Category: Anatomy

Introduction

The chief objective in quality management is constant development. The process of improving the anatomic pathology laboratory requires several machines. One of the tools is the turnaround time used to indicate the level of efficiency in the laboratory and how its patient care may be affected if the process gets a fault. The quality and safety of patient care are managed efficiently by the nursing of surgical specimen turnaround time. Turnaround time refers to finishing a process or accomplishing a demand. This paper aims to show the role of monitoring the turnaround time in anatomic pathology. The importance will be shown from the institution’s viewpoint and why monitoring a turnaround and the organizational administrations point of view is vital.

To deliver quickly and lower TAT, measurement is critical; but, for large product and service that are tough to sustain, it becomes a complicated task. These cash cow items are eventually turned on to fresh virgin groups. The cause for such a shift to new teams might be due to the loss of current workers or the outsourcing of the task. To external parties in order to save money in any scenario, the essential challenge remains the same: providing high-quality service. Remedies within a specified time frame tend to be more accurate. Recently, just a few projects have been completed in this area. It is critical to plan ahead and follow a methodical procedure. It is critical to comprehend the issues in order to fix them.

Keywords: Turnaround time, a pathology laboratory, management perspective.

Monitoring Turnaround Time in the Anatomic Pathology Laboratory

Turnaround time (TAT) is characteristically designated as the period it takes from when a test is demanded to when the results are produced. The Time includes the period taken for preparation, before and after analysis, and during analysis stages. Efforts to improve the general service quality, such as reducing laboratory turnaround time, demonstrate a more robust dedication to clients’ needs. The patient’s contentment is enhanced by providing medical reports within a defined time limit, demonstrating the physician’s competence. It is a crucial part of a laboratory’s quality assurance system, and it has been identified as a critical performance metric of a lab’s overall efficiency and efficacy. Customer contentment leads to a brand’s or agency’s capacity to achieve and surpass the requirements and preferences of its intended market.

In laboratory facilities, quality has traditionally been defined exclusively in scientific or empirical issues, emphasizing imprecision and inaccurate goals. One of the main aims of anatomic pathology labs is to accurately forecast the turnaround time for samples from patients from the Time they are acquired to the Time the decision is assembled. For doctors, quality of service is more essential than price because it includes the examination’s quality and reliability and its availability, cost, utility, and deadline. There is a demand for a quick, rust-resistant, cost-effective, and dependable alternative. If the result arrives on Time, the clinician may be willing to forgo correct analysis for a shorter turnaround time.

Depending on the type of exam, each method differs. For instance, if Specimen A is to be gathered and processed immediately, while Collection B must be whirled, the Time necessary for the test on Study A differs from the Time needed for the test on Measure B. This shows that each test has a different turnaround time. Moreover, pathology examinations can be divided into two categories: standard and exceptional. As a result, a list for all tests done for a lab depending on the Time necessary for each diagnosis based on its category and significance. When one has compiled a list, they may assign a TAT to each item depending on its importance and nature.

Despite this, most physicians use TAT to measure anatomic laboratory service levels. Users immediately notice TAT delays, yet outstanding TAT is overlooked. One of the most typical reasons for consumer discontent with the laboratory is a slow turnaround time. The laboratory personnel devote a lot of Time and resources to resolving customer complaints and improving client services standards. Some labs are incapable of increasing their turnaround times despite advances in analytical apparatus, transport links, and technology. As Time goes by, emergency section response times have enhanced slightly (EDs). Because of the rising focus on testing outside the laboratory, TAT is becoming an increasingly essential service performance parameter for laboratories. Nonetheless, several companies are having trouble meeting their interior goals in this area.

Anatomic pathology labs are under increased pressure to lower turnaround times associated with patient stays. It is generally understood that the kind of cell under investigation and the pigment orders requested for images influence the production time for samples and drops. Following a multivariable study, it was discovered that physician behaviors such as communication with other examiners, identification of malignancy, and the number of samples required to be reviewed had a substantial effect on turnaround time. This paper purposes to demonstrate the role of identifying the turnaround time in anatomic pathology. The significance will be shown from the organization’s perspective and why checking a turnaround and the directorial administrations point of view is important.

Importance of Monitoring Turnaround Time

The analysis of samples in an anatomic pathology lab is separated into three main steps. The process involves critical, analytical, and post-analytical stages, each with multi-step sequential phases that significantly impact patient care. A group of experts from across the world came together to create a set of criteria that laboratories could use worldwide to help them analyze and improve specimen administration to reduce client health hazards. Delays in filing influence exposure periods, client experience, and healthcare expenses. Systemic delays in gathering, analyzing, and presenting testing specimens in developing countries have been documented. This study aims to assess the TAT in the institution’s histology unit and contrast it to prior studies. Through this investigation, researchers will examine the effect of turnaround time on the anatomic pathology lab, health officers, and patients.

Diagnosing mistakes and patient mistreatment in the anatomical pathology laboratory must be avoided by health care providers and pathologists working together. The aim is to obtain measurable performance improvements in a branch of science dealing while mitigating the chance of unfavorable outcomes in inpatient care. The anatomy pathology lab can reduce turnaround time using technological advances like the sample is placed tools, barcode scanners, automated and intelligent staining mechanisms, or digitalized coordinating structures. Modern storage technology would help guarantee that samples are in good shape, preventing data corruption due to interfering samples. Because there is proof that the process of receiving might uncover errors, the advisory group recommends that anatomic pathologists develop guidelines for examining pathology instances. This is done to uncover future problems and translation issues to enhance the overall quality of healthcare.

When it comes to laboratory quality standards, the turnaround time is essential to succeed. Inter-laboratory restrictions, poorly organized internal competitiveness, Transdisciplinary competitiveness, defective equipment, quality control, assurance systems, politics, and economics have all been blamed for the TAT difference between advanced and developing nations. Pre-analytical, analytical, and post-analytical phases accounted for 53.0%, 27.7%, and 19.3% of total Time spent in the laboratory, correspondingly, regarding the findings of this research (Makris, 2019). Even though there is a statistical variance in TAT between industrialized and underdeveloped countries, this study found that wealthy nations have achieved some improvement. The examination also suggested that realistic timeliness targets for histology labs be set. This should be reviewed regularly to ensure that the law is followed and that customer satisfaction improves in this location.

Using WSI innovation, many pathology laboratories have already gone “fully computerized” for original diagnosis. Nevertheless, not many labs can migrate to WSI because it is not commercially viable. Numerous new commercial solutions aim to boost the productivity of digital pathology technologies by combining imaging techniques that may be used to streamline the lab process. The study also revealed the necessity for novel approaches to handling duties in these anatomy pathology labs. As a result, the turnaround time would be reduced, enhancing patient protection.

In AP labs, virtual reality is becoming increasingly popular. Since its premiere, studies have shown that the adoption of AR technologies, such as Microsoft Holo Lens, has improved the efficiency and effectiveness of laboratory facilities in anatomic pathology. Holo Lens is a ground-breaking augmented reality (AR) device used in pathology for medical and non-clinical purposes. The device is light, comfortable to wear, and easy to control (Donaldson, 2019). It also boasts sufficient processing power and high-resolution imaging capabilities to fulfill the demands of the vast majority of consumers. This equipment is well-suited for autopsy, gross and microscopic examination, and digital pathology. AR in pathology for both clinical and non-medical objectives is beneficial. The Holo Lens opens up a slew of novel pathological options involving virtual workspace, autopsy, and dynamic techniques for modifying digital spatial information to better quality management.

Sophisticated laboratory information systems (LISs) are complex, networked software programs and structures that cater to various lab data processing needs. A laboratory management system (LIS) handles tasks like sample and sample order processing, sample handling and tracking, evaluation and discussion assistance, and the creation and distribution of patient reports all through the patient assessment process. Aside from that, laboratory systems engineering (LISs) provide the administration with reports and other data they need to operate their businesses and assist quality and constant advancement initiatives.

