ABSTRACT
"What do students studying medicine need to know" is an important question for curriculum planners, anatomy educators and students. The Core Regional Anatomy Syllabus (CRAS), published by the Anatomical Society in 2016, contains 156 learning outcomes (LOs) and has informed "what needs to be known." This project explored how CRAS had impacted undergraduate anatomy and anatomists in the United Kingdom. A cross-sectional study was designed in two phases. Phase 1, involved a survey of students in clinical years (N = 164). Phase 2 included a survey of anatomist's views (n = 50) and focus groups of anatomy educators (N = 16). The students' perspective showed that specific regions of CRAS are deemed less relevant. These were also the body areas where students perceived their anatomical knowledge to be more deficient. Only 46% (n = 75) of students estimated that they knew over 50% (n = 78) of the LOs. Phase two revealed that all anatomists were aware of the syllabus and 48% (n = 24) had checked the CRAS against their own institutional LOs. Anatomists had shared CRAS with colleagues 64% (n = 32) and students at 34% (n = 17), respectively. Forty-six percent (n = 23) of anatomists reported having changed their teaching in some way because of CRAS. The focus groups generated four key themes: "support for CRAS," "standardization and validation," "professional identity," and "limitations and leverage." Overall CRAS has been well received and is establishing itself within the anatomical community as the new standard for anatomy teaching for medical students.
Subject(s)
Anatomy, Regional/education , Curriculum/standards , Education, Medical, Undergraduate/standards , Societies, Scientific/standards , Teaching/standards , Anatomists/statistics & numerical data , Cross-Sectional Studies , Delphi Technique , Education, Medical, Undergraduate/methods , Faculty/statistics & numerical data , Female , Humans , Male , Qualitative Research , Students, Medical/statistics & numerical data , Surveys and Questionnaires/statistics & numerical data , United KingdomABSTRACT
It has become almost a truism that, as for many biomedical sciences courses, gross anatomy tuition for healthcare curricula (including medicine and dentistry) should be integrated with clinical components to improve vocational relevance. Nevertheless, many fundamental questions remain to be answered relating to the content to be taught, who teaches the discipline, how the students react, and whether the students are prepared to integrate the clinical and biomedical components. We additionally need evidence of how the delivery of clinical content is influenced by technical developments such as medical imaging. This article documents some examples, or case scenarios, showing how interactions between professional anatomists and clinicians can be fostered, as well as providing illustrations of different teaching styles. From a review of the literature, as well as from our own experiences, we conclude that, for many branches of medicine, it is essential to have access to human bodies for both anatomical and clinical education and training and that postgraduate anatomical teaching remains important for a variety of specialities. We therefore support the notion that a close relationship between professional anatomists and surgeons can reinforce core anatomical knowledge by deepening the understanding of its clinical importance. Paradoxically, however, there is evidence that medical students do not believe that the teachers of anatomy should necessarily be clinically qualified. Furthermore, while students appreciate the value of using clinical examples, scenarios or case histories in anatomy teaching, they remain ambivalent about their use in assessments or examinations. This article also emphasises that anatomy is important both as a scientific and a clinical, translational discipline and argues that the discipline is crucial for appreciation of the human body, not just in disease, but also in health
No disponible
Subject(s)
Humans , Anatomy/education , Anatomy/methods , Education, Dental/trends , Education, Medical/methods , Pelvic Floor/anatomy & histology , Neuroanatomy/education , Tissue Preservation/instrumentation , Sacrum/anatomy & histology , Angiography/instrumentation , Angiography/methods , Pelvis/anatomy & histology , Veins/anatomy & histology , Arteries/anatomy & histologyABSTRACT
The formulation of core syllabuses for the biomedical sciences within medical and dental courses is partially driven by the need to cope with decreased time allocations for these subjects as a result of major curricular changes taking place worldwide. There is also a requirement to deal with the request for increased clinical relevance. In response to such demands, the International Federation of Associations of Anatomists (IFAA) is devising core syllabuses for the anatomical sciences relating to the education and training of both scientific and clinical professions. The process initially involves using Delphi Panels consisting of a team of anatomists, scientists, and clinicians who evaluate syllabus content in detail and accord each element/topic 'essential,' 'important,' 'acceptable,' or 'not required' status. Their conjectures, published on the IFAA website, provide merely a framework to enable other stakeholders to comment. The approach is international in scope, is conceptually 'democratic,' and is developmentally fluid in being readily available for amendment. The aim is to set internationally recognized standards and thus to provide guidelines concerning anatomical knowledge when engaged in course development. This article presents the deliberations of an IFAA Delphi Panel into a core syllabus for oral anatomy, histology, and embryology within the dental curriculum. Clin. Anat. 31:231-249, 2018. © 2017 Wiley Periodicals, Inc.
