Facial Sutures Research Articles

Craniofacial Suture Fusion in Primates

Timing of craniofacial suture fusion is important to questions of demographics and primate ontogeny. There has been much work concerning the fusion of calvarial sutures over the last century, but little work focusing on facial sutures. Here we assess the relationships of facial suture fusion among primates. 1436 skulls of Homo, Pan, Gorilla, Pongo, Hylobates, Macaca and Papio were observed at 5 facial suture sites for stage of fusion. Calvarial volume (early) and dental eruption (late) were utilized as indicators of stage of ontogeny. Patterns of fusion were assessed by Gutmann scaling. Homogeneity of slopes and ANOVA were used to determine differences in timing of fusion. All groups demonstrated reproducible patterns of fusion within groups but variation suggesting slightly different sites of onset and termination of suture fusion between species groups. For calvarial growth, groups segregated by regression slopes, Homo having a very steep slope, indicating remodeling throughout ontogeny, less steep slopes for Pongo, Macaca, and Papio, and flat regression slopes Pan, Gorilla, and Hylobatiadae, indicating very early facial suture remodeling. Similar patterns are observed when dental eruption is used for staging. Thus, Homo appears to be unique in its delay and patency of sutures into late ontogeny. Only Gorilla and Hylobatidae are observed to, as a general rule, fuse all facial suture sites by senescence.Grant Funding Source: N//A

Effects of growth hormone on the ontogenetic allometry of craniofacial bones.

Organism size is controlled by interactions between genetic and environmental factors mediated by hormones with systemic and local effects. As changes in size are usually not isometric, a considerable diversity in shape can be generated through modifications in the patterns of ontogenetic allometry. In this study we evaluated the role of timing and dose of growth hormone (GH) release on growth and correlated shape changes in craniofacial bones. Using a longitudinal study design, we analyzed GH deficient mice treated with GH supplementation commencing pre- and post-puberty. We obtained 3D in vivo micro-CT images of the skull between 21 and 60 days of age and used geometric morphometrics to analyze size and shape changes among control and GH deficient treated and non-treated mice. The variable levels of circulating GH altered the size and shape of the adult skull, and influenced the cranial base, vault, and face differently. While cranial base synchondroses and facial sutures were susceptible to either the direct or indirect effect of GH supplementation, its effect was negligible on the vault. Such different responses support the role of intrinsic growth trajectories of skeletal components in controlling the modifications induced by systemic factors. Contrary to the expected, the timing of GH treatment did not have an effect on catch-up growth. GH levels also altered the ontogenetic trajectories by inducing changes in their location and extension in the shape space, indicating that differences arose before 21 days and were further accentuated by a truncation of the ontogenetic trajectories in GHD groups.

At Birth, Tarsiers Lack a Postorbital Bar or Septum

Among primates, partial or complete posterior closure of the orbit has been widely accepted as a shared derived characteristic justifying an exclusive tarsier‐anthropoid clade, while some regard the tarsier lateral orbit as an elaborated postorbital bar (POB). To test these competing hypotheses while minimizing the confounding effect of tarsier orbital hypertrophy, we compared tarsiers and other primates at early (fetal and newborn) ages using dissection, micro‐CT scans and soft tissue histology. Our findings demonstrate unanticipated variation in the anatomy and development of the zygomaticofrontal (ZFA) articulation, which forms the orbit's lateral framework. Tarsiers uniquely exhibit a combination of two features: absence of a pre‐ and peri‐natal frontal spur to join with the zygomatic to form the ZFA; and, the spur's substitution by an elaborate ligament, which envelops the eye laterally as an expansive postorbital membrane (POM) that merges with the anterolateral fontanelle of the lateral cranial vault. In lacking a frontal spur, tarsiers are distinct from strepsirhines, while the ligamentous structure of the POM distinguishes its ZFA from that of anthropoids, which is a typical facial suture at and prior to birth. The POM of tarsiers may be thought of as an accessory fontanelle, a structural compromise that provides flexible stability and spatial separation of bones while anticipating rapid postnatal growth of an enormously enlarged eye. We regard the tarsier POM as part of a neomorphic eyeball hypertrophy complex, and reject the hypothesis of derived homology of the postorbital septa of adult tarsiers and anthropoids on histological, developmental and functional grounds. © 2013 Wiley Periodicals, Inc.

