A preliminary study on the normal values of the thoracic Haller index in children.

OBJECTIVES: The Haller index (HI) is widely utilized as a quantitative indicator to assess the extent of the pectus excavatum (PE) deformity, which is the most common chest wall abnormality in children. Both preoperative correction planning and postoperative follow-up need to be based on the standard of normal thoracic growth and development. However, there is currently no established reference range for the HI in children. Consequently, the goal of this study was to conduct a preliminary investigation of normal HI values among children to understand thoracic developmental characteristics. METHODS: Chest computed tomography images obtained from January 2012 to March 2022 were randomly selected from the imaging system of the Children's Hospital of Chongqing Medical University. We divided the images of children into a total of 19 groups: aged 0-3 months (1 group), 4-12 months (1 group) and 1 year to 17 years (17 groups), with 50 males and 50 females, totaling 100 children in each group. HI was measured in the plane where the lowest point of the anterior thoracic wall was located and statistically analysed using SPSS 26.0 software. RESULTS: A total of 1900 patients were included in the study. Our results showed that HI, transverse diameter and anterior-posterior diameter were positively correlated with age (P < 0.05). Using age as the independent variable and HI as the dependent variable, the best-fit regression equations were HI-male = 2.047 * Age0.054(R2 = 0.276, P<0.0001) and HI-female = 2.045 * Age0.067(R2 = 0.398, P<0.0001). Males had significantly larger thoracic diameters than females, and there was little difference in the HI between the 2 sexes. CONCLUSIONS: The HI rapidly increases during the neonatal period, slowly increases during infancy and stops increasing during puberty, with no significant differences between the sexes.

Cirugías por traumatismo torácico: caracterización y variables asociadas a mortalidad / Thoracic trauma surgery: indications, findings and mortality associated variables

Resumen Introducción: El traumatismo torácico (TT) es la causa de aproximadamente un cuarto de las muertes por traumatismos. Los pacientes tratados con cirugía por traumatismo torácico (CTT) presentan un amplio espectro de características y pronósticos. Objetivos: Describir características clínicas, indicaciones, temporalidad, morbilidad, mortalidad y las variables asociadas a mortalidad en pacientes con CTT. Materiales y Método: Estudio observacional de pacientes tratados con CTT, período enero-1981 a diciembre-2019. Revisión de protocolos prospectivos de TT y base de datos. Se realizó regresión logística para variables asociadas a mortalidad. Se utilizó SPSS25® con prueba chi-cuadrado para comparar clasificación, tipo de TT y su distribución temporal, considerando significativo p < 0,05. Resultados: En total 808 casos (18,2%) de 4.448 TT requirieron CTT. Fueron hombres 767 (94,9%) y la edad promedio fue 31,5 ± 13,8 años. El traumatismo fue penetrante y por arma blanca en la mayoría de los casos. Fueron politraumatizados 164 (20,3%). La cirugía fue urgente en 474 (58,7%), precoz en 41 (5,0%) y diferida en 293 (36,3%) casos. La mortalidad global fue de 6,7% y fue significativamente mayor en TT contusos, politraumatizados y en cirugía urgente. La mortalidad fue 9,7% en CTT urgente, 4,9% en precoz y 2,0% en diferida (p < 0,001). Se observaron variables independientes asociadas a mortalidad. Conclusión: En nuestra serie, las CTT se realizaron principalmente en hombres jóvenes con TT penetrantes. Correspondieron a un grupo heterogéneo en cuanto a las indicaciones, hallazgos y lesiones intratorácicas y/o asociadas. Múltiples variables demostraron influir significativamente en la mortalidad de los pacientes tratados con CTT.

