Ophthalmic artery arising from the external carotid artery system: the middle meningeal artery in South African patients.

BACKGROUND: The ophthalmic artery is the first branch of the internal carotid artery. It arises from the supraclinoid segment of the internal carotid artery within the subarachnoid space and enters the orbit via the optic canal. However, due to complex embryogenesis, the ophthalmic artery can arise from different parts of the internal carotid artery or the distal branches of the external carotid artery. This is usually associated with a variation in the course of the ophthalmic artery through the superior orbital fissure instead of coursing through the optic canal. The ophthalmic artery and its branches vascularise the eyeball and its contents. Consequently, information about its morphologic variation is essential for treating clinical conditions such as central retinal artery occlusion, retinoblastoma chemoembolization, and ophthalmic artery aneurysm. CASE PRESENTATION: We report on two cases of the ophthalmic artery arising from the middle meningeal artery in one adult (33-year-old Indian female) and one pediatric (2-year-old African male) South African patient examined by digital subtraction angiography. The patients were diagnosed with arteriovenous malformations and bilateral retinoblastoma, respectively. CONCLUSIONS: The ophthalmic artery plays a vital role in vision generation. Thus, its anatomy is of clinical interest to neurosurgeons, ophthalmologists, and interventional radiologists.

Right vertebral artery arising from the right common carotid artery with an absent brachiocephalic trunk.

The right and left vertebral arteries are the first branches of the ipsilateral subclavian arteries. However, in the presence of anatomical variation due to complex embryogenesis, the vertebral artery can arise directly from the aortic arch or any of its major branches. The atypical origin of the vertebral artery is commonly associated with the left vertebral artery. Anatomical variation in the origin of the right vertebral artery is rare. Most available reports are case reports from international studies. We report on a case of right vertebral artery arising from the ipsilateral common carotid artery with an absent brachiocephalic trunk in a South African patient examined by digital subtraction angiography. Reports on anatomical variations are of diagnostic importance prior to surgical interventions or endovascular treatment of cerebrovascular diseases such as cerebral aneurysms and arteriovenous malformations.

An anatomical investigation of the proximal vertebral arteries (V1, V2) in a select South African population.

INTRODUCTION: The most common type of vascular complication during cervical spine surgery is the vertebral artery (VA) injury. The presence of anatomical variation in the artery's morphology has been a significant factor for arterial injury during surgery. Therefore, physicians planning interventions in the craniospinal region need to be aware of the extents of variations. In addition to vascular injury, anatomical variations can predispose to some pathologies in the posterior circulation territory. To provide useful data to interventional radiologists, anatomists, and surgeons, we evaluated the anatomical features of the V1 and V2 segments of the VA in a South African population. MATERIALS AND METHODS: The study is an observational, retrospective chart review of 554 consecutive South African patients (Black, Indian and White) who had undergone computed tomography angiography (CTA) from January 2009 to September 2019. RESULTS: The VA exhibited morphological variation in its course. We report the incidence of variant origin of the left VA, all from the aortic arch. Variation in the level of entry into the transverse foramen ranged between C7 and C3. A left dominant pattern was observed; we also report on hypoplasia of the VA. In addition, we report incidence of VA tortuosity at V1, V2 to be 76.6% and 32.1%, respectively. CONCLUSIONS: The baseline data established in this study regarding the diameter, variant origin, and level of entry into the transverse foramen will assist neurosurgeons and interventional radiologists in interpreting, diagnosing, and planning and executing various vascular procedures and treatment of pathology in the vicinity of the VA.

Reflective journals: unmasking student perceptions of anatomical education.

