Variant Anatomy and Its Terminology

Sciatic Nerve and Its Anatomical Variations: In-Depth Understanding Acquired During Dissection Classes

Knowledge of anatomical variability is extremely important in order to better understand the etiology of pain, if present, or to avoid iatrogenic consequences. Sometimes the anatomical "anomalies" have the same anamnesis but different causes. For example, sciatic neuralgia may be caused by a herniated disc or it may have a different origin. The sciatic nerve (SN), also known as the ischial nerve, is the widest in the human body. This huge peripheral nerve originates from the roots of the lumbosacral plexus (L4-S3) and passes through the great sciatic foramen, under the piriformis muscle (PM). However, there is much variability in the pattern of SNs about the muscle, which has been known since the first half of the 20th century. In the present study, we describe six different case reports of anatomical variations of the SN and its interplay with the PM. The observations were made during dissection classes at the ICLO Teaching and Research Centre (Verona, Italy), on both male and female cadavers aged between 58 and 84 years. The SN was reported as a single and divided nerve into the tibial nerve (TN) and the common peroneal nerve (CPN), passing alone above, below, or between the PM. However, the two parts of the SN may also interact with the PM in different ways, adding to the anatomical variability. A thorough knowledge of the anatomical variations in any part of the human body is extremely important. The various techniques used, from imaging to autopsy or surgery, are also useful in the SN pathway. Thus, the anatomical features and the understanding of each variation are useful for a correct approach that can lead to an effective and correct treatment with a favorable outcome.

Anatomical variation is the norm: A novel curriculum framework

Anatomical variation is an inherent part of every health curriculum, due in large to the negative clinical consequences that can ensue if anatomical variation is not thoroughly understood. However, current literature fails to describe any structured whole-of-course pedagogy for the teaching of anatomical variation in higher education. This study therefore aimed to (i) propose a whole-of-course curriculum framework to guide academic development and implementation of anatomical variation resources and assessment; and (ii) assess the depth of anatomical variation knowledge in a multiyear undergraduate health-science cohort (n = 152) at the Queensland University of Technology. Current anatomical variation pedagogy, and subsequently the need for the curriculum framework, were explored using a scoping review protocol. As part of this study, anatomical variation was novelly defined as macroscopic differences in morphology (shape and size), topography (location), developmental timing, or frequency (number) of an anatomical structure between individuals that form during embryological or subadult development and result in no substantive, observable interruption to physiological function. The framework incorporated three themes of anatomical variation learning outcomes: description of anatomical variation, theories of the professional implications of variation, and investigation of variant formation. These themes were strongly aligned with the concepts recommended for teaching identified through the scoping review. Significant deficits in anatomical variation student knowledge were identified, with the third-year cohort recording a mean total score of only 54.6%. A strong recommendation to implement the anatomical variation curriculum framework in all medical and health-science curricula is made to intentionally develop student understanding of anatomical variation and improve future clinical practice.

Regarding a human costoscapular joint by Prof. Dr. H. von Luschka (1870): A translation

Knowledge of variant anatomy was important during the time of Dr. Hubert von Luschka (1820-1875) and continues to be of relevance in current practice to prevent medical and surgical errors and to improve patient outcomes. Dr. H. von Luschka described an anatomical variant observed in the left scapula of a 40-year-old male: a connection between the medial superior angle of the scapula, piercing through the serratus posterior muscle to connect via a synovial capsule to the articular surface of the thoracic wall. The clinical relevance of this so-called "Luschka's tubercle" of the shoulder continues to be discussed. This translation is intended to broaden access to this hallmark manuscript to a wide audience of English readers. The introduction places the manuscript in the context of historical and current discussions. Three authors, all proficient in the German and English languages and educated in the anatomy of the shoulder, conducted the translation. The skeletal process that is part of the described joint structure appears similar to what is now called Luschka's tubercle. The full structure, including its connecting parts, are not currently included in anatomical nomenclature. In conclusion, Luschka's text and named tubercle continue to contribute to the discussion of scapulothoracic joint disorders.