Background: Thoracic Trauma (TT) is the cause of approximately a quarter of trauma deaths. The patients who undergo Thoracic Trauma Surgery (TTS) present a wide spectrum of characteristics and prognosis. Aim: To describe clinical characteristics, indications, temporality, morbidity, mortality and mortality associated variables in TTS patients. Materials and Method: Observational study of TT hospitalized patients, period January-1981 to December-2019. A review of operation notes and database was done. A logistic regression for mortality associated variables was made. To compare classification, type of TT and its temporal distribution, SPSS25® with chi-square test was used, considering significant p < 0.05. Results: A total of 808 (18.2%) of 4.448 TT patients required TTS, 767 (94.9%) were men with average age: 31.5 ± 13.8. The trauma was penetrating trauma due to a stab in most cases, 164 (20.3%) were polytraumatized. The surgery was urgent in 474 (58.7%), early in 41 (5.0%) and delayed in 293 (36.3%) cases. The global mortality was 6.7% and was significantly higher in the blunt TT, polytrauma, urgent and early surgery patients. Mortality in urgent TTS was 9.7%, early 4.9% and 2.0% in delayed (p < 0.001). Independent variables associated with mortality were observed. Conclusions: In our series, TTS were performed mainly in young men with penetrating TT. The group was heterogeneous regarding surgical indications, findings and intrathoracic or associated injuries. Multiple variables showed to influence significantly on mortality in patients who underwent TTS.

Muscle-sparing thoracotomy: Anatomy and technique.

The thoracotomy incision is essential for many thoracic surgery procedures. A number of different variations exist, and different techniques can be used, depending both on the patient and on the technical factors. The muscle-sparing technique was first described by Noirclerc et al. in 1973. [1] Initially, it was thought that preservation of the muscular structures compared with the results of a traditional posterolateral thoracotomy, in which the latissimus dorsi and sometimes the serratus anterior are often divided, would benefit long-term outcomes.  However, subsequent study results  have not demonstrated any difference in postoperative outcomes. The unequivocal benefit of a muscle-sparing approach is to preserve the latissimus dorsi for any future intervention, such as a procedure involving the chest wall and the intrathoracic flaps. In this video tutorial, we describe our approach to this commonly used incision, including the anatomy and the technical aspects used to provide optimal operative exposure and minimal postoperative complications while preserving the underlying musculature.

Influence of chest conformation on ventricular-arterial coupling during normal pregnancy.

PURPOSE: There is still controversy regarding the changes of ventricular-arterial coupling (VAC) during normal pregnancy. The possible influence of chest shape on VAC during normal pregnancy has never been investigated. METHODS: Between October 2019 and June 2020, 59 healthy pregnant women (33.7 ± 4.4 years/old) were consecutively included. They underwent obstetric visit, modified Haller index (MHI) assessment, and complete echocardiographic evaluation with blood pressure measurement to assess arterial elastance (Ea), end-systolic elastance (Ees), and Ea/Ees as an index of VAC, at 12-14 weeks and 36-38 weeks gestation, then 6-9 weeks after delivery. RESULTS: VAC progressively increased from the first to the third trimester of pregnancy, then decreased in the postpartum (P < 0.0001) in the whole study population. Women with concave-shaped chest wall (MHI >2.5, n = 31) but not women with normal chest shape (MHI ≤2.5, n = 28) showed a progressive increase in VAC during normal pregnancy. Women with MHI >2.5 showed a significantly less pronounced increase in stroke volume index (SVi) from the first to the third trimester of pregnancy. There was a strong linear correlation between third trimester MHI and VAC (r = 0.93). CONCLUSIONS: Anatomical and/or extrinsic mechanical factors rather than impaired arterial elastance or reduced left ventricular contractility may contribute to changes in VAC during normal pregnancy in women with concave-shaped chest wall.

Lymphatic Pathways of the Thorax: Predictable Patterns of Spread.

OBJECTIVE. This article reviews thoracic lymphatic pathways and tributaries, discusses lymphatic anatomic variants and their clinical implications, and emphasizes common patterns of thoracic lymphadenopathy from extrapulmonary malignancies. CONCLUSION. Recognition of common patterns and pathways of thoracic lymphatic drainage can help identify the site of tumor origin and allow a more focused examination of disease extent, both of which are important for disease prognosis and management.

