Structural Anatomy

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/32563

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The Evaluation of Elongated Styloid Processes in regard to possible Clinical and Pathological Outcomes - A Case Series
(2024-03-21) Cornejo, Federico; Desai, Ananya; Cheng, Jack; Chen, Liling; Cruise, Forrest; McKean, John; Menegaz, Rachel; Crowe, Nicole
Background: Eagle’s syndrome (ES) is defined as elongation or ossification of the styloid process that may compress adjacent anatomy, producing variable symptomology. ES is subclassified into Classic ES or Stylocarotid syndrome. Classic ES may present asymptomatically, or with dull, recurring cervicofacial pain, and Stylocarotid syndrome may present with parietal headaches, and presyncope/syncopal episodes. The etiology of the abnormal ossification of the styloid process or stylohyoid ligament is unknown but likely caused by reactive metaplasia/hyperplasia or anatomical variance. Although a styloid process greater than 30mm in length is generally considered elongated, clinical guidelines for measuring styloid process length, and specific histological characterizations for ES have not been formally established. However, elongated styloid processes can be structurally classified as uninterrupted (one unsegmented process), pseudo-articulated (two parts in close proximity), or segmented (three or more parts). Styloid processes may also be classified into four calcification patterns including outlined calcification, partial calcification (multiple bone pieces surrounded by a continuous calcified process), nodular calcification (segmented, bumpy surfaced bone pieces due to thickened calcifications), and complete calcification. However, no clinical correlation has been identified between patient presentation and morphology/calcification pattern. Case Information: A 62-year-old deceased Caucasian male (147lbs / 5’6”) with an elongated stylohyoid process was discovered during routine dissection. Medical history was significant for liver and renal disease. Cause of death was reported as “chronic alcoholism”. Social history was significant for off-and-on incarceration for more than 40 years, and chronic alcohol, tobacco, and non-prescription illicit drug use of unknown types, amount, frequency, or duration. No other history was available. The styloid processes of the patient were imaged in-situ using a 3D C-arm X-ray machine. Furthermore, bilateral styloid processes were collected from the patient and seven other anatomical donors (6 M/1 F, age range 61-76) by detaching them from the base of the temporal bone and excising portions of the hyoid bone to maintain the stylohyoid ligament intact. Calipers were used to measure the length of the styloid processes and their calcifications. The primary donor exhibited elongated, asymmetrical processes (31.9 mm left, 37.8 mm right). Significant variation in styloid process lengths were observed in this sample (mean length 28.5 mm; standard deviation 13.5 mm; range 14.5-68.3 mm). Generally, the styloid processes demonstrated bilateral asymmetry across the sample. This asymmetry was notably pronounced in one donor with a significantly elongated styloid process (20.5 mm left, 68.3 mm right), co-occurrent with thyroid cartilage calcification. Conclusions: There is presently no consistent diagnostic measure of an elongated stylohyoid process available for providers to assess patient risk for Eagle’s Syndrome or its future progression. In this study, styloid length was found to be a continuous variable with no clear “cutoff” between elongated and normal lengths at 30mm. Furthermore, the lack of histological evidence detailing the condition's progression hinders diagnostic measures and risk assessment. We recommend further studies perform histologic analysis to better understand the progression of elongated styloid processes. Based on additional samples, a standardized diagnostic measurement can be created to improve treatment regimens and health risk screenings.
Exploring Anatomical Variations: A Case Study of an Aortic Arch and Left Superior Intercostal Artery Variants with Clinical Considerations
(2024-03-21) Stokes, Cameron; Hall, Alex; Shevtsov, Allison; Lau, Azelia; Lovely, Rehana
Background: In its usual pattern, the aortic arch has three branches, namely, from right to left, brachiocephalic trunk, left common carotid artery, and left subclavian artery. Normally, as one of the branches off the left subclavian artery, the costocervical trunk gives off the left superior intercostal artery. The aim of this case is to describe a variation in the aortic arch wherein the left common carotid artery branches from the brachiocephalic trunk, with an additional rare finding of the left superior intercostal artery branching directly from the left subclavian artery. Case Information: As part of the cadaveric anatomy laboratory requirement of the Cardiopulmonary System Course (MEDE7615), our group performed a dissector-directed study of the thoracic cavity of a 67-year-old female donor to the UNTHSC Willed Body Program. Upon removal of the anterior part of the rib cage and subsequent exposure of the mediastinum and its contents, a variation in the branching pattern of the aortic arch in the superior mediastinum was dissected, cleaned, and identified. Following dissection of the aortic arch and its branches, we observed variations in the aortic arch and left superior intercostal artery. In this donor, the left common carotid artery branched from the brachiocephalic artery. This created only two vessels off the aortic arch rather than the three typically seen. We also observed that, on the left side, the superior intercostal artery branched directly from the subclavian artery and not from the costocervical trunk of the subclavian artery. This variant placed the left superior intercostal artery in a position more inferior and posterior in the upper part of the left pleural cavity. Conclusion: Awareness of the aortic arch and left superior intercostal artery variations are clinically relevant to ensure prevention of potential surgical errors and ambiguity when viewing radiologic images.
