Variations in the origins and absence of the common digital arteries of the hand: a cadaveric study.

We studied anomalies of the common digital arteries by dissecting 33 fresh cadaver hands under magnification. In the majority of the dissected hands (25 hands), common digital arteries took off from the superficial palmar arch and ran superficial and parallel to the flexor tendons. Variations were found in eight out of 33 hands. In four hands the common digital artery to the second web space was replaced by an atypical vessel, originating from the deep palmar arch, that crossed posterior to the index flexor tendons proximal to the A1 pulley. In eight hands, the common digital artery to the fourth web space was replaced by an atypical deeper vessel, originating from the superficial palmar arch and crossing posterior to the little finger flexors. No nerve anomalies were identified. Unrecognized, these atypical arteries to the second and/or fourth web spaces could lead to vascular complications during surgery, especially pollicization.

Continuous Positive Airway Pressure Thresholds for Nasolacrimal Air Regurgitation in a Cadaveric Model.

PURPOSE: To elucidate the mechanisms underlying nasolacrimal air regurgitation (AR) in the setting of continuous positive airway pressure therapy. METHODS: Twelve nasolacrimal systems of 6 fresh female human cadavers were evaluated individually for AR using continuous positive airway pressure therapy before any nasolacrimal procedure. Cadavers were then randomly assigned to undergo nasolacrimal duct probing or endoscopic dacryocystorhinostomy and then each hemisystem was again evaluated for AR. The pressure where AR was first observed (discovery pressure) or maximum possible pressure in systems without AR was recorded. In systems that demonstrated AR, the pressure was then gradually decreased to the lowest pressure where regurgitation persisted. This pressure was recorded as the secondary threshold pressure. RESULTS: None of the 12 unoperated nasolacrimal systems or the 6 systems that underwent nasolacrimal duct probing demonstrated AR through the maximum continuous positive airway pressure therapy (30 cm H2O). After endoscopic dacryocystorhinostomy, all 6 nasolacrimal systems demonstrated AR. The mean discovery pressure was 16.0 cm H2O (range, 14.0-18.0 cm H2O) and mean secondary threshold pressure was 7.25 cm H2O (range, 6.5-8.0 cm H2O). CONCLUSIONS: Air regurgitation during continuous positive airway pressure therapy in the setting of prior endoscopic dacryocystorhinostomy can be replicated in a cadaver model. The secondary threshold pressures required for AR in this model were similar to AR pressures reported clinically. Prior to dacryocystorhinostomy, patients using continuous positive airway pressure therapy should be counseled on AR, and physicians should consider this phenomenon when evaluating ophthalmic complaints in postoperative patients on positive airway pressure therapy.

National survey on anatomical sciences in medical education.

The drivers for curricular change in medical education such as the addition of innovative approaches to teaching, inclusion of technology and adoption of different assessment methods are gaining momentum. In an effort to understand how these changes are impacting and being implemented in gross anatomy, microscopic anatomy, neuroanatomy/neuroscience, and embryology courses, surveys were sent out to course directors/discipline leaders at allopathic Medical Schools in the United States during the 2016-2017 academic year. Participants in the study were asked to comment on course hours, student experiences in the classroom and laboratory, amount of faculty participation, the use of peers as teachers in both the classroom and laboratory, methods used for student assessment and identification of best practices. Compared to data published from a similar survey in 2014, a number of changes were identified: (1) classroom hours in gross anatomy increased by 24% and by 29% in neuroanatomy/neuroscience; (2) laboratory hours in gross anatomy decreased by 16%, by 33% in microscopic anatomy, and by 38% in neuroanatomy/neuroscience; (3) use of virtual microscopy in microscopic anatomy teaching increased by 129%; and (4) the number of respondents reporting their discipline as part of a partially or fully integrated curriculum increased by greater than 100% for all four disciplines. Anat Sci Educ 11: 7-14. © 2017 American Association of Anatomists.

Surgical hip dislocation through a direct lateral approach: A cadaveric study of vascular danger zones.

