Zygomatic Arch Research Articles

Anatomical Basis for Malar Augmentation Injection With the Zygomatic Ligamentous System.

The malar augmentation injection has gained popularity in recent years, but the exact location of each injection site has not been clearly identified. To discover ideal injection sites by comprehensively considering the distributions of ligaments, muscles, and vessels. Eighteen cadaver heads were dissected to investigate the zygomatic ligamentous system and to measure the position of muscles. Sixty-six cadaver heads were subjected to computed tomographic scanning and three-dimensional vessel reconstruction. Radiological evaluation of the fillers was performed before and after experimental injection in one hemiface and dissected to confirm safe delivery. Five patients were enrolled in a prospective clinical study. 2D and 3D photographs were taken before and after the injections for comparison. Site 1 was defined along the zygomatic arch, except the first 1/4 length and the midline of the arch. Site 2 was on the body of the zygoma, superior to the level of the infraorbital foramen and medial to the jugale. Site 3 was defined in the anteromedial midface approximately 30 mm below the lateral canthus. Injections at these 3 sites can be performed within the range of the ligaments to achieve effective lifting effects and minimize potential complications.

Biomechanical comparative analysis of temporomandibular joint, glenoid fossa and head of the condyle of conventional models prothesis with new PEEK design

This article reviews the design of the temporomandibular joint (TMJ) prostheses used for TMJ joint replacement from 2000 to 2020. The TMJ is a complex joint, with distinct anatomical and functional characteristics making it challenging to maintain. Many authors from the early 20th century reported techniques for TMJ reconstruction, with the goal of restoring its shape and ideal function. Many prototypes have been developed in pursuit of an ideal prosthesis that adheres to the principles of biomechanics and biocompatibility, with good long-term performance and lower cost.The TMJ prosthesis is divided in two parts: the glenoid fossa and the mandibular ramus component.These two parts are fixed with metal screws in the glenoid fossa and fixed in the zygomatic arch with 4 or 5 screws. The mandibular part is fixed to the mandible ramus with 8 or 9 titanium screws.In our review, since 2000 to 2020, little has changed to improve the design and allow for natural mandible movement. From 2000 to 2006, 48 TMJ surgeries were performed using UHMWPE with this design. All patients had good results, preserving opening mouth and lateral movements.All the designs are similar in principle. The glenoid fossa, which resembles a box, limiting the rotation and translation movement. It is known that lateral movements are lost in function as the lateral pterygoid muscle is detached.

Design and Use of a Pair of Computer-Designed Surgical Templates in Reduction of a Comminuted Zygomatic Arch Fracture.

Isolated depressed zygomatic arch fractures are often treated with closed reduction. Reduction is usually performed through the Gillies approach or Keen approach. comminuted zygomatic arch fractures generally require open reduction and fixation to achieve good results. This article describes how to use a pair of surgical templates to assist in the fixation of comminuted zygomatic arch fractures with absorbable plates. A pair of computer-designed surgical templates were applied to restore the main part of zygomatic arch. Placing a surgical template on the medial side of the zygomatic arch can provide a supporting force and improves the stability of the reduced bone fragments. The lateral template of zygomatic arch limits the excessive uplift of bone fragments. The operation was performed according to the predetermined procedure. Postoperative computed tomography showed satisfactory reduction effect. In conclusion, with the aid of surgical templates, the reduction and fixation of comminuted zygomatic arch fractures can be more easily performed using absorbable plates.

Profiles of facial soft tissue changes during and after orthodontic treatment in female adults