Long-term Follow-up of Hip Resurfacing Arthroplasty Patients: A Comprehensive Review of Outcomes Over 15 Years
(2024-03-21) Wong, Zachary; Saluja, Anand; Spaan, Jonathan; Su, Edwin
Purpose: Hip resurfacing arthroplasty (HRA) has emerged as a promising alternative to total hip arthroplasty (THA) for managing severe osteoarthritis, especially in younger, active males seeking a return to high impact activities. While short to medium-term follow-up studies have demonstrated favorable clinical outcomes and survival rates, there is increasing interest in the long-term durability of HRA, in terms of implant survivorship and patient outcomes and attitudes. The existing body of literature on HRA longevity is predominantly limited to follow-up periods of up to 10 years. As such, the purpose of this study was to evaluate the long-term survivorship of HRA with a minimum follow-up period of fifteen years. Methods: A retrospective review of hip resurfacing arthroplasties performed by a single surgeon at a high-volume surgical center between 2006-2008 was conducted. Given that the majority of these patients were male, we elected to focus exclusively on male patients to control for potential confounding factors related to sex and standardize our findings. Patient demographics were collected including age, BMI, and laterality. Patient reported outcome measures (PROMs) including Hip Disability and Osteoarthritis Outcome Score, Joint Replacement (HOOS-JR), Harris Hip Score (HHS), Visual Analogue Scale (VAS), and UCLA Activity Scores were collected at fifteen years post-operation. Subject satisfaction surveys were also collected, and Kaplan-Meier survival analyzed implant revisions. Results: A total of 312 patients (369 hips) out of 470 (543 hips) with a minimum 15-year follow up were included in this study, representing a follow-up rate of 66.4%. The mean age at surgery was 50.5 ± 7.8 years and the mean BMI was 27.9 ± 4.3 kg/m2. The mean scores for HOOS JR, HHS, VAS, and UCLA activity scores at final follow-up were 97.5 ± 6.7, 96.7 ± 8.3, 0.3 ± 0.9, and 7.9 ± 1.9, respectively. Out of the 369 HRA implants, 24 were revised to total hip arthroplasty, indicating 93.5% survivorship. Excluding patients who required revision, 98.9% of patients expressed satisfaction with the procedure. Conclusions: Positive outcomes in PROMs and subject satisfaction scores accompanied by high implant survival, indicate that the metal-on-metal HRA procedure exists as a safe and effective solution for end-stage osteoarthritis in young (50.5 ± 7.8 years) male patients at long-term follow-up. Favorable outcomes persisting 15-years after primary procedure suggests that HRA may serve as a viable alternative to THA, its longstanding counterpart, at high-volume centers with proper expertise of the procedure. This avenue warrants further exploration in the future of our study, with potential implications for the optimization of patient care and surgical decision-making in this population.
Total Hip Arthroplasty Using the United Orthopedic Conformity Stem Femoral Hip System: A Review of Outcomes
(2024-03-21) Wong, Zachary; Saluja, Anand; Spaan, Jonathan; Su, Edwin
Purpose: Total hip arthroplasty (THA) is one of the most common and successful orthopedic procedures, markedly enhancing patient quality of life, reducing pain severity, and maximizing post-operative function. This study assesses the United Conformity Stem Femoral Hip System, distinguished by its standard and high offset options and the ability for precise adjustment to optimize joint stability and tension based on the surrounding soft tissue, with the goal of improving patient outcomes for THA. Methods: A cohort of 415 patients, who underwent primary THA with the United Conformity Stem Femoral Hip System from November 2019 to November 2021, was retrospectively reviewed to evaluate the clinical effectiveness, safety, and survival over the first 2 years post-operation. The primary endpoints of our study were significant improvements in four patient-reported outcome measures (PROMs), including Hip Disability and Osteoarthritis Outcome Score-Joint Replacement (HOOS-JR), Lower Extremity Activity Scale (LEAS), Visual Analog Scale (VAS), and Harris Hip Score (HHS) at 24 months post-procedure when compared to preoperative scores. Secondary outcomes included implant survival and radiographic assessment for stability. Results: Within the cohort, a total of 209 females and 66 males achieved a minimum of 2-year follow-up (66%). The mean age was 61.5 ± 9.9 years, with a mean BMI of 26.0 ± 5.4 kg/m2. At the 2-year follow-up, statistically significant improvements in HOOS-JR, LEAS, VAS, and HHS were observed compared to their baseline preoperative scores. Radiographic evaluations of the implants by two independent observers corroborated these PROMs findings. The cohort reported three revisions, one of which involved stem revision. Conclusions: Our study affirms that the United Conformity Stem Femoral Hip System yields notable enhancements in functional capability and short-term radiographic stability in our evaluation of 2-year outcomes in primary THA, irrespective of surgical approach (anterior or posterior). These findings support the United Conformity Stem System’s capacity to meet the rising expectations of patients and surgeons alike, while providing excellent short-term outcomes.
