A detailed review of the spinal accessory nerve and its anatomical variations with cadaveric illustration

The spinal accessory nerve, considered part of the eleventh cranial nerve, provides motor innervation to sternocleidomastoid and trapezius. A comprehensive literature review and two cadaveric dissections were undertaken. The spinal accessory nerve originates from the spinal accessory nucleus. Its rootlets unite and ascend between the denticulate ligament and dorsal spinal rootlets. Thereafter, it can anastomose with spinal roots, such as the McKenzie branch, and/or cranial roots. The spinal accessory nerve courses intracranially via foramen magnum and exits via jugular foramen, within which it usually lies anteriorly. Extracranially, it usually crosses anterior to the internal jugular vein and lies lateral to internal jugular vein deep to posterior belly of digastric. The spinal accessory nerve innervates sternocleidomastoid, receives numerous contributions in the posterior triangle and terminates within trapezius. Its posterior triangle course approximates a perpendicular bisection of the mastoid-mandibular angle line. The spinal accessory nerve contains sensory nociceptive fibres. Its cranial nerve classification is debated due to occasional non-fusion with the cranial root. Surgeons should familiarize themselves with the variable course of the spinal accessory nerve to minimize risk of injury. Patients with spinal accessory nerve injuries might require specialist pain management.

Surface anatomical landmarks for spine surgery: A CT-based study of the sternal notch and sternal angle in 1,035 patients

BACKGROUND

Understanding the location of surface anatomical landmarks in relation to the cervical and thoracic spine is important for a wide array of clinical applications. The objective of this study was to investigate the influence of patient demographic and anthropometric characteristics on the locations of the sternal notch and sternal angle in relation to the spine using computed tomography (CT) of a large cohort of young adult patients without spinal pathology.

METHODS

Vertebral levels corresponding to the sternal notch and sternal angle were analyzed using CT of 1,035 patients. Influences of patient height, weight, body mass index (BMI), sex, and ethnicity were assessed.

RESULTS

567 male and 468 female patients were included in this study. Mean patient height, weight, BMI, and age were 1.68 ± 0.11 m, 81.94 ± 24.39 kg, 27.79 ± 7.9 kg/m2, and 25.9 ± 5.9 years. Of the 1,035 patients, 495 were Hispanic or Latino, 321 were Caucasian, 130 were African American, 68 were Asian, 5 were identified as "other," and 16 did not have racial or ethnic data available. The location of the sternal notch in relation to the thoracic spine demonstrated a bimodal distribution pattern clustered at the T2 and T3 vertebral bodies. The location of the sternal angle in relation to the thoracic spine demonstrated a bimodal distribution pattern clustered at the T4 and T5 vertebral bodies. Moderate, negative correlations were observed between patient weight and location of the sternal notch (r = -0.447; p <.001) and sternal angle (r = -0.499; p <.001), respectively. Zero significant correlations were observed between patient height and location of the sternal notch (r = -0.045; p =.377) or sternal angle (r = -0.080; p =.229). A weak, negative correlation was observed between patient BMI and location of the sternal notch (r = -0.378; p <.001). A moderate, negative correlation was observed between patient BMI and location of the sternal angle (r = -0.445; p <.001). The locations of the sternal landmarks did not differ based on patient sex, race or ethnicity.

CONCLUSIONS

The location of the sternal notch most frequently corresponds to the T2 or T3 vertebral body, while the sternal angle is most frequently located at the T4 or T5 vertebral body. Increased patient weight is associated with relatively cephalad sternal landmarks. Patient height, sex, and ethnicity are not associated with either sternal landmark.