BackgroundSome female adults who received orthodontic treatment often complain about thinner faces, protruding cheekbones and sunken temples, even at the beginning of treatment. The present research aimed to explore facial soft tissue changes during and after orthodontic treatment, as well as the related factors affecting facial soft tissue changes.MethodsThis study used 3dMD stereo photography technology to compare facial soft tissue changes among adult females who received orthodontics. A total of 52 adult females (24 teeth extraction, 28 non-teeth extraction cases) were included and potential correlations between related factors (facial morphology features, the change of occlusal height and dental arch width) were evaluated during different treatment periods.ResultsOverall, 3D-negative soft tissue changes of the buccal region moderately correlated with distances of nasion-menton and subnasale-menton (both rs = 0.30, P < 0.05) as well as the ratio of subnasale-menton/right gonion-left gonion (rs = 0.33, P < 0.05) and nasion-menton/right zygomatic point-left zygomatic point (rs = 0.30, P < 0.05). Among the 3D angle measurements, the right chelion-median upper lip point-left chelion angle was found to have a moderate correlation with 3D negative changes of the upper cheilion region (rs = 0.31, P < 0.01). Analysis of occlusal height changes revealed that an increase in the posterior facial height (nasion-gonial distance) may be a risk factor for negative changes in the zygomatic arch area. In addition, a moderate positive correlation between the maxillary first molar width changes and 3D-negative changes of the lower cheek region was found (rs = 0.41, P < 0.05).ConclusionsAfter orthodontic treatment, adult females with wide and short faces may be prone to negative soft tissue changes. Changes of posterior facial height and arch width between the first molars were also risk factors for negative changes of facial soft tissues. Extraction is not a major factor producing facial soft tissue changes.

Proposal for a modified classification of isolated zygomatic arch fractures.

BackgroundAlthough the zygomatic arch is an important structure determining facial prominence and width, no consensus exists regarding the classification of isolated zygomatic arch fractures, and the literature on this topic is scarce. To date, five papers have subdivided zygomatic arch fractures; however, only one of those proposed classifications includes the injury vector, although the injury vector is one of the most important factors to consider in fracture cases. Furthermore, the only classification that does include the injury vector is too complicated to be suitable for daily practice. In addition, the existing classifications are clinically limited because they do not consider greenstick fractures, nondisplaced fractures, or coronoid impingement. In the present study, we present a rearrangement of the previously published classifications and propose a modified classification of isolated zygomatic arch fractures that maximizes the advantages and overcomes the disadvantages of previous classification systems.MethodsThe classification criteria for isolated zygomatic arch fractures described in five previous studies were analyzed, rearranged, and supplemented to generate a modified classification. The medical records, radiographs, and facial bone computed tomography findings of 134 patients with isolated zygomatic arch fractures who visited our hospital between January 2010 and December 2019 were also retrospectively analyzed.ResultsWe analyzed major classification criteria (displacement, the force vector of the injury, V-shaped fracture, and coronoid impingement) for isolated zygomatic arch fracture from the five previous studies and developed a modified classification by subdividing zygomatic arch fractures. We applied the modified classification to cases of isolated zygomatic arch fracture at our hospital. The surgery rate and injury severity differed significantly from fracture types I to VI.ConclusionUsing our modified classification, we could determine that both the injury force and the injury vector meaningfully influenced the surgery rate and the severity of the injuries.

Gillies temporal acess surgical technique for closed zygomatic arch reduction

Fracture of the zygomatic arch is one of the most common facial bone fractures. By means of minimally invasive surgeries it is intended to preserve anatomical structures to the maximum, without extensive incisions or dissections, providing the best functional results with less operative trauma, the Gillies approach being widely used in this regard. Objective: To report a clinical case of a patient with a zygomatic arch fracture, in which a reduction was used through the temporal access of Gillies, as well as, guide the surgeon in treatment planning. Case report: Patient AFL, 62 years old, male, was referred to the Maxillofacial Surgery and Traumatology Service of the Restauração Hospital (Recife / PE), with a history of falling from a height, evolving with fracture of the left zygomatic arch, treated by closed reduction through the temporal access of Gillies. Results: In this way, the Gillies approach proved to be a rather traumatic technique, effective in our case, restoring esthetics and function with minimally invasive surgery. Conclusion: It is effective in our case, restoring aesthetics and function with minimally invasive surgery.

Cross Facial Nerve Grafting for Smile Restoration: Thoughts on Improving Graft Inset.