Variant Blood Supply of the Superficial Face: A Case Report
(2024-03-21) Stucki, Brenton; Fowers, Rylan; Judd, Dallin; Van Alfen, Braden; Rosales, Armando; Lovely, Rehana
Introduction: The facial and transverse facial arteries provide the major arterial supply for the superficial face. The facial artery arises from the external carotid artery, in the carotid triangle of the neck, and crosses the angle of the mandible as it ascends the anterolateral face. Following a distinctive course, it continues by running along the oral commissure where it gives off the superior and inferior labial branches. Continuing its trajectory, the artery ascends along the nasolabial sulcus, providing the lateral nasal branch, and concludes its course by terminating as the angular branch near the medial aspect of the eye. The transverse facial artery, which arises from the superficial temporal artery, has a significant role in lateral face vascularization by supplying blood to the parotid gland, masseter, and integument and terminating near the buccal area. Case Presentation: During a unilateral dissection of a previously hemisected head of a 78-year-old donor from the UNTHSC Willed Body program, variations of the facial and transverse facial arteries were observed. The superficial and deep structures of the face were subsequently dissected and cleaned to expose arterial origins and terminations. The variant anatomical structures were then noted and photographed. The facial artery arose from the external carotid between the lingual and occipital arteries. After crossing the angle of the mandible, the variant facial artery terminated below the oral fissure, supplying blood to the lower face only. The transverse facial artery arose from the superficial temporal, running deep to the parotid gland extending across the lateral face. It then continued in the typical path of the facial artery, following the nasolabial sulcus supplying the muscles and tissues above the oral fissure. It was observed that this variant transverse artery supplied blood to the superficial face instead of the facial artery. Conclusion: The face, like the rest of the human body, has a variety of documented anatomical variations. The observed anatomical variations of the facial and transverse facial arteries highlight the complexity and diversity regarding the vascular supply of the face. The documentation of such variations serves as vital information in clinical and surgical practice to yield the best patient outcomes during treatment.
Intersection Syndrome of the Chiasma Crurale: A Novel Clinical Manifestation on Ankle MRI
(2024-03-21) Hernandez, Christian; Luu, Dustin; Jensen, Richard
Background: Intersection syndrome describes a painful pathology occurring at the crossing of tendon sheaths, commonly noted in the forearm in the setting of overuse injury. Rarely, intersection syndrome may occur in other areas of similar musculotendinous intersections; one such location, the chiasma crurale, describes the intersection of the flexor digitorum longus tendon and the posterior tibialis tendon located on the posteromedial leg. Magnetic resonance imaging of the chiasma crurale in cadaveric legs has previously been observed; however, no clinical pathology has been reported on MRI. Case Information: A 64-year-old female (BMI: 44.3) with a past medical history of pes planus, bilateral knee replacement, and unspecified discectomy, complains of recurrent shooting pain in her left lower extremity that has been worsening for the past 3 weeks without improvement from an ambulatory boot. She is tender to palpation at the insertion of the PTT, sinus tarsi, and great toe. She was offered surgical and conservative options for treatment and opted for conservative treatment with an ambulatory boot. Conclusions: In this case report, we present a novel clinical finding discovered on ankle MRI, of intersection syndrome of the chiasma crurale.