At Birth, Tarsiers Lack a Postorbital Bar or Septum

Among primates, partial or complete posterior closure of the orbit has been widely accepted as a shared derived characteristic justifying an exclusive tarsier-anthropoid clade, while some regard the tarsier lateral orbit as an elaborated postorbital bar (POB). To test these competing hypotheses while minimizing the confounding effect of tarsier orbital hypertrophy, we compared tarsiers and other primates at early (fetal and newborn) ages using dissection, micro-CT scans and soft tissue histology. Our findings demonstrate unanticipated variation in the anatomy and development of the zygomaticofrontal (ZFA) articulation, which forms the orbit's lateral framework. Tarsiers uniquely exhibit a combination of two features: absence of a pre- and peri-natal frontal spur to join with the zygomatic to form the ZFA; and, the spur's substitution by an elaborate ligament, which envelops the eye laterally as an expansive postorbital membrane (POM) that merges with the anterolateral fontanelle of the lateral cranial vault. In lacking a frontal spur, tarsiers are distinct from strepsirhines, while the ligamentous structure of the POM distinguishes its ZFA from that of anthropoids, which is a typical facial suture at and prior to birth. The POM of tarsiers may be thought of as an accessory fontanelle, a structural compromise that provides flexible stability and spatial separation of bones while anticipating rapid postnatal growth of an enormously enlarged eye. We regard the tarsier POM as part of a neomorphic eyeball hypertrophy complex, and reject the hypothesis of derived homology of the postorbital septa of adult tarsiers and anthropoids on histological, developmental and functional grounds.

Characterization of the bending strength of craniofacial sutures

The complex, thin and irregular bones of the human craniofacial skeleton (CFS) are connected together through bony articulations and connective tissues. These articulations are known as sutures and are commonly divided into two groups, facial and cranial sutures, based on their location in the CFS. CFS sutures can exhibit highly variable degrees of interdigitation and complexity and are believed to play a role in accommodating the mechanical demands of the skull. This study aimed to evaluate the mechanical behavior of CFS bone samples with and without sutures and to determine the effect of sutural interdigitations on mechanical strength. Sagittal, coronal, frontozygomatic and zygomaticotemporal sutures along with adjacent bone samples not containing sutures were excised from six fresh-frozen cadaveric heads. The interdigitation of the sutures was quantified through μCT based analysis. Three-point bending to failure was performed on a total of 29 samples. The bending strength of bone samples without sutures demonstrated a non-significant increase of 14% as compared to samples containing sutures (P=0.2). The bending strength of bones containing sutures was positively correlated to the sutural interdigitation index (R=0.701, P=0.002). The higher interdigitation indices found in human cranial vs. facial sutures may be present to resist bending loads as a functional requirement in protecting the brain.

Phenotype profile of a genetic mouse model for Muenke syndrome.

The Muenke syndrome mutation (FGFR3 (P250R)), which was discovered 15 years ago, represents the single most common craniosynostosis mutation. Muenke syndrome is characterized by coronal suture synostosis, midface hypoplasia, subtle limb anomalies, and hearing loss. However, the spectrum of clinical presentation continues to expand. To better understand the pathophysiology of the Muenke syndrome, we present collective findings from several recent studies that have characterized a genetically equivalent mouse model for Muenke syndrome (FgfR3 (P244R)) and compare them with human phenotypes. FgfR3 (P244R) mutant mice show premature fusion of facial sutures, premaxillary and/or zygomatic sutures, but rarely the coronal suture. The mice also lack the typical limb phenotype. On the other hand, the mutant mice display maxillary retrusion in association with a shortening of the anterior cranial base and a premature closure of intersphenoidal and spheno-occipital synchondroses, resembling human midface hypoplasia. In addition, sensorineural hearing loss is detected in all FgfR3 (P244R) mutant mice as in the majority of Muenke syndrome patients. It is caused by a defect in the mechanism of cell fate determination in the organ of Corti. The mice also express phenotypes that have not been previously described in humans, such as reduced cortical bone thickness, hypoplastic trabecular bone, and defective temporomandibular joint structure. Therefore, the FgfR3 (P244R) mouse provides an excellent opportunity to study disease mechanisms of some classical phenotypes of Muenke syndrome and to test novel therapeutic strategies. The mouse model can also be further explored to discover previously unreported yet potentially significant phenotypes of Muenke syndrome.