Needs assessment of essential anatomy: The perspective of adult primary care resident physicians

Curricular development and modification involve first identifying a problem and then performing a needs assessment, which can guide the design of curricular components. Pedagogical changes, coupled with reductions in curricular time for gross anatomy, pose challenges and impose restrictions within medical school curricula. In order to make anatomy education effective and efficient, it is important to determine the anatomy considered essential for medical education through a targeted needs assessment. In this study, 50 adult primary care resident physicians in family medicine (FM) and internal medicine (IM) were surveyed to assess the importance of 907 anatomical structures, or groups of structures, across all anatomical regions from a curated list based on the boldface terms in four primary anatomy texts. There were no statistically significant differences in the ratings of structures between the two groups for any anatomical region. In total, 17.0% of structures, or groups of structures, were classified as essential, 58.0% as more important, 24.4% as less important, and 0.7% as not important. FM residents rated tissues classified as skeleton, nerves, fasciae, anatomical spaces, blood vessels, lymphatics, and surface anatomy (p < 0.0001) significantly higher than IM residents, but there were no differences in the rating of muscles or organs (p > 0.0056). It was notable that 100.0% of cranial nerves were classified as essential, and 94.5% of surface anatomy structures were classified as essential or more important. It is proposed that results of this study can serve to inform curricular development and revision.

The human clavicle's nutrient foramen's prevalence, number, location, and direction: A systematic review and meta-analysis

INTRODUCTION

The clavicle's nutrient foramen is a surrogate marker for its nutrient artery. Knowing its location may be useful for interpreting fractures and to avoid iatrogenic lesions. The aim of this review was to determine the prevalence, number, location, and direction of the nutrient foramen.

METHODS

Embase, Medline, PubMed, Scopus, and Web of Science were searched and supplemented by Google Scholar, hand-searching major anatomical journals, and the reference list of included studies (updated March 08, 2022). Titles and abstracts were screened for eligibility, and observational studies with quantitative data were included based on full text evaluation. Internal validity was assessed using the anatomical quality assessment tool. Pooled prevalence proportions were derived using a random effects DerSimonian-Laird model using the Freeman-Tukey double arcsine transformation with Miller's inverse back-transformation.

RESULTS

From 18,889 unique reports, 33 studies with 3760 clavicles and 3358 foramina were included. All studies suffered from untransparent reporting. The prevalence of the nutrient foramen was 97.75%, 95% confidence interval 94.70%-99.60%. It was mainly found as a single foramen on the middle third segment's posterior surface with acromial (lateral) obliquity. Results were stable over time, robust to sensitivity analyses, albeit limited by unexplained heterogeneity and asymmetry.

CONCLUSION

This review may aid in interpreting fractures passing through a high-risk area (mean foraminal index range 36.31-61.03%) for lesions to the nutrient artery. Practical implications are a need to update current inaccurate textbook descriptions and further advocate evidence-based anatomy to improve conduct and reporting of anatomical research.

A Scoping Review of Effective Teaching Strategies in Surface Anatomy

To become skilled physicians, medical students must master surface anatomy. However, the study of surface anatomy is less emphasized in medical and allied health science curricula, and the time devoted to direct engagement with the human body is limited. This scoping review was designed to answer one research question: "What are the elements and strategies that are effective in teaching surface anatomy?" The review was performed using a five-stage scoping review framework, including research question identification, relevant study identification, study selection, data charting, and result collating and reporting. Three databases were searched using two search terms combined with a Boolean operator: "teaching" and "surface anatomy." The initial pool of 3,294 sources was assessed for duplication, and study eligibility was evaluated using inclusion and exclusion criteria. Data were abstracted from 26 original articles by one researcher and verified by two other researchers. A thematic analysis was performed, and several elements of effective teaching strategies for surface anatomy were identified, namely contextualized teaching, embracing experiential learning, and learning facilitation. This review revealed that a multimodal approach was most commonly used in surface anatomy instruction. Hence, future research should explore the effectiveness of multimodal teaching strategies that adopt the three aforementioned primary elements of effective teaching in an authentic learning environment. It is pertinent to clarify the effectiveness of these teaching strategies by evaluating their impact on student learning, organizational changes, and benefits to other stakeholders.

Surgical applied anatomy: alive and kicking

BACKGROUND

Contention exists amongst anatomists, clinicians and surgeons about how much anatomical knowledge medical students need, although what is taught should be aligned with current surgical practice. The aim of this study was to explore the scope of recent advances in applied anatomy as highlighted in the ANZ Journal of Surgery in each of the surgical specialties.