Renal Artery Triplication: An Unusual Morphological Variant

Renal vasculature depicts great morphological variability and clinical significance due to the great number of procedures performed on kidneys. The current imaging report presents a right-sided renal artery (RA) triplication and origin from the abdominal aorta (AA), which was incidentally identified during computed tomography angiography (CTA). The typical RA corresponded to the main hilar artery (MHA), the second RA corresponded to the superior polar artery (SPA), and the third RA corresponded to the inferior polar artery (IPA). RA triplication occurs in 0.9%-4.5% and depicts wide morphological variability. The current report corresponds to one superior polar, one inferior polar, and a main hilar renal artery, which represents a rare morphological type of RA triplication. Kidney transplantation surgery, endoscopic surgery, and renal angiography require adequate knowledge of RAs and their variants to avoid pitfalls and iatrogenic lesions from clinicians.

Axillary arch (of Langer): A large-scale dissection and simulation study based on unembalmed cadavers of body donors

Connective or muscular tissue crossing the axilla is named axillary arch (of Langer). It is known to complicate axillary surgery and to compress nerves and vessels transiting from the axilla to the arm. Our study aims at systematically researching the frequency, insertions, tissue composition and dimension of axillary arches in a large cohort of individuals with regard to gender and bilaterality. In addition, it aims at evaluating the ability of axillary arches to cause compression of the axillary neurovascular bundle. Four hundred axillae from 200 unembalmed and previously unharmed cadavers were investigated by careful anatomical dissection. Identified axillary arches were examined for tissue composition and insertion. Length, width and thickness were measured. The relation of the axillary arch and the neurovascular axillary bundle was recorded after passive arm movements. Twenty-seven axillae of 18 cadavers featured axillary arches. Macroscopically, 15 solely comprised muscular tissue, six connective tissue and six both. Their average length was 79.56 mm, width 7.44 mm and thickness 2.30 mm. One to three distinct insertions were observed. After passive abduction and external rotation of the arm, 17 arches (63%) touched the neurovascular axillary bundle. According to our results, 9% of the Central European population feature an axillary arch. Approximately 50% of it bilaterally. A total of 40.74% of the arches have a thickness of 3 mm or more and 63% bear the potential of touching or compressing the neuromuscular axillary bundle upon arm movement.

Exploring the uncharted: Missing anatomical names in the Terminologia Anatomica

Effective communication and precise navigation within the intricacies of the human body rely on robust anatomical terminology. Since its creation by the Federative Committee on Anatomical Terminology (FCAT), the Terminologia Anatomica (TA 1998) has consistently served as the benchmark in the field. However, the constant advancement of anatomical knowledge requires regular revisions, updates, and enhancements of anatomical nomenclature to accommodate the latest scientific discoveries. The recent adoption of the second edition of Terminologia Anatomica (TA 2019) by the International Federation of Associations of Anatomists (IFAA) has drawn attention to certain notable omissions. Despite over a century of dedicated work establishing standard anatomical terminology, specific widely recognized gross anatomical structures are still absent from the official listing in the Terminologia Anatomica. There is, however, a consensus that the inclusion of names for trivial or variably present structures should be avoided. Accordingly, this article focuses on a thoughtfully selected group of anatomical structures, which are so important that they are routinely discussed during anatomy courses, despite their exclusion from the official lists of anatomical terms. These basic structures hold fundamental importance for both anatomy education and clinical practice. Consequently, their appropriate nomenclature warrants consideration for inclusion in future editions of TA.

Anatomical and physiological adaptation of the scrotal artery with muscular reinforcement in the middle layer and connective reinforcement of the adventitia