Ontogeny of the redlichiid trilobiteMetaredlichia cylindricafrom the lower Cambrian (Stage 3) of South China

A number of immature and mature exoskeletons allow the first detailed description of the ontogeny of the early Cambrian redlichiid trilobiteMetaredlichia cylindrica, from black shale of the Shuijingtuo Formation in Hubei Province, South China. The material includes numerous complete protaspides, within which two stages can be differentiated according to the appearance of a shallow furrow that separates the protopygidial area from the protocranidium. Also, identification of the subsequent ontogenetic stages, including meraspides and holaspides, depends on isolated cranidia that display prominent morphological changes such as the contraction of frontal glabellar lobe, appearance of the fourth pair of glabellar furrows, and modification of the facial suture from proparian to opisthoparian. Incorporating the whole ontogenetic sequence allows us not only to trace the developmental trends of various structures with growth, but also to assign the protaspides to their adults correctly, particularly with the help of meraspid specimens.

The biomechanical effect of the bipartite zygoma: A Finite Element Analysis of the impact of an auxiliary facial suture in the midface

Typically the zygoma is a single facial bone bounded by sutures where it abuts the maxilla, frontal, sphenoid, and temporal bones. Rarely, the zygoma is transected by an extra suture arising perpendicularly from the facial aspect of the maxillozygomatic suture and running dorsolaterally to the zygomatic aspect of the temporal fossa giving the bone a bipartite morphology (Incidence of 2.5–6.5% in human populations). In the midface, which is normally under heavy stresses during feeding, the biomechanical effect of bipartite zygoma has so far not been explored. We hypothesized that the bipartite zygoma condition would alter the pattern of stress distribution in the face during mastication. The bipartite zygoma condition was created in a Finite Element Model of a skull from a Tufted Capuchin monkey (USNM518342), and the model was analysed and compared to a model with typical zygoma condition. Results revealed that the bipartite morphology disrupts the normal inferosuperior stress flow from maxilla to frontal through the zygoma. The superior half of the zygoma in the upper face was spared high stress flow at the expense of the inferior half of the zygoma in the midface. In this way, the stresses incurred during normal activities (i.e. feeding) were shunted from the upper facial regions to the relatively gracile yet already heavily stressed temporal arm of the zygomatic arch, suggesting that the bipartite morphology is less optimal than the typical case. How the temporal arm of the zygomatic arch adapts in this situation needs further studies.Grant support: NSF HOMINID BCS‐0725183 and NSF BCS‐0100825 (CT images of USNM518342 courtesy of Dr. James Rossie. www.digimorph.org).

Middle Furongian (late Cambrian) shumardiids from the Sesong Formation, Taebaek Group, Korea

The trilobite family Shumardiidae is characterized by small size, lack of eyes, yoked librigenae, and a small number of thoracic segments. Here we report the successive occurrence of three middle Furongian shumardiid species from the Sesong Formation of Korea: Elaphraella? taebaeksanensis n. sp., Elaphraella microforma, and Elaphraella nodus. They appear to represent the oldest shumardiid morphology known so far. This genus lacks the anterolateral swellings on the glabella and has a conical glabella. Its yoked librigenae also encompass a comparatively wide genal field. Elaphraella? taebaeksanensis has a highly inflexed facial suture which may reflect the presence of small palpebral lobes. Taken together, the plesiomorphic morphology of the Shumardiidae can be summarized as having a conical glabella, small palpebral lobes, highly arched anterior cephalic margin, a wide librigenal field, and no anterolateral swellings on the glabella.