Sternalis is muscle: An anatomic variation and its clinical implications.

This report presents a case description of sternalis muscle which is an accessory muscle of anterior thoracic wall. A 56-year-old woman underwent mastectomy for breast cancer along with free flap reconstruction, revealing the presence of aberrant sternalis muscle. It was divided transversely during partial rib resection to expose internal mammary vessels. The case proceeded with successful flap transfer. Clinical implications of this anatomic variation is discussed. The authors conclude that plastic surgeons should be aware of this muscular anomaly.

The practicality of a two-incision surgical approach for hypoglossal nerve stimulator implantation.

INTRODUCTION: Determine the feasibility of a two-incision surgical approach to hypoglossal nerve stimulator implantation based on anatomic considerations. METHODS: Upper airway stimulation (UAS) using the Inspire system uses three implanted devices-the implantable pulse generator (IPG), stimulation lead and sensing chest wall lead. The traditional surgical approach requires three skin incisions located on the submandibular neck, anterosuperior chest wall and inferolateral chest wall. Our surgical team sought to determine the anatomic considerations of combining the two chest wall incisions into one. In order to minimize morbidity and reduce operative time, the chest wall sensing lead was placed posterolateral to the IPG site via the same incision. RESULTS: Using an adult cadaver for anatomical analysis, access to the third and fourth intercostal spaces was made more difficult by the pectoralis major humeral head and upper arm. The intercostal space was narrower, the musculature along the anterior axillary line and anterior chest wall was devoid of the innermost intercostal muscle group found more laterally. Furthermore, there were much thinner external and internal intercostal muscle components as they transitioned to a membranous layer anteriorly in comparison to the inferolateral chest wall. CONCLUSION: Lack of the innermost intercostal muscle and thinning of the external and internal intercostal muscles lateral to the IPG site leaves little barrier between the thoracic musculature and parietal pleural increasing the risk of complications such as pleurisy and pneumothorax. Given the anatomical findings, a two-incision surgical approach for UAS therapy is at higher risk for complications.

The Attachments of the Breast to the Chest Wall: A Dissection Study.

BACKGROUND: The anatomical descriptions of the attachments of the female breast to the chest wall vary in their structure, location, and terminology within the published literature. METHODS: A dissection study of the attachments of the breast to the chest wall was conducted on 18 female embalmed breasts in the coronal (n = 15) and sagittal planes (n = 3). RESULTS: Perimeter, posterior wall, and horizontal septum attachments were observed. The perimeter along its entire length was attached to the chest wall. Regional and anatomical variation was observed in this structure and location. Sharp dissection was required to remove it from the chest wall, in contrast to the blunt dissection required to remove the posterior wall and horizontal septum attachments. CONCLUSIONS: The breast attaches to the chest wall along its entire perimeter, posterior wall, and horizontal septum, with the perimeter functioning as the primary anchor of the breast to the chest wall. The structure of the perimeter attachment is both periosteal and fascial and requires sharp dissection to remove it from the chest wall. The fascial structures of the posterior wall and horizontal septum require blunt dissection only. The structure of the perimeter has regional variation, and its location on the chest wall has anatomical variation. Detailed anatomical descriptions and illustrations are supported by photographic evidence of cadaver dissections in two planes. Clinical and anatomical terminology are linked, with clinical implications for medical anatomy education, breast modeling, and breast surgery.

The pectoralis quartus and chondro-epitrochlearis combined muscle variation: description and surgical relevance

The authors describe a rare unilateral muscle variation in the thoracic wall combining the pectoralis quartus and chondro-epitrochlearis muscles. A routine dissection was performed in the upper right limb of a male adult cadaver with approximately 35-50 years of age, embalmed in formalin 10%. An accessory muscle, the pectoralis quartus, was identified and was associated with a tendon that was inserted in the medial humeral epicondyle, characteristic of the chondro-epitrochlearis muscle tendon. Such variations have significant clinical relevance to orthopedics, mastology, neural and vascular surgery, and other specialties, for surgical approaches in both the axillary and brachial regions.