Subject(s)
Curriculum/standards , Education, Dental/standards , Mouth/anatomy & histology , Anatomy/education , Animals , Delphi Technique , Embryology/education , Histology/education , Humans , Mouth/embryologyABSTRACT
PURPOSE: To analyse the variations of the renal arteries in two samples, cadaveric and computerized tomographic (CT) images, as well as to propose a simple classification of such variations based on the obtained results and an extensive review of the literature on the topic. MATERIAL AND METHODS: Sixty human dissected kidneys and their vessels, and 583 abdominal CT were studied. RESULTS: A total of 86 arteries were described in the cadaveric sample, whereas 1223 were analysed in the radiological one. Five types (a-e) and patterns (I-V) have been stablished in the classification. Type a, aortic hilar artery, incidences were 79% in cadavers and 95% in CT; Type b, hilar upper polar artery, incidences were 10% in cadavers and 2% in CT; Type c, aortic upper polar artery, incidences were 5% in cadavers and 2% in CT; Type d, aortic lower polar artery, incidences were 3% in cadavers and 1% in CT; Type e, hilar lower polar artery, incidences were 2% in cadaver and less than 0.1% in CT. The pattern represents the number of arteries reaching one kidney. Patterns I-IV were found in cadavers (I: 78%; II: 19%; III and IV: 2%); in CT sample only patterns I (88%) and II (12%). Pattern V was added because it has been described in the reviewed literature. CONCLUSIONS: Type a and pattern I are the most prevalent, both in the cadaveric and the CT samples. Also in the consulted literature. There are no differences in the types and pattern incidences by side or sex. A simple, comprehensive and useful classification is proposed.
Subject(s)
Renal Artery/abnormalities , Renal Artery/pathology , Tomography, X-Ray Computed/methods , Vascular Malformations/diagnostic imaging , Vascular Malformations/pathology , Adult , Aged , Aged, 80 and over , Angiography/methods , Cadaver , Female , Humans , Male , Middle Aged , Prevalence , Renal Artery/diagnostic imaging , Reproducibility of Results , Sensitivity and Specificity , Sex Characteristics , Spain/epidemiology , Vascular Malformations/epidemiologyABSTRACT
There is increasingly a call for clinical relevance in the teaching of biomedical sciences within all health care courses. However, this presupposes that there is a clear understanding of what can be considered core material within the curricula. To date, the anatomical sciences have been relatively poorly served by the development of core syllabuses, particularly for specialized core syllabuses such as neuroanatomy. One of the aims of the International Federation of Associations of Anatomists (IFAA) and of the European Federation for Experimental Morphology (EFEM) is to formulate, on an international scale, core syllabuses for all branches of the anatomical sciences using Delphi Panels consisting of anatomists, scientists, and clinicians to initially evaluate syllabus content. In this article, the findings of a Delphi Panel for neuroanatomy are provided. These findings will subsequently be published on the IFAA website to enable anatomical (and other cognate learned) societies and individual anatomists, clinicians, and students to freely comment upon, and elaborate and amend, the syllabuses. The aim is to set internationally recognized standards and thus to provide guidelines concerning neuroanatomical knowledge when engaged in course development.
Subject(s)
Curriculum/standards , Educational Measurement/standards , Learning , Neuroanatomy/education , Students, Medical , HumansABSTRACT
There is increasingly a call for clinical relevance in the teaching of the biomedical sciences within all health care programs. This presupposes that there is an understanding of what is "core" material within the curriculum. To date, the anatomical sciences have been poorly served by the development of core syllabuses, although there have been commendable attempts to define a core syllabus for gross anatomy in medicine and for some medical specialties. The International Federation of Associations of Anatomists and the European Federation for Experimental Morphology aim to formulate, on an international basis, core syllabuses for all branches of the anatomical sciences. This is being undertaken at the initial stage using Delphi Panels consisting of a team of anatomists, scientists, and clinicians who evaluate syllabus content and accord each element/topic "essential," "important," "acceptable," or "not required" status. Their initial conjectures, published on the International Federation of Associations of Anatomists' website, provide merely a framework to enable anatomical (and other cognate learned) societies and individual anatomists, clinicians, and students to comment upon the syllabuses. This article presents the concepts and methodological approaches underlying the hybrid Delphi process employed. Preliminary findings relating to the development of a neuroanatomy core syllabus are provided to illustrate the methods initially employed by a Delphi Panel. The approach is novel in that it is international in scope, is conceptually democratic, and is developmentally fluid in terms of availability for amendment. The aim is to set internationally recognized standards and thus to provide guidelines concerning anatomical knowledge when engaged in course development.