Every breath you take: Experimentally investigating respiratory responses to hot environments
(2024-03-21) Tran, Baonhu; Ward, Lyndee; Boettger, Chloe; Counts, Caroline; Cowgill, Libby; Ocobock, Cara; Cho, Elizabeth; Maddux, Scott
The human body loses heat to the environment through two mechanisms: the skin and the respiratory system. Accordingly, it has previously been hypothesized that respiration may play an important role in overall thermoregulatory responses to heat stress. However, previous studies investigating respiratory responses to heat have generally failed to account for variation in humidity levels seen across hot environments (i.e., hot-humid vs. hot-dry conditions). Thus, the goal of this study was to experimentally test for potential differences in respiratory responses to heat stress given variation in air humidity. A mixed-sex sample of human volunteers (5 females, 6 males) were subjected to three different climatic conditions: room temperature (22°C, 50% relative humidity (RH)), hot-dry (44°C, 15% RH), and hot-humid (37°C, 85% RH).Test subjects were exposed to each climatic condition for 45 minutes, with metabolic and respiratory data collected for 30 minutes using a wearable COSMED K-5 metabolic system. Respiratory frequency (Rf, breaths/minute) and oxygen consumption (VO2, ml/minute)were assessed. Results of a repeated-measures ANOVA found a statistically significant difference in Rf values between the climatic conditions (F=5.05, p=0.017). Subsequent Tukey-Kramer multiple-comparison post-hoc test results indicate that participants exhibited significantly higher Rf values in the hot-dry condition (mean=17.498) compared to the room temperature (mean=15.859)and hot-humid (mean=15.764) conditions. In contrast, no significant differences for VO2 consumption between the three climatic conditions (F=2.33, p=0.123) were found. These results indicate that in the hot-dry climatic condition, participants breathe more frequently without increasing the total amount of air inspired (i.e., taking more frequent but shallower breaths). These results are largely consistent with findings of previous studies that have demonstrated similar physiological responses to heat stress. Furthermore, our study highlights the existence of differential respiratory responses in hot-dry vs. hot-humid conditions, suggesting that humidity may play an important role in mediating respiratory responses to heat stress. Additional research into the impacts of humidity on respiratory function is thus warranted.
Deconstructing adaptation in the human nasal airway: An iterative assessment of intranasal airflow and nasal morphology in two and three dimensions.
(2024-03-21) Ward, Lyndee; Patabendige, Hasintha; Yokley, Todd; Dennis, Brian; Maddux, Scott
INTRODUCTION: Nasal geometries have been established as being strongly correlated with climate. In cold-dry climates geometries tend to be tall/narrow, while in hot-humid climates geometries are short/broad. This pattern suggests that taller/narrower nasal airways functionally enhance intranasal air-conditioning (i.e., heat and moisture transfers) by increasing nasal surface area relative to intranasal volume, but this hypothesis has not been empirically tested. METHODS: This study employs 3D models of decongested nasal passages generated from cranial CT scans of individuals of predominantly European (5 males, 6 females) and African (5 males, 5 females) ancestry to directly investigate proposed form-function relationships. Each 3D model then underwent an airflow simulation using computational fluid dynamics to collect measurements of intranasal air temperature, humidity, and airflow velocity across consecutive planes of the 3D models. Morphological measurements of nasal passage area, perimeter, and circularity (i.e., shape) were subsequently collected from the same cross-sectional planes for which airflow measurements were collected. spanning the length of the passage. Multivariate regressions were then performed to assess relationships between morphological and physiological variables at each 2D plane and cumulatively across the entire 3D passage. RESULTS: Regression results indicate that nasal passage morphology, particularly turbinate chamber circularity was significantly associated with intranasal air-conditioning (R2 =0.54, p=0.029). Consistent with proposed hypotheses, individuals with taller/narrower (i.e., less circular) turbinate chamber cross-sectional shapes were found to be associated with higher total inspiratory heat and moisture transfers. CONCLUSIONS: This study provides support for climatic pressures selecting for intranasal air conditioning promoted adaptive changes in nasal morphology during human evolution, likely accounting for the observance of taller/narrower nasal passages in Pleistocene and Holocene Homo sapiens following migrations into colder and/or drier environments.
Masticatory muscle morphology in early postnatal mice with osteogenesis imperfecta
(2024-03-21) Ansari, Zahra; Miller, Courtney; Emmanuel, Tanusha; Handler, Emma; Gonzales, Lauren; Organ, Jason; Menegaz, Rachel
Purpose: Osteogenesis imperfecta (OI) is a connective tissue disorder resulting from mutations in COL1A1 or COL1A2, responsible for encoding type I collagen alpha chains. While OI is primarily distinguished by manifestations of bone fragility, including recurrent fractures and bone deformities, muscle abnormalities have also been documented in those affected by OI. While prior research has shown postcranial muscle weakness in mouse models of OI, it remains unclear whether this also applies to feeding musculature and if these differences are present at birth or develop postnatally. This study investigates the development of the masticatory muscles during the early postnatal period in a mouse model. Our hypothesis posits that mice affected by OI will exhibit decreased muscle mass, and therefore potentially weaker muscles, in comparison to unaffected mice. Methods: Cranial tissues from OIM mice (B6C3Fe a/a-Col1a2oim/J) and unaffected wild type (WT) littermates were collected at day of birth (P0) and postnatal day 14 (P14). Tissues were fixed and stained with 1.25% buffered Lugol’s solution, then micro-CT scanned with a reconstruction of 0.02 mm3 voxels. 3D Slicer software was used to isolate and measure the volumes of the superficial masseter, deep masseter, and temporalis muscles. Muscle volumes were compared between genotypes using a Mann-Whitney U test. Results: At birth, no significant differences were observed in body mass or muscle volumes between OIM and WT mice. A trend was observed for OIM mice to have lower superficial masseter volumes compared to WT mice at P0, but this difference was not significant. At P14, OIM mice have significantly lower body weights (p=0.002). Data collection is ongoing for volumetric muscle data from the P14 stage. After birth, body masses diverge rapidly between OIM and WT mice. These growth curves suggest poor feeding performance during the suckling stage in OIM mice. Although masticatory muscle volumes (similar to body mass) start out similar between genotypes at birth, a trend for decreased superficial masseter volume in OIM mice suggests feeding musculature will also lag behind unaffected mice during early postnatal growth. Conclusion: The production of strain above an osteogenic threshold by feeding musculature is critical to typical craniofacial growth during early life. Weaker masticatory muscles may produce lower (yet still osteogenic) levels of strain, contributing to the midfacial hypoplasia seen in OIM mice. A better understanding of muscle development during this critical growth period will provide insight on feeding disorders seen in OI, and the development of the craniofacial phenotype in pediatric patients with OI.