METHODS

The 2018 volume of the ANZ Journal of Surgery was narrowed to 254 articles by applying the search term 'anatomy'. The main topic was extracted from each paper. The content of the paper was assessed for 'novel description' or 'novel application' of anatomical knowledge and classified accordingly.

RESULTS

Most papers with an anatomical focus were from general surgery, which focused on surgical techniques, outcomes and management. Vascular surgery had the highest percentage of papers with a novel description and application of anatomy. Although cardiothoracic and paediatric surgery had no papers with a novel description of anatomy, novel applications of anatomy were a focus in each speciality.

CONCLUSION

The trend towards novel applications of anatomical knowledge in all surgical specialties should encourage medical schools to shape their anatomy curricula in tandem with such advances as they evolve. The high proportion of novel applications and descriptions of anatomy in general surgery indicates continued growth as a benchmark of anatomical understanding. Vascular surgery's proportion of novel application and description of anatomy may change the way students will learn vascular anatomy to incorporate endovascular, radiologically based approaches.

Reappraisal of the classical abdominal anatomical landmarks using in vivo computerized tomography imaging

INTRODUCTION

With expanding scope of interventions it becomes mandatory to have correct and evidence-based knowledge of surface anatomy of internal abdominal structures. Information available in text books is derived from work done on cadaveric studies. Current study was designed to provide data of key abdominal surface anatomical landmarks and their variations in living subjects using CT imaging of adult population.

MATERIALS AND METHODS

Cross-sectional study was conducted using 100 abdominopelvic CT scans of patients of Indian origin.

RESULTS

Vertebral levels of origin of celiac trunk varied from T11 to L1/2 intervertebral disc, superior mesenteric artery from T12 to L2, inferior mesenteric artery from L2 to L4 and aortic bifurcation from L3 to L5. Origin of both renal arteries varied between T12 and L2 and the formation of inferior vena cava varied from L3 to L5. Vertebral levels of upper pole of both kidneys ranged from T11 to upper L3. Spleen was related to 9th to 11th ribs in 36% and 10th to 12th ribs in 34% scans. Most common vertebral levels of subcostal plane, planum supracristale and planum intertuberculare noticed were lower L2, L4 and lower L5, respectively.

CONCLUSIONS

Data derived from imaging investigations of living subjects and variations from the conventional descriptions observed in the current study might be helpful for clinicians.

Age-related changes in inguinal region anatomy from 0 to 19 years of age

Knowledge of the age-related changes in inguinal region anatomy is essential in pediatric urological and abdominal surgery, yet little is published. This study aimed to determine the position of inguinal region structures and growth of the surrounding pelvis and inguinal ligament in subjects from 0 to 19 years of age. Anonymized contrast-enhanced CT DICOM datasets of 103 patients (63 male: 40 female) aged from 0 to 19 years had left and right sides analyzed by three independent observers. Exclusion criteria were applied. Growth of the pelvis and inguinal ligament were determined using fixed bony reference points. The position of the deep inguinal ring and femoral vasculature were determined as ratio of inguinal ligament length, measured from the anterior superior iliac spine. Growth of the pelvis in vertical and horizontal dimensions and of the inguinal ligament followed a positive polynomial relationship with increasing age, with no observed increase in growth rate during puberty. From 0 to 19 years, the deep inguinal ring moved superolaterally with respect to the inguinal ligament (from 0.74 to 0.60 of the distance along the inguinal ligament) and the femoral artery and vein moved medially (from 0.50 to 0.58, and 0.61 to 0.65 of the distance along the inguinal ligament, respectively). The position of the femoral artery, vein, and deep inguinal ring followed a logarithmic relationship with age. No significant left:right side or male:female differences were observed. From 0 to 19 years of age the femoral vasculature and deep inguinal ring change position as the pelvis grows around them. Clin. Anat. 32:794-802, 2019. © 2019 Wiley Periodicals, Inc.