The histology of blood vessels shows they are structured in three layers or tunics: tunica intima, which includes the internal limiting lamina with high elastin content; tunica media of smooth muscles fibers of circular disposition, which includes the external limiting lamina; and tunica adventitia of connective tissue. The vascular system is essential in regulating body temperature, especially in the scrotum and testis. This study aimed to analyze the histology of the scrotal arteries and their possible relationship to testicular temperature homeostasis. This study used scrotal samples from human adults, anonymized and obtained from the University of Chile's teaching bank. The control group corresponds to an arteriole of muscle tissue. The results show that the middle layer of the scrotal artery is made up of smooth muscle fibers distributed in two layers: a longitudinal inner sublayer and a circular outer sublayer, different from the findings in muscle tissue arteries, with a single, circularly arranged muscle layer. This arrangement could be related to testicular temperature homeostasis by reducing the temperature of the testis and seminiferous tubules. The results described in this work suggest that these anatomical adaptations may be very significant in the face of the constant increase in global temperature. Further and better research is required to understand the mechanisms of thermoregulation in human reproduction and the histological particularities of the tissues that form the scrotum. RESEARCH HIGHLIGHTS: The human scrotal artery has a histological composition adapted for regulation of testicular temperature. The muscular double middle layer of the scrotal artery retains intravascular temperature.

The coracobrachialis muscle: typical morphology, accessory forms, and the issues with terminology

The coracobrachialis muscle (CB) represents one of the anterior arm compartment muscles. It has been defined by classic anatomy textbooks and old papers, as a muscle of one belly arising from the coracoid process tip and partially from the tendon of the biceps brachii short head, and inserted into the humeral shaft, above the bone's midpoint. However, recent cadaveric studies have confirmed that in the majority of cases, the CB is a two-headed muscle consisting of a superficial and a deep head. This finding has caused confusion regarding the terminology of CB's morphology. Typical CB morphology, according to recent data should not be considered the muscle of one belly, but the two-headed muscle. In particular, the musculocutaneous nerve's (MCN) course plays an important role in defining the CB morphological characteristics. If the MCN courses medially to the CB, with no signs of penetration after dissection, it can be concluded, that the CB is composed of one head; otherwise, if the muscle is composed of two or more heads, the MCN will courses between the CB bellies. In conclusion, it is of paramount importance to adopt common-universal terminology. Hence, considering recent findings, if the CB origin and/or the insertion differs from the typical anatomy, an "atypical CB" is the proper definition of the muscle, while if this "atypical CB" coexists with a typical CB, the terminology "accessory CB" may be used.

Is the promontory a promising site to diagnose otitis media in paleopathology? A search for evidence

OBJECTIVE

The promontory of the middle ear was recently suggested to be an appropriate site for diagnosing otitis media (OM) in archaeological bones by endoscopic inspection. The present study scrutinized the underlying assumption that a bulgy, irregular promontorial surface represents a pathological condition.

MATERIALS

We compared an allegedly healthy individual and an allegedly diseased individual in skeletal remains of two human individuals from the early Medieval period in Germany.

METHODS

The specimens were studied using microscopic analyses of thin ground sections.

RESULTS

The osseous architecture of the three-layered promontorial wall was the same in both specimens. Both the contour of the resorption front of the middle layer and the thickness of the overlying outer periosteal layer showed some variation, resulting in an either smooth or a bulgy promontorial surface, while signs of resorptive or proliferative changes at the periosteal surface were missing in both cases.

CONCLUSIONS

Our results suggest that an irregular promontorial surface represents normal variation in the development of the otic capsule rather than a pathological condition. We therefore conclude that the promontory is not an appropriate site for diagnosing OM in archaeological bone.

SIGNIFICANCE

The study contributes to evidence-based diagnoses in paleo-otological studies. Our assumption is in line with clinical and experimental findings indicating that the otic capsule is protected against bone remodeling.

LIMITATIONS

Only two specimens were studied.

SUGGESTIONS FOR FURTHER RESEARCH

SEM-studies to detect more subtle changes to the promontorial surface.

Exploring the inclusion of anatomical variation in medical education

The role of anatomical variability in safe clinical practice is underappreciated. A lack of familiarity of anatomical variations is at the center of a multitude of medical and surgical errors. The recent rise in litigation due to such errors suggests that patient care may be compromised. This makes the knowledge of anatomical variation essential to medical education. Empirical studies were identified by searching several databases and repositories, and the Medical Education Research Quality Instrument (MERSQI) was used to assess study quality. Eight studies were eligible for this systematic review; three of which were conference abstracts. Thematic summary of these studies yielded six themes namely: (1) importance of anatomical variation in medical education; (2) the ideal time to introduce anatomical variation in medical education; (3) important anatomical variations to include in medical education; (4) approaches to teaching anatomical variation; (5) assessing knowledge on anatomical variation; (6) barriers to including anatomical variation in medical education. Including anatomical variations in medical education would improve clinical reasoning and surgical outcomes. Following the completion of this review, three recommendations were made: (1) increasing the emphasis of anatomical variation in medical education; (2) developing more resources for anatomical variation education; (3) investigating the implications of lack of knowledge of anatomical variation in medical education through further research.