The attitudes and awareness of emergency department (ED) physicians towards the management of common dentofacial emergencies

Abstract – Objective: Dentofacial emergencies are a common presentation to the emergency department (ED) but there is little recent data on physicians’ knowledge, confidence and attitudes in handling these cases.Method: A questionnaire was administered to 103 ED physicians. The sample was primarily drawn from London hospitals as well a smaller contribution from around the UK and included physicians with a range of experience and at different grades.Results: The majority of the 102 participants (76.5%) did not receive any formal training in managing dentofacial emergencies. The percentage of participants who were happy to manage common dentofacial emergencies is as follows: dental trauma (20.4%); major facial trauma (39.8%); interpreting facial X‐rays (68.0%); and facial suturing (85.4%). When questioned 12.1% of the participants felt that ED physicians should be responsible for managing dental emergencies compared to 22.4% who felt that ED physicians should manage maxillofacial emergencies. Only 3.9% of the participants would opt to be treated by an ED doctor in the event of them presenting to the ED with a dental injury. The remaining 72.5% would prefer to be seen by a maxillofacial surgeon, 23.5% by a dentist and none of the participants opted to be seen by the emergency nurse practitioner.Conclusion: ED physicians do not feel confident in managing some dentofacial emergencies. This may be attributed to a lack of training in this area as well as exposure to these types of emergencies. There is a need for greater awareness, validated guidelines and training resources for ED physicians to treat dentofacial emergencies as well more research in this field of emergency medicine.

Endoscopically Assisted Nasojejunal Feeding Tube Placement: Technique and Results in Five Dogs

Interest in noninvasive feeding tube placement in companion animals led to the adaption of a human technique utilizing endoscopy to place nasojejunal feeding tubes. Data from medical records in which nasojejunal feeding tubes were attempted were reviewed. Feeding tubes were attempted and successfully placed in five dogs within a median of 35 min. Feeding tubes remained in place for approximately 7 days. Complications included facial irritation (5/5), sneezing (5/5), fractured facial sutures (4/5), vomiting (3/5), diarrhea (3/5), crimping of feeding tube (3/5), regurgitation (1/5), epistaxis (1/5), clogging of the feeding tube (2/5), and oral migration with premature removal of the feeding tube (1/5). The deployment technique used in this study was found to be cumbersome. Despite minor complications, endoscopy can be used to rapidly and accurately place nasoenteric feeding devices.

Facial suture synostosis of newborn Fgfr1P250R/+ and Fgfr2S252W/+ mouse models of Pfeiffer and Apert syndromes

Apert and Pfeiffer syndromes are hereditary forms of craniosynostosis characterized by midfacial hypoplasia and malformations of the limbs and skull. A serious consequence of midfacial hypoplasia in these syndromes is respiratory compromise due to airway obstruction. In this study, we have evaluated Fgfr1(P250R/+) and Fgfr2(S252W/+) mouse models of these human conditions to study the pathogenesis of midfacial hypoplasia. Our histologic and micro-CT evaluation revealed premature synostosis of the premaxillary-maxillary, nasal-frontal, and maxillary-palatine sutures of the face and dysplasia of the premaxilla, maxilla, and palatine bones. These midfacial abnormalities were detected in the absence of premature ossification of the cranial base at postnatal day 0. Our results indicate that midfacial hypoplasia is not secondary to premature cranial base ossification but rather primary synostosis of facial sutures. Birth Defects Research (Part A), 2011.

Microanatomical assessment of fusion in facial sutures of bushbabies.

Microanatomical assessment of fusion in facial sutures of bushbabies.

