Emerging Imaging Techniques in Anatomy: For Teaching, Research and Clinical Practice.

Visualisation plays a key role in anatomy, where the depiction of gross anatomical structures is essential in understanding and conceptualising content during research and medical teaching. Technology has allowed us to utilise imaging techniques for the visualisation of anatomical features, pathology and correlating physiological functions in a non-invasive manner which is atypical to traditional forms of anatomical investigation. These imaging methods develop integration between anatomy and clinically oriented medical study as well as biomechanics. The progressive research in anatomy can benefit from the vast field of biomechanics which allows for precise and conclusive results regarding the biomechanical integrity of anatomical structures and allows for intricate planning of procedures. 3D imaging techniques have enhanced the modelling of internal structures which are especially essential when implemented as diagnostic tools. An integration of these modalities into medical training accommodates for a more clinically orientated and immediate visualisation as produced when utilising ultrasound imaging which has the added advantage of 3D modelling and manipulation. Immersive technology has revolutionised teaching and learning particularly during the new age of hybrid education. Visualisation in anatomy has many clinical and educational applications which can optimise research, create interactive learning experiences and aid medical practise.

The surgical anatomy of the axillary approach for nerve transfer procedures targeting the axillary nerve.

PURPOSE: The exact relational anatomy for the anterior axillary approach, targeting the axillary nerve for nerve transfers/grafts, has not been fully investigated. Therefore, this study aimed to dissect and document the gross anatomy surrounding this approach, specifically regarding the axillary nerve and its branches. METHODS: Fifty-one formalin-fixed cadavers (98 axilla) were bilaterally dissected simulating the axillary approach. Measurements were taken to quantify distances between identifiable anatomical landmarks and relevant neurovascular structures encountered during this approach. The musculo-arterial triangle, described by Bertelli et al., to aid in identification on localization of the axillary nerve, was also assessed. RESULTS: From the origin of the axillary nerve till (1) latissimus dorsi was 62.3 ± 10.7 mm and till (2) its division into anterior and posterior branches was 38.8 ± 9.6 mm. The origin of the teres minor branch along the posterior division of the axillary nerve was recorded as 6.4 ± 2.9 mm in females and 7.4 ± 2.8 mm in males. The musculo-arterial triangle reliably identified the axillary nerve in only 60.2% of the sample. CONCLUSION: The results clearly demonstrate that the axillary nerve and its divisions can be easily identified with this approach. The proximal axillary nerve, however, was situated deep and therefore challenging to expose. The musculo-arterial triangle was relatively successful in localising the axillary nerve, however, more consistent landmarks such as the latissimus dorsi, subscapularis, and quadrangular space have been suggested. The axillary approach may serve as a reliable and safe method to reach the axillary nerve and its divisions, allowing for adequate exposure when considering a nerve transfer or graft.

Vertebrae at the thoracolumbar junction: A quantitative assessment using CT scans.

The thoracolumbar junction is often associated with traumatic injuries, due to its biomechanical instability. Reasons for this instability are currently still under debate; however, contributing factors such as the rapid change in spinal curvature and facet orientation from the thoracic to lumbar transition have been implicated. Normally, the superior facet orientation in the thoracic region is angled in a coronal plane, whereas vertebrae in the lumbar region have facets angled in the sagittal plane. Distinguishing between thoracic, lumbar, and transitional vertebrae at the thoracolumbar junction based on articular facet angles, using quantitative methods on CT scans has, to the authors' knowledge, not yet been reported in the literature. Therefore, this study aimed to evaluate whether quantitative measurements can be clinically applied and used to differentiate vertebrae at the thoracolumbar junction using CT scans and, additionally, to record possible cases of congenital defects or variations observed in the spine. A sample (n = 173) of CT scans representative of the Windhoek population in Namibia was retrospectively assessed using radio-imaging software. Measurements of the angle formed by the superior facets of the vertebrae at the thoracolumbar junction (T11-L1) were recorded. Based on the results of this study, quantitative morphometry of the superior facet of vertebrae can differentiate between thoracic, lumbar,. and transitional vertebrae at the thoracolumbar junction. All individuals with identified thoracolumbar transitional vertebrae (TLTV) in this sample had at least one other congenital anomaly of the spine.