Assessment of Canalis Sinuosus located in maxillary anterior region by using cone beam computed tomography: a retrospective study

Background

The aim of the study is to determine the distribution, location, diameter, and distance measurements of Canalis Sinusosus (CS) in relation with age and sex.

Methods

300 Cone-Beam Computed Tomography (CBCT) images were evaluated. The distance between CS and nasal cavity floor (NCF), buccal cortical bone margin (BCM), alveolar ridge (AR), respectively.The presence of CS smaller than 1 mm, and the diameter of CS larger than 1 mm were determined. Accessory canals (AC) were classified according to their position relative to the teeth.

Results

435 CS with a diameter of at least 1 mm and 142 CS < 1 mm were identified. The most frequently observed location of CS was the region of the right central incisors. The mean diameter of the canals ( CS ≥ 1) was 1.31 ± 0.19 on the right side and 1.29 ± 0.17 on the left side. No gender differences were found in canal diameter were observed (p > 0.05). There was no significant difference between men and women in the distance between CS and the NCF on the right side, and a significant difference was found in the distance of CS-NCF on the left side (p = 0.047). There were no significant differences between age groups in all parameters.

Conclusion

CBCT is a useful tool for identifying CS. Location and diameter of ACs could not be associated with a specific age group or sex.

Atavistic and vestigial anatomical structures in the head, neck, and spine: an overview

Organisms may retain nonfunctional anatomical features as a consequence of evolutionary natural selection. Resultant atavistic and vestigial anatomical structures have long been a source of perplexity. Atavism is when an ancestral trait reappears after loss through an evolutionary change in previous generations, whereas vestigial structures are remnants that are largely or entirely functionless relative to their original roles. While physicians are cognizant of their existence, atavistic and vestigial structures are rarely emphasized in anatomical curricula and can, therefore, be puzzling when discovered incidentally. In addition, the literature is replete with examples of the terms atavistic and vestigial being used interchangeably without careful distinction between them. We provide an overview of important atavistic and vestigial structures in the head, neck, and spine that can serve as a reference for anatomists and clinical neuroscientists. We review the literature on atavistic and vestigial anatomical structures of the head, neck, and spine that may be encountered in clinical practice. We define atavistic and vestigial structures and employ these definitions consistently when classifying anatomical structures. Pertinent anatomical structures are numerous and include human tails, plica semilunaris, the vomeronasal organ, levator claviculae, and external ear muscles, to name a few. Atavistic and vestigial structures are found throughout the head, neck, and spine. Some, such as human tails and branchial cysts may be clinically symptomatic. Literature reports indicate that their prevalence varies across populations. Knowledge of atavistic and vestigial anatomical structures can inform diagnoses, prevent misrecognition of variation for pathology, and guide clinical interventions.

Morphological Peculiarities of the Pelvic Autonomic Nervous System and Their Impact on Clinical Interventions in the Lesser Pelvic Region