The Global Impact of Sutures Assessed in a Finite Element Model of a Macaque Cranium

The biomechanical significance of cranial sutures in primates is an open question because their global impact is unclear, and their material properties are difficult to measure. In this study, eight suture-bone functional units representing eight facial sutures were created in a finite element model of a monkey cranium. All the sutures were assumed to have identical isotropic linear elastic material behavior that varied in different modeling experiments, representing either fused or unfused sutures. The values of elastic moduli employed in these trials ranged over several orders of magnitude. Each model was evaluated under incisor, premolar, and molar biting conditions. Results demonstrate that skulls with unfused sutures permitted more deformations and experienced higher total strain energy. However, strain patterns remained relatively unaffected away from the suture sites, and bite reaction force was likewise barely affected. These findings suggest that suture elasticity does not substantially alter load paths through the macaque skull or its underlying rigid body kinematics. An implication is that, for the purposes of finite element analysis, omitting or fusing sutures is a reasonable modeling approximation for skulls with small suture volume fraction if the research objective is to observe general patterns of craniofacial biomechanics under static loading conditions. The manner in which suture morphology and ossification affect the mechanical integrity of skulls and their ontogeny and evolution awaits further investigation, and their viscoelastic properties call for dynamic simulations.

Microanatomical Assessment of Nasomaxillary Suture Patency

In addition to acting as a growth site, sutures in the facial skeleton are important for distributing mechanical forces during mastication. In the present study, the extent of fusion of a facial suture is assessed in two samples of adult bushbabies (Galago moholi and Otolemur garnettii). Microanatomical techniques were used to determine the loci of osseous bridges across the nasomaxillary suture (NMS). Histological sections containing sutures with osseous bridging were rated as "fused." One of the specimens was studied using micro-computed tomography before paraffin embedding and serial sectioning. At all ages, O. garnettii shows more advanced fusion of the NMS than G. moholi. The youngest O. garnettii shows multiple foci of fusion of the NMS; however, 13% of the posterior most suture is patent. Throughout the NMS of this animal, sutural fusion is isolated to one or two small osseous bridges, typically of woven bone. These bridges are most often on the external (superficial) surface of the suture, but in numerous sections the site of fusion occurs deep to an external notch. In G. moholi, the youngest adults studied showed little or no fusion across the NMS. However, the nasal and maxillary bones were indirectly tethered at some levels by other bones that were fused to both nasal and maxillary bones. These results indicate that microanatomical evidence is required to fully assess the extent of fusion of facial sutures. These findings also support previous observations of differing magnitude of suture fusion between the two species.

A technique for the quantification of the 3D connectivity of thin articulations in Bony sutures

The anatomy and development of cranial and facial sutures have been studied in detail using histological sections, 2D radiographs and more recently CT imaging. However, little attention has been paid to evaluating and quantifying the connectivity of these thin cortical bone articulations. More recent technological advances such as micro-CT imaging has the potential to be used to provide quantitative measurements of 3D connectivity in bony articulations. This study presents a new technique for quantifying the connectivity of bony projections inside cranial and facial sutures using a combination of skeletonization, thinning algorithms and 3D intensity mapping. The technique is demonstrated in five sutures through semi-automated analysis and image processing of μCT scans. In the sagittal, coronal and frontozygomatic sutures an average bone connectivity of 6.6–11.6% was found with multiple bony projections providing an interlocking structure between adjacent bones. Much higher bone connectivity was present in the zygomaticotemporal and zygomaticomaxillary sutures (22.7–37.4%) with few bony projections. This method combining μCT scanning and image processing techniques was successfully used to quantify the connectivity of thin bone articulations and allowed detailed assessment of sutural fusion in 3D. The wider application of this technique may allow quantification of connectivity in other structures, in particular fracture healing of long bones.

Two middle Cambrian diceratocephalid trilobites,Cyclolorenzella convexaandDiceratocephalus cornutus, from Korea: development and functional morphology

Park, T.-Y. & Choi, D.K. 2010: Two middle Cambrian diceratocephalid trilobites, Cyclolorenzella convexa and Diceratocephalus cornutus, from Korea: development and functional morphology. Lethaia, Vol. 43, pp. 73–87. Silicified sclerites of the latest middle Cambrian trilobites, Cyclolorenzella convexa and Diceratocephalus cornutus, have been recovered from the Sesong Formation, Korea. Their morphological similarity and stratigraphic occurrences suggest that D. cornutus is a descendant of C. convexa. The ontogenies of both trilobites demonstrate that a pair of long frontal horns in the cephalon of D. cornutus is an evolutionarily novel structure. It is inferred that redeployment of some pre-existing regulatory gene played a significant role in constructing the frontal horns of D. cornutus. The frontal horns may have been a defensive structure to deter predators. The facial suture of D. cornutus, which extends onto the frontal horns and splits them into the dorsal and ventral halves, was a solution to enable easier forward egression during ecdysis. □Functional morphology, Korea, Middle Cambrian, ontogeny, trilobites.