Proximal tibial dimensions in a formalin-fixed neonatal cadaver sample: an intraosseous infusion approach.

PURPOSE: Methods to administer intramedullary medication and fluid infusion in both adults and children date to the early twentieth century. Studies have shown that intraosseous access in the proximal tibia is ideal for resuscitation efforts as fewer critical structures are at risk, and neither is the blood flow to the lower limbs compromised. Insertion of a needle in children younger than 5 years does have the risk to damage to the epiphyseal growth plate. Therefore, the aim of this study was to determine the ideal intraosseous insertion site distal to the epiphyseal growth plate in neonates. METHODS: The samples consisted of both the left and right sides of 15 formalin-fixed neonatal cadavers. The dimensions were measured on the superior surfaces of each section, anteromedial border, cortical thickness, and medullary space. RESULTS: The most desirable location to gain vascular access is at 10 mm inferior to the tibial tuberosity. CONCLUSION: The smallest cortical thickness (1.32 mm), the largest medullary space (4.50 mm), and the largest anteromedial surface (7.72 mm) were observed at 10 mm inferior to the tibial tuberosity. It is imperative that health care professionals are familiar with the osteological sites that could be safely used for an intraosseous infusion procedure.

The position of the common facial vein in neonates: An alternate route for central venous catheter placement.

INTRODUCTION: We determine the location of the common facial vein (CFV) in a sample of neonates and assess the safety of this vein as an alternative access route for a central venous catheter (CVC). MATERIALS AND METHODS: We dissected both the left and right sides of the neck region in 24 neonatal, formalin-fixed cadavers, exposing the underlying soft tissues and neurovascular structures. We identified the CFV, which we then pinned together with the internal jugular vein, cervical branch of facial nerve, marginal mandibular branch of the facial nerve, the cricoid cartilage, brachiocephalic vein, and the mastoid and sternal attachments of the sternocleidomastoid muscle. We measured the CFV and the related pinned structures. RESULTS: In neonates, the CFV intersected the anterior border of sternocleidomastoid on average 19.53 mm (left) and 21.73 mm (right) from its sternal attachment. CONCLUSION: We found the CFV inferior to the upper one third and just superior to half of the length of the sternocleidomastoid muscle, indicating a possible "safe-zone" where a skin incision could be made over the anteromedial border of sternocleidomastoid. The CFV is easily identified from surrounding landmarks. It could be used as a safe, alternative route for inserting a CVC if its average length (8.72 mm) and diameter (1.50 mm) are taken into account.

A quantitative analysis of the dimensions and content of the vertebral triangle.

PURPOSE: The vertebral triangle (VT) located in the root of the neck most commonly contains the vertebral artery (VA), cervical sympathetic chain and certain roots of the brachial plexus. Although other structures have been reported, few studies have reported on the overall content of this space. Based on the current literature, there is a general paucity of anatomical information pertaining to the dimensional anatomy of the VT and specifically the structures related to it. Therefore, this study aimed to quantitatively analyze the size, position, content, and anatomical structures in relation to the vertebral triangle in a South African sample. METHODS: Forty-three VTs were dissected on bodies donated to science. Measurements taken include the dimensions of the triangle, as well as distances between prominent structures and landmarks of the VT. Observations were made on the presence/absence of the varying neurovascular structures within the VT. RESULTS: Mean height was 30.1 ± 1.51 mm (R) and 32.9 ± 1.78 mm (L). Mean width was 18.3 ± 0.74 mm (R) and 19.3 ± 0.98 mm (L). The C8 spinal nerve was found on average approximately halfway [16.4 ± 0.74 mm (R) and 15.9 ± 0.95 mm (L)] in the VT. The VA was present in the VT in 100% of the sample and the C7 spinal nerve and inferior sympathetic ganglia were present in more than 80% of the sample. CONCLUSION: Understanding the VT and the content is of the utmost importance and of great interest to neurosurgeons, to avoid these important neurovascular structures and prevent iatrogenic complications during surgery.