Experimental Measurements of Ultrasound Attenuation in Human Chest Wall and Assessment of the Mechanical Index for Lung Ultrasound.

Knowledge of the acoustic attenuation characteristics of the chest wall is necessary to estimate the acoustic exposure at the pleural surface during lung ultrasound and is useful in the prediction of bio-effects (e.g., pulmonary capillary hemorrhage) and the development of safe, effective lung imaging. Currently, this property is not well characterized in humans. The aim of this work was to characterize ultrasonic attenuation in human chest wall such that the ultrasound exposures of the lung can be estimated for clinically relevant conditions. In this study, we experimentally measured ultrasound transmitted through the intercostal tissue of 15 human cadaver chest wall samples relative to ultrasound transmitted through saline to determine attenuation coefficients for each sample. A GE Vivid 7 diagnostic ultrasound machine (GE Vingmed, Horten, Norway) and 3 S and 5 S phased array probes were used at center frequencies from 1.6 to 5 MHz. The chest wall samples varied in thickness from 2.3-5.5 cm with a median thickness of 3.8 cm. The frequency-normalized attenuation coefficient was approximately 1.44 dB/cm/MHz based on a linear best fit through all attenuation measurements. Attenuation characteristics varied appreciably between samples, and the sample-averaged linear attenuation coefficient was 1.43 ± 0.32 (mean ± standard deviation) dB/cm/MHz. This attenuation is higher than that previously measured in mammalian chest wall samples (1.1-1.3 dB/cm/MHz for mice and rats) and is much greater than that used by the mechanical index (0.3 dB/cm/MHz). Mechanical index values calculated using saline values de-rated by 0.3 dB/cm/MHz were up to 1.2 MPa/MHz1/2 greater than those calculated using the measured through-tissue ultrasound waves. We conclude that the mechanical index overestimates exposures for lung ultrasound and thus may not be an appropriate dosimetry metric for pulmonary ultrasound.

Ultrasound-guided superficial serratus plane block in dog cadavers: an anatomical evaluation and volume dispersion study.

OBJECTIVE: To evaluate the anatomy of the serratus plane in dogs to establish the optimal landmarks for a superficial serratus plane (SSP) block and evaluate ropivacaine-methylene blue solution dispersion with three volumes of injection. STUDY DESIGN: Prospective experimental cadaveric study. ANIMALS: A formaldehyde solution-preserved dog cadaver and 15 frozen/thawed adult dog cadavers. METHODS: The thoracic wall of the formaldehyde-preserved cadaver was dissected. An SSP injection was performed on each hemithorax of the cadavers, with the ultrasound transducer placed over the fourth and fifth ribs, at the level of the shoulder joint. A needle was inserted in-plane in a caudocranial direction until it could be visualized between the serratus ventralis thoracis and latissimus dorsi muscles. Dog cadavers were injected with a ropivacaine-methylene blue solution at 0.3, 0.6 and 1.0 mL kg-1 and were dissected to determine the spread of the dye. RESULTS: The thoracic wall muscles identified in the formalinized cadaver were the cutaneous trunci, latissimus dorsi, external abdominal oblique, serratus ventralis thoracis, scalenus, serratus dorsalis cranialis and external intercostal. The nerves identified in the SSP included the lateral cutaneous branches of intercostal nerves, intercostobrachial nerves and long thoracic nerve. The solution was successfully injected at the SSP in 26 of 29 (89.7%) attempts. Dermatomal dye spread, median (range), was 4 (3-6), 4 (2-5) and 5 (4-8) for 0.3, 0.6 and 1.0 mL kg-1, respectively, with no significant difference among them. CONCLUSIONS AND CLINICAL RELEVANCE: Injections for an SSP block were easily performed under ultrasound guidance, using the fourth and fifth ribs at the level of the shoulder joint as reference landmarks. An injected volume of 0.3 mL kg-1 may be sufficient for hemithorax analgesia in dogs. Further studies in dogs are required to determine the utility of this technique.

