Mixed Reality Anatomy Using Microsoft HoloLens and Cadaveric Dissection: A Comparative Effectiveness Study.

PURPOSE: As the amount of curricular material required of medical students increases, less time is available for anatomy; thus, methods to teach anatomy more efficiently and effectively are necessary. In this randomized controlled trial, we looked at the effectiveness of a mixed reality (MR) device to teach musculoskeletal anatomy to medical students compared with traditional cadaveric dissection. METHOD: Participating students were divided into three cohorts. Cohort 1 first studied upper limb anatomy in MR followed by lower limb anatomy through cadaveric dissection. Cohort 2 studied upper limb anatomy with cadaveric dissection followed by lower limb anatomy in MR. After the six sessions, a third cohort of 33 students who never received any teaching in MR was recruited to participate in the final practical exams as a control group. All 64 students completed two practical exams with equivalent content, one in the cadaver lab and one using MR. RESULTS: The average scores were 73.8% + 12.3 on the cadaver exam and 74.2% + 13.0 in MR. There is no statistical difference between these scores (p > 0.05). A correlation was found between the MR practical exam and cadaver practical exam scores (r = 0.74, p < 0.01) across all students. CONCLUSIONS: To our knowledge, this study marks the first time that MR was compared with traditional anatomy learning modalities in a multi-session, group course. Our results clearly indicate that medical students, regardless of the study modality, performed similarly on the MR and the cadaver practical exams.

GARLA: Integrating Traditional and Modern Methodologies in Anatomy Education.

GARLA is an anatomy curriculum that combines dissection with applied anatomy. A two-week intensive dissection Boot-Camp is followed by a tripartite curriculum consisting of Gross Anatomy using a mixed reality headset, radiology, and physical exam/ultrasound skills. Student feedback has generally been positive.

Hyperostosis frontalis interna: an anthropological perspective.

Hyperostosis frontalis interna (HFI) is manifested by the accretion of bone on the inner table of the frontal bone. Despite the vast literature on HFI, ambiguity exists as to its etiology, osteogenesis, demography, and history. This stimulated the present broad-scale study of HFI which included the evaluation of 1,706 early 20th century skulls (1,007 males and 699 females) from the Hamann-Todd and Terry human osteological collections, as well as 2,019 pre-19th century East-Mediterranean, Amerindian, and Central European skulls. In addition, 72 cadavers were dissected for gross inspection and histology. Special attention was paid to the relationship of the brain and meninges to endocranial lesions. HFI is an independent condition, not a symptom of a more generalized syndrome as suggested in the past. It can appear in a variety of forms but each is the result of the same process and probably of the same etiology. Investigators' previous failure to recognize the mild stages of HFI (types A and B) as an early form of the general HFI process led to erroneous statistics and interpretations of observations. HFI should also be considered a phenomenon separate from HCI, hyperostosis cranialis diffusa (HCD), and other endostoses, even when it appears in association with them. To avoid ambiguity and facilitate the description of cranial hyperostoses, uniform nomenclature (HFI, HCD) has been recommended. HFI is rarely seen in historic populations, regardless of geographical origin. It is most commonly found among females and is believed to be associated with prolonged estrogen stimulation. While its magnitude of manifestation and frequency are much higher in females, HFI is not a purely female phenomenon. Males with hormonal disturbances such as atrophic testis were found to manifest HFI type D. HFI is associated with age insofar as it is much less frequent in females under 40 years of age. Although advanced cases of HFI (types C and D) have been observed in individuals as young as 40 years of age, it is more frequently found after age 60. The frequency of HFI type D will not increase from age 60. Type-predicted analysis by cohort reveals significant ethnic differences. Changes in African American (AA) females appear earlier in life and progress more rapidly than in European American (EA) females. Analysis of radiographs shows a discrepancy between the anatomic prevalence of HFI and its radiological recognition, which is very poor for mild cases. This apparently resulted in the misconceptions that HFI is entirely an old-age phenomenon, and that it is exclusively female. Histological analysis shows that the inner table along with the closely attached dural layer play a major role in the osteogenesis of HFI. Contrary to previous models, no evidence for diploe or ectocranial plate involvement was found. Cadaver study suggests that the predilection for the frontal area may be related to an altered blood supply and/or vascular stretching.