The anatomical features of an ultrasound-guided erector spinae fascial plane block in a cadaveric neonatal sample.

BACKGROUND: Since its inception, the erector spinae plane block has been used for a variety of truncal surgeries with success in both adults and children. However, the anatomical features, route of spread, and dermatomal coverage are still not fully understood in a pediatric population. OBJECTIVES: To identify the anatomical features of the erector spinae fascial plane space by replicating an erector spinae plane block in a fresh neonatal cadaveric sample. The primary aim was to determine the spread of the dye within the fascial plane, while the secondary aims were to determine whether the needle direction or entry site affected the spread. METHODS: The block was replicated bilaterally using 0.1 mL/kg of iodinated contrast dye in nine fresh unembalmed preterm neonatal cadavers. The dye was introduced under ultrasound guidance at vertebral level T5 and T8. Additionally, the needle was oriented cranial-caudal vs caudal-cranial to determine if the needle orientation influenced the spread of dye. The block was also replicated midway between the adjacent transverse processes as opposed to the lateral tip of the transverse process to determine the spread. RESULTS: From the total sample size, 14 "blocks" were successfully replicated, while 4 "blocks" were either incomplete or failed blocks. Contrast dye was found in the paravertebral, intercostal, and epidural spaces, including posteriorly over the neural foramina. Results revealed that the needle direction or entry site did not influence the spread within the fascial plane. CONCLUSION: Contrast material was found in the paravertebral, epidural, and intercostal spaces over an average of 5 vertebral levels when using 0.1 mL/kg.

The extent of cranio-caudal spread within the erector spinae fascial plane space using computed tomography scanning in a neonatal cadaver.

BACKGROUND: The erector spinae plane block (ESP) is a novel approach for blockade of the spinal nerves in infants, children, and adults. Until recently, the gold standard for truncal procedures includes the paravertebral and epidural blocks. However, the exact mechanism by which this blockade is achieved is subject to debate. METHODS: 2.3 mL (1 mL/kg) of iodinated contrast dye was injected bilaterally into the erector spinae fascial plane of a fresh unembalmed preterm neonatal cadaver (weighing 2.3 kg), to replicate the erector spinae plane block and to track the cranio-caudal spread of the contrast dye using computed tomography. The "block" was performed at vertebral level T8 on the right-hand side and at vertebral level T10 on the left-hand side. RESULTS: Contrast dye was spread over three dermatomal levels from T6 to T9 on the right-hand side, while on the left-hand side, the spread was seen over four dermatomal levels from T9 to T11/12. Contrast dye also spread over the costotransverse ligament, into the paravertebral space and further lateral from the lateral border of the erector spinae muscle into the intercostal space. However, no spread was seen in the epidural space. CONCLUSION: The erector spinae plane block is a versatile technique that can be part of the multimodal postoperative analgesic strategy for truncal surgery. In this study, contrast material dye was tracked over four vertebral levels in the paravertebral space (suggesting an approximate volume of 0.5-0.6 mL per dermatome).

Sulcal pattern variation in extant human endocasts.

Our knowledge of human brain evolution primarily relies on the interpretation of palaeoneurological evidence. In this context, an endocast or replica of the inside of the bony braincase can be used to reconstruct a timeline of cerebral changes that occurred during human evolution, including changes in topographic extension and structural organisation of cortical areas. These changes can be tracked by identifying cerebral imprints, particularly cortical sulci. The description of these crucial landmarks in fossil endocasts is, however, challenging. High-resolution imaging techniques in palaeoneurology offer new opportunities for tracking detailed endocranial neural characteristics. In this study, we use high-resolution imaging techniques to document the variation in extant human endocranial sulcal patterns for subsequent use as a platform for comparison with the fossil record. We selected 20 extant human crania from the Pretoria Bone Collection (University of Pretoria, South Africa), which were detailed using X-ray microtomography at a spatial resolution ranging from 94 to 123 µm (isometric). We used Endex to extract, and Matlab to analyse the cortical imprints on the endocasts. We consistently identified superior, middle and inferior sulci on the frontal lobe; and superior and inferior sulci on the temporal lobe. We were able to label sulci bordering critical functional areas such as Broca's cap. Mapping the sulcal patterns on extant endocasts is a prerequisite for constructing an atlas which can be used for automatic sulci recognition.