BACKGROUND: In medical education, reflection has been considered to be a core skill in professional competence. The anatomy laboratory is an ideal setting for faculty/ student interaction and provides invaluable opportunities for active learning and reflection on anatomical knowledge. MATERIALS AND METHODS: This study was designed to record student attitudes regarding human cadaveric dissection, explore their experiences of anatomy through an analysis of their journal-reflective writings and determine whether this type of creative writing had a beneficial effect on those students who chose to complete them. A total of 75 journals from Medical and Allied Health Science students were collected and analysed. RESULTS: Results were categorised according to the following themes: (i) Dissecting room stressors (27.6%); (ii) Educational value of dissection (26.3%); (iii) Appreciation, Gratitude, Respect and Curiosity for the cadaver (18.9%); (iv) Positive and negative sentiments expressed in the dissecting room (25.8%); (v) Benefit of alternate teaching modalities (4.6%); (vi) Spirituality/Religious Beliefs (3.7%); (vii) Shared humanity and emotional bonds (3.69%); (viii) Acknowledgement of human anatomical variations (3.2%); (ix) Beauty and complexity of the human body (1.8%) and (x) Psychological detachment (0.9%). Students appreciated the opportunity to share their emotions and reflect on the humanistic dimension of anatomy as a subject. Student reflections illustrated clearly their thoughts and some of the difficult issues with which they wrestled. CONCLUSIONS: The anatomy laboratory is seen as the budding clinician's first encounter with a patient, albeit a cadaver. This was the first time that reflective journals were given to students in the discipline. Reflective journals allow students to express themselves in an open-ended and creative fashion. It also assists students to integrate anatomy and clinical medicine and assists in applying their basic anatomical knowledge in an authentic, yet safe environment.

Enthesopathic patterns of two South African female cadavers.

Enthesopathy is considered to be an osseous phenomenon, either disease-specific or bone-site specific, which occurs at the enthesis of bone. Upon routine cadaveric dissection of the glenohumeral region in two Caucasian females, enthesopathy of the right proximal humerus was observed unilaterally in both cases. Case 1 exhibited an inconsistent pattern of bony protuberances and crests dispersed across the lesser and greater tuberosities of the right humeral head. Varying degrees of ossification of the distal subscapularis muscle was also observed. Case 2 presented with a distinctively large enthesophyte that protruded supero-medially from the proximal right humerus. In addition, ossification of the distal-most aspect of the supraspinatus muscle was identified. Cases 1 and 2 were both reflective of osteophytic enthesopathy as proliferative change was clearly visible on the proximal aspect of each humerus. Whilst the presence of enthesopathies may be indicative of underlying pathology, it may prove beneficial to the field of bioarchaeology for the remodelling of lifestyles of ancient civilizations through the provision of current day variations as seen in these two case studies.

An arthroscopic evaluation of the anatomical "critical zone".

BACKGROUND: The "critical zone", a region of speculated vascularity, is situated approximately 10 mm proximal to the insertion of the supraspinatus tendon. Despite its obvious role as an anatomical landmark demarcator, its patho-anatomic nature has been identified as the source of rotator cuff pathology. Although many studies have attempted to evaluate the vascularity of this region, the architecture regarding the exact length, width and shape of the critical zone, remains unreported. This study aimed to determine the shape and morphometry of the "critical zone" arthroscopically. MATERIALS AND METHODS: The sample series, which was comprised of 38 cases (n = 38) specific to pathological types, employed an anatomical investigation of the critical zone during routine real-time arthroscopy. Demographic representation: i) sex: 19 males, 19 females; ii) age range: 18-76 years; iii) race: white (n = 29), Indian (n = 7) and coloured (n = 2). RESULTS: The incidence of shape and the mean lengths and widths of the critical zone were determined in accordance with the relevant demographic factors and patient history. Although the cresenteric shape was predominant, hemispheric and sail-shaped critical zones were also identified. The lengths and widths of the critical zone appeared markedly increased in male individuals. While the increase in age may account for the increased incidence of rotator cuff degeneration due to poor end-vascular supply, the additional factors of height and weight presented as major determinants of the increase in size of the critical zone. CONCLUSIONS: In addition, the comparisons of length and width with each other and shape yielded levels of significant difference, therefore indicating a directly proportional relationship between the length and width of the critical zone. This detailed understanding of the critical zone may prove beneficial for the success of post-operative rotator cuff healing.

An anatomical investigation of the carotid canal.