OBJECTIVE: There is limited information on the potential danger to the vascularity of the femoral head during surgical dislocation of the hip using the direct lateral approach. The objective of this study was to investigate the topographical anatomy of the medial femoral circumflex artery (MFCA), the primary source of blood supply to the femoral head, in relationship to the direct lateral approach. METHODS: Seven unembalmed cadaver hips had dye injection into either the profunda femoris artery or the MFCA. Surgical hip dislocation was then performed through a direct lateral approach, noting the danger zones to the MFCA branches during each step of the exposure. RESULTS: None of the MFCA branches were found to cross the anterior surgical field superficial to the capsule. The deep (main) branch of the MFCA pierced the inferior capsule at the level of the lesser trochanter after emerging posterior to iliopsoas tendon. Ascending branches up the medial femoral neck were identified at this level. The deep branch then coursed posteriorly terminating in a variable number of vessels ascending the posterior femoral neck. Dislocation of the femoral head did not stretch or alter the course of the deep branch of the MFCA. CONCLUSION: Safe surgical hip dislocation preserving the MFCA can be performed though a direct lateral approach as long as the inferomedial portion of the anterior capsule is preserved (main branch of the MFCA pierces the capsule at this level). Extracapsular injury is possible from inadvertent dissection at the level of the lesser trochanter or aggressive retraction on the iliopsoas. The posterior capsule should be left intact and instrumentation around the posterior neck should be avoided.

Longitudinal cohort study on medical student retention of anatomical knowledge in an integrated problem-based learning curriculum.

BACKGROUND: When modifying a curriculum to accommodate changes in the methods of subject matter presentation or fit within a shortened time frame, student retention of knowledge remains an important issue. AIM: This study evaluates medical student retention of anatomical knowledge as they matriculate through an anatomy curriculum where the instruction hours are less than half of the current national average. METHOD: Medical students completed an assessment tool developed to evaluate their baseline level of anatomical knowledge at the beginning of the first year. They then completed the instrument at the end of their 1st, 2nd, 3rd, and 4th years to assess their retention of anatomical knowledge during medical school. Data collection began in September 2010 and concluded in June 2015. RESULTS: Results demonstrate that students began medical school with a low level of anatomical knowledge (baseline), that knowledge increased during their first year (p < 0.001), continued to increase during their second year (p < 0.001), but was over 90% maintained through years 3 and 4. CONCLUSION: In conclusion, an anatomy course with reduced hours (∼60), using active learning methods, contextual learning, cadaver demonstrations, increased exposure to imaging, and longitudinal reinforcement can help students build a strong foundation of anatomical knowledge.

Frontalis Muscle Asymmetry and Lateral Landmarks.

PURPOSE: To investigate frontalis muscle asymmetry and characterize its lateral interdigitation with the orbicularis oculi muscle. METHODS: After making a mid-coronal incision and bluntly dissecting to the orbital rim, the frontalis muscle was exposed, marked, and photographed. The right and left muscle bellies were analyzed and compared in both pixels and cm ratios generated with NIH ImageJ software. A ratio of ≥1.5 was considered significantly asymmetric. The lateral interdigitation of the frontalis and orbicularis oculi muscles was measured from the supraorbital notch with a metric ruler. Data were analyzed using 2-sample t tests, paired t tests, log scales, and nonparametric tests were performed for sensitivity analyses. A p value of ≤0.05 was considered statistically significant. RESULTS: Fifty-eight hemifaces of 29 Caucasian cadavers were studied for muscle belly asymmetry. Thirty-six hemifaces of 18 Caucasian cadavers (9 males) were dissected for lateral landmarks and average age of these specimens was 73 years (range: 35-91 years). Significant asymmetry in muscle belly area was found in 6/29 (20%) specimens, with the right muscle belly larger in all 6 specimens. On average, the right muscle belly area was 1.23 times that of the left (p = <0.001). The average frontalis-orbicularis interdigitation occurred 3.4 cm lateral to the supraorbital notch. CONCLUSIONS: Significant frontalis muscle belly asymmetry exists in 20% of Caucasians cadavers. The right muscle belly was larger on average and in all cases of significant asymmetry. The frontalis muscle interdigitates with the orbicularis oculi on average 3.4 cm lateral to the supraorbital notch.