Port Strategies for Robot-Assisted Lobectomy by High-Volume Thoracic Surgeons: A Nationwide Survey.

OBJECTIVE: Robot-assisted lobectomy is the fastest growing technique for pulmonary lobectomy, but the diversity of approaches has led to apprehension about port placement among learning surgeons. The aim of this study was to survey high-volume thoracic surgeons who perform robot-assisted lobectomy to understand and consolidate common themes of port placement. METHODS: An electronic online survey was created, and the link was emailed to the 100 highest volume robotic thoracic surgeons in the United States. The survey included an interactive graphical interface, which allowed each respondent to mark the preferential robotic port placement in the chest wall for each of the 5 pulmonary lobectomies. Results were analyzed individually and in aggregate. A heat map was generated to show trends. RESULTS: One hundred surgeons were surveyed (response rate: 62%). Most (90%) respondents utilized a 4-arm approach and 79% used a completely 4-arm portal approach with CO2 insufflation. Exact locations for each robotic port were reported by 60% of the surveyed surgeons and the results varied; however, most surgeons generally used the seventh to ninth interspaces for the camera and instruments. The use of multiple different interspace levels was common. Ninety-four percent of respondents used an additional nonrobotic assistant port. CONCLUSIONS: There is not a universal port strategy for robot-assisted lobectomy. However, placement of the camera and robotic ports low in the seventh to ninth interspaces is the most common approach. There are some nuances of stapling port strategies and sequence of port placement, which are identified.

Defining the shape of the scapulothoracic gliding surface.

PURPOSE: The aim of the study is to evaluate the difference in shape of the upper part and lower part of the Scapulothoracic Gliding Surface (STGS). METHODS: 3D-CT images of the thoracic cage of 50 patients were created in MIMICS ®. Three anatomical landmarks (insertion m. serratus anterior on 5th rib; transverse process of 2th and 7th vertebra) were used as an anteroposterior cutting plane to define the STGS. The upper part of the STG was defined as rib 2-5 and the lower part as 5-8. Next, in MATLAB ®, a script was used to create the sphere with best fit for upper and lower parts of STGS. The Root-Square-Mean Error (RSME) (mm) between two closest points on the fitted sphere and the STGS of both parts were calculated to determine the goodness-of-fit. RESULTS: The RSME was found to be significantly lower for the area ribs 2-5 (mean 7.85 mm, SD 1.86) compared the area of ribs 5-8 (mean 10.08 mm, SD 1.90). CONCLUSION: The STGS of the upper thoracic wall (2-5) is more spherical shaped than the STGS of the lower thoracic wall (rib 5-8).

Chest circumference in full-term newborns: how can it be predicted?

BACKGROUND: Although over the years a number of studies have used chest circumference (CC) as a sensitive tool to identify the health status of infants, a particularly important aspect for this population is the lack of data on normal values and prediction equations. In order to facilitate and validate the interpretation of CC data in newborn (NB), the aim was to study the relation between CC and other anthropometric variables and develop a predictive equation for CC in a population of full-term newborns. METHODS: Cross-sectional study, carried out with full-term infants. The anthropometric (CC, head circumference - HC, length, age and weight) and hemodynamic variables were evaluated during the first 24 h of life. Bivariate analysis was performed between CC and HC, weight, length and type of delivery, followed by multiple linear regression analysis, including variables that were significant in the bivariate analysis. For data analysis, we used the SPSS program, considering p < 0.05 and 95% CI. RESULTS: The birth weight of the 120 NB varied between 2580 and 4225 g (mean 3360 g) and the gestational age between 37 and 42 weeks (mean 39 weeks). Approximately 61% of the sample were delivered vaginally and 67 (56%) were boys. The variables that remained statistically associated with CC after multivariate analysis were weight (ß 0.003, CI: 0.002: 0.003, p = 0.001) and HC (ß 0.287, CI: 0.156: 0.417, p = 0.001). For the linear regression model, the predictive equation of CC was 14.87+ (0.003 x weight) + (0.287 x HC), with a prediction of 76%. CONCLUSION: The results show a positive correlation between CC and weight, length and HC, and based on the linear regression model, the predictive equation for CC is based only on weight and HC.