BACKGROUND: The carotid canal (CC) located in the petrous temporal bone transmits the internal carotid artery, internal carotid venous plexus and sympathetic nerve plexus from the neck into the cranial cavity. It is an accessible passage into the cranial cavity and is considered an important anatomical landmark for neurosurgeons. The aim of this study was to investigate the topographical, morphometric and morphological parameters of the CC. MATERIALS AND METHODS: An examination of the CC and related adjacent structures in 81 dry skull specimens was performed. Distribution of sample by sex was 34 females and 47 males, and by race 77 African and 4 Caucasian. The mean age was 50 years (range: 14-100 years). RESULTS: The external opening of the CC was found to be round-shaped, oval-shaped and tear-drop-shaped in 28.4%, 49.4% and 22.2% of the specimens, respectively. (1) Mean diameters [mm]: (a) medio-lateral 7.52 mm and (b) antero-posterior 5.41mm. Statistically significant difference in the vertical diameter was recorded in the race groups and laterality of the samples. (2) Mean distances [mm] between: (a) medial margins of external opening of CC was 50.03 mm, (b) lateral margins of external opening of CC was 62.73 mm and (c) external openings of CC and foramen lacerum was 15.6 mm. There was a statistically significant correlation between race and location of the opening of external CC in relation to foramen lacerum (viz. postero-lateral, lateral and diagonal, and lateral). CONCLUSIONS: The present study corroborated previous reports on the CC; however, the tear-drop shaped external CC opening was a unique finding. The knowledge of the reference measurements pertaining to the CC and its relationship to adjacent structures may postulate a suitable surgical "safe-zone" range within the CC area.

An anatomical investigation of the superficial and deep palmar arches.

BACKGROUND: The superficial palmar arch (SPA) and deep palmar arch (DPA) provide the dominant vascular supply to the hand. The SPA is considered to be highly variable and can be classified as either complete or incomplete. The simplest definition states that the anastomosis between the vessels contributing to the arch represent a complete arch, while an incomplete arch is described as characterised by an absence of anastomosis between the vessels contributing to it. This study aimed to describe the anatomical landmarks, formation and branching patterns of the SPA and DPA. In this study, the SPA and DPA were dissected in 50 specimens (n = 100 adult hands), respectively. MATERIALS AND METHODS: A complete SPA was observed in 92% of specimens and classified into three types. In Type A (44%), the SPA was formed by the anastomosis of the superficial palmar branch of the radial artery with the ulnar artery. Type B (46%) was formed by the ulnar artery alone and Type C (2%) was formed by anastomosis of the ulnar artery with the superficial palmar branch of the radial artery and the persistent median artery. RESULTS: An incomplete SPA was observed in 8% of the specimens and divided into three types formed by the radial and ulnar arteries. The DPA was divided into five types viz. Type G (72%), where the DPA was formed by anastomosis of the deep palmar branch of the radial artery (DPBRA) with the deep palmar branch of the ulnar artery (DPBUA). Type H (12%), was formed by anastomosis of the DPBRA, the DBUA and the interosseous artery. Type I (8%), was formed by the anastomosis of the DPBRA with the superior and inferior DPBUA. Type J (4%), the deep ulnar artery had two branches whereby either one branch anastomosed with the DPBRA to form the DPA. Type K (4%), the DBUA exhibited two deep branches with one branch anastomosing with the DPBRA to complete the DPA. CONCLUSIONS: The interosseous artery anastomosed with either the DPA or the additional DPBUA. Knowledge of the variability of the SPA and DPA is crucial for safe and successful hand surgeries.

Laryngeal nerve "anastomoses".

Laryngeal nerves have been observed to communicate with each other and forma variety of patterns. These communications have been studied extensively and have been of particular interest as it may provide an additional form of innervation to the intrinsic laryngeal muscles. Variations noted in incidence may help explain the variable position of the vocal folds after vocal fold paralysis. This study aimed to examine the incidence of various neural communications and to determine their contribution to the innervation of the larynx. Fifty adult cadaveric en-bloc laryngeal specimens were studied. Three different types of communications were observed between internal and recurrent laryngeal nerves viz. (1) Galen's anastomosis (81%):in 13%, it was observed to supply the posterior cricoarytenoid muscle; (2) thyroarytenoid communication (9%): this was observed to supply the thyroarytenoid muscle in 2% of specimens and (3) arytenoid plexus (28%): in 6%, it supplied a branch to the transverse arytenoid muscle. The only communication between the external and recurrent laryngeal nerves was the communicating nerve (25%). In one left hemi-larynx, the internal laryngeal nerve formed a communication with the external laryngeal nerve, via a thyroid foramen. The neural communications that exist in the larynx have been thought to play a role in laryngeal innervation. The results of this study have shown varying incidences in neural communications. Contributions from these communications have also been noted to various intrinsic laryngeal muscles which may be a possible factor responsible for the variable position of the vocal folds in certain cases of vocal fold paralysis.

The variant course of the suprascapular artery.