Anatomy of the greater occipital nerve block in infants.

BACKGROUND: Pain relief for posterior fossa craniotomies as well as occipital neuralgia, are indications for the use of the greater occipital nerve block in children. The greater occipital nerve originates from the C2 spinal nerve and is accompanied by the occipital artery as it supplies the posterior scalp. AIMS: The aim of this study was to develop a unique, yet simple technique for blocking the greater occipital nerve in children through the evaluation of the anatomy of this nerve and the accompanying occipital artery in the occipital region. METHODS: The greater occipital nerve and occipital artery were dissected and exposed in six formalin-fixed cadavers (five infants [average age of 51.4 days] and one 2-year-old) from the Department of Anatomy, University of Pretoria. Measurements between the nerve and selected bony landmarks were obtained. The relationship between the greater occipital nerve and the occipital artery at the trapezius muscle hiatus was also evaluated. RESULTS: The greater occipital nerve is on average 22.6 ± 5.6 mm from the external occipital protuberance in infants. The average width of the medial three fingers measured at the proximal interphalangeal joint, for each respective cadaver is 20.4 ± 4.0 mm, with a strong correlation coefficient of 0.97 between the aforementioned distances. In 83.3% of the specimens, the occipital artery lies lateral to the greater occipital nerve at the trapezius muscle hiatus. CONCLUSION: In infants, the greater occipital nerve can be blocked approximately 23 mm from the external occipital protuberance, medial to the occipital artery. This distance is equal to the width of the medial three fingers at the proximal interphalangeal joint of the patient.

Apprasial of the surface anatomy of the Thorax in an adolescent population.

Surface anatomy is considered a fundamental part of anatomy curricula and clinical practice. Recent studies have reappraised surface anatomy using CT, but the adolescent age group has yet to be appraised. Sixty adolescent thoracoabdominal CT scans (aged 12-18 years) were examined. The surface anatomy of the central veins, cardiac apex, diaphragmatic openings, and structures in relation to the sternal angle plane were analyzed. The results showed that the brachiocephalic vein (left and right) formed mostly posterior to the sternoclavicular joint. The superior vena cava formed close to the second costal cartilage, ±16.3 mm to the right of the midline. The apex of the heart was located in relation to the fifth intercostal space; ±78.6 mm to the left of the midline. The caval hiatus was in relation to T9 and T10; the esophageal hiatus was at T10; whereas the aortic hiatus was at T11. The sternal angle plane was in relation to the upper half of T5, which was also where the bifurcations of the trachea and pulmonary trunk were observed. The SVC/azygos vein junction and the concavity of the aortic arch were observed to be more than 10 mm superior to this plane. The results of this study further highlight the substantial variability of the surface anatomy between age groups. It also emphasizes the notion that surface anatomy is a dynamic variable and cannot be treated as a static observation. Clin. Anat. 32:762-769, 2019. © 2019 Wiley Periodicals, Inc.

Determining the extent of the dural sac for the performance of caudal epidural blocks in newborns.

BACKGROUND: Information regarding the position and relationship of vital structures within the caudal canal is important for anesthesiologists who perform a caudal block. This information can be acquired by anatomical dissection, with ultrasound technology, or radiological studies. AIMS: The aim of this study was to determine the position of the dural sac in neonates by measuring the distance of the termination of the dural sac from the apex of the sacral hiatus in neonatal cadavers. METHODS: After careful dissection, the distance from the apex of the sacral hiatus to the dural sac was measured in a sample of neonatal cadavers. RESULTS: In 39 neonatal cadavers, the mean distance from the apex of the sacral hiatus to the dural sac was 10.45 mm. The range of this distance was between 4.94 and 26.28 mm. The mean distance for females was 9.64 mm (range from 6.66 to 15.09); that for males was 10.90 mm (range between 4.94 and 26.28). Linear regression with the log of this distance as the outcome variable gave an estimated 3.3% increase in the distance for each 1 cm increase in the length of the neonate (95% CI for this proportion was 1.91-4.71). CONCLUSION: Anesthesiologists should be aware of the short distance between the sacral hiatus and the dural sac when performing caudal blocks, the shortest distance was 4.94 mm. Armed with this knowledge, caudal techniques should be modified to improve the safety and reduce the risk of complications, such as dural puncture.