Student perceptions of an interprofessional educational experience: The importance of goal articulation.

The education of future health care professionals must involve activities where interprofessional collaboration and the functioning of interdisciplinary teams are the goals and not the exceptions. This type of interprofessional education (IPE) will benefit students as they will be better able to communicate with and mobilize the skills of other health care workers, work toward common goals related to patient care, and develop a more cost-effective treatment strategy in the long term. Such an IPE program was initiated in the clinical anatomy course for physician assistant students from the University of Mount Union that was taught, in part, by medical students from the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University. Surveys of both student groups at the end of the course indicated that although this was a useful IPE experience, the value of this program as an IPE experience was not entirely appreciated by the participating students. It turned out that although the goals and importance of these types of IPE activities are clear to the faculty, they must also be made clear to all of the students.

Regional Variations in Orbicularis Oculi Histology.

PURPOSE: To investigate and compare the histologic compositions of the pretarsal, preseptal, and orbital orbicularis oculi muscle (OOM) using nonpreserved, fresh-frozen, human cadavers. METHODS: The OOM was exposed using sharp and blunt dissection. A metric ruler was used to measure and mark 0.5 cm × 1 cm samples from each portion of the right, superior OOM. Samples were excised, fixed in formalin, and completely embedded in paraffin. Five-micrometer-thick, hematoxylin- and eosin-stained sections were generated for each sample and analyzed by an anatomical pathologist. The relative percentages of the 4 main tissue types (skeletal muscle, fibrous tissue, adipose tissue, and neurovascular tissue) were quantified. RESULTS: Forty-two samples were obtained from 14 Caucasian cadavers. On average, the pretarsal samples were composed of 83.5% skeletal muscle, 0.0% adipose, 5.0% neurovascular, and 11.5% fibrous tissue. Average preseptal OOM was 46.5% skeletal muscle, 12.7% adipose, 9.2% neurovascular, and 31.5% fibrous tissue. The orbital OOM was, on average, 42.7% skeletal muscle, 32.7% adipose tissue, 6.9% neurovascular, and 17.7% fibrous tissue. CONCLUSIONS: The OOM represents a histologically heterogeneous structure.

Anatomy and histology of the frontalis muscle.

PURPOSE: To determine the gross and histologic configurations of the medial and lateral frontalis muscle. METHODS: After making a midcoronal incision and bluntly dissecting to the orbital rim, the frontalis muscle was marked and measured. A protractor was used to measure the frontalis-orbicularis angle (FOA) and, when present, the angle of central bifurcation (AOB). Three strips of full-thickness forehead soft tissue measuring 0.5 cm × 8 cm were excised 3, 4.5, and 6 cm above the supraorbital notch and analyzed histologically for the presence of skeletal muscle fibers. Data were analyzed using 2-sample t tests, paired t tests, Pearson correlations, and mixed effect models. A p value of ≤ 0.05 was considered statistically significant. RESULTS: Sixty-four hemifaces of 32 cadavers (16 males) were dissected. All specimens were Caucasian. The average age was 78.2 years (range, 56-102 years). The average FOA was 88.7° (13.0°), and the average AOB was 90.0° (26.4°). A visible midline bifurcation occurred in 28 of 32 subjects (88%) at an average height of 4.7 cm (range, 2.4-7.2 cm) superior to the supraorbital notch. Continuous skeletal muscle fibers were present within the midline bifurcation histologically in 89%, 75%, and 11% of specimens 3.5, 5.0, and 6.5 cm above the supraorbital notch, respectively. In 46% of individuals, skeletal muscle fibers were continuously present microscopically within the gross bifurcation. CONCLUSION: While a medial frontalis muscle bifurcation occurs grossly in most senescent Caucasians, muscle fibers exist microscopically within this zone in nearly half of individuals.

Intranasal landmarks for adequate L-strut preservation during endoscopic septoplasty.