The suprascapular artery (SSA) has been identified to be of clinical relevance in surgical intervention and fracture healing of the shoulder. Despite the classic description of its course and relation to the superior transverse scapular ligament, it is subject to much variation. The aims of this study were: (i) to describe the course of the SSA in relation to the superior transverse scapular ligament, (ii) tob determine the prevalence of the course of the SSA in relation to the superior transverse scapular ligament, (iii) to determine the prevalence of the variant origin of the SSA in cases presenting with variant course of the latter, and (iv) to establish a difference in laterality and that between adults and foetuses. The course of the SSA was investigated through the macro- and micro dissection of the antero-andpostero-superior shoulder regions of 31 adult and 19 foetal cadaveric specimens (n = 100). The SSA was observed to pass inferior to the superior transverse scapular ligament accompanied by the suprascapular nerve (20%), which corroborated the findings of previous studies. Subsequently, this variant course of the SSA also appeared to present with the variant origin of it in many instances (13%): from the 3rd part of the subclavian artery (4%), 1st part of the axillary artery (2%), 2nd part of the axillary artery (5%) and SSA (2%). Injury to the SSA may cause more serious trauma than that of arteries which are isolated from the great vessels, therefore the recognition and knowledge of variation in the origin and course of the SSA is significant in the treatment of diseases in the shoulder and cervical regions. Furthermore, the accompaniment of the suprascapular nerve with the SSA at the suprascapular notch inferior to the superior transverse scapular ligament may lead to neuropathy syndromes due to the pulsation of the artery against the nerve within the confined notch.

The intramyocardial left anterior descending artery: prevalence and surgical considerations in coronary artery bypass grafting.

BACKGROUND: Major coronary arteries usually have a subepicardial course and only dip into the myocardium near or at their termination. However, occasionally a segment of the epicardial artery may have an intramural course, and it is often referred to as a myocardial bridge. The left anterior descending (LAD) artery is the most commonly bridged vessel. Its prevalence has been evaluated at both autopsy and angiography. However, in the literature reviewed it is apparent that there are no reports of the prevalence of the intramyocardial LAD (IMLAD) artery in coronary artery bypass graft (CABG) series. OBJECTIVES: To document the prevalence of the IMLAD artery in a series of CABGs and to describe the surgical techniques used in these cases. METHODS: A retrospective analysis of 1349 surgical reports of consecutive CABGs performed over a period of 23 years was conducted. RESULTS: An IMLAD artery was present in 293 patients (21.7%). The prevalence was 20.2% (51/253) in females and 22.1% (242/1096) in males. The IMLAD arteries extended into the interventricular septum in 3.8% (11/293) of the patients. CONCLUSION: An intramyocardial course of the LAD artery is relatively common in patients undergoing CABG and poses a challenge in bypass grafting. Techniques are described to address this anatomical variation when it is encountered at surgery.

Determination of the median nerve safe-zone in the carpal tunnel using the distal forearm bony prominences.

BACKGROUND: The compression of the median nerve (MN) in the carpal tunnel (CT) is one of the most common aetiologies of entrapment neuropathy syndromes in clinical practice. The aim of this study was to investigate the relationship of the palpable bony prominences of the distal forearm (radial styloid process [RSP] and ulnar styloid process [USP]) with MN in the CT, in order to determine a safe-zone of the MN during carpal tunnel procedures. MATERIALS AND METHODS: This study involved the bilateral dissection of the CT region of 30 adult cadaveric specimens (n = 60). RESULTS: The mean distance between the RSP and USP was 49.34 mm. The mean distance of the MN from the RSP and the USP were 22.44 mm and 26.66 mm, respectively. The mean diameter of the MN within the CT deep to the flexor retinaculum was 5.93 mm. In addition, the MN was located postero-lateral and postero-medial to palmaris longus tendon (PLT) in 78.33% and 21.67% of specimens, respectively. CONCLUSIONS: This study found that the MN was located less than 60% of the RSP-USP distance from the RSP. Furthermore, the MN was mostly located postero-lateral to the PLT. Therefore, injection or surgical incision made at/medial to a point 60% of the RSP-USP distance from the RSP will be outside the safe-zone of the MN. The knowledge of this surface anatomical relationship of the MN may be useful during decompression for CT syndrome.

Double aortic arch: an unusual congenital variation.

Double aortic arch is a rare variation of the aortic arch that may cause tracheal and esophageal compression. Two postnatal cases of double aortic arch and their outcomes are reported. Both patients presented with stridor, repeated respiratory infections and episodes of apnea. Computerized tomography angiographic three-dimensional reconstruction revealed that in both patients, the right common carotid artery and right subclavian artery had separate origins from the right loop of the double aortic arch. The left subclavian artery and left common carotid artery arose separately from the left aortic arch. Both patients underwent corrective surgery and made an uneventful recovery.

