The circulatory system and hormones
Frank J. Dye in Human Life Before Birth, 2019
In addition, a second partition arises from the wall of the atrial region of the heart, the septum secundum. This crescent-shaped partition has its limbs directed toward where the sinus venosus enters the atrial region of the developing heart. The initial opening of the septum secundum does not close. Rather, the edges of its opening provide a valvular mechanism for the foramen ovale (see Figure 15.4B). This valve is designed so that blood returning from the rest of the body will supply both atria. The necessity for this valve has to do with the flow of blood. In the adult, blood returns to the left atrium from the lungs. However, because of the underdeveloped nature of the lungs during prenatal existence, the lungs supply essentially no blood to the left atrium. Instead, blood is supplied to the left atrium from the right atrium via the foramen ovale. This provides the left atrium with a load to pump, which is necessary for its proper development.
Epistaxis
John C Watkinson, Raymond W Clarke, Louise Jayne Clark, Adam J Donne, R James A England, Hisham M Mehanna, Gerald William McGarry, Sean Carrie in Basic Sciences Endocrine Surgery Rhinology, 2018
The sphenopalatine foramen is the portal for the major arterial supply of the nasal cavity. Lateral to the foramen lies the pterygopalatine space. The foramen is formed by a U-shaped notch in the vertical portion of the palatine bone which is closed posterosuperiorly by the sphenoid bone. The foramen transmits the sphenopalatine artery, vein and the nasal palatine nerve (maxillary division of the trigeminal nerve). Clinically this foramen is the key to the procedure of endonasal endoscopic sphenopalatine artery ligation (ESPAL). Surgical localization of the foramen can be difficult. Bolger et al. studied a small bony projection which lies anterior to the foramen in 96% of cases.20 This landmark is called the crista ethmoidalis and its recognition during surgery may help in finding the foramen. The crista is variable in size but consistent in its position anterior to the artery and so it is a key landmark for the endoscopic surgeon (See Figure 106.8).
Vascular Assessment and Management
John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed in Paediatrics, The Ear, Skull Base, 2018
The vascular anatomy of the skull base is complex. It is important that the likely sources of arterial supply are considered thoroughly, together with any common anatomical variants and potential pathways of communication between the intra- and extracranial arteries, before embolization is attempted. As a general statement, any foramen, especially those carrying a cranial nerve, can be expected to contain a potential site of communication between these circulations. In addition, at each segmental level, residual metameric communications can be expected, particularly between the vertebral arteries and the ascending cervical, deep cervical, ascending pharyngeal and occipital arteries. Unless actively sought, these small vessels are easily overlooked, even on high-quality angiography. Even a small volume of embolic material in these vessels can lead to cranial nerve palsies or stroke. The operator should also be aware that in the course of embolization, as blood flow towards the target decreases, the direction of flow in collateral pathways may reverse and result in flow through extra- to intracranial anastomoses that were not evident on the initial angiogram. Repeated angiograms may have to be performed in the course of the procedure to exclude this possibility.
Secular trends in cranial chord variables: a study of changes in sexual dimorphism of the North Indian population during 1954–2011
Published in Annals of Human Biology, 2019
Vineeta Saini
Among skull elements, facial bones are the first to be destroyed, while the neurocranium (skull cap or vault) is usually recovered in good condition. In forensic anthropology several studies have been conducted on the foramen magnum (Uysal et al. 2005; Gapert et al. 2009; Ukoha et al. 2011), nasal (Joy et al. 2009; Oladipo et al. 2009) and orbital regions (Lidstone 2011; Jain et al. 2015) of the human skull. In spite of providing low classification accuracies regardless of the population, these anatomical regions are investigated abundantly in forensic anthropological studies. However, researchers have not given much consideration to the usefulness of chord measurements of the neurocranium (cranial vault) in sex classification, even though the chord variables are frequently examined to understand cranial abnormalities such as metopism in various populations (Bryce and Young 1917; Woo 1949; Baaten et al. 2003; Yadav et al. 2010) and Hominin evolution (Trinkaus 1984; Lieberman et al. 2002; Kimbel et al. 2004; Reynolds and Gallagher 2012).
Change in gene expression levels of GABA, glutamate and neurosteroid pathways due to acoustic trauma in the cochlea
Published in Journal of Neurogenetics, 2021
Meltem Cerrah Gunes, Murat Salih Gunes, Alperen Vural, Fatma Aybuga, Arslan Bayram, Keziban Korkmaz Bayram, Mehmet Ilhan Sahin, Muhammet Ensar Dogan, Sevda Yesim Ozdemir, Yusuf Ozkul
Control mice were sacrificed after the initial DPOAE measurements without being exposed to noise. Post-AT(1) mice and Post-AT(15) mice were sacrificed on day 1 and day 15 after the noise exposure, respectively. Under identical deep general anaesthesia, the mouse was decapitated with scissors. The skin of the head was dissected from posterior to anterior as far as the orbits. The dorsal skull was split from the foramen magnum to the orbits and cut laterally, posterior to the orbits, on both sides. The bony flaps were bent outward and the brain was removed afterwards. The bony labyrinths were recognized anterior to the foramen magnum in the base of the skull. The fibrous connections between the temporal bones and the rest of the skull were dissected and the temporal bones were separated from the skull on both sides. Next, the bulla was opened, and the cochlea was located under the microscope. Then, the malleus, incus and stapes were removed. While fixing the temporal bone with forceps, the bony wall of the cochlea was cracked with other forceps by holding between the oval and round windows and taken off piece by piece carefully. After peeling the bone all around the cochlea, membranous structures were removed completely and put in the Eppendorf Tube with 1 ml Trizol solution and mixed at room temperature until dissolving the content. Then they stored at −80 °C.
Detection and characterization of the accessory mental foramen using cone-beam computed tomography
Published in Acta Odontologica Scandinavica, 2018
Yihan Li, Xiangwen Yang, Bichu Zhang, Bin Wei, Yao Gong
The presence of the AMF was evaluated according to the following criteria:At least one additional buccal foramen, which was smaller than the ipsilateral MF in size, appeared on three-dimensionally reconstructed images of the mandible regardless of its location (Figure 1(a)).A bony canal, connecting the additional buccal foramen with the mandibular canal, was observed on axial images (Figure 1(b,c)) and coronal images (Figure 1(d)).Any additional buccal openings showing discontinuity with the mandibular canal were considered as nutrient foramina and excluded from the analysis.