BACKGROUND: A 10- to 15-mm L-strut in the dorsal and caudal areas of the nasal septum is preserved during septoplasty to maintain structural stability and prevent external deformity. However, during endoscopically performed septoplasty the surgeon has a very different perspective, which may create a more challenging situation to ensure adequate strut preservation. No reliable intranasal landmarks have been established. We establish intranasal landmarks that may be used during endoscopic septoplasty (ES) to safely maintain sufficient caudal and dorsal support. A cadaveric anatomic study was performed. METHODS: Measurements were made using calipers in 15 human cadavers (8 male and 7 female subjects), totaling 30 nasal passages. The caudal strut distance was measured from the inferior concha to the caudal aspect of the quadrangular cartilage. The dorsal strut height was measured from a line parallel to the nasal dorsum that extended from the middle turbinate (MT) axilla to the nasal vestibule (termed the "axillary line"). RESULTS: Using the inferior concha and the vertical MT attachment as endoscopic landmarks, the average caudal and dorsal struts measured 18.9 and 16.4 mm,, respectively. Strut size was larger in male subjects than female subjects; however, dimensions remained >10 mm in all cadavers, establishing these landmarks as safe and effective for determining extent of cartilage resection. CONCLUSION: The inferior turbinate and vertical MT attachment may be used to guide the extent of cartilage resection during ES. Use of the described conchal and axillary lines as landmarks allow for preservation of an adequate L-strut during ES and may reduce support related complications.

An update on the status of anatomical sciences education in United States medical schools.

Curricular changes continue at United States medical schools and directors of gross anatomy, microscopic anatomy, neuroscience/neuroanatomy, and embryology courses continue to adjust and modify their offerings. Developing and supplying data related to current trends in anatomical sciences education is important if informed decisions are going to be made in a time of curricular and course revision. Thus, a survey was sent to course directors during the 2012-2013 academic years to gather information on total course hours, lecture and laboratory hours, the type of laboratory experiences, testing and competency evaluation, and the type of curricular approach used at their institution. The data gathered were compared to information obtained from previous surveys and conclusions reached were that only small or no change was observed in total course, lecture and laboratory hours in all four courses; more gross anatomy courses were part of an integrated curriculum since the previous survey; virtual microscopy with and without microscopes was the primary laboratory activity in microscopic anatomy courses; and neuroscience/neuroanatomy and embryology courses were unchanged.

Use of angular vessels in head and neck free-tissue transfer: a comprehensive preclinical evaluation.

IMPORTANCE: The angular artery, its perforating branches, and their zones of tissue perfusion have been described extensively for facial reconstruction. Various cutaneous and mucosal flaps with either anterograde or retrograde perfusion play an important role in facial and oral reconstruction. However, these flaps share the limitations of pedicled nature and donor-site intolerance. Free-tissue transfer (FTT) has transformed capabilities and outcomes in head and neck reconstruction. While less constrained by tissue volume and subtype, FTT has its own limitations, including pedicle reach for anastomosis to inflow and outflow vasculature in upper face reconstruction. The angular vessels, owing to their relatively high central location and accessibility via a camouflaged nasolabial fold incision, may have value in midface and nasal reconstruction. OBJECTIVES: To detail a technique for consistently locating the angular vessels while preserving the integrity of adjacent neuromuscular structures and to evaluate the caliber and consistency of the angular artery and vein for their usability in microvascular anastomosis. DESIGN AND SETTING: We conducted a PubMed literature search for the terms angular artery, melolabial flap, nasolabial flap, retroangular flap, and any associations with FTT. We also performed 26 anatomic cadaveric dissections on 13 fresh cadavers to evaluate the angular arteries and veins. MAIN OUTCOMES AND MEASURES: Vessel caliber, length, and variability were analyzed and utility for use in FTT was assessed. A total of 26 angular arteries and 26 angular veins were included in the analysis. Anatomic relationships were used to develop a surgical schema for dissection and isolation of the angular vessels specifically for FTT. RESULTS: The angular vessels have consistent anatomic relationships facilitating localization and have a consistent caliber amenable to use in microvascular FTT. The mean (SD) artery diameter was 2.34 (0.67) mm prior to dilation and 3.21 (0.87) mm after dilation. The diameters of the vein before and after dilation were 3.57 (0.53) mm and 6.40 (0.81) mm, respectively. There was no statistical difference between the vessels on the right and left sides. CONCLUSIONS AND RELEVANCE: We describe for the first time the anatomic cadaveric dissection and analysis of the angular arteries and veins specifically to determine compatibility with regard to FTT. We found good FTT compatibility. LEVEL OF EVIDENCE: NA.