Numerous research is also looking at the future of anatomical pathology to ensure the quality of care. Another innovation that might reduce turnaround time is three-dimensional publishing, making interpreting lab tests easier, allowing the operation to be performed more swiftly and effectively (Rimmer, 2019). Anatomic pathology samples that are tri-dimensional reproducible can benefit significantly from three-dimensional digital printing. Three-dimensional (3D) printing technology is becoming more common as a safe and inexpensive method of producing 3D physical copies of natural-world objects (Reeser & Doiron, 2019). A 3D model of an item is built using this approach, with visual materials of depth, form, and texture. A transparent, precise replica of the image would aid pathologists in quickly analyzing and testing evidence.

The relevance of pathology and medical sciences (PALM) to a functioning public health system is underappreciated in the policy and administrative sectors. In reaction to the quality control obstacle, technological innovations such as telepathology and point-of-care examination play a vital role in supplying PALM solutions, assuming they are used correctly (Sattar, 2021). The study also emphasizes the need to maintain PALM quality, arguing that all labs in low- and middle-income nations (LMICs) should participate in quality control and vocational programs to reach this aim. The report proposed a PALM program suited to these countries to implement these ideas and provide equal access to essential commodities in LMICs. As part of a more extensive federal laboratory planning process, it was incorporated into a publicly recognized laboratory structure.

Turnaround Time and Quality Assurance

Hospitals cannot improve quality without first analyzing it, and they can’t evaluate it without precise, trustworthy data. Healthcare systems desire extensive and exact data to evaluate the quality of operative procedures provided by comparable facilities to patient characteristics in the exact geographical location (Barnali & Basu, 2020). Gathering relevant data is also an effective way to improve healthcare, and it is one of four steps in the constant quality enhancement process. This would be enhanced when a significant amount of information is collected (Dobrescu et al., 2021). Hospitals and caregivers must be held accountable to four essential requirements for improving patient outcomes to be successful. The first fundamental that would help improve the quality of services is by building and managing contextual, relevant norms. There also should be the production of the right resources that help manage people’s health. Submission to an authentication process would also allow an audit function to check the infrastructure, methods, and outcomes as components of the vetting process in an organization.

Quality and Assurance standards for the regular measurement and evaluation of core performance data for Histopathology Laboratory as part of the National Quality Assurance Program in Histopathology. The role of the program is to establish national QA benchmarks in histopathology to ensure good quality (O’Keane et al., 2019). Ahead of the event, collecting and analyzing information for the period will be required. Establishing benchmarks is a document that contains the following information; Individual histology is monitored using essential quality monitors and related indicators (St-Pierre, 2017). Their actions would be monitored by laboratories and, finally, suggestions for each necessary quality monitor’s value. There are existing domestic and international benchmarks for each significant indicator where accessible.

For an overlap on improvement, defining and quantifying quality is necessary. To be legitimate, a measurement must precisely represent the significance of the notions. Some other significant aims are ensuring that mistakes in an organization are avoided in the delivery of services and enhancing capacity building for data-driven decision-making (Fan et al., 2020). Management support fosters excellence at all levels of healthcare by building internal connections, concentrating on issue detection and management, and assisting in allocating resources optimization – supporting good standards, cooperation, and improved two-way interaction. The goal of operations and maintenance research would help understand the variables related to perceived customer satisfaction variability.

This Q-Probes program, which has covered pre-analytical, analyzed elements in the disciplines of causes of health problems, histopathological, and postmortem pathology, has set essential minimum requirements in AP pathogenesis. Its study’s findings have already been publicized, referenced, and used to produce scientific assessment standards and some other governmental suggestions, among several other issues. Q-Probes can be used in the anatomical or therapeutic microbiology laboratory to explore a methodology, outcome, or feature in greater depth.

The Q-Probes program, which has tackled before analytical, analytical, and after analytical elements in the disciplines of surgical pathology, cytopathology, and postmortem pathology, has set necessary federal standards in AP pathology. The Q-Probes study’s findings have been printed, referenced, and used to produce laboratory evaluation standards and other governmental suggestions, among other things. Q-Probes can be used in anatomic or medical pathology laboratories to explore a technique, outcome, or structure in greater depth (Parkash et al., 2017). Only a few research in anatomic pathology have looked at the effectiveness of Lean quality enhancement measures like education in increasing patient safety. Continuous improvement can improve pathological patient care through cultural shifts and specific work process adjustments.

After designing various plans or requirements, the management committee must connect and communicate with the staff to ensure performance and reliability. This allows the workforce to be prepared for any change that may occur. To ensure the achievement of project aims, it is critical to communicate often about the project’s scope, targets, aspirations, deliverables, schedules, progress, risks, challenges, and successes. Through two-way interaction, the personnel who work in the location are probably fully aware of any changes that may be made to improve the quality of service (Liakh & Lytvyn, 2020). Employee ideas and solutions are frequently the most effective and lengthy when produced via engagement, responsibility, and attention. Ensure that one action is taken from conversations with staff and that development is shared.

Lean and Six Sigma policies should be implemented to ensure the turnaround time in medical laboratories. This is done using a problem-solving technique that includes determining, testing, assessing, enhancing, and regulating (DMAIC) (Andrews-Todd & Kerr, 2019). When implemented in clinical laboratories, these ideas can drastically reduce turnaround time. This may be accomplished by identifying critical process areas that can be altered and delivering excellent and cost-effective solutions that can be adjusted to restricted funding levels. Middleware should also be installed to ensure that the laboratories are efficient. Web logic technologies provide a link between the laboratory information management systems (LIS) and any other testing equipment, and they frequently include genuine displays and reporting (Crovini & Ossola, 2021). This enables specialists and experts to assess turnaround time and quality assurance in real-time, ensuring that devices perform consistently and adequately. It frequently comes with many extra features, like regulated decision assistance, auto-verification, and specimen administration.

Automation should also be done to improve the turnaround time. Laboratory automation allows staff to accomplish other duties while specimens are being collected and analyzed, reducing the number of human laboratory analytical processes. With automated devices that spin, decamp, portion, label, and sort specimen bottles accessible, automation may be used on a modest scale, reducing turnaround time both for statistics and daily tests (Theparee et al., 2018). All existing technologies must communicate with the lab’s LIS and middleware for employees to precisely track the status of all samples and automated instruments. Moreover, automation can reduce the number of human mistakes, resulting in a greater level of patient care.

Conclusion

Lead Time is the length of Time necessary to satisfy a customer’s requests or needs, as specified by the seller or service providers. The lead-time is the period between how a client places an order and when they receive their final approval. Consequently, the Turnaround Time is the time it takes to complete a task and supply the product when sent to a sorting facility following the patient’s preference. Improving laboratory turnaround time is a crucial goal that all medical labs aim for. Moreover, optimizing turnaround time seldom needs a one-size-fits-all approach; instead, it necessitates collaboration from the whole team and the implementation of tactics that create meaning inside the lab’s structure.

References

Andrews-Todd, J., & Kerr, D. (2019). Application of ontologies for assessing collaborative problem-solving skills.International Journal of Testing, 19(2), 172-187.

Barnali, B., & Basu, R. (2020). A Study on patients’ experience regarding the quality of healthcare services provided in the Alipurduar District of India.Journal of Healthcare Quality Research, 35(4), 237-244.

Crovini, C., & Ossola, G. (2021). Is risk reporting a possible link between financial and management accounting in private firms?Financial Reporting, (1), 29-60.

Dobrescu, A., Rogers, P., & Ferriday, D. (2021). Exploring relationships between the amounts a parent serves themselves, how much they would serve their pre-school child, and the amount their child would choose.Appetite, 157, 104868.

Donaldson, L. (2019). Easy to wear multifunctional device offers many applications.Materials Today, 30, 4.

Fan, C., Yan, D., Xiao, F., Li, A., an, J., & Kang, X. (2020). Advanced data analytics for enhancing building performances: From data-driven to effective data-driven approaches.Building Simulation, 14(1), 3-24.

Liakh, I, & Lytvyn, O. (2020). HR management by values as an innovative way to improve personnel work.Business Inform, 6(509), 328-333.

Makris, K. (2019). Are stroke biomarkers ready for research and clinical use? Focus on the pre-analytical, analytical and post-analytical variability. Clinica Chimica Acta, 493, S743.

O’Keane, J., Phelan, S., & Treacy, A. (2019). The Irish national histopathology quality improvement program: An overview.Diagnostic Histopathology, 25(12), 463-470.

