Women in late pregnancy experience an increase in collateral venous blood flow when lying supine, likely as a response to marked compression of the IVC in this position. However, cardiac output and aortic blood flow were found to decrease while in the supine position.

Accurate surface anatomy is essential for safe clinical practice. Numerous inconsistencies in clinically important surface markings exist between and within anatomical reference texts. The aim of this study was to investigate key thoracic surface anatomical landmarks in vivo using computed tomographic (CT) imaging. High-resolution thoracic CT scans from 153 supine adults (mean age 63, range 19-89 years; 53% female) taken at end tidal inspiration were analyzed by dual consensus reporting to determine the surface anatomy of the sternal angle, central veins, heart, lungs, and diaphragm. Patients with kyphosis/scoliosis, distorting space-occupying lesions, or visceromegaly were excluded. The position of the cardiac apex, formation of the brachiocephalic veins, and vertebral levels of the sternal angle, xiphisternal joint, and aortic hiatus were consistent with commonly accepted surface markings although there was a wide range of normal variation. In contrast, common surface markings were markedly inaccurate for the following: the position of the tracheal bifurcation, aortic arch, and azygos vein termination (below the plane of the sternal angle at T5-T6 vertebral level in most individuals); the superior vena cava/right atrial junction (most often behind the fourth costal cartilage); the lower border of the lung (adjacent to T12 vertebra posteriorly); and the level at which the inferior vena cava and esophagus traverse the diaphragm (T11 in most). Surface anatomy must be reappraised using modern imaging in vivo if it is to be evidence based and fit for purpose. The effects of gender, age, posture, respiration, build, and ethnicity also deserve greater emphasis.

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Surgical release of the lingual frenulum (frenotomy) has become an increasingly common procedure, performed from birth through to adulthood. Surprisingly, detailed anatomy of the in‐situ lingual frenulum has never been described, and no anatomical basis has been proposed for the individual variability in frenulum morphology. The lingual frenulum is frequently referred to as a “cord” or “submucosal band” of connective tissue, yet there is no evidence to support this anatomical construct. This paper aims to describe the anatomy of the in‐situ lingual frenulum and its relationship to floor of mouth structures. Fresh tissue microdissection of the lingual frenulum and floor of mouth was performed on nine adult cadavers with photo‐documentation and description of findings. The lingual frenulum is a dynamic structure, formed by a midline fold in a layer of fascia that inserts around the inner arc of the mandible, forming a diaphragm‐like structure across the floor of mouth. This fascia is located immediately beneath the oral mucosa, fusing centrally with the connective tissue on the tongue's ventral surface. The sublingual glands and submandibular ducts are enveloped by the fascial layer and anterior genioglossus fibers are suspended beneath it. Lingual nerve branches are located superficially on the ventral surface of the tongue, immediately deep to the fascia. The lingual frenulum is not a discrete midline structure. It is formed by dynamic elevation of a midline fold in the floor of mouth fascia. With this study, the clinical concept of ankyloglossia and its surgical management warrant revision. Clin. Anat. 32:749–761, 2019. © 2019 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.

Vertebral levels of key landmarks in the neck are well documented in anatomy texts but are they accurate? This study aimed to investigate the vertebral levels of the hard palate, hyoid bone, thyroid cartilage, cricoid cartilage, and bifurcation of the common carotid artery (CCA) using computed tomography (CT). After excluding patients with distorting pathology, 52 CT scans of the neck from supine adults with a standardized head position (mean age 63 ± 17 years, range 30-94 years; 21 female) were available for analysis by dual consensus reporting. Only the vertebral level of the hard palate (C1) was consistent with contemporary descriptions. Other landmarks were located most frequently at the following vertebral levels: the center of the body of the hyoid bone at C4 (54% of cases); the superior limit of the laminae of the thyroid cartilage at C4 in women (60%) and C5 in men (52%) (P = 0.02); the inferior border of the cricoid cartilage in the midline anteriorly at C6 in women (37%) and C7 in men (47%) (P = 0.008); and the bifurcation of the left and right common carotid arteries at C3 (left 56%, right 62%). The bifurcation of the CCA was a mean of 1.6 ± 1.2 cm above the superior border of the thyroid laminae. Vertebral levels of key bony/cartilaginous structures in the neck differ from standard descriptions but in the absence of a standardized cervical axial plane have limited value and clinical utility.