Osteology Modules for the Human Structure Course

Background and Objective: The COVID-19 pandemic has created a need to deliver much content for the Human Structure (HS) course virtually. Because osteology is a fundamental component of human gross anatomy, the goal of this project was to create quality interactive osteology modules for HS that can be delivered online. Project Methods: To ground our module development in best practices for teaching and learning human gross anatomy, we reviewed 100 articles from PubMed databases and selected 9 for discussion during weekly literature review meetings. Key search terms included: education research, computer-assisted instruction (CAI), technology-enhanced learning (TEL), clinically based anatomy, integrated learning, medical education, and more. We created the modules using Microsoft PowerPoint™ and EndNote X9™ for referencing purposes. Bone images were captured and edited with a Nikon USA™ D850 DLSR camera and Adobe Photoshop, respectively. Additional images were obtained from IUSM online textbooks, miscellaneous websites, and the radiology database Radiopaedia™. Each module includes pertinent clinical correlations, radiology, and post-module quizzes for students to assess their higher-order knowledge. Results: We created 7 osteology modules using best practices for human gross anatomy teaching and learning: (1) Vertebral Column, (2) Thorax, (3) Shoulder Girdle & Brachium, (4) Elbow, Antebrachium, Hand, (5) Pelvic Girdle & Thigh, (6) Knee, Leg, Foot, (7) Cranium & Hyoid. Conclusion and Potential Impact: Studies have demonstrated that CAI/TEL and radiological imaging work synergistically with traditional didactic methods to facilitate learning of human gross anatomy. Our modules will be used statewide in the HS course for first-year medical students as a CAI learning tool. Looking forward, we plan to use both qualitative and quantitative methods to determine if use of these modules results in better exam performance or aids in other aspects of the learning process.

Three-Component Model of the Spinal Nerve Branching Pattern, based on the View of the Lateral Somitic Frontier and Experimental Validation

ABSTRACTOne of the decisive questions about human gross anatomy is unmatching the adult branching pattern of the spinal nerve to the embryonic lineages of the peripheral target muscles. The two principal branches in the adult anatomy, the dorsal and ventral rami of the spinal nerve, innervate the intrinsic back muscles (epaxial muscles), as well as the body wall and appendicular muscles (hypaxial muscles), respectively. However, progenitors from the dorsomedial myotome develop into the back and proximal body wall muscles (primaxial muscles) within the sclerotome-derived connective tissue environment. In contrast, those from the ventrolateral myotome develop into the distal body wall and appendicular muscles (abaxial muscles) within the lateral plate-derived connective tissue environment. Thus, the ventral rami innervate muscles that belong to two different embryonic compartments. Because strict correspondence between an embryonic compartment and its cognate innervation is a way to secure the development of functional neuronal circuits, this mismatch indicates that we may need to reconcile our current understanding of the branching pattern of the spinal nerve with regard to embryonic compartments. Accordingly, we first built a model for the branching pattern of the spinal nerve, based on the primaxial-abaxial distinction, and then validated it using mouse embryos.In our model, we hypothesized the following: 1) a single spinal nerve consists of three nerve components: primaxial compartment-responsible branches, a homologous branch to the canonical intercostal nerve bound for innervation to the abaxial compartment in the ventral body wall, and a novel class of nerves that travel along the lateral cutaneous branch to the appendicles; 2) the three nerve components are discrete only during early embryonic periods but are later modified into the elaborate adult morphology; and 3) each of the three components has its own unique morphology regarding trajectory and innervation targets. Notably, the primaxial compartment-responsible branches from the ventral rami have the same features as the dorsal rami. Under the above assumptions, our model comprehensively describes the logic for innervation patterns when facing the intricate anatomy of the spinal nerve in the human body.In transparent whole-mount specimens of embryonic mouse thoraces, the single thoracic spinal nerve in early developmental periods trifurcated into superficial, deep, and lateral cutaneous branches; however, it later resembled the adult branching pattern by contracting the superficial branch. The superficial branches remained segmental while the other two branches were free from axial restriction. Injection of a tracer into the superficial branches of the intercostal nerve labeled Lhx3-positive motoneurons in the medial portion of the medial motor column (MMCm). However, the injection into the deep branches resulted in retrograde labeling of motoneurons that expressed Oct6 in the lateral portion of the medial motor column (MMCl). Collectively, these observations on the embryonic intercostal nerve support our model that the spinal nerve consists of three distinctive components.We believe that our model provides a framework to conceptualize the innervation pattern of the spinal nerve based on the distinction of embryonic mesoderm compartments. Because such information about the spinal nerves is essential, we further anticipate that our model will provide new insights into a broad range of research fields, from basic to clinical sciences.

Exploring Anatomic Variants to Enhance Anatomy Teaching: Musculus Sternalis

The opportunity to encounter and appreciate the range of human variation in anatomic structures—and its potential impact on related structures, function, and treatment—is one of the chief benefits of cadaveric dissection for students in clinical preprofessional programs. The dissection lab is also where students can examine unusual anatomic variants that may not be included in their textbooks, lab manuals, or other course materials. For students specializing in physical medicine, awareness and understanding of muscle variants has a practical relevance to their preparations for clinical practice. In a routine dissection of the superficial chest muscles, graduate students in a human gross anatomy class exposed a large, well-developed sternalis muscle. The exposure of this muscle generated many student questions about M sternalis: its prevalence and appearance, its function, its development, and its evolutionary roots. Students used an inquiry protocol to guide their searches through relevant literature to gather this information. Instructors developed a decision tree to assist students in their inquiries, both by helping them to make analytic inferences and by highlighting areas of interest needing further investigation. Answering these questions enriches the understanding and promotes “habits of mind” for exploring musculoskeletal anatomy beyond simple descriptions of function and structure.