Parkash, V., Fadare, O., Dewar, R., Nakhleh, R., & Cooper, K. (2017). Can the misinterpretation amendment rate be used to measure the interpretive error in anatomic pathology? Implications of a survey of the directors of anatomic and surgical pathology. Advances in Anatomic Pathology, 24(2), 82-87.

Reeser, K., & Doiron, A. (2019). Three-dimensional printing on a rotating cylindrical mandrel: A review of additive-lathe 3d printing technology. 3D Printing and Additive Manufacturing, 6(6), 293-307.

Rimmer, A. (2019). According to royal college, allowing more doctors to work less than full Time could reduce burnout. BMJ, l5778.

Sattar, A. (2021). High-risk mapping and response play a vital role in dengue fever control.Pakistan Journal of Zoology.

St-Pierre, G. (2017). Establishing the first performance indicators in the spine: Benchmarks from CSORN.The Spine Journal, 17(10), S145.

Theparee, T., Das, S., & Thomson, R. (2018). Total laboratory automation and matrix-assisted laser desorption ionization-time of flight mass spectrometry improve turnaround times in the clinical microbiology laboratory: A retrospective analysis.Journal of Clinical Microbiology, 56(1).

Introduction

The altitude gradient influences substantial changes in human physiology. Across different altitudes, temperature and humidity decrease as increased latitude changes. However, altitudinal gradients do not differ in the length of the day and solar angle of incidence as in latitudinal variations. Still, they result in dramatic barometric pressure changes influencing diverse biological processes, including metabolism rate and aerodynamic performances. Mountainous places tend to be functionally isolated due to the elevation belts constraining physiological capacity. This paper looks into high-altitude human physiological adaptations to altitudinal temperature, oxygen, and air density, even though the adverse effects of high altitude are not confined to humans alone but extend to plants and animals and play a role in speciation.

High Elevation Adaptation

Athletes born and living in a high-altitude area have naturally larger lungs to cater to the need for increased oxygen in the low-oxygen concentration area. This adaptation gives them a ‘barrel chest’ appearance since the rib cage is wider. Athletes from lowlands moving to a high-altitude location to train cannot adapt to the rib cage and lung sizes. Athletes born in mountainous areas have also been noted to have many red blood cells compared to those living in lowlands.

People moving from low-altitude lowlands to mountainous regions usually suffer headaches, nausea, and brain swelling due to a short-term lack of oxygen (Kenneth, 2020). This difference is explained by their respiratory systems that are not adapted to mountainous areas. Therefore, developing a response or adaptation to these low-oxygen concentration areas takes time.

Why Athletes Train In High-Altitude Areas

People born in mountainous areas have been noted to have many red blood cells compared to those living in low lands, making them good marathon athletes. Athletes moving from lowlands to highlands experience health problems that require them to adapt to new environments. In response, the body of such an athlete produces additional red blood cells for efficient and effective transport of oxygen within the body. The body takes from two weeks to two months to adapt to living at high altitudes. The adaptation can be hindered by conditions that hamper the proper production of red blood cells, and such people should seek physician’s counsel before moving (Storz, 2021). The conditions of these people may get worse rather than improve, characterized by breathing problems and arthritis. Nevertheless, as a result of the increased number of red blood cells and expanded rib cage, athletes who successfully adapt develop endurance in athletics. This is the reason why athletes train in high lands.

Why Some People Cannot Cope With High Altitude Conditions

Genetic adaptations play a role in aiding high-altitude dwellers to adapt to high and dry living conditions as well. Whereas some people living in high-altitude areas experience breathlessness, palpitations, and dizziness, others have no such health problems. Their bodies have increased red-blood cells; more viscous blood may sometimes block blood vessels. This difference has been linked to genetic adaptations. The genetic changes allow high-altitude inhabitants to extract enough oxygen from the thin mountain air. They, as a result, have less likelihood of suffering heart attacks and strokes of chronic mountain sickness. The genetic component allows high-altitude dwellers to adapt quickly and live better in these high and dry environmental conditions. According to Storz (2021), people living in mountainous regions and whose ancestors had done so for generations had less chronic mountain sickness. They were found to have differences in 11 gene regions compared to people from low lands. The genetic mutations have helped athletes from the highlands do better than low-land athletes.

Conclusion

The ability of high mountain dwellers to live in high and dry conditions and develop endurance in athletics is, therefore, a result of many adaptation responses to their environments. Lowland athletes can also acquire these traits by moving to the highlands to train and developing secondary adaptations that can increase their athletic endurance. However, before one makes such a decision, it is imperative to seek physician counsel.

References

Kenneth, S. S. (2020). Anatomy & physiology: The unity of form and function. McGraw Hill.

Storz, J. F. (2021). High-altitude adaptation: mechanistic insights from integrated genomics and physiology. Molecular biology and evolution, 38(7), 2677-2691.

Introduction

The Institute of Human Anatomy’s YouTube video, “The Anatomy of Pain,” visually explores the structures involved in pain’s transmission and processing. The video was selected because it provides an excellent illustration of the physical basis for pain. The new knowledge acquired is that there are two facets to every person’s experience of pain, and they work together to make the experience unique (“Institute of Human”, 2021). One is a specific, localized feeling in a section of the body, while the other is a more generalized, unpleasant quality of varied intensity that is typically accompanied by actions meant to alleviate or end the experience.

Discussion

Most directly related to the video was a concept from the unit’s textbook readings on developmental psychology: a complicated matrix of peripheral and visceral neurons, the central nervous system, and the brain serve the perception of pain. While pain is the leading cause of patient visits to the doctor, it defies precise categorization since only the person experiencing it can fully understand and articulate it (Santrock, 2022). Pain is characterized by a combination of a noxious sensory experience and an unpleasant physiochemical and emotional response. Either way, it is meant to alert the person to the impending danger. It is the clinician’s responsibility to both identify and address the origins of the patient’s discomfort.

Conclusion

To explain the link further, various modifying elements within the neural system influence pain transmission. Many factors contribute to pain perception, including chemical modulation, the additive effects of inflammatory byproducts, and the inhibitory impact of large-diameter sensory afferent fibers. Pain is a multifaceted, biopsychosocial experience involving a wide range of neural circuits, neurochemicals, mental operations, and emotional responses (Santrock, 2022). The brain does not only take in pain signals from the body; it actively controls sensory output by descending extensions from the medulla that sway the spinal dorsal horn.

References

Institute of Human Anatomy. (2021). The anatomy of pain [Video]. YouTube. Web.

Santrock, J. W. (2022). A topical approach to life-span development (11^th ed.). McGraw-Hill Higher Education.

Introduction

The muscles of the head and neck (Fig. 1) are divided into two groups: masticatory and mimic muscles. In some cases, they function together for articulating speech, chewing, swallowing, and yawning. The masticatory muscles are four paired muscles located on the sides of the skull. They all start on the bones of the skull and attach to the lower jaw, setting it in motion (Bordoni & Varacallo, 2022). The masticatory muscle begins from the lower edge of the zygomatic bone, the zygomatic arch; attaches to the masticatory tuberosity of the outer surface of the lower jaw. She raises the angle of the lower jaw.

Discussion

The temporal muscle begins from the temporal surface of the frontal bone, the parietal bone, the scales of the temporal bone (temporal fossa), the large wing of the sphenoid bone, the temporal fascia; attaches to the coronal process of the lower jaw. It raises the lower jaw (the biting muscle); the posterior tufts pull the jaw back. The medial pterygoid muscle begins from the pterygoid fossa of the pterygoid process of the sphenoid bone (Georgakopoulos & Lasrado, 2021). It attaches to the pterygoid tuberosity of the inner surface of the lower jaw. The medial pterygoid muscle raises the angle of the lower jaw.

The lateral pterygoid muscle begins from the suspensory crest of the large wing of the sphenoid bone, the outer surface of the lateral plate of the pterygoid process. It attaches to the neck of the lower jaw, the intra-articular disc and the capsule of the temporomandibular joint. With unilateral contraction, it shifts the jaw in the opposite direction, and with bilateral contraction, the lower jaw moves forward (Abuhaimed et al., 2022). Facial muscles are located under the skin, start from the bones of the skull and are woven into the skin. During contraction, the skin is shifted, changing its relief, forming facial expressions.