Subject(s)
Anatomy/education , Curriculum/standards , Curriculum/trends , International Cooperation , Delphi Technique , Europe , Guidelines as Topic , Humans , Medicine , Neuroanatomy/educationABSTRACT
Changes in motoneurons innervating laryngeal muscles after section and regeneration of the recurrent laryngeal nerve (RLN) are far from being understood. Here, we report the somatotopic changes within the nucleus ambiguus (Amb) after the nerve injury and relates it to the resulting laryngeal fold impairment. The left RLN of each animal was transected and the stumps were glued together using surgical fibrin glue. After several survival periods (1, 2, 4, 8, 12, 16 weeks; at least six rats at each time point) the posterior cricoarytenoid (PCA) and thyroarytenoid (TA) muscles were injected with fluorescent-conjugated cholera toxin and the motility of the vocal folds evaluated. After section and subsequent repair of the RLN, no movement of the vocal folds could be detected at any of the survival times studied and the somatotopy and the number of labeled motoneurons changed. From 4 wpi award, the somatotopy was significantly disorganized, with the PCA motoneurons being located rostrally relative to their normal location. A rostrocaudal overlap between the two pools of motoneurons supplying the PCA and TA muscles was observed from 2 wpi onwards. Hardly any labeled neurons were found in the contralateral Amb in any of the experimental groups. An injury of the RLN leads to a reinnervation of the denervated motor endplates of PCA and TA. However, misdirected axons sprout and regrowth from the proximal stump to the larynx. As a result, misplaced innervation of muscles results in a lack of functional recovery of the laryngeal folds movement following a RLN injury.
Subject(s)
Medulla Oblongata/physiology , Motor Neurons/physiology , Nerve Regeneration/physiology , Recurrent Laryngeal Nerve Injuries/physiopathology , Recurrent Laryngeal Nerve/physiology , Animals , Laryngeal Muscles/innervation , Male , Medulla Oblongata/cytology , Motor Neurons/cytology , Rats , Rats, Sprague-DawleyABSTRACT
This study set out to ascertain whether the context in which anatomy is learnt made a difference to students' perceptions of learning. An Approach to Learning Inventory (ASSIST) and a 31-item Anatomy Learning Experience Questionnaire (ALE) were administered to 224 students (77 dental, 132 medical and 19 speech and language) as a multi-site study. Results revealed that 45% adopted a strategic, 39% a deep and 14% a surface approach. Trends between professions are similar for a deep or strategic approach (both ~ 40%). However, a surface approach differed between professions (7% dentistry, 16% medicine, 26% speech and language science). Dental students responded more to being able to use their knowledge than did other groups (P = 0.0001). Medical students found the dissecting environment an intimidating one and subsequently reported finding online resources helpful (P = 0.015 and P = 0.003, respectively). Speech and language science students reported that they experienced greater difficulties with learning anatomy; they reported finding the amount to learn daunting (P = 0.007), struggled to remember what they did last semester (P = 0.032) and were not confident in their knowledge base (P = 0.0001). All students responded strongly to the statement 'I feel that working with cadaveric material is an important part of becoming a doctor/dentist/health care professional'. A strong response to this statement was associated with students adopting a deep approach (P = 0.0001). This study has elucidated that local curriculum factors are important in creating an enabling learning environment. There are also a number of generic issues that can be identified as being inherent in the learning of anatomy as a discipline and are experienced across courses, different student groups and institutions.