Apprasial of the surface anatomy of the Thorax in an adolescent population

Surface anatomy is considered a fundamental part of anatomy curricula and clinical practice. Recent studies have reappraised surface anatomy using CT, but the adolescent age group has yet to be appraised. Sixty adolescent thoracoabdominal CT scans (aged 12-18 years) were examined. The surface anatomy of the central veins, cardiac apex, diaphragmatic openings, and structures in relation to the sternal angle plane were analyzed. The results showed that the brachiocephalic vein (left and right) formed mostly posterior to the sternoclavicular joint. The superior vena cava formed close to the second costal cartilage, ±16.3 mm to the right of the midline. The apex of the heart was located in relation to the fifth intercostal space; ±78.6 mm to the left of the midline. The caval hiatus was in relation to T9 and T10; the esophageal hiatus was at T10; whereas the aortic hiatus was at T11. The sternal angle plane was in relation to the upper half of T5, which was also where the bifurcations of the trachea and pulmonary trunk were observed. The SVC/azygos vein junction and the concavity of the aortic arch were observed to be more than 10 mm superior to this plane. The results of this study further highlight the substantial variability of the surface anatomy between age groups. It also emphasizes the notion that surface anatomy is a dynamic variable and cannot be treated as a static observation. Clin. Anat. 32:762-769, 2019. © 2019 Wiley Periodicals, Inc.

The Inaccuracy of Surface Landmarks for the Anterior Approach to the Cervical Spine in Southern Chinese Patients

Study Design

Observational study.

Purpose

To assess the correlational accuracy between the traditional anatomic landmarks of the neck and their corresponding vertebral levels in Southern Chinese patients.

Overview of Literature

Recent studies have demonstrated discrepancies between traditional anatomic landmarks of the neck and their corresponding cervical vertebra.

Methods

The center of the body of the hyoid bone, the upper limit of the lamina of the thyroid cartilage, and the lower limit of the cricoid cartilage were selected as representative surface landmarks for this investigation. The corresponding vertebral levels in 78 patients were assessed using computed tomography.

Results

In both male and female patients, almost none of the anatomical landmarks demonstrated greater than 50% correlation with any vertebral level. The most commonly corresponding vertebra of the hyoid bone, the lamina of the thyroid cartilage, and the cricoid cartilage were the C4 (47.5%), C5 (35.9%), and C7 (42.3%), respectively, which were all different from the classic descriptions in textbooks. The vertebral levels corresponding with the thyroid and cricoid cartilage were significantly different between genders.

Conclusions

The surface landmarks of the neck were not accurate enough to be used as the sole determinant of vertebral levels or incision sites. Intra-operative fluoroscopy is necessary to accurately locate each of the cervical vertebral levels.

Surface anatomy of major anatomical landmarks of the neck in an adult population: A Ct Evaluation of Vertebral Level

To compare the projectional surface anatomy of healthy individuals in an adult population with those with a thyroid mass, using computed tomography (CT). Sixteen slice CT images of 101 individuals were analyzed using a 32-bit Radiant DICOM viewer to establish the relationships among major anatomical landmarks in the neck and their vertebral levels. The structures investigated included: hard palate (HP), hyoid bone (HB) including body and lesser horns, soft palate (SP), thyroid gland (TG) (both superior and inferior poles), thyroid gland anteroposterior (APD) and superoinferior (SID) diameters, thyroid isthmus (TI) superoinferior dimension, epiglottis, vertebral arteries (right and left), and both right and left parotid glands (superior and inferior extents). The vertebral levels noted most frequently were: body of hyoid bone (C4, 42.71%); lesser horns of hyoid bone (C3, 36.46%); thyroid gland superior pole (C6, 31.25%); and thyroid gland inferior pole (T2, 30.2%). TG-ID, TG-APD, and TG-SID were not significantly different between males and females in the healthy group; however, there was a significant gender difference in thyroid gland inferior diameter in the pathology group [males 2.16(±1.16) vs. females 3.37(±1.30), P = 0.01, paired sample t-test]. Further studies are needed to determine whether neck pathology in those with a thyroid mass affects the dimensions of the thyroid gland. Moreover, the surface anatomy of the neck should be revisited using modern imaging techniques to address inconsistencies in anatomy and clinical reference texts. Clin. Anat. 30:781-787, 2017. © 2017Wiley Periodicals, Inc.