Brief communication: Histology and micro CT as methods for assessment of facial suture patency

The extent of fusion in facial sutures has implications for topics ranging from biomechanics to phylogeny reconstruction. An unfortunate limitation of studying sutural fusion in skeletal specimens is that it is difficult to assess whether apparently patent sutures are in fact fused internally. Both histology and microcomputed tomography (CT) are potential tools for solving this, but relatively few studies have attempted to discern the limits of micro CT for visualization of microanatomical structures. We examined microanatomical aspects of facial sutures in adult cadaveric samples from captive bushbabies. Premaxillary and nasopremaxillary sutures were examined in serially sectioned snouts of four greater bushbabies (Otolemur garnettii) and four lesser bushbabies (Galago moholi). Sections containing sutures with osseous bridging were rated as "fused," and the presence or absence of grooves on the external side was recorded. One bushbaby was studied using micro CT prior to physical sectioning. O. garnettii and two of the G. moholi show multiple foci of fusion. Histological examination confirmed that sutural fusion is limited to the internal surface in numerous sections, resulting in an external notch. Such points of internal fusion could be clearly visualized in raw CT slices. The presence of such notches suggests that external examination can underestimate the degree of suture fusion. Thus, microanatomical evidence may be needed to fully assess biomechanical correlates and phylogenetic interpretations based on fusion of facial sutures. Our results also indicate micro CT may be a useful tool to obtain this evidence.

Cambrian trilobite Ovatoryctocara granulata Tchernysheva, 1962 and its biostratigraphic significance

The genus Ovatoryctocara Tchernysheva, 1962, and its key species Ovatoryctocara granulata Tchernysheva, 1962, are revised. Ovatoryctocara granulata occurs near the base of the Ovatoryctocara Zone and ranges up into the lower portion of the Kounamkites Zone in the Siberian Platform. O. granulata also appears in southeastern Guizhou, South China, but O. granulata in northern Greenland may represent an indefinite species. Specimens of Ovatoryctocara from Newfoundland cannot be identified to species level. Specimens including two cranidia and three pygidia from the lower part of the Aoxi Formation at Yaxi Village, Shizhu Town, eastern Tongren, northeastern Guizhou, were previously assigned to O. granulata, which is now reassigned as a new species O. yaxiensis sp. nov. It bears the following main features: glabella club-shaped, slightly expanded medially, with four pairs of lateral furrows, of which S1–S3 are triangular pits, S4 is shallow, connecting with axial furrow; shorter palpebral lobe situated a little anterior to the midway of facial suture across the fixigenae, longer posterolateral area (exsag.); semielliptical pygidium consisting of seven axial rings with a terminal piece and with eight pairs of marginal tips giving a sawtooth-like shape of the lateral margins in dorsal view. Although O. granulata is a widely distributed species, the FAD of O. granulata, for a global stage boundary, still has some disadvantages. First, its distribution is not as wide as that of Oryctocephalus indicus (Reed, 1910). Second, specimens of O. granulata are common only in Siberia. Third, the stratigraphic range of the species has not been studied in detail in all continents. Fourth, O. granulata is relatively small and easily affected by post-burial distortion. Last but not least, there exists obviously a facies change between the Ovatoryctocara Zone (lower Amgan Stage; deeper water facies) and the underlying Anabaraspis splendens Zone (Toyonian Stage; shallow water facies) in Siberian Platform. Nevertheless, the stratigraphic correlation utility of O. granulata in South China and Siberia is discussed.

P.134 The effect of immediate and delayed facial nerve suture after nerve transection

P.134 The effect of immediate and delayed facial nerve suture after nerve transection