The elusive diploic veins: anthropological and anatomical perspective.

Diploic veins (Canales diploicae), which were identified in dogs by Dupuytren more than 200 years ago (Hecker [1845] Die anatomische Verhaltnisse und Krankheiten der Venae diploicae und Vasa emissaria. Erfahrungen und Abhandlungen im Gebiete der Chirurgie und Augenheilkunde. Erlangen), have remained inadequately understood and scantily referenced in the anatomical and anthropological literature. The tunnels formed by diploic veins are among the few known skeletal markers of soft tissue alteration. Protected by two bony laminae, diploic vein tunnels often resist postdepositional destruction and may provide a new way to assess living and extinct hominid populations. This basic research was carried out to enable future utilization of the diploic venous channels in anthropologic research. In the present study, diploic venous channels were observed radiographically in 108 human adults aged 19 years and above, 18 infants and children aged 1-18 years (Hamann-Todd Osteological Collection), eight fetuses aged 7-9 months (the Johns Hopkins Collection), and seven nonhuman primates (Hamann-Todd Osteological Collection). In addition, seven documented cases of parents and children were radiographed for genetic evaluation (Osteological Collection of The Hungarian Natural History Museum). Five distinct diploic distribution patterns were identified and described in this study. This was at variance with the impressions reported in dissection-based studies. Independence of diploic vein pattern from demographic (gender and age) and size factors and their tendency to be symmetrical make them amenable and reliable traits for skeletal population study. Diploic vein patterns appeared to be more complicated in humans than in nonhuman primates, raising the possibility of future phylogenetic applications.

The elusive petroexoccipital articulation.

In the present study, 1,869 skulls from the Hamann-Todd Collection were examined (macroscopically and by radiographs) for closure of the petroexoccipital articulation (jugular synchrondrosis). The results demonstrated the the petroexoccipital articulation underwent closure between 20 and 50 years of age in most human skulls evaluated. Approximately 7-10% of the human skulls underwent complete union of the petroexoccipital articulation before 20 years of age. In 5-9% of the population, the joint remained completely open. After 50 years of age, there was no increase in the frequency of individuals with incomplete closure. The frequency of "partial closure" was similar (4-8%) for all age groups (20-25, 30-35, 40-45, 50-55, 60-65, and 70+), excluding the 30-35 year old group (17.5%). The time interval necessary for closure to occur appeared to be very short. No significant differences in closure rates due to ethnic origin, gender, or laterality were noted. The utility of the pteroexoccipital articulation as an age estimator is discussed.

Why do we fail in aging the skull from the sagittal suture?

The controversy over the reliability of ectocranial suture status (open vs. closed) as an age estimation stimulated the pursuit of Meindl and Lovejoy's suggestion (Meindl and Lovejoy [1985] Am. J. Phys. Anthropol. 68:57-66) for large scale analysis. The extent of the sagittal suture closure was assessed in 3,636 skulls from the Hamann-Todd and Terry collections. The debate over whether cranial suture ossification represents a pathologic or an age-predictable pathologic process also stimulated a comparison with age and two stress markers, hyperostosis frontalis interna and tuberculosis. Sagittal suture closure was found to be age-independent and sexually biased. The wide confidence intervals (for age) appear to preclude meaningful application of suture status for age determination. No correlation was found with the tested biological stressors.

Size and location of the human temporomandibular joint.

The literature abounds with conflicting data on various morphometric aspects of the temporomandibular joint (TMJ). The purpose of this study was to observe the effects of sex, ethnic group, and edentulism on TMJ osseous morphology and to define possible factors which might influence variation in this structure. TMJs and related craniofacial structures were measured directly on 229 dry skulls and matching mandibles. Analysis of variance, principal component analysis, and cluster analysis were performed. Our results indicate that 1) the anteroposterior-related TMJ dimensions are independent of sex, ethnic group, and edentulism; 2) the transverse TMJ dimension is related to cranial breadth measures; and 3) the projected distance, along a midsagittal plane, between the TMJ and foramen magnum is independent of sex, ethnicity, and edentulism. It is our assertion that the TMJ must not be considered as a single morphological structure but rather viewed as a functional unit with component parts which are subordinate to completely different sets of influences.