Summary:Cross facial nerve grafts (CFNGs) are one of the most ubiquitous and time-honored surgical tools used in facial reanimation. They may be used for targeting different mimetic muscles in the subacute setting as well as to innervate newly placed muscle flaps in varied facial subunits. In our experience, when used specifically for smile reanimation in two-stage strategies with either traditional “babysitting” approaches in nerve transfers or free functional muscle transfers, the second stage may present some challenges in CFNG identification as well as injury to the previously banked nerve graft. We present some technical modifications in the first-stage CFNG inset that can make the second stage easier and safer. These modifications include: (1) marking the course of the nerve graft with surgical metal clips and inserting loose circumferential sutures throughout the distal course of the nerve in the recipient area to avoid displacement; (2) transferring the nerve graft through the nasal sills rather than lips, protecting it from damage during insertion of free functional muscle transfer; and (3) routing the nerve from the lateral nose to the preauricular area over the zygomatic arch, allowing easier dissection and banking of adequate graft length to provide tension-free coaptation with the flexibility of nerve coaptation in variable positions.

The diversification of the lynx lineage during the Plio-Pleistocene—evidence from a new smallLynxfrom Longdan, Gansu Province, China

AbstractA new small-sized lynx from Longdan, Gansu Province, China, Lynx hei sp. nov., is described in this study. The new species displays the characteristic Lynx generic traits, such as distinct buccal grooves in the upper canine, presence of an anterior groove in the upper canine, absence of upper premolar 2, and a moderately developed mastoid process, but it is markedly smaller than the previously described Lynx issiodorensis specimens from the same site and is also smaller overall than most living species, comparable to Lynx rufus in size. The new species has a relatively wide and deep zygomatic arch, similar to that of living Lynx lynx, Lynx pardinus and Lynx canadensis but wider than that of Lynx rufus. Our phylogenetic analyses suggest that Lynx hei falls within the crown group Lynx, being the sister to Lynx rufus or, less probably, a sister to Lynx issiodorensis + three other living species of Lynx. The Plio-Pleistocene Lynx issiodorensis is supported as the ancestor of Lynx lynx, Lynx pardinus and Lynx canadensis. Our phylogenetic study suggests that Lynx diversification over the Plio-Pleistocene was achieved initially by body size differentiation, putatively forced by intraspecific competition with other carnivorans, followed by morphological divergence.

Morphological types and localization patterns of pterion in the skulls of adults from southeastern China.

To study the morphological types and relative location of the pterion and its precise relationship with the middle meningeal artery (MMA) in the skulls of adults from southeastern China. Dry skulls (n = 250) of adults were obtained from a university specimen bank and analyzed. The morphological types of the pterions were observed. The distances from the center of the external pterion (Pec) to the relevant intracranial and extracranial marker points were measured using a digital vernier caliper. The anterior, middle, and posterior end points of the external pterion were drilled perpendicular to the bone surface. The precise relationships of the external pterion with the internal pterion and the groove of the frontal branch of the MMA were observed and measured after sawing the skull. The morphological types of the pterion in the skulls of adults from southeastern China were sphenoparietal suture (SP) (85%), epipteric (12.4%), frontotemporal suture (1.4%), and stellate (1.2%) types. The mean widths of the external and internal pterions were R, 10.68 ± 4.22mm; L, 11.13 ± 4.40mm and R, 14.66 ± 4.04mm; L, 14.14 ± 4.29mm, respectively, and the width of the internal pterion was slightly longer than that of the external (P < 0.05). No significant difference in pterion width was found between the genders or sides of the skull (both P > 0.05). The distances from the Pec to the posterolateral aspect of the frontozygomatic suture, zygomatic process of the frontal bone, midpoint of the zygomatic arch, and external acoustic meatus were 29.95 ± 3.75mm, 34.88 ± 4.08mm, 40.86 ± 3.59mm, and 53.79 ± 3.82mm, respectively. These distances were slightly longer on the right side of the skull than on the left side (P < 0.01) and longer in men than in women (P < 0.01). The distances from the Pec to the frontal crest, optic canal, and anterior clinoid process were 62.79 ± 1.15mm, 45.39 ± 2.48mm, and 45.47 ± 2.05mm, respectively. The external and internal pterions were not on the same level, and all the internal pterions were located below the external ones. In the vast majority of the skulls, the groove of the frontal branch of the MMA passed through the posterior end of the external pterion (Pep) or the area between the Pec and Pep. The morphology of the pterion in the skulls of adults from southeastern China is predominantly of the SP type, mostly symmetrically distributed. The distance from the pterion to the extracranially relevant marker points differs among the ethnic groups, between the genders, and between the sides of the skull. All the internal pterions are located below the external ones. Most of the frontal branch of the MMA is located below the mid-posterior segment of the lateral pterion. The characterization of the morphology, the relative position of the pterion and the precise relationship of this structure with the MMA in the skulls of adults from southeastern China may provide an anatomical basis for teaching and clinical practices.