The impact of left main coronary artery morphology on the distribution of atherosclerotic lesions in its branches.

BACKGROUND: Atherosclerotic occlusion of a coronary vessel is the commonest cause of ischaemic heart disease. The distribution of atherosclerotic lesions is not random,with stenoses preferentially situated at branch ostia, bifurcation points, and the proximal segments of daughter vessels. The aim of this study was to determine the effect of the intrinsic anatomical properties of the left main coronary artery(LMCA) on the distribution of atherosclerotic lesions in its branches. MATERIALS AND METHODS: A retrospective review of 170 consecutive coronary angiograms obtained from the cardiac catheterisation laboratories of private hospitals in the eThekwini Municipality area of KwaZulu-Natal, South Africa was performed. The LMCA was absent in 19/170 (11.2%). The remaining angiograms(n = 151) were divided into two groups: normal 63/151 (41.7%) and those with coronary artery disease (CAD) 88/151 (58.3%). The CAD group was sub-divided into proximal 42/88 (47.7%), mixed (proximal and distal) 26/88 (29.6%) and distal20/88 (22.7%) sub-groups based on the location of atherosclerotic lesions in the branches of the LMCA. RESULTS AND CONCLUSIONS: The mean length, diameter and angle of division of the LMCA were as follows: Total angiograms: 10.4 mm, 3.8 mm and 86.2o; normal group:10.5 mm, 3.9 mm and 85.7o, CAD group: 10.2 mm, 3.7 mm and 86.3o; proximal sub-group: 10.9 mm, 3.7 mm and 91.6o, mixed sub-group - 9.8 mm, 3.7 mm and 85o and distal sub-group - 9.1 mm, 3.8 mm and 79.4o, respectively. The vessels with proximally located lesions were recorded to have longer lengths and wider angles of division than vessels with distal lesions. Coronary angiographic delineation of the LMCA anatomy may be predictive of a coronary arterial arrangement that may favour the progression of proximally located lesions.

The prevalence and clinical importance of an "additional" terminal branch of the left coronary artery.

The left coronary artery (LCA) usually divides into two (anterior interventricular artery [AIA] and left circumflex [LCx] artery) or less frequently into the AIA, LCx,and one or more "additional" terminal branch/es (ATBs). These ATBs of the LCA have no unanimity regarding their anatomical nomenclature. There is a lack of common consensus on the criteria used for their definition, and they are also absent from the current Terminologia Anatomica (1998). This study, therefore,aimed to document the prevalence of the ATBs of the LCA, discuss their clinical importance, and propose an anatomical nomenclature. This study was conducted by reviewing 367 coronary angiograms. The termination patterns of the LCA were classified into 3 categories based on the number of their branches, viz. (a) bifurcation78.2%, (b) trifurcation 20.4%, and (c) quadrifurcation 1.4%, respectively. The presence of an ATB was recorded in 21.8% of the angiograms. The identification of this vessel may be of clinical importance because the extent of its supply may decrease the effect of occlusion of the LCx artery and AIA on the myocardium.The term "left ramus medianus artery" is proposed as the nomenclature for the ATB of the LCA.

The effects of COVID-19 on placental morphology.

The impact of the COVID-19 infection, caused by Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), during the pandemic has been considerably more severe in pregnant women than non-pregnant women. Therefore, a review detailing the morphological alterations and physiological changes associated with COVID-19 during pregnancy and the effect that these changes have on the feto-placental unit is of high priority. This knowledge is crucial for these mothers, their babies and clinicians to ensure a healthy life post-pandemic. Hence, we review the placental morphological changes due to COVID-19 to enhance the general understanding of how pregnant mothers, their placentas and unborn children may have been affected by this pandemic. Based on current literature, we deduced that COVID-19 pregnancies were oxygen deficient, which could further result in other pregnancy-related complications like preeclampsia and IUGR. Therefore, we present an up-to-date review of the COVID-19 pathophysiological implications on the placenta, covering the function of the placenta in COVID-19, the effects of this virus on the placenta, its functions and its link to other gestational complications. Furthermore, we highlight the possible effects of COVID-19 therapeutic interventions on pregnant mothers and their unborn children. Based on the literature, we strongly suggest that consistent surveillance for the mothers and infants from COVID-19 pregnancies be prioritised in the future. Though the pandemic is now in the past, its effects are long-term, necessitating the monitoring of clinical manifestations in the near future.