Factors affecting the rate and pattern of the first costal cartilage ossification.

In the present study, the extent of costochondral ossification of the first rib was determined from 78 chest roentgenograms of 13 healthy male soldiers subjected to a periodic follow-up. Roentgenography was performed at a mean interval of 2.9 years over a 15-year period. Mean subject age was 24 years at the commencement of the study and 37 years at its termination. Our results show that ossification of the first costal cartilage may start early in adult life and progress at individual rates. The ossification process proceeded from the costal toward the sternal end of the cartilage in an anteromedial direction. The morphological age-related changes ranged from the formation of small osseous islands in the cartilage to a complete ossification between the first rib and the sternum. The main conclusion of the study is that the degree of ossification of the first costal cartilage as an indicator of age does not provide the precision necessary for anthropological or forensic studies.

Ohalo II H2: a 19,000-year-old skeleton from a water-logged site at the Sea of Galilee, Israel.

The discovery of well-preserved human remains at the site of Ohalo II in the northern Jordan Valley substantially augments the meager fossil record of the Levantine late Upper Pleistocene. The Ohalo II H2 specimen, dated to ca. 19,000 B.P., is the most complete early Epipaleolithic hominid discovered in Israel and promises to contribute to the clarification of a number of problematic issues in the local evolution of anatomically modern humans. In addition to a description of the burial and its Kebaran context, a detailed anatomical description of the skeleton is offered and morphometric comparisons are made to other Upper Paleolithic hominids. Ohalo II H2 is shown to demonstrate affinities in the craniofacial skeleton to fossils from the early Upper Paleolithic and late Epi-Paleolithic of the Levant.

The microscopic structure and function of the vascular retrodiscal pad of the human temporomandibular joint.

The highly vascular retrodiscal pad attaches the articular disc of the temporomandibular joint to osseous structures posterior to it. There is debate as to whether or not the pad includes erectile tissue. Histological examination of 11 retrodiscal pads revealed thick-walled muscular arteries, thin-walled veins and numerous vascular sinuses, which is different from the erectile tissue of the corpora cavernosa. Its histological features and position within the joint suggest that the retrodiscal pad may function differently from other human joints due to: (1) the large amount of distraction it undergoes relative to its size and (2) its location anterior to the ear.

Anatomical relationships and superior reinforcement of the TMJ mandibular fossa.

Only a few cases of condylar penetration into the middle cranial fossa have been documented in the literature. This study attempts to provide an anatomical explanation for this rare phenomenon. Mandibular (glenoid) fossa position in relation to important endocranial and exocranial structures located in close proximity to the TMJ, and relative condyle-fossa size, were evaluated on a dry skull sample. Additional osseous relationships were observed on cadaver material using dissection and x-ray. The anatomic relationships of the mandibular fossa and superior structures that appear to buttress it are described. It is concluded that the temporal squama that lies superior to the mandibular fossa provides a powerful buffer, which prevents condylar endocranial penetration in cases of an appropriate traumatologic mechanism.

Bird T. Baldwin: a holistic scientist in occupational therapy's history.

Holistic patient care and the scientific research method are two important aspects of occupational therapy. Bird T. Baldwin contributed to the formulation of these tenets at the beginning of this century. Baldwin, a psychologist by training, became the director of the occupational therapy department at Walter Reed General Hospital in Washington, DC, during World War I. In his department, functional rehabilitation was achieved via scientifically analyzed purposeful activities. He believed that purposeful activity was superior to exercise. Activity choice was based on physical, vocational, social, and emotional considerations. True to his scientific approach, Baldwin designed and adapted devices to provide standardized treatment protocols. Because Bird T. Baldwin's approach to rehabilitation remains of value today, a review of his work is relevant to the occupational therapy community.