Dimensions and anatomic variations of the orbicularis oculi muscle in nonpreserved, fresh-frozen human cadavers.

PURPOSE: To determine average dimensions of the orbicularis oculi muscle (OOM) from the orbital rim and to investigate polymorphic variations through anatomical dissection of nonpreserved, fresh-frozen human cadavers. METHODS: The OOM was exposed using sharp and blunt dissection until its distal borders were identified. A metric ruler was used to measure the superior (S line), inferior (I line), and lateral (L line) dimensions of the OOM from the orbital rim. Data collection included age, gender, and race. Data were analyzed using 2-sample t tests, paired t tests, and mixed effect models. A p-value of ≤0.05 was considered statistically significant. RESULTS: A total of 40 hemifaces of 20 cadavers were dissected. All specimens were Caucasian. Ten specimens were men. Average age was 73.9 years (56-92 years). The overall S line was 1.4 cm (95% confidence interval [CI], 1.23-1.57), the I line was 1.2 cm (95% CI, 1.00-1.36), and the L line was 2.5 cm (95% CI, 2.27-2.68). Men had significantly larger average T, L, and S line values than women (p = 0.003, 0.005, 0.008, respectively). I lines did not differ significantly between genders (p = 0.28). CONCLUSIONS: In senescent Caucasians, the OOM extends approximately 1.4 cm superior, 1.2 cm inferior, and 2.5 cm lateral to the orbital rim. The muscle extends significantly further superiorly and laterally in Caucasian men than in women. Knowledge of the extent of the OOM should improve the understanding and the treatment of conditions affecting this region.

Intraoperative sub-tenon injection increases optic nerve length transection during enucleation.

PURPOSE: To determine the effect of sub-Tenon injection on the length of optic nerve resected during enucleation. METHODS: Case-control laboratory study on 22 orbits of 11 unpreserved, fresh-frozen human cadavers. Each cadaver underwent a conventional enucleation technique on one side and an otherwise identical technique on the contralateral side that included sub-Tenon injection of 2.5 ml normal saline in each oblique quadrant. Resected optic nerve lengths were measured and compared using Student t tests. RESULTS: The mean optic nerve length was 15.2 mm (range, 5.0-21.0 mm) in the sub-Tenon injection group and 11.3 mm (range, 5.0-19.0 mm) in control group (p = 0.015). CONCLUSIONS: Sub-Tenon injection during enucleation allows for significantly longer optic nerve resection lengths in unpreserved, fresh-frozen human cadavers.

Validation of a method for measuring medical students' critical reflections on professionalism in gross anatomy.

Improving professional attitudes and behaviors requires critical self reflection. Research on reflection is necessary to understand professionalism among medical students. The aims of this prospective validation study at the Mayo Medical School and Cleveland Clinic Lerner College of Medicine were: (1) to develop and validate a new instrument for measuring reflection on professionalism, and (2) determine whether learner variables are associated with reflection on the gross anatomy experience. An instrument for assessing reflections on gross anatomy, which was comprised of 12 items structured on five-point scales, was developed. Factor analysis revealed a three-dimensional model including low reflection (four items), moderate reflection (five items), and high reflection (three items). Item mean scores ranged from 3.05 to 4.50. The overall mean for all 12 items was 3.91 (SD = 0.52). Internal consistency reliability (Cronbach's α) was satisfactory for individual factors and overall (Factor 1 α = 0.78; Factor 2 α = 0.69; Factor 3 α = 0.70; Overall α = 0.75). Simple linear regression analysis indicated that reflection scores were negatively associated with teamwork peer scores (P = 0.018). The authors report the first validated measurement of medical student reflection on professionalism in gross anatomy. Critical reflection is a recognized component of professionalism and may be important for behavior change. This instrument may be used in future research on professionalism among medical students.

