A reappraisal of pediatric abdominal surface anatomy

Surface anatomy is fundamental to clinical and surgical practices. As the surface anatomy varies with age, the purpose of this study is to provide age-standardized surface markings for the abdomen in children. A total of 155 abdominal computed tomography scans of healthy children aged 0–18 years were categorized into six groups, and the surface anatomy of the major vascular structures, solid viscera, and anatomical planes in the abdomen was analyzed. The vertebral levels of the celiac trunk, superior mesenteric artery, and hepatic portal vein formation were higher in the youngest age group, whereas the levels of the inferior mesenteric artery, formation of the inferior vena cava, and renal arteries did not differ with age. The right kidney lay between T12 and L3 and the left at T11-L3; however, both kidneys were in lower positions in younger children. The spleen was most commonly located between the 8th and 11th ribs except in toddlers. In all age groups, the hepatic portal vein formation was within the transpyloric plane and the aortic bifurcation was above the supracristal plane. In vivo reassessment of the surface anatomy enables the substantial variability of surface landmarks to be highlighted. This study demonstrates that taking account of age-related variations will increase the accuracy and therefore the clinical relevance of surface anatomy.     

Architecture and organization of mouse posterior parietal cortex relative to extrastriate areas

The posterior parietal cortex (PPC) is a multifaceted region of cortex, contributing to several cognitive processes, including sensorimotor integration and spatial navigation. Although recent years have seen a considerable rise in the use of rodents, particularly mice, to investigate PPC and related networks, a coherent anatomical definition of PPC in the mouse is still lacking. To address this, we delineated the mouse PPC, using cyto‐ and chemoarchitectural markers from Nissl‐, parvalbumin‐and muscarinic acetylcholine receptor M2‐staining. Additionally, we performed bilateral triple anterograde tracer injections in primary visual cortex (V1) and prepared flattened tangential sections from one hemisphere and coronal sections from the other, allowing us to co‐register the cytoarchitectural features of PPC with V1 projections. This revealed that extrastriate area A was largely contained within lateral PPC, that medial PPC overlapped with the anterior portion of area AM, and that anterior RL overlapped partially with area PtP. Furthermore, triple anterograde tracer injections in PPC showed strong projections to associative thalamic nuclei as well as higher visual areas, orbitofrontal, cingulate and secondary motor cortices. Retrograde circuit mapping with rabies virus further showed that all cortical connections were reciprocal. These combined approaches provide a coherent definition of mouse PPC that incorporates laminar architecture, extrastriate projections, thalamic, and cortico–cortical connections.