The neck muscles are topographically anatomically divided into superficial, medium, and deep. The superficial muscles are the subcutaneous muscle of the neck and the sternocleidomastoid muscle. The subcutaneous muscle of the neck is located directly under the skin, covering the entire front surface of the neck. It tightens the skin; pushing it forward, the muscle promotes the expansion of veins and the outflow of blood from the head (Powell et al., 2022). The subcutaneous muscle begins from the thoracic fascia, the skin of the upper chest at the level of the second rib (Bordoni & Varacallo, 2019). It attaches to the chewing fascia, the edge of the lower jaw, the corner of the mouth. The subcutaneous muscle of the neck pulls the corner of the mouth down, pulls the skin of the neck, prevents compression of subcutaneous veins.

Conclusion

The middle, or muscles of the hyoid bone, include: the muscles lying above the hyoid bone lie between the lower jaw and the hyoid bone. They are part of a complex apparatus, including the lower jaw, hyoid bone, larynx, windpipe, and play an important role in the act of articulate speech. Deep muscles include lateral muscles attached to the ribs. The anterior rectus muscle of the head starts from the anterior surface of the lateral mass of the atlas (Flynn & Vickerton, 2020). It attaches to the lower surface of the basilar part of the occipital bone. The lateral rectus muscle of the head begins from the transverse process of the atlas; it attaches to the lower surface of the jugular process of the occipital bone. It tilts his head to the side.

References

Abuhaimed, A. K., Alvarez, R., & Menezes, R. G. (2022). Anatomy, head and neck, styloid process. National Journal for Biotechnology Information, 40(13), 942–945.

Bordoni, B., & Varacallo, M. (2022). Anatomy, head and neck, sternocleidomastoid muscle. National Journal for Biotechnology Information, 42(2), 1–7.

Bordoni, B., & Varacallo, M. (2019). Anatomy, head and neck, temporomandibular joint. Europe PMC, 234(8), 540–547.

Flynn, W., & Vickerton, S. (2020). Anatomy, head and neck, larynx cartilage. Europe PMC, 382(21), 1941– 1960.

Georgakopoulos, B., & Lasrado, S. (2021). Anatomy, head and neck, inter-scalene triangle. National Journal for Biotechnology Information, 36(6), 397–402.

Powell, V., Esteve-Altava, B., Molnar, J., Villmoare, B., Pettit, A., & Diogo, R. (2018). Primate modularity and evolution: First anatomical network analysis of primate head and neck musculoskeletal system. Scientific Reports, 8(2341), 15–43.

Introduction

The head and the neck are more than merely distinguishing traits that people use to recognize their close friends and family members. The carotid and vertebral arteries are responsible for supplying the head and neck with the overwhelming bulk of the body’s blood flow. The internal and external carotid arteries, thyrocervical trunk, vertebral arteries, cervical plexus, cranial nerves, and head and cervical lymph nodes are the head and neck’s most significant pathways and networks. Therefore, this essay provides the anatomy of the head and neck blood circulation through the above-mentioned blood vessels.

Carotid Arteries

The right subclavian artery is the other segment of the innominate trunk from which the right typical carotid passage emerges. The left common carotid artery is immediately branched from the aortic arch. The left and right common carotid arteries proceed up the neck, laterally to the larynx and esophageal, and do not separate in the neck. The carotid arteries divide at the region of the superior edge of the thyroid cartilage (C4) into the external and internal carotid arteries (Charlick & Das, 2021). This divergence happens in the carotid triangular anatomical region. The common carotid and internal carotid arteries, termed the carotid sinus, are moderately dilated in this region and are crucial for gauging and controlling blood pressure.

The internal stenosis artery ascends the neck from the common carotid artery, traveling caudally to the temporomandibular neck and laterally to the fibrous capsule of the ear. Within the oropharynx, the artery terminates and divides into the cursory temporal artery and the pharyngeal artery. It produces a total of six branches: the ascending pharyngeal, superior thyroid, posterior auricular, facial, occipital, and lingual arteries as shown in figure 1 (Charlick & Das, 2021). The internal carotid arteries supply no components in the neck, which enter the nasal mucosa via the carotid channel in the petrous portion of the skull base.

Vertebral Arteries

The vertebral arteries are bilateral tubes that emerge just dorsal to the front scalenes from the saphenous arteries. They traverse the posterior part of the neck, penetrating through the foramen transversarium in the lateral aspect of the vertebral column (Saw et al., 2019). The vertebral tubes enter the skull through the foramen magnum and merge to produce the basilar artery, which supplies the brain. They distribute numerous meningeal, musculoskeletal, and spinal extensions to surrounding tissues along their journey (Saw et al., 2019). The vertebral and carotid internal flows are not entirely distinct constructs since they link at the cerebral arterial circle, situated at the bottom of the skull as illustrated in figure 2.

Thyrocervical Trunk

The thyrocervical trunk, as shown in figure 3, is an additional main neck artery. In addition to its genesis from the subclavian artery, it gives credence to the suprascapular artery, inferior thyroid artery, transverse cervical artery, and ascending cervical artery (Pérez-García et al., 2018). These tributaries supply the trapezius, thyroid gland, levator scapulae, sternocleidomastoid, rhomboids, lateral muscles of the upper neck, and surrounding tissues with fresh blood (Pérez-García et al., 2018).

Cervical Plexus and the Head Nerves

The spinal nerves that run from the C1 to the C5 level combine to form the cervical plexus, sending the motor and sensory extensions to the neck and head as shown in figure 4 and 5. Within the anterior cervical region of the neck is a neuronal loop known as the ansa cervicalis. It is comprised of five branches that may be found in the carotid triangle. These branches are the thyrohyoid, omohyoid, sternothyroid, geniohyoid, and sternohyoid nerves (Brown & Dellon, 2018). The lower occipital, larger auricular, transverse cervical and supraclavicular nerves are all perceptive branches, whereas the ansa cervicalis, phrenic, rhomboids, and serratus anterior nerves are illustrations of functional divisions.

Cranial nerves are the 12 peripheral nervous system neurons that arise from the skull’s foramina and perforations. The position of their skull exit dictates their number order (1-12) since they all originate from the brain’s nucleus (Romano et al., 2019). The twelve cranial nerves in their order number are listed herein: olfactory, optic, oculomotor, trochlear, trigeminal, abducent, facial, vestibulocochlear, glossopharyngeal, vagus, accessory, and hypoglossal (Romano et al., 2019). The first two begin in the brain’s frontal lobe, whereas the following ten emerges from the hypothalamus.

Head and Cervical Lymph Nodes

There are various lymph node groupings or assemblages in the neck and head. They are essential for lymphatic drainage and the normal functioning of the immune system. The lymph nodes in the forehead are grouped into the following factions: the submental, submandibular, parotid, mastoid, fascial, sublingual, and occipital (Norris & Anzai, 2022). Each group is accountable for emptying the nearby structures. Additionally, the lymph nodes of the neck are grouped. Nonetheless, rather than being grouped, they form three primary networks: the upper horizontal, anterior cervical, and lateral cervical (superficial and deep) channels (Norris & Anzai, 2022). Each set, like the head, empties the adjacent structures as elaborated in figure 6.

Conclusion

The anatomy of blood circulation in the head and neck provides a useful insight into some of the vital arteries and nerves that play a role in ensuring efficient and effective blood supply within the human head and neck. The arteries and nerves involved in blood supply are the internal and external carotid arteries, thyrocervical trunk, vertebral arteries, cervical plexus and cranial nerves, and head and cervical lymph nodes.

References

Brown, D. L., & Dellon, A. L. (2018). Surgical approach to injuries of the cervical plexus and its peripheral nerve branches. Plastic and Reconstructive Surgery, 141(4), 1021-1025.

Charlick, M., & Das, J. M. (2021). Anatomy, Head and Neck, Internal Carotid Arteries. In StatPearls. StatPearls Publishing.

Norris, C. D., & Anzai, Y. (2022). Anatomy of neck muscles, spaces, and lymph nodes. Neuroimaging Clinics, 32(4), 831-849.