A technical approach to dissecting and assessing cadaveric veins pertinent to chronic cerebrospinal venous insufficiency in multiple sclerosis.

OBJECTIVE: To establish a detailed technical procedure for studying the anatomical correlates of chronic cerebrospinal venous insufficiency in cadavers of multiple sclerosis and control subjects, and to present our findings of the normal anatomic venous structures, with reference to previous descriptions from the literature. METHODS: This study examined the internal jugular veins (IJVs), the brachiocephalic veins, and the azygos vein from 20 cadavers (10 control and 10 multiple sclerosis). These veins were exposed, isolated by clamps from the rest of the venous system, flushed with water, and then injected with fluid silicone from the superior ends of both IJVs. After the silicone cured to its solid state, the venous tree was removed en bloc and dissected longitudinally to expose the luminal surface. All vein segments were analyzed for anatomic variation. Anatomical analysis for this manuscript focused on normal vein architecture and its variants. RESULTS: Thirty-seven of 40 IJVs contained valves: 29 bicuspid, 6 tricuspid, and 2 unicuspid. The average circumferences of the right and left IJVs were 2·2 and 1·8 cm, respectively. Thirteen of 20 azygos veins contained a valve, located on average 3·6 cm away from the superior vena cava junction. Nine of the 13 azygos valves were bicuspid; four were tricuspid. Only one of the 40 brachiocephalic veins contained a valve. DISCUSSION: We detailed a technical approach for harvesting cadaveric neck and thoracic veins with relevance to chronic cerebrospinal venous insufficiency. The anatomy of the venous system has significant variability, including differing number of valves in different regions and variable characteristics of the valves. Average vein circumference was less than that typically reported in imaging studies of live patients.

Motor nerve to the vastus lateralis.

Objective To further delineate the anatomy of the motor nerve to the vastus lateralis (MNVL) in the context of its use as a possible interpositional nerve graft in facial nerve rehabilitation.Methods Twelve fresh human cadaveric thighs were dissected to investigate the anatomic location and branching pattern of the MNVL muscle.Results There were 3 to 6 primary nerve branches (mean, 4.4) supplying the vastus lateralis. The mean primary branch length was 93.8 mm (range, 51-196 mm), and each primary branch had a mean of 2.3 subsequent branches. There were 2 larger caliber branches (>2 mm in diameter) supplying the proximal and distal muscle. The nerve branches are variable in their relation to the vascular pedicle and perforating vessels of the descending branch of the lateral circumflex femoral artery.Conclusion The nerve to the vastus lateralis is a readily available, redundant motor nerve suitable for facial nerve cable grafting.

Anatomists provide the foundation for learning pathophysiology.

The need for interdisciplinary graduate training programs which prepare students to conceptualize the application of their research in clinical settings continues to grow. Though several programs have been cultivated to address this need, demand still outweighs supply. The following describes a curriculum developed with the intent of incorporating medical knowledge into a PhD graduate training program. Development of this Molecular Medicine program by the Cleveland Clinic Lerner College of Medicine in collaboration with Case Western Reserve University was funded by the Howard Hughes Medical Institute "Med into Grad" initiative. The core curriculum of this program begins with a foundation in Human Physiology and Disease course in which anatomy faculty introduce students to a basic overview of gross anatomy structure and function. This course is followed by five fundamental basic science courses, a composite course focusing on principles of clinical and translation research, a course on laboratory techniques and three, 12-week research rotations. In the second year of the program, students begin their dissertation research, complete their qualifying examination, and partake in an individually tailored Clinical Experience course. Interdisciplinary graduate programs like this provide another venue for faculty in anatomical sciences to help aspiring translational scientists relate basic science knowledge to human pathophysiology and health.