A huge high rising cervico-facial lymphangioma in an adolescent male: from pterygoid to hyoid

&lt;p class="abstract"&gt;Cervicofacial lymphangioma is a benign swelling of the neck and is commonly seen in paediatric population. Common sites of involvement are the submandibular space and the posterior triangle and rarely involves the face. We present a rare case of a huge cervico-facial lymphangioma in a 14 year old male where the swelling presented one year back and had progressively increased in size extending from the medial pterygoids and pterygomandibular space above to myelohyoid muscle below. Intraoperatively, it was closely abutting the submandibular gland mimicking salivary gland retention cyst and the facial artery was traversing through the mass. Complete surgical excision of the mass was performed along with removal of the ipsilateral submandibular gland. Salivary gland mucocele and cervicofacial lymphangioma were the two main differential diagnosis in our case. Intraoperative findings of macrocystic spaces with septations pointed towards a lymphangioma. Post operative histopathology confirmed it to be lymphangioma lined with endothelial cells. We concluded from this case that cervicofacial swellings in higher age groups should have lymphangiomas as differential diagnosis. As the swelling ascended up to the skull base, careful radiological assessment, meticulous surgical plan and cranio-caudal exposure from the zygomatic arch above to the hyoid below helped in complete surgical excision of the mass. &lt;/p&gt;

Stabilisation of an isolated zygomatic arch fracture with a ballooned Foley catheter

Zygomatic arch fractures have a potential for re-depression following surgery, which may necessitate the use of a splint to stabilise the reduction. An isolated zygomatic arch fracture reduced by Gillies temporal approach and stabilised by a ballooned Foley catheter is presented.

Radiologic exploration of the morphometric and morphological features of the carotid canal

ObjectivesThe carotid canal is a foramen located in the petrous part of the temporal bone. Detailed knowledge about the anatomy of the base of the skull is important, as many surgeries are done there for various malignancies and aneurysms. The aim of this study was to collect various morphometric measurements of the carotid canal to aid neurosurgeons with various surgical approaches to easily locate the second fragment of the internal carotid artery. MethodsA retrospective study was done, and 500 CT scans on both sides of the skull were analysed. Various morphometric parameters related to the carotid canal were measured. The shape of the carotid canal was also noted. Statistical analysis was done for all the parameters. ResultsThe mean anteroposterior diameter and width of the carotid canal was 0.535 and 0.683 cm, respectively. The mean distance of the carotid canal from the external acoustic meatus, zygomatic arch, and mandible was 2.27, 3.28, and 2.34 cm, respectively. The mean distance of the carotid canal from the midline of the base of the skull was 2.97 cm. The mean angle between the zygoma root, external aperture of the carotid canal, and external acoustic meatus was 27.08°. The mean angle between the external acoustic meatus, external aperture of the carotid canal, and supramastoid crest was 26.74°. The carotid canal was round in most cases (50.5%). ConclusionThese measurements will aid neurosurgeons to identify various surgical approaches to easily locate the second part of the internal carotid artery, and they can serve as a reference to guide surgeries at the base of the skull.

Skin landmarks to main cerebral structures: how to identify the main cerebral sulci? A radiological study about lateral, central, and parietooccipital sulci.

In a previous cadaveric work, we identified and described useful and reproducible surface skin landmarks to lateral sulcus, central sulcus and preoccipital notch. Potential limitations of this cadaveric study have been raised. Thus, the objective of this study was to confirm radiologically the accuracy of these previously described surface skin landmarks on brain magnetic resonance imaging (MRI) of healthy subjects. Healthy adult volunteers underwent a high-resolution brain MRI and measurements of the orthogonal skin projection (OSP) of the anterior sylvian point (AsyP), the superior Rolandic point (SroP) and the parietooccipital sulcus were made from nasion, zygomatic bone and inion, respectively. These measures were compared to our previous cadaveric findings. Thirty-one healthy volunteers were included. ASyP was 33 ± 2mm above the zygomatic arch, and 32.3 ± 3mm behind the orbital rim. The lateral sulcus was 63.5 ± 4mm above the tragus. The SRoP was 196.9 ± 6mm behind the nasion. The superior point of the parietooccipital sulcus was 76.0 ± 4mm above the inion. These measurements are comparable to our previously described cadaveric findings. We here described three useful, simple and reproducible surface skin landmarks to lateral, central and parietooccipital sulci. Knowledge of these major landmarks is mandatory for Neurosurgical practice, especially in an emergency setting.