Pérez-García, C., Malfaz, C., del Valle Diéguez, M., Gil, F. F., Lorente, J. S., Boyra, M. E., Leyte, M. G., Pérez-Higueras, A., & Castro-Reyes, E. (2018). Embolization through the thyrocervical trunk: Vascular anatomy, variants, and a case series. Journal of NeuroInterventional Surgery, 10(10), 1012-1018.

Romano, N., Federici, M., & Castaldi, A. (2019). Imaging of cranial nerves: A pictorial overview. Insights into Imaging, 10(1), 1-21.

Saw, A. E., McIntosh, A. S., Kountouris, A., Newman, P., & Gaida, J. E. (2019). Vertebral artery dissection in sport: A systematic review. Sports Medicine, 49(4), 553-564.

Introduction

The skeletal component of the head that maintains the face and covers the brain is called the cranium or skull. It is further separated into the cranial vault and the facial bones. The facial bones hold the lower and upper jaw teeth, enclose the eyes, form the nasal cavity, and reinforce the facial tissues. The middle and inner ear components are housed inside the rounded brain case, which also encloses and safeguards the brain. The mature skull comprises 22 separate bones, 21 immovable and fused to form a single unit (Anderson et al., 2022). The lower jaw is the only bone in the skull that can be moved and is the 22nd bone.

Discussion

The facial bones that make up the anterior skull serve as the skeletal framework for the eye and other facial features. The apertures of the nasal cavity and orbit dominate this view of the cranium. The orbit forms the bony prominence in which the eyeball and the muscles that move it and raise the top eyelid are situated. The supraorbital margin refers to the outside edge of the anterior orbit. A little opening known as the supraorbital foramen can be found close to the supraorbital margin’s midpoint.

The nasal septum divides the nasal cavity, which is located inside the nasal region of the skull, into two halves. The vomer bone makes up the bottom section of the nasal septum, while the transverse plate of the ethmoid bone forms the top portion (Jamil & Callahan, 2022). The nasal canal takes a triangular shape, with a wide inferior area that narrows to a smaller superior space on either side. The inferior nasal concha, a separate skull bone, is the largest of the two bony plates on the lateral wall of the nasal cavity. The medial nasal concha, which comprises a portion of the ethmoid bone, is situated directly above the inferior concha (Lipsett & Khalid Alsayouri, 2022). The superior nasal concha is the ethmoid bone’s third bony plate component. Above the middle concha, it is considerably smaller and hidden from view.

The massive, rounded brain case, located above, and the mandibles, located below, are the main features of a view of the lateral skull. The bone bridge known as the zygomatic arch divides these regions. The bony arch that runs from the cheek region upward from the ear canal is called the zygomatic arch, located on the skull’s edge. The zygomatic process of the temporal bone, which extends forward from the temporal bone, and the temporal process of the zygomatic bone, which is shorter and farther back, join to produce it. The zygomatic arch gives rise to one of the main muscles that lift the jaw upward while biting and eating. The temporal fossa is a small area located on the lateral aspect of the braincase, just above the zygomatic arch (Singh & Varacallo, 2022). Another area known as the infratemporal fossa is located deep in the vertical region of the jaw, underneath the zygomatic arch. The infratemporal and temporal fossa have muscles that work with the jaw to chew.

Conclusion

A suture is an immovable connection that connects two nearby skull bones. Thick, fibrous connective tissue fills the little space between the bones, holding them together. The lengthy sutures that connect the bones of the skull are not straight; rather, they wind in an asymmetrical, tightly twisted pattern. The sagittal and coronal sutures are the two lines of sutures that may be observed on the top of the skull (Russell & Russell, 2021). Across the cranium’s coronal plane, the coronal suture extends from side to side. The left, right, and right parietal bones are connected to the frontal bone through this joint. The sagittal suture runs parallel to and posterior to the coronal suture all along the midline at the anterior portion of the skull, where the left and right parietal bones are joined by it. The sagittal joins the lambdoid suture in the skull’s rear, where it ends. From its intersection with the sagittal suture, the lambdoid suture runs laterally to either side and downwards.

References

‌Amazon (2022). Laminated human skull diagram anatomy educational chart poster dry erase sign 18×12: Industrial & scientific. Amazon.com. Web.

Anderson, B. W., Kortz, M. W., & Kharazi, A. (2022). Anatomy, head and neck, skull. Nih.gov; StatPearls Publishing. Web.

Jamil, R. T., & Callahan, A. L. (2022). Anatomy, sphenoid bone. Nih.gov; StatPearls Publishing. Web.

Lipsett, B. J., & Khalid Alsayouri. (2022). Anatomy, head and neck, skull foramen. Nih.gov; StatPearls Publishing. Web.

Russell, W. P., & Russell, M. R. (2021). Anatomy, head and neck, coronal suture. Nih.gov; StatPearls Publishing. Web.

Singh, O., & Varacallo, M. (2022). Anatomy, head and neck, frontal bone. Nih.gov; StatPearls Publishing. Web.

Introduction

The cranial nerves are a group of 12 pairs of nerves located in the back of the human brain. They transmit electrical information between a person’s brain, face, neck, and torso. Cranial nerves aid in the senses of taste, smell, hearing, and touch (Smith & Border, 2019). If information is conveyed from the brain to the exterior, the nerve is efferent (motor). If the neuron passes from the extremities to the brain, it is an afferent (sensory) nerve. Sensory neurons are the 12 peripheral nervous system fibers that arise from the cranium’s foramina and fissures. Their number order (1-12) is dictated by the placement of their skull departure (rostral to caudal) since all of them start in the brain’s nucleus.

Discussion

Two are located in the frontal cortex (Olfactory and Optic), one has a component in the spinal column (Accessory), and the rest are located in the brainstem. Cranial nerves provide sensory and motor impulses to the tissues of the head and neck, hence regulating their functioning. Only the vagus nerve penetrates beyond the neck to perfuse the viscera of the thorax and abdomen. Table 1 below shows the twelve cranial nerves in their order number.

Table 1: List of the Twelve Cranial Nerves

Olfactory Nerve (Cranial Nerve One)

The numerous extensions of the olfactory nerve, known as fila olfactoria, travel via the cribriform plate of the ethmoid bone from the nasal cavity (Crespo et al., 2019). They conclude in the olfactory bulb, from which the olfactory tract proceeds. The olfactory tract fibers spread and terminate in the brain’s olfactory cortex (Crespo et al., 2019). Its neurons are located in the olfactory region, the nasal mucosa that borders the ceiling of the nasopharynx.

Optic Nerve (Cranial Nerve Two)

Everyone’s optic nerves travel through the bone-lined optical tube from the matching retina to the brain. The right optic nerve is derived from the right eye, while the left optic nerve is derived from the left eye. Optic fibers within the brain converge at the occipital lobe, a region just behind the pituitary gland (Smith & Czyz, 2021). Behind the skull, the nerves separate and send information to the right and left occipital hemispheres.

Oculomotor Nerve (Cranial Nerve Three)

Each oculomotor nerve originates in the center of the brain, which is the upper portion of the cerebellum. A person’s oculomotor nerve passes to the eye on the exact hemisphere as the neuron through the cavernous sinus, a bone tube (Raza et al., 2018). The oculomotor nerve differentiates into numerous branches, each transmitting signals to a specific muscle.

Trochlear Nerve (Cranial Nerve Four)

The trochlear nerve of an individual originates from the midbrain, underneath the position of the oculomotor nerve. This fiber powers the superior oblique tendon by traveling to the individual’s ipsilateral (same-side) eyeball (Agarwal et al., 2020).

Trigeminal Nerve (Cranial Nerve Five)

There are three somatic sensory extensions of the trigeminal nerve in humans: the ophthalmic nerve, the mandibular nerve, and the maxillary nerve. The ophthalmic nerve recognizes feeling from the upper region of the face, the maxillary nerve identifies sensibility from the central section of the face, and the mandibular division collects feeling from the bottom part of the face and has movement patterns (White et al., 2021). Underneath the midbrain, the trigeminal nerve exits from the pons Varolii to the hypothalamus.

Abducens Nerve (Cranial Nerve Six)

The lateral rectus tendon is innervated by cranial nerve 6, which is a broad somatic efferent neuron in the human body. This nerve arises from the inferior pons and extends toward the rectus abdominis muscle in the eye (Lucio et al., 2022).