The validity of arterial measurements in a South African embalmed body population.

INTRODUCTION: Knowledge of the normal arterial diameter at a given anatomical point is the first step toward quantifying the severity of cardiovascular diseases. According to several studies, parameters such as weight, height, age and sex can explain morphometric variations in arterial anatomy that are observed in a population. Before the development of a reference database against which to compare the diameters of arteries in a variety of pathological conditions, the compatibility between embalmed body measurements and computed tomography (CT) measurements must first be established. PURPOSE: The aim of this study was to compare embalmed body measurements and CT measurements at 19 different arterial sites to establish whether embalmed body measurements are a true reflection of a living population. METHODS: A total of 154 embalmed bodies were randomly selected from the Department of Anatomy at the University of Pretoria and 36 embalmed bodies were randomly selected from the Department of Human Anatomy at the University of Limpopo, Medunsa Campus. Dissections were performed on the embalmed body sample and the arterial dimensions were measured with a mechanical dial-sliding caliper (accuracy of 0.01 mm). 30 CT images for each of the 19 arterial sites were retrospectively selected from the database of radiographic images at the Department of Radiology, Steve Biko Academic Hospital. Radiant, a Digital Imaging and Communications in Medicine (DICOM) viewer was used to analyze the CT images. RESULTS: The only statistically significant differences between the embalmed body measurements and CT measurements were found in the left common carotid- and the left subclavian arteries. The null hypothesis of no statistically significant difference between the embalmed body and CT measurements was accepted since the P value indicated no significant difference for 87% of the measurements, the exception being the left common carotid- and the left subclavian arteries. CONCLUSIONS: With the exception of two measurements, measurements in embalmed bodies and living people are interchangeable and concerns regarding the effect of distortion and shrinkage are unfounded. Even small changes in arterial diameter greatly influence blood flow and blood pressure, which contribute to undesirable clinical outcomes such as aortic aneurysms and aortic dissections. This study completes the first step towards the development of a reference database against which to compare the diameters of arteries in a variety of pathological conditions in a South African population.

Anatomical description of the sciatic nerve block at the subgluteal region in a neonatal cadaver population.

INTRODUCTION: Sciatic nerve blocks provide intraoperative and prolonged postoperative pain management after lower limb surgery (posterior knee, foot, skin graft surgery). Accurate needle placement requires sound anatomical knowledge. Anatomical studies on children are uncommon; most have been performed on adult cadavers. We studied the location of the sciatic nerve at the gluteal level in neonatal cadavers to establish useful anatomical landmarks. METHODS: We identified the sciatic nerve in the gluteal and thigh region of 20 neonatal cadavers. The skin covering the gluteal and thigh region was reflected laterally, and the underlying structures and muscles were identified. We located the sciatic nerve and measured the distance from the nerve to the greater trochanter of the femur and to the tip of the coccyx with a mechanical dial caliper. The total distance between the two landmarks was then recorded. RESULTS: We combined measurements from both sides to form a sample size n = 40. The sciatic nerve was 14.9 ± 2.4 mm lateral to the tip of the coccyx. The total distance between the greater trochanter and the tip of the coccyx was 27.3 ± 4.0 mm. CONCLUSION: Our results provide anatomical evidence that the optimal needle insertion point is approximately halfway between the greater trochanter and the tip of the coccyx-a landmark readily palpable in neonates and infants.

Descriptive study of the differences in the level of the conus medullaris in four different age groups.