Giant Cell tumor of the Zygomatic Arch in a Pediatric Patient: Rare Case Report

Introduction: A giant cell tumor (GCT) is a rare tumor, usually benign, which can be locally aggressive, with an almost unknown incidence in the skull. Case report: Case report of a pediatric patient diagnosed with Ewing’s sarcoma (ES) and later GCT when sought medical care for an increased volume in the zygomatic arch and the right preauricular region. Imaging exams showed an expansive lesion in the zygomatic and squamous portion of the right temporal bone, with an extradural intracranial component in the middle fossa, with no evidence of infiltration. From the anatomopathological view, fusocelullar neoplasia was seen. The CD68 marker was positive and the S100 marker was negative. Tumor resection by microsurgery was performed. The patient remains in follow-up, with imaging exams at neurosurgery and orthopedics, the latest magnetic resonances of the skull showing a reduction in the size of the lesion. In addition, the patient did not submit to adjuvant therapy and is currently without complaints. Conclusion: This is an important case due to its rarity and clinical data that contributes for the understanding of the pathologies presented, allowing that, in the future, new studies are able to optimize the treatment, and the prognosis for these patients.

The masseter muscle thickness is a predictive marker for postoperative pneumonia after endovascular aneurysm repair.

Oral frailty is characterized by a decrease in the oral and swallowing function and is a risk factor for pneumonia. In the current study, we analyzed the association between the masseter muscle thickness (MMT) and postoperative pneumonia and mortality after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm. Overall, 247 patients were retrospectively evaluated. The primary end point was postoperative pneumonia. The MMT was measured as the maximum thickness of the masseter muscle 2cm caudal to the zygomatic arch using computed tomography images obtained within 3months before EVAR. Pneumonia was defined as the presence of progressive infiltrates, consolidation, or cavitation on imaging and a fever or leukocytosis. Twenty (8.1%) cases of postoperative pneumonia occurred within 1year after EVAR. We found that patients with a low MMT (≤ 30th percentile: males, 10.4mm; females: 8.8mm) had a significantly higher risk of developing postoperative pneumonia within 1year after elective EVAR than those with a high value. A comparison of the utility of the MMT and psoas muscle index (PMI) for predicting the 1-, 3-, and 5-year all-cause mortality revealed that the MMT had superior predictive performance. The MMT before elective EVAR predicted postoperative pneumonia and life expectancy, and its predictive performance was superior to that of the PMI.

Endoscopic Endonasal Approach to the Pterygopalatine Fossa and Infratemporal Fossa: Comparison of the Prelacrimal and Denker's Corridors.

Both the endoscopic transnasal Denker's and prelacrimal approaches provide surgical access to the pterygopalatine fossa (PPF) and infratemporal fossa (ITF). This study compares the potential maximum exposure of the PPF and ITF and quantifies the difference in surgical freedom via endoscopic Denker's and prelacrimal approaches. Six cadaveric specimens (12 sides) were dissected using a prelacrimal approach on one side and an endoscopic Denker's approach on the contralateral side. The contents of the PPF and ITF were sequentially exposed. Surgical freedom for each corridor was subsequently calculated. This study confirms that both the prelacrimal and Denker's approaches provide adequate exposure of the PPF and ITF. The maximum exposure boundaries were similar for both approaches, including the middle cranial fossa superiorly, floor of the maxillary sinus inferiorly, zygomatic arch and temporomandibular joint laterally, and post-styloid space posteriorly. However, the data revealed a statistically significant difference (p < 0.05) regarding the surgical freedom of the prelacrimal (388.17 ± 32.86 mm2) and the endoscopic Denker's approaches (906.35 ± 38.38 mm2). When compared with an endoscopic Denker's approach, a prelacrimal approach seems to achieve a similar extent of exposure (ie, visualization) of the PPF and ITF. Nonetheless, the endoscopic Denker's approach offers superior surgical freedom; thus, it is preferred for the management of complex lesions which requires increased instrument maneuverability with a 3- or 4-handed technique.