ThoraSite: A device to improve accuracy of lateral decompression needle and chest tube placement.

BACKGROUND: Multiple reports have detailed an unacceptably high error rate in the siting of decompression needles and tubes and describe associated iatrogenic injuries. The objective of the current study was to measure the accuracy of the novel ThoraSite template for identifying an acceptable intercostal space (ICS) for lateral needle or tube thoracostomy. METHODS: Two trained operators used the ThoraSite to place radiopaque needles in the left and right lateral chests of 12 cadavers. An independent radiologist reviewed fluoroscopy images to determine the primary outcome: the ICS in which each needle was placed. Secondary outcomes were ICS's palpable through ThoraSite's Safe Zone; needle placement relative to the anterior axillary line (AAL) and midaxillary line (MAL); and percent correct placement (defined as the third, fourth, or fifth ICS from 1 cm anterior to the AAL to 1 cm posterior to the MAL). RESULTS: The six female and six male cadavers spanned 4 ft and 11 inches (150 cm) to 6 ft and 7 inches (201 cm), 80 lb (36 kg) to 350 lb (159 kg), and 16 kg/m to 42 kg/m body mass index. All 24 needles were placed in either the third (4 [17%] of 24 needles), fourth (10 [42%] of 24 needles), or fifth ICS (10 [42%] of 24 needles). In 10 (42%) of 24 assessments, two ICSs were palpable in ThoraSite's Safe Zone. All palpable ICSs were either the third (8 [24%] of 34), fourth (15 [44%] of 34); or fifth ICS (11 [32%] of 34). Twenty-three (96%) of 24 needles were inserted from 1 cm anterior to the AAL to 1 cm posterior to the MAL. Twenty-three (96%) of 24 needle placements were correct. CONCLUSION: ThoraSite use was associated with needle placement in the third, fourth, or fifth ICS in an area roughly spanning the AAL to MAL in anatomically diverse cadavers. By facilitating appropriate needle/tube placement, ThoraSite use may decrease iatrogenic injuries. Future study involving representative users may be useful to further evaluate ThoraSite accuracy. LEVEL OF EVIDENCE: Therapeutic and care management, level IV.

[Scapula - friend and foe].

A well-functioning scapula provides a stable base for the humerus and allows free motion of the arm through a smooth glide over the posterior thoracic wall. This is possible through intimate interaction between anatomy and muscles. This can be disturbed by painful conditions, nerve dysfunctions, over-/underperformance of muscles, anatomic variations and trauma. In this review, we describe anatomy, biomechanics and different pathologies of the scapula: muscular imbalances, nerve dysfunctions, snapping scapula, tumours and fractures. We discuss, how the different conditions are diagnosed and treated.

Accessory muscles of the anterior thoracic wall and axilla. Cadaveric, surgical and radiological incidence and clinical significance during breast and axillary surgery.

BACKGROUND: The present study aims to summarise the accessory muscles of the anterior thoracic wall and axilla that can be encountered during breast and axillary surgery and record their incidence and clinical significance. Moreover, the laterality of the atypical muscles is highlighted and possible gender dimorphism is referred. Accessory anterior thoracic wall muscles include: Langer's axillary arch, sternalis muscle, chondrocoracoideus, chondroepitrochlearis, chondrofascialis, pectoralis minimus, pectoralis quartus and pectoralis intermedius. MATERIALS AND METHODS: The anatomical, surgical and radiological literature has been reviewed and an anatomical study on 48 Greek adult cadavers was performed. RESULTS: Literature review revealed the existence of accessory muscles of the anterior thoracic wall and axilla that have a significant incidence that can be considered high and may, therefore, have clinical significance. For the most common of these muscles, which are axillary arch (Langer's) and sternalis muscle, the cadaveric incidence is 10.30% and 7.67%, respectively. In the current cadaveric study, accessory thoracic wall muscles were identified in two cadavers; namely a bilateral sternalis muscle (incidence 2.08%) extending both to the anterior and posterior surface of the sternum and a left-sided chondrocoracoideus muscle (of Wood) (incidence 2.08%). CONCLUSIONS: Despite the fact that accessory anterior thoracic wall and axillary muscles are considered to be rare, it is evident that the incidence of at least some of them is high enough to encounter them in clinical practice. Thus, clinicians' awareness of these anatomical structures is advisable.

