estudio comparativo de corte transversal. Un total de 48 los especímenes de corazón adulto (se utilizaron 27 hombres y 21 mujeres), obtenidos durante autopsias en la ciudad de Nairobi y desde el depósito de cadáveres Chiromo, después de la aprobación ética. Las cúspides valvares fueron extraídas. Fueron realizadas secciones de cuatro milímetros en el parte más ancha de las cúspides anteriores y posteriores. Estas fueron procesadas por inclusión en parafina, corte y tinción con tricrómico de Masson y fucsina-resorcina de Weigert con contraste Van de Gieson, para demostrar la presencia de músculo cardíaco, fibras colágenas y elásticas. T.

Regional histomorphometry of the hepatic inferior vena cava; a possible sphincteric mechanism / Histomorfometría regional de la vena cava inferior hepática; un posible mecanismo de esfínter

This study was aimed at identifying the changes in diameter and structural composition of the Hepatic Inferior Vena Cava in its infrahepatic, intrahepatic and suprahepatic portions. Eighty adult liver specimens from the Chiromo and Nairobi City mortuaries were used for morphometry, while twenty of them were processed for light microscopy. A constriction was noted in the mid-portion of the HIVC, while structurally; the intrahepatic portion had thicker fibromuscular adventitia. It is plausible that these are sphincteric apparatus to prevent backflow of blood in the Hepatic Inferior Vena Cava.

Este estudio tiene por objetivo identificar los cambios en el diámetro y la composición estructural de la vena cava inferior hepática en sus porciones infrahepática, intrahepática y suprahepática. Ochenta hígados de especímenes adultos de los depósitos de cadáveres de la ciudad de Nairobi y Chiromo fueron usadas para morfometría, mientras que veinte de ellos fueron procesados para microscopía de luz. Se observó una constricción en el medio de la HIVC, mientras que estructuralmente, la porción intrahepática había una gruesa adventicia fibromuscular. Es posible que este sea un aparato esfinteriano para evitar el reflujo de sangre en la vena cava inferior hepática.

Anatomic position of the pterion among Kenyans for lateral skull approaches

The pterion is a point of sutural confluence seen in the norma lateralis of the skull where frontal, parietal, temporal and sphenoid bones meet. The position of the pterion exhibits population-based variations. Location of this point is important in surgical approaches to the anterior and middle cranial fossae. Specific measurements were taken on both sides of 90 (51 male, 39 female) Kenyan human skulls. The distances from the center of pterion to the frontozygomatic suture were 38.88+3.49 mm on the right side and 38.24+3.47 mm on the left side. The pterion was 30.35+3.40 mm and 30.34+4.34 mm above the mid point of the zygomatic arch on the right and left sides, respectively. Males had statistically significant higher pteria compared to females being 39.31+3.28 mm and 37.35+2.97 mm above the midpoint of the zygoma, respectively. Frontozygomatic suture and mid point of the zygoma can reliably be used in locating the pterion. This information may be useful in planning prior to surgery especially where neuronavigation devices equipments are scarce.

La pterion es un punto de confluencia sutural visto en la norma lateral del cráneo, donde se unen los huesos frontal, parietal, temporal y esfenoides. La posición del pterion exhibe variaciones en la población. La ubicación de este punto es importante en abordajes quirúrgicos a las fosas craneales anterior y la media. Mediciones específicas se han realizado en ambos lados de 90 cráneos humanos Kenyanos (51 varones, 39 mujeres). Las distancias desde el centro de pterion a la sutura frontocigomática 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 cigomático en los lados derecho e izquierdo, respectivamente. Los hombres presentaron un pterion estadísticamente significativo superior en comparación 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 frontocigomática y el punto medio del cigoma pueden ser utilizados como referencia fiables para localizar a el pterion. Esta información puede ser útil en la planificación previa a la cirugía, sobre todo cuando los equipos dispositivos de neuronavegación son escasos.

Gender-associated violence at a women's hospital in Nairobi, Kenya.

OBJECTIVE: To describe the pattern of gender-associated violence amongst adult survivors. DESIGN: Descriptive case analysis of prospectively collected data. SETTING: The gender violence and recovery centre (GVRC), a shelter and violence treatment facility for the gender-associated violence at the Nairobi Women's hospital (NWH). SUBJECTS: Data on 663 consecutive adult patients who presented to GVRC between February 2003 and April 2004 were evaluated. RESULTS: The patients age ranged from 18 to 74 years (mean 27.7 years). Four hundred and eight patients (61.5%) presented following sexual assault. Most of assaults were perpetrated at night. A stranger was the assault perpetrator in 75.1% and 2% of sexual and non-sexual assault respectively. An intimate partner was the perpetrator in majority (86.5%) of nonsexual violence. Most physical injuries were minor bruises and swellings. The rate of positive spermatozoa from high vaginal swabs was only 15.9% in cases of sexual assault. Sexual assault was significantly associated with single status of the victim and assault by more than one assailant. CONCLUSIONS: Violence against women is a common public health problem in the city of Nairobi. Women are vulnerable both in and out of the home. More efforts, including massive public education, are needed to protect this vulnerable population.