Facial Nerve (Cranial Nerve Seven)

The seventh cranial nerve is a multifunctional nerve with general and specific components. A broader main stem containing motor neurons and a narrower transitional nerve containing perception and parasympathetic axons emerge from the cerebellum (Takezawa et al., 2018). The two segments exit the brain structure via the internal acoustic meatus and go through the facial tract. Together, they exit the skull via the stylomastoid foramen after joining to create the facial nerve proper (Takezawa et al., 2018).

Vestibulocochlear Nerve (Cranial Nerve Eight)

Vestibulocochlear nerve sensation neurons are situated in the inner ear and penetrate the lower portion of the pons together. The vestibular and auditory elements of the vestibulocochlear nerve obtain information depending on hair cells’ motion in the inner ear (Walijee et al., 2021). This data is employed to notify a person’s body of their position, allowing them to retain their equilibrium, transmit sound impulses to their brain, and interpret the noises they perceive.

Glossopharyngeal Nerve (Cranial Nerve Nine)

The glossopharyngeal nerve originates from the hypothalamus, the lowest portion of the cerebellum positioned above the spinal column, and descends to the throat and mouth (García Santos et al., 2018).

Vagus Nerve (Cranial Nerve 10)

The vagus nerve arises from the medulla and proceeds beside the carotid artery in the neck, outside the skull. In addition, the vagus nerve separates into segments that travel to the heart, digestive tract, and lungs (Butt et al., 2020).

The auxiliary nerve assists in raising the shoulders and rotating the head and neck. This fiber emerges from the brainstem and descends toward the sternocleidomastoid and trapezius musculature outside the cranium (Johal et al., 2019).

Hypoglossal Nerve (Cranial Nerve 12)

This nerve coordinates the mobility of a person’s tongue with their capacity to speak and gulp down and is located in the base of the tongue. Following its beginning in the cerebellum, the hypoglossal nerve descends beyond the oral mucosa to reach the skeletal muscles of the tongue (Iaconetta et al., 2018).

References

Agarwal, N., Ahmed, A. K., Wiggins III, R. H., McCulley, T. J., Kontzialis, M., Macedo, L. L., Choudhri, A. F., Ditta, L. C., Ishii, M., Gallia, G. L., Aygun, N., & Blitz, A. M. (2021). Segmental imaging of the trochlear nerve: Anatomic and pathologic considerations. Journal of Neuro-Ophthalmology, 41(1), 7-15.

Butt, M. F., Albusoda, A., Farmer, A. D., & Aziz, Q. (2020). The anatomical basis for transcutaneous auricular vagus nerve stimulation. Journal of anatomy, 236(4), 588-611.

Crespo, C., Liberia, T., Blasco‐Ibáñez, J. M., Nácher, J., & Varea, E. (2019). Cranial pair I: The olfactory nerve. The Anatomical Record, 302(3), 405-427.

García Santos, J. M., Sánchez Jiménez, S., Tovar Pérez, M., Moreno Cascales, M., Lailhacar Marty, J., & Fernández-Villacañas Marín, M. A. (2018). Tracking the glossopharyngeal nerve pathway through anatomical references in cross-sectional imaging techniques: A pictorial review. Insights into Imaging, 9(4), 559-569.

Iaconetta, G., Solari, D., Villa, A., Castaldo, C., Gerardi, R. M., Califano, G., Stefania, M., & Cappabianca, P. (2018). The hypoglossal nerve: anatomical study of its entire course. World Neurosurgery, 109, 486-492.

Johal, J., Iwanaga, J., Tubbs, K., Loukas, M., Oskouian, R. J., & Tubbs, R. S. (2019). The accessory nerve: A comprehensive review of its anatomy, development, variations, landmarks and clinical considerations. The Anatomical Record, 302(4), 620-629.

Lucio, L. L., Freddi, T. D. A. L., & Ottaiano, A. C. (2022). The Abducens nerve: Anatomy and Pathology. In Seminars in Ultrasound, CT and MRI. WB Saunders.

Raza, H. K., Chen, H., Chansysouphanthong, T., & Cui, G. (2018). The aetiologies of the unilateral oculomotor nerve palsy: A review of the literature. Somatosensory & Motor Research, 35(4), 229-239.

Romano, N., Federici, M., & Castaldi, A. (2019). Imaging of cranial nerves: A pictorial overview. Insights into imaging, 10(1), 1-21.

Smith, A. M., & Czyz, C. N. (2021). Neuroanatomy, cranial nerve 2 (Optic). In StatPearls. StatPearls Publishing.

Smith, C. F., & Border, S. (2019). The twelve cranial nerves of christmas: Mnemonics, rhyme, and anatomy–seeing the lighter side. Anatomical Sciences Education, 12(6), 673-677.

Takezawa, K., Townsend, G., & Ghabriel, M. (2018). The facial nerve: Anatomy and associated disorders for oral health professionals. Odontology, 106(2), 103-116.

Walijee, H., Vaughan, C., Munir, N., Youssef, A., & Attlmayr, B. (2021). Microvascular compression of the vestibulocochlear nerve. European Archives of Oto-Rhino-Laryngology, 278(10), 3625-3631.

White, T. G., Powell, K., Shah, K. A., Woo, H. H., Narayan, R. K., & Li, C. (2021). Trigeminal nerve control of cerebral blood flow: a brief review. Frontiers in Neuroscience, 15, 1-9.

Introduction

The various teeth in the oral cavity have vastly different root canal systems. Extensive knowledge of the morphology of these canals structuring by practitioners is very important if successful edodontic therapy is to be achieved. This essay seeks to analyze the root canal system and to this end, the anatomy of the root canal of the mandibular first molar has been detailed in the first part of the paper. The second part of the report analyzes the various anatomical considerations that have to be taken during preparation and the final part studies the various problems that arise during molar teeth instrumentation and how they can be handled.

Root canal anatomy of the mandibular first molar

In order to understand the morphology of the root canal of the mandibular first molar, we must first have knowledge of the basic components of a typical root canal1. The pulp cavity which houses the dentine cavity normally assumes the external shape of the tooth. Physiological and pathological factors however contribute to the modification of its shape and size through production of secondary and sometimes tertiary dentine and cementum material2. This pulp cavity comprises two parts; the pulp chamber which is found within the crown of the tooth and the root canal(s) which are located within the root of the tooth. Other features that contribute to the formation of the root canal include lateral, furcation and accessory canals which are related to the canal orifices alongside intercanal connections and apical foramina. The actual root canal originates as funnel shaped orifices normally found either at the cervical line or slightly distal to it. It then runs through the horns to end at the apical foramina which open at the surface of the root. These apical foramina are located at about 0 and 3mm from the center of the root apices3. A vast majority of root canals have curvatures towards the facial-lingual direction. These curvatures may occur gradually along the length of the root canal. The canal may also be straight for most of the length and then acquire a sharp curvature when approaching the apex4. In a few cases, the canals may acquire double‘s’ curvatures. Branches of the main chamber that houses the pulp communicate with the outer part of the roots. These are called accessory canals. Accessory canals present in a number of ways but the most important and most common are the lateral canals which extend horizontally towards the external surface of the root from the middle of the primary canal and the furcation canals which occur in the bifurcation or trifurcation of teeth with more than one foot. The lateral canals serve as passages for irritants away from the pulp and towards the periodontium.

Landmarks both histological and anatomical distinguish the apical root canal; these are: the cemento-dential junction, the apical constriction and the apical foramen. The root canal tapers from the orifices of the canal to the apical constriction commonly located about 0.5 to 1.5 mm within the apical foramen. The apical constriction is the region where the root canal acquires the smallest diameter. The cemento-dential junction is the region of the canal where the dentine and the cementum meet. The pulp tissue ends here marking the beginning of the periodontal tissues. The apical foramen is the region of the cemental canal which opens up to the external surface of the root. This apical foramen assumes the shape of a funnel and it is the region of the root canal with the largest diameter. The root canal tends to widen from the apical constriction towards the apical foramen. On average the length between the major and minor diameters is 0.5 mm in young children and 0.67 in older people. This length increases with age generally due to an increase in the accumulation of cementum. Canals take various pathways on the way to the apex; some canals may branch, others divide and there are those which end up rejoining. In total eight configurations of the pulp space components have been identified. These variations are listed as types 1-8 and are briefly described below:

• Type 1- Has just one canal all the way to the apex.
• Type 2- Has two canals which join to end up as one canal at the apex (2-1)
• Type 3- One canal which splits into two and later the two rejoin to end up as one canal at the apex (1-2-1)
• Type 4- Has two canals that run all the way to the apex
• Type 5- One canal splits into two (1-2) and then the two canals traverse the rest of the length to the apex.
• Type 6- Two canals join together then split to end up as two canals at the apex (2-1-2)
• Type 7- One canal splits into two canals which rejoin before splitting again towards the apex (1-2-1-2)
• Type 8- Has three canals from the pulp cavity all the way to the apex. This type of formation is however extremely rare.