A reappraisal of pediatric thoracic surface anatomy

Accurate knowledge of surface anatomy is fundamental to safe clinical practice. A paucity of evidence in the literature regarding thoracic surface anatomy in children was identified. The associations between surface landmarks and internal structures were meticulously analyzed by reviewing high quality computed tomography (CT) images of 77 children aged from four days to 12 years. The results confirmed that the sternal angle is an accurate surface landmark for the azygos-superior vena cava junction in a plane through to the level of upper T4 from birth to age four, and to lower T4 in older children. The concavity of the aortic arch was slightly below this plane and the tracheal and pulmonary artery bifurcations were even lower. The cardiac apex was typically at the 5^th intercostal space (ICS) from birth to age four, at the 4^th ICS and 5^th rib in 4-12 year olds, and close to the midclavicular line at all ages. The lower border of the diaphragm was at the level of the 6^th or 7^th rib at the midclavicular line, the 7^th ICS and 8^th rib at the midaxillary line, and the 11^th thoracic vertebra posteriorly. The domes of the diaphragm were generally flatter and lower in children, typically only one rib level higher than its anterior level at the midclavicular line. Diaphragm apertures were most commonly around the level of T9, T10, and T11 for the IVC, esophagus and aorta, respectively. This is the first study to provide an evidence-base for thoracic surface anatomy in children. Clin. Anat. 30:788-794, 2017. © 2017Wiley Periodicals, Inc.

Surface anatomy and anatomical planes in the adult turkish population

Surface anatomy and anatomical planes are widely used in education and clinical practice. The planes are largely derived from cadaveric studies and their projections on the skin show discrepancies between and within anatomical reference textbooks. In this study, we reassessed the accuracy of common thoracic and abdominopelvic anatomical planes using computed tomography (CT) imaging in the live adult Turkish population. After patients with distorting pathologies had been excluded, CT images of 150 supine patients at the end tidal inspiration were analyzed. Sternal angle, transpyloric, subcostal, supracristal and pubic crest planes and their relationships to anatomical structures were established by dual consensus. The tracheal bifurcation, azygos vein/superior vena cava (SVC) junction and pulmonary bifurcation were usually below the sternal angle while the concavity of the aortic arch was generally within the plane. The tip of the tenth rib, the superior mesenteric artery and the portal vein were usually within the transpyloric plane while the renal hila and the fundus of the gallbladder were below it. The inferior mesenteric artery was below the subcostal plane and the aortic bifurcation was below the supracristal plane in most adults. Projectional surface anatomy is fundamental to medical education and clinical practice. Modern cross-sectional imaging techniques allow large groups of live patients to be examined. Classic textbook information regarding anatomy needs to be reviewed and updated using the data gathered from these recent studies, taking ethnic differences into consideration.

The pediatric inguinal canal: Systematic review of the embryology and surface anatomy

The inguinoscrotal region is one of the most common areas operated on in pediatric surgery. Despite this, the surface anatomy of the pediatric inguinal canal is variably defined. The aim of the current systematic review is to evaluate the development and surface anatomy of the pediatric inguinal canal. A systematic review of inguinal canal anatomy in children was conducted using the electronic databases: Medline, PubMed, Scopus, and Google Scholar. Relevant anatomical measurements and relationships were reviewed. The anatomical structures forming the walls of the inguinal canal were identified in fetuses as early as 8-10 weeks gestation. No studies addressed the developmental basis of this early defect in the lower anterior abdominal. Later gonadal development and descent has a defined role. In vivo measurements of children carried out during open surgery are inconsistent. Some studies showed rapid growth velocity of the length of the inguinal canal up to 2 years of age (with height and growth of the bony pelvis) before plateauing, while others suggested no increase in canal length prior to 10 years of age. The position of the deep inguinal ring was equally unclear; some studies suggested this was medial to the midpoint of the inguinal ligament. No studies described the position of the superficial ring, challenging the assumption that the rings are superimposed in the neonate. The dearth of studies analyzing pediatric inguinal anatomy means that changes in the position of the rings with respect to the lengthening of the canal remain unclear.