Craniofacial Bone Mineral Density at Muscle Attachment Sites in Mice with Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a genetic disease commonly caused by mutations in the COL1A1 or COL1A2 gene affecting the production of type I collagen, a major component of bone that determines the toughness of bone, or its resistance to fracture. Thus, patients with OI present with brittle bones and higher rates of skeletal fractures. Additionally, defects in the collagen framework of developing bones impair their biomineralization, further compromising bone mechanical properties. Previous work in our lab investigated BMD at cranial locations which experience compressive forces during feeding (e.g. joints). Muscles also contribute to cranial growth through tensile forces exerted on bone during contraction, but the relationship between muscle function and bone quality in OI is unclear. The aim of this study is to quantify the BMD in a mouse model of OI, with a focus on skeletal sites associated with cranial musculature. We hypothesize that the mice with OI will have lower BMD in skeletal areas associated with muscle attachment compared to their unaffected littermates.To test our hypothesis, we used the homozygous recessive OI murine (OIM) mouse (B6C3Fe a/a‐Col1a2oim/J), a model for the severe type III OI seen in humans. Adult (16 weeks old) OIM mice (n=11) and wildtype (WT, n=13) littermates were CT scanned, and BMD was measured using the Bruker CTAnalyzer software in 7 regions of interest encompassing muscle attachment sites on the mandible, zygomatic arch, and parietal bone. For each region, BMD values were compared between genotypes by a Kruskal‐Wallis test.OI mice had significantly lower BMD at the coronoid process (p=0.007), parietal bone (p=0.031), and posterior mylohyoid line (p=0.007) compared to WT mice. No significant differences were found in BMD at the gonial angle or zygomatic arch. This suggests a disproportionate weakness of the temporalis and mylohyoid muscles in mice with OI, but not in the masseter muscle. While type I collagen defects impact the structural organization of skeletal muscle, it is possible that masseter muscle function is preserved in OIM mice because of its key roles in rodent feeding and postural control of the jaw. The imbalance between temporalis and masseter muscles may contribute to the prevalence of dental malocclusions in human patients with type III OI.The findings of this study support further exploration of specific muscle groups (e.g. jaw adductors/temporalis, hyoid muscles/mylohyoid) and efforts to improve their functions during feeding, as a way of recovering facial growth and preventing dental malocclusions in OI. A better appreciation of muscle‐bone interactions in the skull and their effect on bone quality can potentially be used to inform oro‐motor therapies to improve feeding function, muscle strength, and facial bone quality for patients with OI.

The effective use of the Anatomage table as a teaching tool for learning the Infratemporal Fossa

The objective of this Vesalius Master’s capstone project was to develop a lesson for teaching the Infratemporal fossa (ITF) using an Anatomage table, to first year students in the Medical Gross Anatomy course. The ITF is an important space within the head and neck, through which many structures pass or are housed but is difficult to visualize both in the cadaver and in 2D images. In contrast, the Anatomage table provides opportunities for rotatable three‐dimensional views. The lesson was designed to enable students to simultaneously visualize structures within the fossa and the relationships of these structures to deeper and more superficial structures in the area. A virtual dissection of the ITF from superficial to deep was created as 4 separate preset screens on the Anatomage table. Preset one showed the structures of the head and neck superficial to the ITF. The second preset showed a deeper view into the ITF in which the zygomatic arch and mandible were removed to see the muscles within in the ITF. Preset three was a view of the cranial nerves (CN), specifically CN V3 and its branches within the ITF. Preset four was a view that showed the vasculature within the ITF, specifically the maxillary artery and its branches. The lesson was designed to use the Anatomage table features to highlight the 3D relationships of these structures, supplemented with a worksheet that followed the virtual dissection and provided students with the high yield information for the course practical and written examinations. The lesson was run 5 times for a total of 35 students. After the session, students completed an evaluation of the effectiveness of this lesson, the lesson resources, and the instructor. Overall, the students felt that this method of teaching the ITF was highly effective for teaching the structures and function of the ITF contents. The students expressed that using the Anatomage table allowed them to orient themselves to the regions in contrast to what other resources allow. The supplemental worksheet was an important complementary resource to the lesson as it functioned as a study guide for the exam. This study demonstrates that the Anatomage table is a useful tool for teaching a region of the body that is difficult to demonstrate in the cadaver. This lesson allowed students to incorporate other relationships within the head and neck and provided context to these relationships. The method of teaching allowed the students to work together and actively engage in the lesson, which was effective for understanding the content. This teaching method can be used both to supplement cadaver teaching and in a context in which cadavers are not accessible.