The roots of the mandibular lower first molar usually have 3-6 canals; the mesial root generally has two to three canals while the distal root may either have one, two or three canals. If there is only one canal in the mesial root, it is referred to as the mesial canal. Whenever multiple canals occur they are named mesiobuccal, mesiolingual and medial-mesial canals. The middle-mesial canal is however rare and occurs in the developmental ridge between the mesiobuccal and mesiolingual canals. If there is only one canal present in the distal root, it is named the distal canal. Whenever more than one canal happen in the distal root, they are referred to as the distolingual, distobuccal and the middle distal canals depending on their particular location. The canal(s) in the distal root are always straight from where they originate in the pulp cavity all the way to about 1-2mm from the apex where they curve up to 90 degrees distally. The distal canals sometimes present with a mesial curvature but this curvature is not acute. The distal canals have oval or flattened cross sections and compared to other canals they are quite large; a factor that makes them easily accessible by instruments. Both the mesiobuccal and mesiolingual canals present with curvatures along their whole extents with the curvatures characteristically peaking in the region towards the apex. These canals majorly curve distally as well as having minor curvatures bucally or lingually at the same time. The canals in the distal root often start together and divide a few millimeters below the floor of the pulp chamber. The canals in the mesial root and the corresponding canals in the distal root can combine before they reach the apex.

The accessory canals of this tooth present in three forms. First is where the furcation canal stretches from the pulp cavity down to the intraducular area. This presentation manifests in 13% of the entire first mandibular molar tooth population. About 23% of the manifestations present as a lateral canal extending from the coronal third of a key root canal and lengthens to the furcation region. Of this presentation, 80% occur in the distal root. Finally, about 10% of molar first teeth have both furcation and lateral canals.

The floor of the pulp cavity from where these root canals originate takes various shapes in the mandibular molar. The most common presentation is the rectangular floor followed by the triangular floor and the least common happens to be the oval shaped chamber floor.

Race and ethnicity heavily influence the number and morphology of the mandibular molar tooth root canals. For instance, the three rooted mandibular molar has over time been given particular attention with surveys revealing that the mongoloid and chinese populations have a higher incidence of this structure as compared to other races.

Anatomical considerations during root canal preparation

For a successful root canal procedure, primary shaping is of utmost importance. This shaping and cleaning has to meet four basic criteria. First, the root canal preparation should assume a funnel shape tapering from the apex of the root to the coronal access cavity. Secondly, the foramen should be kept as small as is practically possible. The apical foramen should also remain in its origin positioning in relation to both the surface of the root and the bone and finally, the preparation should follow the shape of the canal as much as possible considering the concavities and the curvatures.

Various anatomical considerations have to be made during the preparation including the original structure of the root canal (i.e. length, curvature, number of canals and diameter), the location of the apical terminus and the thickness of the dentine and cementum that form the boundaries of the root canal. The major objective of the procedure is to gain direct access to the canal system while at the same time maintain the natural structure of the tooth.

Before starting the root canal procedure, the dentist should be able to determine the possible number of canals present. The floor of the pulp chamber and the wall of the cavity serve as important guides in establishing the kind of morphology that is present in the root canal system. In the identification of the pulp chamber boundaries and the orifices of the root canal, it has been established that the most important marker is the junction between the cementum and enamel. Six laws have been established to help determine the positioning and morphology of the root canals. These laws are briefly explained below.

1. Law of symmetry 1: If a line is drawn in a messiodistal direction through the floor of the pulp chamber, the orifices of the canals will be equidistant from this line. The only exceptions to this rule are the maxillary molars.
2. Law of symmetry 2: The canal orifices will lie across the floor of the pulp chamber in a line that runs perpendicular to a line drawn in the messiodistal direction through this floor. This presents in all teeth except for maxillary molars.
3. Law of color change: The floor of the pulp chamber is always darker compared to its walls.
4. Law of the orifices location 1: The openings of the root canals are always located in the region where the floor and walls meet.
5. Law of the orifices location 2: The openings of the root canals are always located at the angles in the region where the floor and the walls meet.
6. Law of the orifices location 3: The openings of the root canals are always located at the terminus of the lines that indicate the fusion of the root during development.

Another anatomical consideration to be made in the cleaning and shaping of the root canal is the size of the pulp cavity. This cavity generally decreases in size with age due to the fact that the formation of dentine is not standardized throughout life and that it forms more rapidly on the roof and floor than on the walls for teeth in the posterior region. As a result, calcification of the root canal may occur with the pulp chamber ending up assuming a flattened appearance. Calcified canals are particularly very difficult to investigate and they require proper illumination and magnification in order to identify them. Proper investigation of the floor and walls of the pulp chamber will give clues pertaining to the kind of canal system present as well as the positioning of the orifices. If there is only one canal, it will be located in the middle of the preparation. Should a canal be located at off-center, then there is a chance that another canal exists on the opposite side.

The morphology and relationship of the canals to each other should also be given consideration during the preparation. If there are multiple canals, they will definitely be smaller than if a single canal was present. The relationship between the canals is significant because the closer the canals are to each other the greater the chances of them joining along the length of the root. Whenever the root canals join, the palatal or lingual canal will present a straight line access in relation to the apex while the buccal canal will have a less direct access to the apex. The location at which the two canals join will usually have a smaller diameter than the rest of the canal. This poses a problem especially if the canals split up again towards the apex because during filling, this constriction will occasion the creation of voids in the apical third. Some canals also begin as a single canal but end up splitting into two. In the incidence of such a split, the two divisions are named buccal and lingual based on their presentation. The lingual canal generally breaks away from the main canal at a very sharp slant; sometimes at almost 90 degrees. The buccal canal exits from the main canal in a straighter angle. Initial identification of the two canals will help guide the modifications that are necessary to achieve unobstructed instrumentation.

The length of the canal and the positioning of landmarks will also help to determine the working length of the preparation. The most important landmark in this part of the root canal procedure is the apical constriction. Being the part of the canal with the smallest diameter, it serves as a logical guide to where the obturation and preparation should end. At this part of the canal, pulp tissue converts into periapical tissue which is avascular. The apical foramen needs to be kept unobstructed to avoid the obstruction of unwanted matter to the periapex. Keeping the foramen open also ensures that the irrigation solution is able to find way into the apical third. Care should therefore be taken not to widen its diameter.

Therefore, ending the procedure at this region helps in the eradication of pathogenic microbes.

The number of roots of a tooth should also be considered during the preparation. For instance, the maxillary molars will have three roots, the mesial, the distal and the palatal roots. The palatal and distal roots can have as many as two canals each while the mesial root can have up to three canals. The ability to identify the various roots on a tooth will help in complete preparation and obturation hence preventing cases of recurrent pain post operatively.

Common problems during molar teeth instrumentation

Perforations and Strip perforation

The molar tooth root canal has numerous curvatures especially in the messiobuccal and the messiolingual canals. These curvatures present complexities during preparation particularly when using instruments which have a sharp cutting edge and operate in a circular motion. If adequate care is not taken in these circumstances, perforations may occur which may later cause destruction of the cementum and sometimes may end up causing infection and irritation of the periodontal ligament. In the root canal procedure, perforations may end up leaving some parts of the original root canal underprepared in the event that the region apical of the perforation is not accessible.