Subject(s)
Anatomy/education , Learning , Students, Health Occupations/psychology , Adult , Cadaver , Clinical Competence , Cross-Sectional Studies , Dissection/education , Female , Focus Groups , Health Knowledge, Attitudes, Practice , Humans , Male , Surveys and Questionnaires , Teaching/methodsABSTRACT
Motoneurons innervating laryngeal muscles are located in the nucleus ambiguus (Amb), but there is no general agreement on the somatotopic representation and even less is known on how an injury in the recurrent laryngeal nerve (RLN) affects this pattern. This study analyzes the normal somatotopy of those motoneurons and describes its changes over time after a crush injury to the RLN. In the control group (control group 1, nâ =â 9 rats), the posterior cricoarytenoid (PCA) and thyroarytenoid (TA) muscles were injected with cholera toxin-B. In the experimental groups the left RLN of each animal was crushed with a fine tip forceps and, after several survival periods (1, 2, 4, 8, 12â weeks; minimum six rats per time), the PCA and TA muscles were injected as described above. After each surgery, the motility of the vocal folds was evaluated. Additional control experiments were performed; the second control experiment (control group 2, nâ =â 6 rats) was performed labeling the TA and PCA immediately prior to the section of the superior laryngeal nerve (SLN), in order to eliminate the possibility of accidental labeling of the cricothyroid (CT) muscle by spread from the injection site. The third control group (control group 3, nâ =â 5 rats) was included to determine if there is some sprouting from the SLN into the territories of the RLN after a crush of this last nerve. One week after the crush injury of the RLN, the PCA and TA muscles were injected immediately before the section of the SLN. The results show that a single population of neurons represents each muscle with the PCA in the most rostral position followed caudalwards by the TA. One week post-RLN injury, both the somatotopy and the number of labeled motoneurons changed, where the labeled neurons were distributed randomly; in addition, an area of topographical overlap of the two populations was observed and vocal fold mobility was lost. In the rest of the survival periods, the overlapping area is larger, but the movement of the vocal folds tends to recover. After 12â weeks of survival, the disorganization within the Amb is the largest, but the number of motoneurons is similar to control, and all animals recovered the movement of the left vocal fold. Our additional controls indicate that no tracer spread to the CT muscle occurred, and that many of the labeled motoneurons from the PCA after 1â week post-RLN injury correspond to motoneurons whose axons travel in the SLN. Therefore, it seems that after RLN injury there is a collateral sprouting and collateral innervation. Although the somatotopic organization of the Amb is lost after a crush injury of the RLN and does not recover in the times studied here, the movement of the vocal folds as well as the number of neurons that supply the TA and the PCA muscles recovered within 8â weeks, indicating that the central nervous system of the rat has a great capacity of plasticity.
Subject(s)
Laryngeal Muscles/innervation , Motor Neurons/physiology , Nerve Regeneration/physiology , Recurrent Laryngeal Nerve Injuries/pathology , Recurrent Laryngeal Nerve , Animals , Disease Models, Animal , Laryngeal Muscles/injuries , Male , Nerve Crush , Rats , Rats, Sprague-Dawley , Recurrent Laryngeal Nerve/cytologyABSTRACT
Neurons innervating the intrinsic muscles of the larynx are located within the nucleus ambiguus but the precise distribution of the neurons for each muscle is still a matter for debate. The purpose of this study was to finely determine the position and the number of the neurons innervating the intrinsic laryngeal muscles cricothyroid, posterior cricoarytenoid, and thyroarytenoid in the rat. The study was carried out in a total of 28 Sprague Dawley rats. The B subunit of the cholera toxin was employed as a retrograde tracer to determine the locations, within the nucleus ambiguus, of the neurons of these intrinsic laryngeal muscles following intramuscular injection. The labelled neurons were found ipsilaterally in the nucleus ambiguus grouped in discrete populations with reproducible rostrocaudal and dorsoventral locations among the sample of animals. Neurons innervating the cricothyroid muscle were located the most rostral of the three populations, neurons innervating the posterior cricoarytenoid were found more caudal, though there was a region of rostrocaudal overlap between these two populations. The most caudal were the neurons innervating the thyroarytenoid muscle, presenting a variable degree of overlap with the posterior cricoarytenoid muscle. The mean number (±SD) of labelled neurons was found to be 41 ± 9 for the cricothyroid, 39 ± 10 for the posterior cricoarytenoid and 33 ± 12 for the thyroarytenoid.