Background: The aim of the work is to define the morphological peculiarities of the pelvic autonomic nervous system (ANS) and their importance in the clinical and surgical interventions in the lesser pelvis. Material and methods: Anatomical variations in the formation of the pelvic ANS were observed in 20 cadavers. The study included 17 men (85%), aged 18 to 84, and 3 women, aged 27 to 86. The average age was 53.8 years. The subjects most often died by violent death in car accidents, by asphyxia, or by sudden death. The study was approved by the Ethics Committee of the Health Care Surveillance Authority, Bratislava, Slovakia. We studied cadavers without congenital or detected anomalies, cancer, deformities of the body, or spinal or abdominal surgeries within 24 h of death. We observed a relationship between the dimensions and the number of ganglia, as well as the number and course of nerve branches and anastomoses. In the pelvic area, we observed the hypogastric plexus superior, hypogastric plexus inferior, and the truncus sympathicus. In all cadavers, we clarified the lumbosacral plexuses after evisceration. In the lumbosacral region, the roots were defined based on their participation in the formation of the plexuses. To show the intimate relationship between both systems, we also focused on the details of the structure (rami communicantes) related to the connections of the ANS with the spinal nervous system. Results: Anatomical variations in the formation of the pelvic ANS were observed in all cases. We included cases with more than two truncus sympathicus ganglia as the segmental type. The segmental form occurred in 14 (70%) cases, and was concentrated in 6 (30%) cases. Rami communicantes provided anastomoses to the spinal nerves. Small ganglia were observed on the rami communicantes. With the concentrated type, we observed the division of the sympathetic and parasympathetic systems. With the segmental and concentrated forms, symptoms of the "diffuse form" may occur, which we observed in all cases. We observed significant right-left asymmetry and differences in the formation of ganglia and anastomoses. Conclusions: This study allowed us to identify and describe the morphological peculiarities of the pelvic ANS and their possible influence on the clinical picture. Asymmetry and dependence of their occurrence on the type of ANS was observed. The variations were frequent. Their preoperative diagnosis is difficult to impossible. The absence or lack of intraoperative vigilance can lead to the damage of pelvic ANS during operations and blockades of the pelvic plexus. The acquired knowledge can be helpful in clarifying clinical signs and symptoms of these conditions.

VARIATIONS OF THE STRUCTURE, TOPOGRAPHY, BLOOD SUPPLY AND INNERVATION OF THE BRACHIORADIALIS IN HUMAN FETUS

OBJECTIVE

The aim of the research was to establish the features of age-related and individual anatomical variability of the brachioradialis, its blood supply, and innervation options.

PATIENTS AND METHODS

Materials and methods: The study of the variant anatomy of the brachioradialis and its vascular and nervous structures was carried out on 25 preparations of human fetuses of 4-7 months, 81.0-270.0 mm parietal-coccygeal length (PCL) using macromicroscopic preparation, injection vessels, and morphometry.

RESULTS

Results: Spindle-like (56%) and round (24%) shapes of the brachioradialis were found in most of the studied fetuses; its elongated flat (12%) and triangular (8%) forms occur less often. In a fetus of 185.0 mm TKD, the right brachioradialis consisted of two separate parts: upper and lower, which were connected at the level of the middle of the forearm into a common short muscle belly. In another human fetus of 220.0 mm TKD, the right brachioradialis also consisted of two separate parts - upper and lower, triangular in shape, but separated by a pronounced horizontal gap.

CONCLUSION

Conclusions: The features of the fetal anatomy of the brachioradialis are established: its variability and bilateral asymmetry of shape and size, variability of the places of origin and attachment, etc. In individual human fetuses, the brachioradialis consists of two separate parts that have special topographical relationships. The area of the greatest concentration of both extra- and intramuscular nerves and arteries is the upper and middle third of the brachioradialis. In the area of the forearm, the course of radial vascular-nerve formations is determined by the brachioradialis.

Osseous variability around the elbow joint

There are many osseous variants that occur around the elbow joint such as supracondylar process, supratrochlear foramen, accessory ossicles, and others. Scientific databases were searched for variants around the elbow joint. Elbow radiographs from our center demonstrating some of these findings were included in the study. The aim of the present review was to provide comprehensive information on the terminology, prevalence, history, etiology, and clinical importance of these variants. These anatomical variants are important for radiologists while interpreting radiographs, computed tomography, and magnetic resonance imaging for trauma and orthopedic surgeons during osteosynthesis at the distal humerus, proximal ulna, and radius.