Os Intermetatarseum: An important consideration in chronic foot pain
(2024-03-21) Patel, Kavita; Jafferji, Fatema
Background: The os intermetatarseum is the rarest accessory bone of the foot. It was first described by Gruber in 1856 but well documented cases have been infrequently reported throughout literature. This accessory bone is located on the dorsal aspect of the foot in between the base of the first and second metatarsals. It varies in shape and size and usually presents bilaterally. Chronic dorsal mid foot pain following impingement of the deep peroneal nerve by the os intermetatarseum is common in symptomatic patients and an important consideration in this case. Case Presentation: A 70 year old Caucasian female with a past medical history of depression, thyroid disease, and neuropathy presents with chronic left foot pain rated 10/10, starting 4 years ago. She describes it as a burning and aching pain that comes and goes. The pain, described as burning and aching, occurs on the left anterior ankle, lateral ankle, and forefoot, aggravated by walking, prolonged standing, and toe extension. Alleviated by leg elevation, rest, and sitting. She has been seen by 2 podiatrists and was given a steroid injection by both. The first injection did not help and the 2nd injection lasted for one year. Physical examination revealed pain upon palpation of the peroneal tendon as it courses posterior to the lateral malleolus and at the tip of the fibula. Both peroneus longus and brevis were intact with manual testing. No pain upon palpation of the 1st metatarsal joint, but pain upon palpation of the left 3rd and 4th metatarsal shaft. The dorsalis pedis pulse was 2/4 bilaterally and the posterior tibial pulse was 2/4 bilaterally. Neurological assessment of positive sensation and light touch were intact bilaterally. There were no significant dermatologic lesions present. Bilateral foot assessment showed adequate skin tone, texture, and turgor with a normal temperature gradient. After the initial visit, the patient was instructed to modify her activity and shoe wear to incorporate more fitted supportive tennis-type shoe. On the one-week follow-up visit to discuss MRI findings, the patient reported her pain level decreased to a 4/10. MRI reveals a marked longitudinal arch, moderate hallux valgus, longitudinal split tear of peroneus brevis retromalleolar to inframalleolar distribution, and short segmental split tear of peroneus longus proximal to cuboid tunnel. There was no convincing evidence of an occult fracture or stress injury. A small intermetatarseum was noted between the bases of the first and second metatarsals dorsally that likely articulates with the 1st metatarsal base. Due to the presence of segmental tears involving the peroneus brevis and longus, the podiatrist catered his treatment plan to address tenosynovitis. After discussing the diagnosis and potential treatment plans the patient opted to undergo surgery. Conclusion: Refractory foot pain aggravated by physical activity and symptoms of deep peroneal nerve compression should prompt consideration of a painful os intermetatarseum. Initially, conservative measures like NSAIDs, shoe adjustments, and rest should be employed to address this potential diagnosis, reserving surgical interventions as a final option.