In performing neuraxial procedures, knowledge of the location of the conus medullaris in patients of all ages is important. The aim of this study was to determine the location of conus medullaris in a sample of newborn/infant cadavers and sagittal MRIs of children, adolescents, and young adults. The subjects of both the samples were subdivided into four developmental stages. No statistical difference was seen between the three older age groups (P > 0.05). A significant difference was evident when the newborn/infant stage was compared with the other, older stages (P < 0.001 for all comparisons). In the newborn/infant group the spinal cord terminated most frequently at the level of L2/L3 (16%). In the childhood stage, the spinal cord terminated at the levels of T12/L1 and the lower third of L1 (21%). In the adolescent population, it was most often found at the level of the middle third of L1 and L1/L2 (19%). Finally, in the young adult group, the spinal cord terminated at the level of L1/L2 (25%). This study confirmed the different level of spinal cord termination between newborns/infants less than one-year-old and subjects older than one year. In this sample the conus medullaris was not found caudal to the L3 vertebral body, which is more cranial than the prescribed level of needle insertion recommended for lumbar neuraxial procedures. It is recommended that the exact level of spinal cord termination should be determined prior to attempting lumbar neuraxial procedures in newborns or infants.

Clinical anatomy of the maxillary nerve block in pediatric patients.

BACKGROUND: Anatomical landmarks in children are mostly extrapolated from studies in adults. Despite this, complex regional anesthetic procedures are frequently performed on pediatric patients. Sophisticated imaging techniques are available but the exact position, course and/or relationships of the structures are best understood with appropriate anatomical dissections. Maxillary nerve blocks are being used for peri-operative analgesia after cleft palate repair in infants. However, the best approach for blocking the maxillary nerve in pediatric patients has yet to be established. OBJECTIVE: To determine the best approach for blocking the maxillary nerve within the pterygopalatine fossa. METHODS: In an attempt to define an optimal approach for maxillary nerve block in this age group three approaches were simulated and compared on 10 dried pediatric skulls as well as 30 dissected pediatric cadavers. The needle course, including depth and angles, to block the maxillary nerve, as it exits the skull at the foramen rotundum within the pterygopalatine fossa, was measured and compared. Two groups were studied: Group 1 consisted of skulls and cadavers of neonates (0-28 days after birth) and Group 2 consisted of skulls and cadavers from 28 days to 1 year after birth. RESULTS: No statistically significant difference (P > 0.05) was found between the left and right side of each skull or cadaver. Only technique B, the suprazygomatic approach from the frontozygomatic angle towards the pterygopalatine fossa, exhibited no statistical significance (P > 0.05) when other measurements made on the skulls and cadavers were compared. Technique A, a suprazygomatic approach from the midpoint on the lateral border of the orbit, as well as technique C, an infrazygomatic approach with an entry at a point on a vertical line extending along the lateral orbit wall, showed statistical significant differences when measurements of the skulls and cadavers were compared. CONCLUSIONS: On the basis of these findings technique B produces the most consistent data for age groups 1 and 2 and supports the clinical findings recently reported.

Anatomical Studies Evaluating Pediatric Regional Anesthesia: A Scoping Review.

BACKGROUND: Pediatric regional anesthesia has been driven by the gradual rise in the adoption of opioid-sparing strategies and the growing concern over the possible adverse effects of general anesthetics on neurodevelopment. Nonetheless, performing regional anesthesia studies in a pediatric population is challenging and accounts for the scarce evidence. This study aimed to review the scientific foundation of studies in cadavers to assess regional anesthesia techniques in children. METHODS: We searched the following databases MEDLINE, EMBASE, and Web of Science. We included anatomical cadaver studies assessing peripheral nerve blocks in children. The core data collected from studies were included in tables and comprised block type, block evaluation, results, and conclusion. RESULTS: The search identified 2409 studies, of which, 16 were anatomical studies on the pediatric population. The techniques evaluated were the erector spinae plane block, ilioinguinal/iliohypogastric nerve block, sciatic nerve block, maxillary nerve block, paravertebral block, femoral nerve block, radial nerve block, greater occipital nerve block, infraclavicular brachial plexus block, and infraorbital nerve block. CONCLUSION: Regional anesthesia techniques are commonly performed in children, but the lack of anatomical studies may result in reservations regarding the dispersion and absorption of local anesthetics. Further anatomical research on pediatric regional anesthesia may guide the practice.