Analysis of multiple variations in azygos venous system anatomy with its classification: A cadaveric study

The azygos venous system varies greatly in mode of its origin, course, number of vertical channels, number of horizontal anastomoses and nature of termination. Anatomical knowledge of such variations is of immense importance in radiological investigations and surgical intervention of posterior mediastinum pathologies. The present study was undertaken on 30 adult embalmed cadavers aging between 40-65 years, to determine the anatomical variations of the azygos system and to classify accordingly. The vertebral level and diameter of the azygos, hemiazygos, accessory hemiazygos veins at their origin and terminations were also observed. The azygos system was classified into 3 types as per the Anson & McVay system: primitive (type I), transient (type II) and unicolumnar (type III). Type II was further subdivided into 5 subgroups (A to E) according to the number of retroaortic communications. Type I was observed in 1 case (3.33%), type II in 27 (90%) and type III in remaining 2 cases (6.67%). The vertebral level of termination of the azygos, hemiazygos, accessory hemiazygos veins were between T2 and T3, T6 and T10, T6 and T9 respectively. Variations in the formation of azygos system is not an uncommon phenomenon and these variations may easily mislead the radiologists while performing CT/MRI of posterior mediastinum or cardiothoracic surgeons while performing vascular surgeries in this region

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Describing the sternalis muscle: a new variant and an amended classification.

PURPOSE: With emphasis on the clinical setting, knowledge of anatomical variation decreases misdiagnoses and surgical complications. We report a previously undocumented variant of sternalis muscle and recommend an augmented classification scheme. METHODS: Dissection of the anterior thoracic wall on an 83-year-old female cadaver revealed bilateral sternalis muscles. The Snosek et al. classification system was referenced to describe the variant types. RESULTS: The right sternalis muscle has a single belly and can be classified using the Snosek et al. classification system as a simple type, right single. The left sternalis muscle presented with three muscle bellies, each having a unique pattern of superior attachments (heads). This variation is previously undocumented and requires a more detailed classification. CONCLUSIONS: We propose the addition of a new subtype of sternalis classification, as well as a modification to the Snosek et al. (Clin Anat 27:866-884, 2014) classification scheme, to include classification of different muscle bellies when multiple are present.

Standard and viscoelastic mechanical properties of respiratory system compartments in dogs: Effect of volume, posture, and shape.

In 9 anesthetized, paralyzed dogs lung and chest-wall standard (viscous resistance, Rint, and quasi-static elastance, Est) and viscoelastic parameters (resistance, Rvel, and time constant, τvel) were measured in the supine posture before and after rib-cage block, after application of an expiratory threshold load, and after 75° head-up tilting before and after wide chest opening. Lung and chest-wall τvel were the same under all conditions. Rvel was independent of volume and posture, and greater for the lung. Chest-wall Rint was independent of flow, volume, and posture. Lung Rint decreased with increasing volume. Chest-wall Rint, Est and Rvel increased with rib-cage block, allowing the assessment of both abdominal-wall and rib-cage characteristics. When chest opening did not elicit bronchoconstriction, the decrease of Rvel was ∼6%. Main conclusions: lung and chest-wall exhibit linear tissue viscoelasticity within the range studied; rib-cage and abdomen characteristics are similar, and asynchronous motion is not expected at physiological respiratory rates; in normal lungs, heterogeneity of parallel time constants plays a marginal role.