Prevalence of Bilateral Frontal Sinus Absence in Cadaveric Specimens: A Cross-Sectional Study
(2024-03-21) Fowers, Rylan; Driskill, Austin; Stucki, Brenton; Van Alfen, Braden; Heidenreich, Taylor; Lovely, Rehana
Purpose: The frontal sinus is one of four pairs of paranasal sinuses, developed early in gestation and continuing pneumatization into teenage years. Due to the differences in pneumatization, large variability exists in the size and dimensions of the frontal sinus, with the majority of radiologic studies showing prevalence of bilateral frontal sinus agenesis to be between 3-5%. While frontal sinus agenesis has not been identified as a frequent cause of patient complaints, it has contributed to worsening symptoms in certain diseases, and this anatomical variation may pose complicated risks to patient treatments, such as surgery. This study aims to demonstrate the prevalence of bilateral frontal sinus agenesis in a population of fixed cadavers from the United States. Methods: The sagittally hemisected skulls of forty-eight cadavers donors of the HSC Willed Body Program were used for this study, and were not separated based on sex, race, or age. All donors were above the age of 35, allowing for complete pneumatization of the frontal sinuses at the time of hemisection. Initial gross observation of the frontal sinus was performed by the researchers at the midline site of hemisection. If the hollow frontal sinus was not identifiable, sagittal cuts with a bone shear were performed in the bilateral supraorbital regions laterally up to two centimeters from the site of midline hemisection in order to determine if the frontal sinus was present. This method was performed on each of the forty-eight cadaveric skulls. During gross observation and further dissection of the supraorbital regions of the skulls, bilateral presence or absence of the frontal sinuses was noted. Results: Three of the forty-eight donors exhibited bilateral agenesis of the frontal sinus leaving forty-five to exhibit unilateral or bilateral presence of frontal sinuses. This correlates to a prevalence of bilateral frontal sinus absence in 6.25% of the population. Conclusion: This study contributes valuable insights to variations and developmental sequences of the frontal sinus. Literature is consistent regarding prevalence of frontal sinus agenesis in various populations, ranging from 2% to 8% depending on the country of origin; the prevalence of bilateral frontal sinus absence in the sample population of this study was 6.25%. Our findings contribute to current data highlighting prevalence rates, which highlights the importance of noting radiologically determined frontal sinus abnormalities in patient histories, ensuring appropriate care during surgeries and future treatments of conditions such as chronic sinusitis and primary ciliary dyskinesia (PCD).
An atypical variation of the Deltoid Muscle- A Case Report
(2024-03-21) Green, Chase; Ballout, Bassam
This case report describes an atypical deltoid variant discovered during cadaveric dissection of a middle-aged male donor. The bilateral spinal segments of the deltoid muscle (DM) were found to be encased in a distinctive fascial compartment, disconjugate from the normal morphology. The spinal segments were found to be innervated by a branch of the axillary nerve and perfused by a branch of the posterior circumflex humeral artery. Divergences from expected anatomy are important clinically in respect to surgical interventions, as correctly identifying in situ anatomy is essential for the accurate diagnosis and treatment of shoulder pathologies. Unexpected anatomical variations can cause unanticipated surgical delays, and the misidentification of in situ anatomy can be a cause for iatrogenic injury –both of which can increase the probability of unfavorable outcomes in the care of the surgical patient.
Evaluating philtrum-to-tragus distance as an external predictor of nasal passage dimensions: A computed tomography (CT) approach
(2024-03-21) Counts, Caroline; Boettger, Chloe; Tran, Baonhu; Ward, Lyndee; Cowgill, Libby; Ocobock, Cara; Cho, Elizabeth; Maddux, Scott
Accurate quantification of nasopharyngeal temperature requires the placement of a flexible intranasal probe into the upper or mid-nasopharynx. Yet, without guidance from medical imaging, data shows that in practice less than half of nasopharyngeal temperature probes are optimally positioned. Still, previous studies have suggested that the distance between the philtrum (external nose) to tragus (external ear) provides a reliable predictor of internal nasal passage dimensions. However, previous attempts to verify the accuracy of this external proxy have returned equivocal results. Accordingly, this study employed measurements collected from CT scans of 11 living participants (4 female, 7 male) to assess associations between external philtrum-tragus length and internal lengths of the nasal cavity, nasopharynx, and total nasal passage (i.e., cavity + pharynx). Results show statistically significant correlations between philtrum-tragus length and internal measurements of nasal cavity (r=0.412, p=0.033) and total nasal passage (r=0.502, p=0.015) length. In contrast, no significant correlation was identified between philtrum-tragus length and nasopharynx length (r=0.110, p=0.320). Despite the small size of the study sample, these suggest that philtrum-tragus length can provide insights for estimating internal dimensions relating to the location of the end of nasal cavity (i.e., choanal aperture) and the posterior wall of nasopharynx. Thus, this external measurement may enhance the accuracy of intranasal probe placement, especially when medical imaging data (i.e., radiographs, CT, MRI) are not available for guidance. Accordingly, additional investigation into the applied utility of philtrum-tragus length with larger sample sizes appears warranted.
Identification of ecological, locomotor, and morphological indicators of semi-terrestriality in anthropoid primates.