Revisiting the anatomy of the ilio-inguinal/iliohypogastric nerve block.

BACKGROUND: The ilio-inguinal/iliohypogastric nerve block (INB) is one of the most common peripheral nerve block techniques in pediatric anesthesia, which is largely due to the introduction of ultrasound (US) guidance. Despite the benefits of US guidance, the absence of an US machine should not deter the provider from performing INB, considering that many institutions, especially in developing countries, cannot afford to provide ultrasound machines in their anesthesiology departments. The aim of this study was to revisit the anatomical position of the ilio-inguinal and iliohypogastric nerves in relation to the anterior superior iliac spine (ASIS), in a large sample of neonatal cadavers, and compare the results with a similar group in a previously published US-guided study. METHODS: With Ethics Committee approval, the ilio-inguinal and iliohypogastric nerves were carefully dissected in 54 neonatal cadavers. RESULTS: In the total sample, the ilio-inguinal nerve was found to be 2.2 ± 1.2 mm from the ASIS, on a line connecting the ASIS to the umbilicus. The iliohypogastric nerve was on average 3.8 ± 1.3 mm from the ASIS. For the entire sample, the optimal needle insertion site was 3.00 mm from the ASIS. Although there is a strong correlation between the needle insertion point and the weight of the neonate, this will only 'fit' for 60% of the population. CONCLUSION: The linear regression formula; needle insertion distance (mm) = 0.6 × weight + 1.8 can be used as a guideline for the position of the ilio-inguinal and iliohypogastric nerves.

Investigation of mandibular second molar root and canal morphology in a Black South African population using cone-beam computed tomography and two classification systems.

PURPOSE: To investigate the root and canal morphology of mandibular second molars, including anatomical variations, in a Black South African population using two classification systems. METHODS: Cone-beam computed tomography images of 386 teeth were evaluated. The number of roots and canal configurations were categorized using the classifications of Vertucci (with modifications by Sert and Bayirli) and Ahmed et al. (including the modified Melton classification). Relationships between variables were assessed using Fisher's exact test (P < 0.05). RESULTS: Mandibular second molars were predominantly two-rooted (91.7%). The majority of teeth had three canals including Type IV mesial (41.2%) and Type I (75.1%) distal (Ahmed et al. configuration: 2MDM M2 D1). Three or more canals were present in almost one-fifth of mesial (n = 72/386, 18.6%) and a small number of distal (n = 21/386, 5.4%) roots. Males displayed additional canals more frequently in the distal root (P = 0.02). C-shaped anatomy was found in 5.7%. Among the C-shapes, the most common was Melton's Type III in the coronal (50%), middle (81%) and apical (72%) thirds. CONCLUSION: In this population, mandibular second molar teeth exhibited diverse morphology, which would have clinical significance for endodontic practitioners. The Ahmed et al. classification provided a better description than the Vertucci classification.

Root and canal morphology of maxillary second molars in a Black South African subpopulation using cone-beam computed tomography and two classifications.

This study investigated the root and canal morphology of maxillary second molars in a Black South African population using high-resolution cone-beam computed tomography. In total, 386 maxillary second molar teeth were evaluated and described according to the classifications of Vertucci (with the additions of Sert and Bayirli), as well as Ahmed et al. Root number, fusions and canal morphology were recorded. Relationships between morphology, sex and age were assessed using Fisher's exact test (p < 0.05). Maxillary second molars were predominantly three-rooted (96.1%), with root fusion observed in 14%. No relationships between sex, age and canal morphology were found. Additional canals were observed in 67.4% of mesiobuccal roots. The Ahmed et al. classification provided a better overall description of the morphology. In this population, maxillary second molar teeth exhibited a diversity of root and canal morphology. Complex variations may render endodontic management more difficult and increase the possibility of missed anatomy.