Revisiting the surface anatomy of the sciatic nerve in the gluteal region in children using computed tomography

No anatomy text specifically describes the course of the sciatic nerve (SN) in the gluteal region in children. Anatomical information is largely derived from cadaveric studies of adults, so accurate anatomical information about the location of the SN in children is required. The aim of this study is to assess the surface anatomy of the SN in children using computed tomography (CT). After excluding studies with pelvic pathology, 75 CT scans were analyzed. Three groups were selected for analysis (0-2, 4-6, and 8-10 years). The position of the SN was measured between the posterior superior iliac spine (PSIS) and the ischial tuberosity (IT) and between the IT and the greater trochanter (GT) using 3-dimensional images. In the 0-2 age group, the SN crossed the middle third of a line between the PSIS and the IT in 94% and the GT and the IT in 80% of cases. In the 4-6 age group, the SN crossed the middle third of a line between the PSIS and the IT in 96% and the GT and the IT in 87%. In the 8-10 age group, the SN crossed the middle third of a line between the PSIS and the IT in 100% and the GT and the IT in 71%. The findings indicate that the SN in children is most accurately located in the middle third along a line drawn from the PSIS to the IT and the GT to the IT. Our study is the first to provide anatomical CT data from living children to guide interventions in the gluteal region.

The umbilicus: a reliable surface landmark for the aortic bifurcation?

PURPOSE

Anatomical surface landmarks are frequently used by clinicians to guide both diagnosis and treatment. Few studies have examined the reliability of vascular anatomical landmarks in living subjects. The umbilicus has traditionally been described as a surface landmark for the bifurcation of the abdominal aorta. This study examined the factors affecting the position of the umbilicus relative to that of the aortic bifurcation in 95 patients.

METHODS

106 consecutive abdominal CT scans were analysed by a surgeon and radiologist. Following exclusion of CT scans with relevant significant intra-abdominal pathology, 95 patients were included in the study. Measurements were taken of the craniocaudal distance between the aortic bifurcation and umbilicus, as well as maximum subcutaneous fat thickness at the level of the umbilicus. Patient age and gender were also documented.

RESULTS

The umbilicus was found to lie -6.3 ± 26.5 mm from the aortic bifurcation. Increasing subcutaneous fat thickness was associated with a more caudal position of the umbilicus relative to the aortic bifurcation. This result was highly statistically significant in males over 65 years old.

CONCLUSIONS

This study suggests that the umbilicus is a reliable clinical surface landmark for the bifurcation of the abdominal aorta. Whilst some variation in craniocaudal distance exists between patients, in the majority of cases, the bifurcation of the abdominal aorta lies within a clinically narrow range of distances from the umbilicus.

The translucent cadaver: a follow-up study to gauge the efficacy of implementing changes suggested by students

In a study conducted in 2011, the use of full body digital X-ray images (Lodox(®) Statscan(®)) and drawings were described for surface anatomy education during which suggestions were made by students on how to improve the method. Educational innovations should continuously be adjusted and improved to provide the best possible scenario for student learning. This study, therefore, reports on the efficacy of implementing some of these suggestions. Suggestions incorporated into the follow-up study included: (1) The inclusion of eight strategically placed labeled digital X-ray images to the dissection halls, (2) The placement of both labeled and unlabeled digital X-ray images online, (3) The inclusion of informal oral questions on surface anatomy during dissection, (4) The requirement of students to submit individual drawings in addition to group drawings into their portfolios, and (5) Integrating information on how to recognize anatomical structures on X-rays into gross anatomy lectures given prior to dissection. Students were requested to complete an anonymous questionnaire. The results of the drawings, tests and questionnaires were compared to the results from the 2011 cohort. During 2012, an increased usage of the digital X-rays and an increase in practical test marks in three out of the four modules (statistically significant only in the cardiovascular module) were reported. More students from the 2012 cohort believed the images enhanced their experience of learning surface anatomy and that its use should be continued in future. The suggested changes, therefore, had a positive effect on surface anatomy education.

Vertebral levels of key landmarks in the neck

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.

A reappraisal of adult thoracic surface anatomy

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.