(2024-03-21) Thompson, Indya; Perchalski, Bernadette; Maddux, Scott; Gonzales, Lauren
Semi-terrestriality , the utilization of both arboreal and terrestrial environments, is commonly discussed in the primatological literature but inconsistently defined, limiting its study in fossil taxa. This project aims to fill that gap by investigating the ecological, morphological and locomotor variables that characterize semi-terrestrial taxa. 18 semi-terrestrial and 17 arboreal anthropoid taxa were identified from the literature. Ecological data were collected from mammalian demographic and environmental databases; postcranial measurements and behavioral data were collected from the literature. Three stepwise canonical variate analyses (CVA) were run (ecological, locomotor, and morphological) to identify factors that discriminate between semi-terrestrial and arboreal primates. The ecological CVA retained population size, social group size, and percentage of leaves in the diet as variables. CV1 (55.8%) differentiated semi-terrestrial platyrrhines from arboreal and semi-terrestrial catarrhines. CV2 (26.9%) distinguished semi-terrestrial platyrrhines and catarrhines cluster away from their arboreal counterparts. The behavioral CVA retained bridging, leaping, quadrupedal walking, climbing, scrambling/clambering and bimanual suspension as variables. CV1 (62.3%) separated semi-terrestrial platyrrhines from semi-terrestrial catarrhines, while CV2 (31.5%) distinguished both semi-terrestrial taxa from arboreal taxa. The morphological CVA did not retain any size-corrected variables, with no iteration of relative long bone lengths differentiating between any of the groups. These results indicate select ecological and locomotor variables can reliably identify semi-terrestrial taxa, helping to improve our understanding of this enigmatic behavior. Future studies should likely include measures of specific bony features to more fully investigate potential morphological indicators of semi-terrestrial behaviors.
Bilateral Accessory Piriformis Variant and its Implications – A Case Report
(2024-03-21) Ballout, Bassam; Van Alfen, Braden; Ballout, Yassine; Rosales, Armando
The piriformis muscle is a major muscle of the gluteal region and can be a cause of sciatic pain known as piriformis syndrome. Routine dissection of a cadaver of unknown age presented with bilateral accessory piriformis muscles. The main piriformis muscle was noted bilaterally with a smaller, accessory muscle separate and distinct from the main piriformis muscles. These accessory muscles originated and attached at the same anatomical landmarks as the main piriformis. The tibial nerve exited from below both piriformis muscles and the common fibular nerve exited between the two muscle bellies. This presentation of accessory piriformis is unique and has seldom been presented in the literature. Anatomical accessory muscles such as this one has important clinical considerations including in surgery, radiology, and the diagnosis of sciatic pain caused by piriformis syndrome.
Assessment of digit skin temperatures via infrared thermography under different climatic conditions.
(2024-03-21) Boettger, Chloe; Tran, Baonhu; Ward, Lyndee; Counts, Caroline; Cowgill, Libby; Ocobock, Cara; Cho, Elizabeth; Maddux, Scott
The responsiveness of the manual/pedal digits (i.e., finger/toes) to temperature changes makes them valuable indicators of thermoregulatory function. Further, while infrared thermography is used in many medical settings, its utility in assessing acute changes in digit skin temperatures remains poorly established. Accordingly, this research investigated the use of forward-looking infrared (FLIR) imaging as a methodological tool for analyzing digital skin temperatures across varying climatic conditions. A Teledyne FLIR E76 camera and associated FLIR Studio software were used to assess peripheral digit skin temperatures in a sample of 25 living human subjects (12 female, 13 male). Images of each hand and foot were captured every 5 minutes over a 45-minute period during exposure to four controlled climatic conditions in an environmental chamber. These experimental conditions included a control (22°C and 50% humidity), hot-humid (37°C and 85% humidity), hot-dry (44°C and 15% humidity), and cold-dry (5°C and 80% humidity) exposures. All images were taken at a perpendicular angle from the skin surface at a distance of 0.45 mm, as measured using the camera’s laser-guided range finder function. Baseline images were similarly taken during a preliminary rest period prior to each experimental exposure. This resulted in a total of 2,200 images collected from the left hand and left foot of the 25 participants. Following theoretical expectations, preliminary findings indicate peripheral digit temperatures predictably decrease during the cold-dry exposure, while the hot-dry and hot-humid exposures induce increases in digit temperatures. These preliminary results suggest that infrared thermography likely provides an expedient mechanism for accurately assessing peripheral skin temperatures in humans under different climatic conditions. Infrared thermography may thus have valuable applications for assessing thermoregulatory function in both clinical and research settings.