Bilateral absence of subclavius muscles with thickened costocoracoid ligaments: a case report with the clinical-anatomical correlation

Anatomical variation is defined as normal flexibility in the topography and morphology of body structures. Such variations are not uncommon in muscles, particularly in the upper limb. Subclavius muscle (SM) has a proximal attachment to the first costochondral junction and the muscle fibers are then directed upwards and laterally to get attached distally to the subclavian groove of the clavicle. Having similar attachments as the subclavius, the costocoracoid ligament (CCL) is the thickening of the proximal part of clavipectoral fascia extending up to the coracoid process. Both SM and CCL help in the maintenance of smooth movements of the pectoral girdle and both may not always be present. Absent SM may be due to anomalous development from the muscle matrix that also forms the inferior belly of the omohyoid apart from the SMs. This anatomical variation may be associated with thickened CCLs and can be correlated to the smooth functioning of the pectoral girdle.

Measuring Terminology Consistency in Translated Corpora: Implementation of the Herfindahl-Hirshman Index

Consistent terminology can positively influence communication, information transfer, and proper understanding. In multilingual written communication processes, challenges are augmented due to translation variants. The main aim of this study was to implement the Herfindahl-Hirshman Index (HHI) for the assessment of translated terminology in parallel corpora for the evaluation of translated terminology. This research was conducted on three types of legal domain subcorpora, dating from different periods: the Croatian-English parallel corpus (1991–2009), Latin-English and Latin-Croatian versions of the Code of Canon Law (1983), and English and Croatian versions of the EU legislation (2013). After the terminology extraction process, validation of term candidates was performed, followed by an evaluation. Terminology consistency was measured using the HHI—a commonly accepted measurement of market concentration. Results show that the HHI can be used for measuring terminology consistency to improve information transfer and message understanding. In translation settings, the process shows the need for quality management solutions.

Anatomical variations of the ethmoid sinuses and their association with health or pathology of the ethmoid and maxillary sinuses in a Southern Chinese population: An analysis using cone-beam computed tomography

Purpose

The aim of this study was to evaluate the prevalence of clinically relevant anatomical variations of the ethmoid sinuses and their potential association with ethmoid and maxillary sinus pathologies on cone-beam computed tomography (CBCT) scans. Additionally, potential associations with different sides and demographic factors, including age and sex, were evaluated.

Materials and Methods

In total, 273 CBCT scans with complete ethmoid and maxillary sinuses were analyzed to determine the prevalence of Agger nasi cell, supraorbital ethmoid cell, Haller cell, Onodi cell, and ethmomaxillary sinus. In addition, the health or pathology of the ethmoid and maxillary sinuses was also recorded to assess correlations with the aforementioned variations.

Results

The prevalence of Agger nasi cell was found to be the highest (95.6%) in this study, followed by Onodi cell (60.4%), Haller cell (29.3%), and supraorbital ethmoid cell (19.4%). Ethmomaxillary sinus was the least common finding (16.5%). Males and persons above 61 years of age had a significantly higher frequency of supraorbital ethmoid cell and Onodi cell, respectively. However, no significant relationships were noted between anatomical variations of the ethmoid sinus and pathologies of the ethmoid or maxillary sinus.

Conclusion

There was a high prevalence of ethmoid sinus variations in this Southern Chinese population. The prevalence of Agger nasi cell and Onodi cell was higher than that of other anatomical variations of the ethmoid sinuses. Anatomical variations of the ethmoid sinuses were not associated with ethmoid or maxillary sinus pathologies in this patient cohort.

Anatomical variations of the thoracic duct in the dog

Anatomical variations can be frequently found in the lymphatic system, which is also true for the shape and course of the thoracic duct (ductus thoracicus), the biggest lymph vessel in the body. From 2012 to 2019, the thoracic duct was successfully dissected in 43 dog carcasses that were used in the anatomy course at the Faculty of Veterinary Medicine, University of Zagreb. The thoracic duct originated from the cranial border of the cisterna chyli as one lymph vessel in 36 dogs (83.7%), as two vessels in six dogs (14%) and as three vessels in one dog (2.3%). We divided the observed thoracic duct variations into six groups according to their anatomical similarities. Considering the specific embryonic development, we can conclude that all observed variations are the result of minor deviations from the standard ontogenesis. However, the importance of thoracic duct variations is significant in surgical procedures done in the thoracic cavity to prevent or cure the chylothorax. Since this research showed variations in 39 out of 43 dogs (90.7%) throughout the whole course of the thoracic duct, great care must be taken while performing the ligation or embolization of the thoracic duct.