Ultrasound has been integrated into a gross anatomy course taught during the first year at an osteopathic medical school. A clinical ultrasound elective course was developed to continue ultrasound training during the second year of medical school. The purpose of this study was to evaluate the impact of this elective course on the understanding of normal anatomy by second-year students. An anatomy exam was administered to students enrolled in the clinical ultrasound elective course before the start of the course and after its conclusion. Wilcoxon signed ranks tests were used to determine whether exam scores changed from the pre-test to the post-test. Scores from two classes of second-year students were analyzed. Students who took the elective course showed significant improvement in the overall anatomy exam score between the pre-test and post-test (P < 0.001). Scores for exam questions pertaining to the heart, abdomen, upper extremity, and lower extremity also significantly improved from the pretest to post-test (P < 0.001), but scores for the neck and eye showed no significant improvement. The clinical ultrasound elective course offered during the second year of medical school provided students with an important review of key anatomical concepts while preparing them for board exams. Our results suggested that more emphasis should be placed on head and neck ultrasound to improve student performance in those areas. Musculoskeletal, abdominal, and heart ultrasound labs were more successful for retaining relevant anatomical information.

Background Studies of mammalian CSF dynamics have been focused on three things: paravascular flow, pressure and pulsatility, and “bulk” flow; and three (respective) potential motive forces have been identified: vasomotor, cardiac, and ventilatory. There are unresolved questions in each area, and few links between the different areas. The American alligator (Alligator mississippiensis) has pronounced plasticity in its ventilatory and cardiovascular systems. This study was designed to test the hypothesis that the greater cardiovascular and ventilatory plasticity of A. mississippiensis would result in more variation within the CSF dynamics of this species. Methods Pressure transducers were surgically implanted into the cranial subarachnoid space of 12 sub-adult alligators; CSF pressure and pulsatility were monitored along with EKG and the exhalatory gases. In four of the alligators a second pressure transducer was implanted into the spinal subarachnoid space. In five of the alligators the CSF was labeled with artificial microspheres and Doppler ultrasonography used to quantify aspects of the spinal CSF flow. Results Both temporal and frequency analyses of the CSF pulsations showed highly variable contributions of both the cardiac and ventilatory cycles. Unlike the mammalian condition, the CSF pressure pulsations in the alligator are often of long (~ 3 s) duration, and similar duration CSF unidirectional flow pulses were recorded along the spinal cord. Reduction of the duration of the CSF pulsations, as during tachycardia, can lead to a “summation” of the pulsations. There appears to be a minimum duration (~ 1 s) of isolated CSF pulsations. Simultaneous recordings of cranial and spinal CSF pressures reveal a 200 ms delay in the propagation of the pressure pulse from the cranium to the vertebral canal. Conclusions Most of the CSF flow dynamics recorded from the alligators, are similar to what has been reported from studies of the human CSF. It is hypothesized that the link between ventilatory mechanics and CSF pulsations in the alligator is mediated by displacement of the spinal dura. The results of the study suggest that understanding the CSF dynamics of Alligator may provide unique insights into the evolutionary origins and functional regulation of the human CSF dynamics.

Disorders of the volume, pressure or circulation of the cerebrospinal fluid (CSF) lead to disease states in both newborns and adults; despite this significance, there is uncertainty regarding the basic mechanics of the CSF. The suboccipital muscles connect to the dura surrounding the spinal cord, forming a complex termed the ‘myodural bridge’. This study tests the hypothesis that the myodural bridge functions to alter the CSF circulation. The suboccipital muscles of American alligators were surgically exposed and electrically stimulated simultaneously with direct recordings of CSF pressure and flow. Contraction of the suboccipital muscles significantly changed both CSF flow and pressure. By demonstrating another influence on CSF circulation and pulsatility, the present study increases our understanding of the mechanics underlying the movement of the CSF.

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Background Cranial fluids of vertebrae mammals are composed of arterial blood, venous blood, and cerebrospinal fluid that can be altered by orthostatic pressures; head‐down postures can elevate intracranial pressure and carotid/jugular luminal area while head up postures produce opposite effects. Previous studies on aquatic and terrestrial snakes showed cardiovascular variation while arboreal snakes showed little cardiovascular variation during orthostatic transitions. Little experimental work regarding orthostatic transitions has been done on alligators. Alligators are known to have unique blood flow patterns due to active regulation of blood flow. The purpose of this study is to investigate the effects of gravitational tilt on vessel luminal diameter and ICP in alligators. Methods Live adult alligators (n = 5, 165 – 183 cm total length) were subjected to gravitational tilts between 45° head‐up to 45° head‐down in 15° increments. Short (30 s) and long (120 s) duration tilts were performed to assess barostatic reflex and ICP using ocular ultrasonography, respectively. Vascular ultrasonography was also used to assess luminal diameter of the carotid artery and jugular vein. Instantaneous heart rate was inferred from EKG recordings throughout tilts. Results Throughout orthostatic transitions, ocular ultrasonography revealed an increase in optic nerve sheath diameter (head down tilts) and a decrease in optic nerve sheath diameter (head up tilts). Head down tilts resulted in jugular and carotid dilation while head up tilts resulted in various jugular luminal diameters and minimal change in carotid diameter. Heart rate increased at the onset of all orthostatic transitions. There was no evidence for a barostatic response. Conclusions Ocular ultrasonography was used to non‐invasively assess intracranial pressure of reptiles. There was a linear relationship between orthostatic transitions and intracranial pressure due to redistribution of CSF. Compared to previous studies, orthostatic transitions produced similar results on vessel flow and diameter. Variations of vessel flow and diameter may be attributed to unusual patters of heart rate or blood shunts in the cephalic venous system. Increases in heart rate in all rotations may be due to a fear response. Additional studies are needed to further understand the underlying regulatory mechanisms that give rise to the alligator's heart rate and blood flow patterns. Support or Funding Information Funding: The Influence of Gravitational Gradients on American Alligators (Alligator Mississippiensis) project has been funded by A.T. Still University's Masters in Biomedical Sciences program. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.