Pre-weaning craniofacial development in mice with Osteogenesis Imperfecta
(2024-03-21) Miller, Courtney; Emmanuel, Tanusha; Gonzales, Lauren; Handler, Emma; Organ, Jason; Menegaz, Rachel
The craniofacial region plays a pivotal role in various physiological functions, including mastication, speech, and respiration. Early life behaviors have a profound role in shaping adult structure and function. In the early stages of life, all mammals undergo the transition from suckling to mastication, a period coinciding with rapid cranial biomineralization. Osteogenesis imperfecta (OI), a genetic disorder that impacts the production of type I collagen, disrupts biomineralization, leading to craniofacial growth differences affecting overall quality of life. This study investigates the preweaning craniofacial growth trajectory in mice OI (the OIM mouse) compared to unaffected wild type (WT mice). We hypothesize that mice with OI will exhibit smaller overall size and greater craniofacial variation than WT mice due to the abnormal collagen synthesis during skull development. Micro-CT based geometric morphometric analyses of the OIM mouse model (B6C3Fe a/a-Col1a2oim/J) were used to compare craniofacial size and shape differences at birth (P0; n=27 OIM / 20 WT) and postnatal days 7 (P7; n=21/21) and 14 (P14; n=16/20). The SlicerMorph package for 3D Slicer software was used to generate landmark point clouds for the cranium and mandible. Dimension ratios were calculated as width/length for the crania. Principal component analysis with Procrustes ANOVA were used to examine differences between genotypes at each time point, and a canonical variate analysis (CVA) used to identify shape features that maximize the distinction between genotypes across all time points. Results reveal the development of significant differences in both shape and size between the genotypes following birth. At birth, size and shape are similar between genotypes. However, by P7 and P14, OIM mice are significantly (p<0.05) smaller and display pronounced shape changes (p<0.001) characterized by larger neurocranium and shorter viscerocranium. Additionally, OIM mice have significant mandibular alterations by P7 (p<0.001) - shorter ramus, more posterior position of the coronoid, and shorter and wider dental arcade. All of these changes align with the suckling developmental stage, suggesting changes in the ratio of growth between the neurocranium and the viscerocranium during early life. Widening the neurocranium while shortening the viscerocranium during this critical developmental stage alters the masticatory muscle line of action, consequently, influences the health of individuals with OI. These findings underscore the suckling stage’s significance in shaping the foundational structures for later life, providing insights into OI craniofacial development, and suggest potential benefits to directing interventions toward an earlier time point for more effective treatment of OI.
Histological Examination of Ectopic Thyroid Tissue in an 88-year-old Caucasian Female: A Case Report
(2024-03-21) Reinsmith, Stephen; Park, Juyoun; Oliver, Madelyn; Ribeiro, Andre
Background: Ectopic thyroid tissue (ETT) is a rare developmental abnormality that accounts for 1% of all mediastinal tumors and has a higher prevalence in females. ETT classically presents as an encapsulated mass separate from the normal subhyoid thyroid gland present on the anterior neck. Case studies have reported that ETT can arise in the mouth, oropharynx, subclavicular area, or mediastinum. Unless large enough to compress the surrounding tissues, individuals with ETT are typically asymptomatic. Therefore, ETT is often an incidental finding during imaging studies, surgery, or at autopsy. Histologically, ETT usually appears identical to "normal" thyroid tissue. Case Information: During routine dissection, an 88-year-old Caucasian female with a cause of death of renal cancer presented with an encapsulated, solitary nodule located at the intersection between the thoracic cavity and superior mediastinum (2.0 x 1.0 x 1.5 cm). The nodule was densely adherent to the medial aspect of the right lung's apex, leaving behind a notable impression following extraction. No attachments to the thyroid proper were noted. Tan-brown, glassy, and multinodular cut surfaces were grossly appreciated following sectioning. Histological examination demonstrated the nodule was entirely composed of benign thyroid tissue with variable sized colloid follicles. No suspicious foci were identified. It is indeterminate if this nodule influenced the donor’s thyroid hormone levels due to the lack of access to a thyroid panel. Next, the thyroid proper was examined to reveal an enlarged, asymmetric gland with disconnected lobes. No obvious isthmus was present. The total gland weighed 85 grams. The external surface of the thyroid proper was tan-brown, bosselated, and featured an intact capsule. The left lobe (5.0 x 3.4 x 1.7 cm; 9 grams) was markedly smaller when compared to the enlarged right lobe (8.6 x 5.2 x 3.4 cm; 76 grams). Sectioning of the left lobe revealed tan, homogenous, and grossly unremarkable cut surfaces; the right lobe revealed tan-brown to maroon, firm, and multinodular cut surfaces. Additionally, a white, soft, and ill-defined area, with intervening colorless gelatinous material, was noted at roughly mid-pole of the right lobe. Conclusion: This report describes a rare case of ETT and other relevant anatomical findings in an 88-year-old Caucasian female. These findings will further contribute to a scarcely documented developmental abnormality in the literature.

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