Fenestration of the vertebrobasilar junction detected with multidetector computed tomography angiography.

The complex embryonic origin of the vertebrobasilar system may result in a wide range of anatomical variations. It has been hypothesized that the formation of fenestrations are likely to occur due to the failure of regression of the bridging arteries that connect the longitudinal neural arteries during embryogenesis. Fenestration of the vertebrobasilar system is a rare anatomical variation that involves a luminal division of the artery, that has a single origin into two separate and parallel channels which are rejoined distally. Fenestrations are important anatomical variants in patients undergoing endovascular and invasive intracranial interventions. Vascular fenestration has been associated with aneurysms, arteriovenous malformations, neuralgia, and vertebrobasilar ischaemia. We report on 3 cases of fenestration at the vertebrobasilar junction in 1 female and 2 male patients, respectively, using multidetector computed tomography angiography. The length of the fenestrated segment of the artery measured 4.41 mm, 3.90 mm, and 5.90 mm, respectively in the patients. Our report is clinically important as the presence of this anatomical variation may influence the management of cervical and intracranial pathologies. Increased awareness of the prevalence of anatomic variations contributes to the advancement of noninvasive imaging capabilities.

British HIV Association and Children's HIV Association position statement on infant feeding in the UK 2011.

To prevent the transmission of HIV infection during the postpartum period, the British HIV Association and Children's HIV Association (BHIVA/CHIVA) continue to recommend the complete avoidance of breast feeding for infants born to HIV-infected mothers, regardless of maternal disease status, viral load or treatment.

Could COVID-19 Trigger a Rebirth in Anatomy Education? A Glimpse of Anatomists' Responses to Pandemics of the Past and Present.

Pandemics are nothing unusual but indeed lead to devastating effects that play a pivotal role in reshaping human history. The COVID-19 outbreak is currently responsible for major educational crises globally as most of the world has been faced with a mandated lockdown, and forced closure of educational institutions, including medical colleges. Anatomists have therefore been challenged to unlock technology in effort to achieve best deliverables for their discipline, without the use of traditional teaching aids such as the cadaver, osteological banks, prosected specimens, models, and microscopic slides. At present, the virtual classroom is the only option for the anatomist, thereby omitting vital aspects of the hidden curriculum such as ethical-reasoning, empathy, respect, professionalism, interpersonal, and communication skills. As body donations dwindle, the era of teaching in a cadaverless environment is upon us. This marks the beginning of a paradigm shift in education and research for anatomists worldwide. Given the variable pathological-morphological presentation in COVID-19-related deaths, it is also likely that the autopsy component of anatomic pathology will be resuscitated to demystify the underlying mechanisms of the virus. Since COVID-19 may never disappear completely, we would like to recommend that international anatomical societies collectively reach out to statutory bodies to devise a standardized method of teaching anatomy, employing readily available cost-effective resources, in the face of pandemics. However, if anatomy as a discipline has survived a millennium, surely anatomists can fight the "scourges" that have plagued them as various perspectives have been bandied about to welcome in a new normal.

Parietal foramen: incidence and topography.

BACKGROUND: The parietal foramen (PF) is a small inconsistent aperture located at the border of the middle 1/3 and posterior 1/3 of the parietal bone near the sagittal suture and is considered an emissary foramen. Cranial emissary foramina are of utmost importance due to the structures that traverse the foramen. Variations in these foramina are common. Knowledge of the PF is important when performing neurosurgical procedures as the emissary vessels are at risk. MATERIALS AND METHODS: The present study used 100 dry adult calvaria to determine the frequency of PF, the diameter of the PF, as well as topography of the PF (using the sagittal suture as an anatomical landmark). RESULTS: A total of 32% of calvaria had PF present bilaterally; whilst 35% of calvaria had unilateral PF. The study also reports 5% calvaria in which PF were present on the sagittal suture. The mean diameter recorded was 1.55 mm (0.74-3.08 mm), and the mean distance between the lateral margin of the PF and the sagittal suture was 9.02 mm (4.44-18.20 mm). CONCLUSIONS: Knowledge of the incidence and topography of the PF may aid neurosurgeons in creating and adjusting techniques and procedures in order to mitigate the risk of injury to emissary veins and other structures emerging from the PF.