Deletion of Sf3b4 in Neural Crest Cells Encapsulates the Variable Expressivity of Craniofacial Abnormalities Observed in Nager and Rodriguez Syndrome Patients

Recently, both Nager syndrome and Rodriguez syndrome patients were identified to carry rare mutations in SF3B4. Both disorders affect the face as well as the limb including both hands and feet. Nager syndrome patients survive and exhibit smaller jaw bones, smaller cheek bones, cleft palate, hearing problems as well as downward slanted eyelids. However, Rodriguez syndrome is much more severe, and patients often die before or soon after birth. We hypothesized that craniofacial abnormalities associated with reduced SF3B4 levels is due to tissue‐specific expression and requirement of this gene in neural crest cells. To generate a conditional mutant mouse line for Sf3b4, we used CRISPR/Cas9 to insert LoxP sequences in intron 1 and 3 of this gene. To test our hypothesis, we mated Sf3b4conditional mutant mice to Wnt1‐Cre2 transgenic mice to delete exons 2 and 3 specifically in neural crest cells. Heterozygous mutant embryos from these matings were normal. Sf3b4L/L;Wnt1‐Cre2 embryos have brain and craniofacial abnormalities, including abnormal forebrain, midbrain and hindbrain, hypoplasia of the maxillomandibular region and midline cleft. Majority of these embryos die before birth and the few mutants that are born are indistinguishable from their wildtype littermates. Additionally, we generated Sf3b4L/‐;Wnt1‐Cre2 mutants with homozygous deletion of Sf3b4 in neural crest cells and heterozygous deletion of Sf3b4 in the body. These mutant embryos also had unfused frontonasal prominence and unfused and severely hypoplastic mandibular region. Sf3b4L/‐;Wnt1‐Cre2begin to die at E13.5 and none survive to birth. Thus, neural crest specific deletion of Sf3b4 in mice is able to model the craniofacial abnormalities presented in patients as well as capture the variable expressivity observed. Our model can further be used to uncover the splicing and molecular events regulated by SF3B4 during craniofacial development.

Posterior-Anterior Cephalometric Study of Neurofibromatosis Type 1 Patients With Facial Plexiform Neurofibroma: Analysis of Skeletal Symmetry Concerning Midfacial and Skull Base Reference Points (Zygomatic Arch, Mastoid, and Juga).

Neurofibromatosis type 1 (NF1) is an autosomal dominant tumor predisposition syndrome that is also characterized by skeletal abnormalities. In the cranial region, skeletal dysplasia is observed that is associated with a characteristic peripheral nerve sheath tumor, the plexiform neurofibroma (PNF). The aim of the study was to determine PNF-associated skeletal asymmetries of the mid-skull and skull base as an indicator of local tumor development. The distances of the zygomatic arch, mastoid, and juga measurement points from the interorbital horizontal plane and median sagittal plane were examined on anterior-posterior cephalograms of 168 NF1 patients (females: 82, males: 86) and compared with the findings of a control group. A distinction was made as to whether the patients had developed a facial PNF. The distances of the measurement points from the reference planes differed between the patient and control group (p<0.05). Within the NF1 patients, differences between certain distances were noted when comparing patients with PNF and without PNF (p<0.05). In PNF patients, discrete changes in the skull contour were also detectable on the non-affected side (p<0.05). The caudal measurement point of the skull base showed no changes in the group comparison. The individually very variable facial PNF in NF1 is associated with deformations and misalignments of midfacial bones that follow a pattern quantifiable with cephalometric analysis.