Subject(s)
Laryngeal Muscles/innervation , Medulla Oblongata/cytology , Sensory Receptor Cells , Animals , Cell Count , Cholera Toxin/administration & dosage , Injections, Intramuscular , Male , Neuroanatomical Tract-Tracing Techniques , Neuronal Tract-Tracers/administration & dosage , Rats , Rats, Sprague-DawleyABSTRACT
BACKGROUND: Two theories explain the origin of human laryngeal ventricles: (1) ventricles derive from the fifth pharyngeal pouches; (2) development independent from the pouches. METHODS: In all, there were 21 serially sectioned human embryos from stages 15 to 23, and 11 fetuses of 9 to 18 weeks. Computer-aided 3-dimentional reconstructions were made. RESULTS: The cranial part of the laryngeal sulcus and future vestibule expands from the pharyngeal floor between the third and fourth pharyngeal pouches during stages 15 and 16 (33-37 days). The primordia of the ventricles appeared at stage 18 (44 days) as 2 lateral swellings in the caudal end of the future vestibule, limited by the third pharyngeal pouches. Active epithelial expansion and subsequent canalization during late embryonic and early fetal periods finalizes their development. CONCLUSIONS: The laryngeal ventricles do not derive from the pharyngeal pouches but the median region of the pharyngeal floor between the third and fourth pharyngeal pouches and arches at the caudal end of the future vestibule.
Subject(s)
Larynx/embryology , Morphogenesis , Pharynx/embryology , Fetus , Humans , Image Processing, Computer-Assisted , Imaging, Three-DimensionalABSTRACT
Previously, we have reported on the legal and ethical aspects and current practice of body donation in several European countries, reflecting cultural and religious variations as well as different legal and constitutional frameworks. We have also established good practice in body donation. Here we shall further extend the legal and ethical frameworks in place and also focus on novelties in the law and different directives. Of particular interest are points that address the commercialization of human bodies and body parts and weaknesses in the legal directives. Therefore, it is important to define what is ethical and what needs to be considered unethical in body donation and the subsequent utilisation of human bodies for teaching and research (AU)
No disponible
Subject(s)
Humans , Tissue and Organ Procurement/ethics , Tissue and Organ Procurement/legislation & jurisprudence , Transplants/ethics , Tissue Donors/ethics , Tissue Donors/legislation & jurisprudence , Bioethical Issues , European UnionABSTRACT
The larynx serves respiratory, protective, and phonatory functions. The motor and sensory innervation to the larynx controlling these functions is provided by the superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN). Classical studies state that the SLN innervates the cricothyroid muscle and provides sensory innervation to the supraglottic cavity, whereas the RLN supplies motor innervation to the remaining intrinsic laryngeal muscles and sensory innervation to the infraglottic cavity, but recent data suggest a more complex anatomical and functional organisation. The current neuroanatomical tracing study was undertaken to provide a comprehensive description of the central brainstem connections of the axons within the SLN and the RLN, including those neurons that innervate the larynx. The study has been carried out in 41 adult male Sprague-Dawley rats. The central projections of the laryngeal nerves were labelled following application of biotinylated dextran amines onto the SLN, the RLN or both. The most remarkable result of the study is that in the rat the RLN does not contain any afferent axons from the larynx, in contrast to the pattern observed in many other species including man. The RLN supplied only special visceromotor innervation to the intrinsic muscles of the larynx from motoneurons in the nucleus ambiguus (Amb). All the afferent axons innervating the larynx are contained within the SLN, and reach the nucleus of the solitary tract. The SLN also contained secretomotor efferents originating from motoneurons in the dorsal motor nucleus of the vagus, and special visceral efferent fibres from the Amb. In conclusion, the present study shows that in the rat the innervation of the larynx differs in significant ways from that described in other species.
Subject(s)
Laryngeal Muscles/innervation , Laryngeal Nerves/physiology , Animals , Brain Stem/anatomy & histology , Dextrans/metabolism , Laryngeal Nerves/metabolism , Male , Rats , Rats, Sprague-Dawley , Solitary Nucleus/physiology , Vagus Nerve/physiologyABSTRACT
The aim of this work was to study the prevalence and form of the ary-thyro-cricoid (ATC) muscular fascicle, a variable muscular slip connecting the oblique and/or transverse arytenoid muscles with the thyroarytenoid (TA) and/or lateral cricoarytenoid (LCA) muscles resembling a sphincter encircling the glottis. Thirty larynges obtained from necropsies of individuals with no known laryngeal pathology were dissected. The ATC fascicle was observed in 96.7% of the larynges. It appeared bilaterally in 60% of subjects and unilaterally in 36.7%. The posterior attachment of the muscular slip was observed to be in common with either the transverse arytenoid (34%), or the oblique arytenoid (28%) or both muscles (38%). Its fibers terminated by intermingling with either those of the LCA muscle (10.6%), or the TA muscle (38.3%) or both (51.1%). These variable attachments mean that there are nine possible variants of this muscular fascicle. The ATC fascicle was supplied by branches originating bilaterally from the recurrent laryngeal (RLN) and internal laryngeal nerves. The existence of this ATC fascicle could explain the variable position (intermediate, paramedian or lateral) adopted by the vocal folds after lesion of the RLN. The bilateral disposition and innervation of the fascicle could also complicate the interpretation of electromyographic techniques used for testing laryngeal nerve function.
