Morphology of the aortic arch branching pattern in raccoon dogs (Nyctereutes procyonoides, Gray, 1834)

BACKGROUND

Aortic arch (AA) branching patterns vary among different mammalian species. Most previous studies have focused on dogs, whereas those on raccoon dogs remain unexplored.

OBJECTIVES

The objective of this study was to describe the AA branching pattern in raccoon dogs and compare their morphological features with those of other carnivores.

METHODS

We prepared silicone cast specimens from a total of 36 raccoon dog carcasses via retrograde injection through the abdominal aorta. The brachiocephalic trunk (BCT) branching patterns were classified based on the relationship between the left and right common carotid arteries. The subclavian artery (SB) branching pattern was examined based on the order of the four major branches: the vertebral artery (VT), costocervical trunk (CCT), superficial cervical artery (SC), and internal thoracic artery (IT).

RESULTS

In most cases (88.6%), the BCT branched off from the left common carotid artery and terminated in the right common carotid and right subclavian arteries. In the remaining cases (11.4%), the BCT formed a bicarotid trunk. The SB exhibited various branching patterns, with 26 observed types. Based on the branching order of the four major branches, we identified the main branching pattern, in which the VT branched first (98.6%), the CCT branched second (81.9%), the SC branched third (62.5%), and the IT branched fourth (52.8%).

CONCLUSIONS

The AA branching pattern in raccoon dogs exhibited various branching patterns with both similarities and differences compared to other carnivores.

Anomalous origin of the right subclavian artery in a Neotropical otter (Lontra longicaudis, Olfers-1818)

The Neotropical otter (Lontra longicaudis) is a mustelid distributed geographically from Mexico to Argentina. Anomalous origins of the aortic arch branches are rarely reported in wild carnivorans. Therefore, this study aimed to report the anomalous branching of the aortic arch in one formaldehyde-fixed specimen of L. longicaudis. The aortic arch provided three branches: the bicarotid trunk and the left and right subclavian arteries. The latter passed dorsally to the esophagus toward the right side without a mark of compression at the esophagus. This is the first report of an anomalous origin of the right subclavian artery in L. longicaudis.

New findings of branching variations in subclavian arteries and supra-aortic arteries in Felis catus

The branching of blood vessels around the heart is varied in each animal. Three branching patterns of the brachiocephalic trunk in cats have been reported. However, supra-aortic arteries in the hearts of cats have never been investigated. In this study, we hypothesized that the variations of the aortic arch, supra-aortic arteries, and vena cava were observed in domestic cats. Sixty-one hearts obtained from the cadavers of domestic cats (Felis catus) were analyzed in terms of anatomical characteristics, size, and the length of these supra-aortic vessels by using a 3D scanner. New variations of the left and right subclavian arteries were observed using the location of the internal thoracic (ITA) and vertebral artery (VA) as the criterion to group the varying patterns. We found four patterns of the left subclavian artery, which included ITA budding contralateral before VA (5%), VA budding opposite to ITA (75%), VA budding contralateral before ITA (13%) and ITA budding ipsilateral before VA (7%). In contrast, only three patterns were found in the right subclavian artery, which included VA budding opposite to ITA (20%), VA budding contralateral before ITA (19%), and ITA budding contralateral before VA (61%). Moreover, although an average vascular diameter in male cats was higher than in female subjects, the supra-aortic blood volume in both sexes was not different. The findings of this study could help fill the existing gap of knowledge on the anatomical variations of supra-aortic arteries in cats and could be used in clinical applications based on relevant anatomical data.

A Quantitative Analysis of Four Undergraduate Human Anatomy Laboratory Curricula: Approaches, Identified Structures, Concepts, and Thematic Emphases

Human anatomy is a foundational course thatserves diverse pre-professional health care majors. However, limited information is available on the teaching approaches, content, and thematic emphases of this course at the undergraduate level when compared with that of medical and other graduate schools. Herein, we document and quantitatively evaluate the laboratory curriculum of four undergraduate human anatomy courses in the USA. For each course, we assess the total number of structures (terms requiring identification during an exam), concepts (terms requiring an explanation), and clinical applications. To facilitate further assessments, we also compare the content distribution of each course with that recommended by the American Association of Clinical Anatomists (AACA). Two courses followed a regional approach emphasizing the use of human cadavers, while the other two followed a system-based approach and used plastic models and non-human cadaveric materials (e.g., cats and sheep). The total amount of information presented to students differed significantly among curricula. The majority of terms (65-88%) taught to students referred to the identification of anatomical structures whereas clinical applications were rare (< 1.3%). Courses using a regional approach expected students to learn as much as twice the number of terms than those following a system-based approach. Functions, innervations, origins, and insertions of muscles are only included in the curriculum of the courses following a regional approach. The proportion of terms devoted to each anatomical module in all curricula was significantly different from each other, as well as from that of AACA recommendation. We discuss these differences in the curriculum, the challenges and limitations inherent with each teaching approach, as well as in the teaching materials used among the curricula. These quantitative analyses aim to provide insightful information about the structure of the undergraduate human anatomy laboratory curriculum and may prove useful when redesigning a course.