The mesial root of the molar tooth is divided into two areas basically referred to as the mesial and distal parts. The mesial region of this root has a thick layer of dentine that is only touched by the endodonic instruments during preparation. This region is referred to as the safety zone. The distal area on the other hand usually presents as a straight layer of dentin commonly referred to as the danger zone. During instrumentation this danger zone becomes exposed to strip perforations if adequate care is not taken. The cleaning and primary shaping processes are designed to provide easy identification of the foramen, facilitate disinfection and enable access by the material used for obturation. Modern instrumentation methods encourage a progressive preparation of the root canal from the crown downwards. The flare technique is particularly encouraged for preparation of the cervical third. Unfortunately this method calls for transportation of the canal towards both the safety and danger zones alike. This leads to undesirable episodes as well as strip perforations of the root which can lead to inflammatory problems and later the dilapidation of supporting structures. The incidence of strip perforations also leads to alveolar bone loss.

Perforations which tend to be common in molar teeth operations can be repaired even though this depends on the extent of damage caused. The level of damage is assessed based on the proximity of injury to support structures. The types of perforations which require most attention are those that occur close to the periodontal ligament. These include the strip perforations of canals whereby the loss of attachment ends up predisposing the patient to infection and inflammation.

Perforations and strip perforations can be prevented in a number of ways. First, before instruments are introduced into the canal an assessment should be carried out on the suitability of the chosen instruments based on their mode of operation. For hand instruments a number of techniques have been established over time and it is up to individuals to choose the one(s) they feel they are most comfortable with and which they can use to achieve optimum results. Of these techniques, the most popular for instrumentation are the ‘crown-down pressureless technique’ and the ‘balanced force technique’. The crown-down presureless technique involves preflaring of the coronal canal before the dentine is removed starting from the crown towards the apical direction. These techniques require extended periods of practice for individuals to master and use effectively. For instruments with rotary systems, the prime consideration is the accuracy of calibration. Electron micrographs will help determine the exact location where the instruments can reach without causing any possible accidents. A general clear understanding of the morphology of various tooth canals will also go a long way in ensuring that rotary instruments are used safely. For instance, in a situation where two canals join, a rotary file if not used with this anatomical consideration in mind can separate as the instrument cuts through the sharp curvatures into the common region of the canal.

False working length

For a successful endodontic canal treatment, the proper working length has to be established. If the length of the root is not determined, incomplete instrumentation and under-filling of the canal may occur. Canals that are not properly filled may lead to unrelenting pain and discomfort occasioned by inflammation of the pulp tissues which are retained. A ledge may also develop in the root canal towards the apex resulting in the formation of a dead space which makes retreatment virtually impossible. Formation of the ledge may result in a continuous periradicular laceration. Improper determination of the length of the root may also result in apical perforation and consequently overfilling associated with possible infection and increased pain may arise.

Molar teeth generally tend to have curvatures especially in the mesiobuccal and mesiolingual canals. These curvatures lead to narrowing and obstruction of the canal due to deposition of dentine. This narrowing of the canal leads to a false sense of apical constriction which binds the file before it gets to the apex. This problem can be handled by preflaring of the canal. Preparing of the coronal part of the root canal before attempting to determine the working length helps in removing most of the obstruction in this part. As a result, there is a marked improvement in the detection of the apical constriction since the file then binds at the apex.

The preflaring process has a number of advantages which cannot be ignored. First, the need to precurve files is significantly reduced. This is because the general curvature of the canal is reduced after preflaring and even when files have to be precurved it is only by a very small angle. Preparation involves proper clearing of the pulp cavity toilet and therefore preflaring in essence provides for efficient removal of debris. Once the restrictive dentine is removed from the coronal region, bigger size files such as numbers 10 and 15 can easily be maneuvered within the canal hence reducing the need to use multiple sets of instruments. This coronal enlargement also helps provide straight-line access and more control in the preparation of the apical third. The enlargement of the coronal part of the canal ensures that most of the necrotic material is cleaned out thus reducing the chance of pushing this infected material apically. Preflaring also ensures that the amount of the solution used for disinfection is greatly increased hence augmenting the effectiveness of the solution. Finally and actually most importantly, preflaring allows for the accurate taking and maintenance of the working length.

By virtue of the curvatures in parts of the root canals and sometimes by the extra root present especially in the maxillary set, molar teeth need adequate access preparation if a successful procedure is to be carried out. Improper preparation and shaping may cause a number of problems during instrumentation. These include insufficient instrumentation and unsatisfactory obturation occasioned by the limited mobility. Another common problem that would arise is the uncalled for damage to tooth structure alongside defective restitutions. Poor perceptibility of the canal structure may also occasion perforations ending up with continuous post operative pain.

Conclusion

Various endodontic texts have been effectively analyzed in this paper and it has been revealed that for desirable results to be attained particularly in the root canal procedure, extensive knowledge of the anatomy of the system is vital.

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Introduction

The esophagus (or gullet) is a 10 inches long midline muscular tube lying at the front of the spine, and it links the throat to the stomach. Furthermore, the esophagus is positioned before the right side of the spine after the windpipe in the upper layer of the chest, and behind the heart in the lower part of the chest (Kantsevoy 9).

The esophagus goes down through three compartments: the neck, the chest, and the abdomen. This chain of movement has led to the standard anatomical splitting up of cervical, thoracic, and abdominal subdivisions. The esophagus, both proximally and distally, is alleviated by bony, cartilaginous, or membranous formations (Braden, and Daniela 2006).

Structure of the Esophagus

The esophagus connects with the pharynx, and begins its formation at the cricoids cartilage opposite cervical vertebra (Dofka 61). It goes down into the chest at the stage of the sterna notch and moves inside the chest cavity on the fore plane of the posterior mediastinum. It moves down the spine and stops at the esophagogastric junction between the thoracic inlet and the diaphragm.

Location of the Esophagus

The esophagus is located slightly to the right of the midline, especially in its course through the thorax, where it descends along the right side of the aorta.

Minor variations of Esophagus

Three minor variations are present in the esophagus. The first variation is present at the bottom of the neck. The second variation is present at the thoracic vertebra. The third variation takes place when the esophagogastric junction (cardia) is positioned lateral to the xiphoid process of the sternum.

Divisions of the Esophagus

The esophagus is approximately 23-27 cm long in diameter, and is divided into three parts:

• Cervical part: it is positioned just at the anterior vertebral column in the neck.
• Thoracic part: this is the longest part of the esophagus and it can be found in the greater and subsequent mediastinum.
• Abdominal part: this is the shortest part of the esophagus and it is located in the peritoneal cavity. It lengthens to the cardiac orifice of the stomach from the diaphragm.

Constrictions of the esophagus

The esophagus has three normal anatomical constrictions, which are projected at the levels of specific vertebrae (Romer and Parsons 344). The constrictions are caused by adjacent structures that indent the esophagus by functional closure mechanisms. These constrictions are visible during gastroscopy, and the scope must be carefully maneuvered past them (normal width of the esophagus is approximately 20mm).

The three normal anatomical constrictions are:

1. Upper Constriction: this corresponds to the esophageal inlet in the cervical part of the esophagus. It is located where the esophagus passes behind the cricoids cartilage and a maximum width of approximately 14mm.
2. Middle constriction: this is located where the esophagus passes to the right of the aortic arch and thoracic aorta (at T4/T5). The maximum width is 14mm.
3. Lower constriction: this is located at the start of the abdominal part of the esophagus, where it pierces the diaphragm (T10/T11). The abdominal part is normally occluded except during swallowing. The maximum width of the lower constriction is 14mm.

The esophagus also presents characteristics curves like an upper curve to the left (in the cervical part), a mid-level curve to the right (in the thoracic part, caused by the adjacent thoracic aorta), and a lower curve to the left (in the abdominal part). Additionally, the esophagus is slightly concave anteriorly in the sagittal plane, following the curvature of the vertebral column (thoracic kyphosis).

Works Cited

Braden, Kuo, and Daniela Urma. Esophagus – anatomy and development. GI Motility online, 2006. 10.1038. Print.

Dofka, Charline. Dental Terminology. New York, NY: Cengage Learning, 2000. Print.

Kantsevoy, Sergey. 2007 Johns Hopkins White Papers: Digestive Disorders. Baltimore, Maryland: Johns Hopkins Health, 2007. Print.

Romer, Sherwood, and Parsons Thomas. (2009). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. Print.