Subject(s)
Larynx/anatomy & histology , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Muscles/innervationABSTRACT
The presence of ganglia associated with the laryngeal nerves is well documented. In man, these ganglia have been less well studied than in other species and, in particular, the cell types within these ganglia are less well characterized. Using a panel of antibodies to a variety of markers found in the paraganglion cells of other species, we were able to show the existence of at least two populations of cells within human laryngeal paraganglia. One population contained chromogranin and tyrosine hydroxylase representing a neurosecretory population possibly secreting dopamine. A second population of choline acetyltransferase positive cells would appear to have a putative parasympathetic function. Further work is needed to characterize these cell populations more fully before it will be possible to assign functions to these cell types but our results are consistent with the postulated functions of these ganglia as chemoreceptors, neurosecretory cells, and regulators of laryngeal mucus secretion.
Subject(s)
Ganglia, Parasympathetic/anatomy & histology , Ganglia, Sympathetic/anatomy & histology , Laryngeal Nerves/anatomy & histology , Larynx/anatomy & histology , Biomarkers/metabolism , Calcitonin Gene-Related Peptide/metabolism , Choline O-Acetyltransferase/metabolism , Chromogranin A/metabolism , Ganglia, Parasympathetic/metabolism , Ganglia, Sympathetic/metabolism , Humans , Immunoenzyme Techniques , Laryngeal Nerves/metabolism , Neuropeptide Y/metabolism , Staining and Labeling , Substance P/metabolism , Tyrosine 3-Monooxygenase/metabolism , Vasoactive Intestinal Peptide/metabolismABSTRACT
BACKGROUND: There are known to be variations in the origins of the superior thyroid artery (STA), an important surgical landmark, and 1 of its branches, the superior laryngeal artery (SLA). METHODS: Three hundred thirty human embalmed heminecks were dissected. The results of previous studies were reviewed, and a meta-analysis is presented. RESULTS: Four different origins for the STA were found. The most frequent was type I, from the carotid bifurcation (49%). Four different origins were also found for the SLA being the most frequent the type I in which the artery arose from STA (78%). The mean external diameters of STA and SLA were 0.26 and 0.20 cm, respectively, with no statistically significant differences by side or sex. CONCLUSION: Variations in the origin of STA and SLA from the carotid arterial tree and the similarity of their diameters mean that there is a significant possibility of their misidentified during surgery.
Subject(s)
Arteries/anatomy & histology , Larynx/blood supply , Thyroid Gland/blood supply , Aged , Aged, 80 and over , Cadaver , Carotid Arteries/anatomy & histology , Female , Humans , Larynx/anatomy & histology , Larynx/surgery , Male , Middle Aged , Neck Dissection , Thyroid Gland/anatomy & histology , Thyroid Gland/surgeryABSTRACT
This study aimed to document the prevalence and morphology of the ceratocricoid muscle in a large sample of fetuses and adults and to explain its possible origin in a sample of embryos. Forty-five embryos, thirty-four fetuses, and ninety human larynges from adults with no known laryngeal pathology were studied. The muscle was observed in 23% of the fetal sample and in 14% of the adult sample. No significant differences were observed in the laterality in any of the groups. The ceratocricoid muscle is attached between the cricoid lamina and the inferior horn of the thyroid cartilage and also into the capsule of the cricothyroid joint. The muscle is innervated by several branches (between one and three) from the anterior division of the recurrent laryngeal nerve as it courses behind the cricothyroid joint. The ceratocricoid muscle develops from tissue within the mesenchymal bridge which connects the external and internal laryngeal sphincters or rings from embryonic stages 15-20. The close relationship of the ceratocricoid muscle to the recurrent laryngeal nerve could mean that it can exert pressure on this nerve. This may be a possible explanation for the causation of certain idiopathic recurrent laryngeal nerve palsies.