Pterygoid Bone Research Articles

Feline head trauma: a CT analysis of skull fractures and their management in 75 cats.

The aim of this study was to describe and evaluate the configurations and management of feline skull fractures and concurrent injuries following head trauma. Medical records and CT images were reviewed for cats with skull fractures confirmed by CT that were managed conservatively or with surgery. Details of signalment, presentation, skull fracture configuration, management, re-examination, and complications or mortality were recorded and analysed. Seventy-five cats (53 males, 22 females) with a mean age of 4.8 ± 3 years met the inclusion criteria. Eighty-nine percent of cats had fractures in multiple bones of the skull, with the mandible, upper jaw (maxilla, incisive and nasal bones) and craniofacial regions most commonly affected. Temporomandibular joint injury occurred in 56% of cats. Road traffic accidents (RTAs) were the most common cause of skull fractures, occurring in 89% of cats, and caused fractures of multiple regions of the skull. RTAs were also associated with high levels of concurrent injuries, particularly ophthalmic, neurological and thoracic injuries. A more limited distribution of injuries was seen in non-RTA cats. Equal numbers of cats were managed conservatively or surgically (47%). Mortality rate was 8% and complications were reported in 22% of cats. Increasing age at presentation and presence of internal upper jaw fractures were risk factors for development of complications. No risk factors were identified for mortality. RTAs were the most common cause of feline skull fractures and resulted in fractures in multiple regions of the skull and concurrent injuries occurred frequently. Problems with dental occlusion were uncommon post-treatment. An increased risk of implant loosening and malocclusion was seen with palatine and pterygoid bone fractures and hard palate injuries. This study provides useful additional information regarding feline skull fractures, concurrent injuries and management techniques following head trauma.

The foramen lacerum: surgical anatomy and relevance for endoscopic endonasal approaches.

The foramen lacerum is a relevant skull base structure that has been neglected for many years. From the endoscopic endonasal perspective, the foramen lacerum is a key structure due to its location at the crossroad between the sagittal and coronal planes. The objective of this study was to provide a detailed investigation of the surgical anatomy of the foramen lacerum and its adjacent structures based on anatomical dissections and imaging studies, propose several relevant key surgical landmarks, and demonstrate the surgical technique for its full exposure with several illustrative cases. Ten colored silicone-injected anatomical specimens were dissected using a transpterygoid approach to the foramen lacerum region in a stepwise manner. Five similar specimens were used for a comparative transcranial approach. The osseous anatomy was examined in 32 high-resolution multislice CT studies and 1 disarticulated skull. Representative cases were selected to illustrate the application of the findings. The pterygosphenoidal fissure is the synchondrosis between the lacerum process of the pterygoid bone and the floor of the sphenoid bone. It constantly converges with the posterior end of the vidian canal at a 45° angle, and its posterolateral end points directly to the lacerum foramen. The pterygoid tubercle separates the vidian canal from the pterygosphenoidal fissure, and forms the anterior wall of the lower part of the foramen lacerum. The lingual process, which forms the lateral wall of the foramen lacerum, was identified in 53 of 64 sides and featured an average height of 5 mm. The mandibular strut separates the foramen lacerum from the foramen ovale and had an average width of 5 mm. This study provides relevant surgical landmarks and a systematic approach to the foramen lacerum by defining anterior, medial, lateral, and inferior walls that may facilitate its safe exposure for effective removal of lesions while minimizing the risk of injury to the internal carotid artery.

A Systematic Review of the Role of Implant Design in the Rehabilitation of the Edentulous Maxilla.

To identify and critically appraise scientific publications evaluating the possible effect of implant design on treatment outcomes in the rehabilitation of patients with a fully edentulous maxilla. Scientific reports were sought in three electronic bibliographic databases, combined with searches for meeting abstracts, and in the grey literature. English, German, or Scandinavian scientific publications on prospective or retrospective longitudinal studies with effects of an implant design or feature on the treatment outcomes were eligible. Minimum requirement for inclusion was at least 10 study participants who were followed up for at least 2 years after implant loading. The PRISMA guidelines were followed for selecting data to extract from the individual studies. These were characteristics of the individual studies, risk of bias within individual studies, and the results of individual studies. Three editorial teams independently identified and extracted the data. The search resulted in 998 primary studies, of which 525 met the inclusion criteria and were read in full text. Of these, 105 studies were included in qualitative syntheses. Seventeen studies were designed with an objective to assess effects of implant design or feature on outcomes, 23 studies described tilted implants to enable placement of longer implants, 30 studies reported effects of implants placed in zygomatic bone with or without additional alveolar implants, and 9 studies reported effects of implants placed in pterygoid bone or other bony buttresses with or without additional alveolar implants. Sixteen articles reported bone augmentation with simultaneous or delayed implant placement in patients with a predominantly Cawood-Howell bone class V and VI maxilla. Ten papers reported effects of implant design on outcomes, despite the lack of an a priori stated objective to assess a particular implant design or feature. There is a lack of compelling data to state that one particular implant system or design feature stands out amidst others, when applied to restoring the fully edentulous maxilla with implant-retained prostheses. This systematic review failed to identify compelling evidence to conclude that any particular implant or feature affects the treatment outcome in patients with a fully edentulous maxilla.

Atypical presentation of craniofacial fibrous dysplasia in an adult

Fibrous dysplasia is a sporadic fibroosseous anomaly affecting the skeletal system. Craniofacial synostosis is one of its subtypes with ocular complications. We report a case of craniofacial fibrous dysplasia in a 44-year-old lady who presented with complaints of recent onset of blurring of vision in both eyes. She gave a history of swelling in the medial aspect of left eye since childhood with minimal increase in size with age. A bony swelling was seen along the medial wall of left orbit associated with deviated nasal septum to the right. She had best corrected visual acuity (BCVA) of 20/20 in eyes, normal color vision, visual fields and fundus findings. Her computed tomography (CT) scan was suggestive of fibrous dysplasia involving multiple bones (frontal, sphenoid, ethmoid, maxillary, and pterygoid bones) bilaterally. Visual evoked potential was abnormal bilaterally.

Principais caracteres da osteologia craniana de Milvago chimango (Vieillot, 1816) e Milvago chimachima (Vieillot, 1816) (Aves: Falconidae)

Knowledge of details of the cranial osteology of Milvago chimango and M. chimachima helps to ensure the monophyly of genus when compared to other birds and falcons. We conducted a study using skulls of three Milvago chimango and three Milvago chimachima specimens from the Smithsonian Institution National Museum of Natural History's Division of Birds. The cranial descriptions were comparative and illustrated by photos from the dorsal, ventral, and lateral flow perspectives. The studied species were then compared with falcons and other birds. Milvago chimango possesses several unique characters, including: the ratio of the distance from the distal portion of the lacrimal bone to the orbital arc, and from the orbital arc to the buccal arc is (1/5); absence of transpalate processes; lack of dorsal process on the pterygoid bone; more robust skull; paraoccipital bone more developed laterally; lacrimal bone smaller and more rostral; palatine bone approximately twice as wide; ethmoide bone more robust and long. In M. chimachima, the distinguishing features are: presence of projections at the caudal end of the palatine bone; developed dorsal process of the pterygoid bone; temporal fossa more tapered dorsoventrally; transverse nuchal crest outlined and visible; nostril closer to the frontonasal suture. Cranial osteology successfully provided diagnostic characters of each species and gender compared to other birds and falcons. to the installation of large enterprises or environmental protection areas. alic'>seedlings.

IMAGING CHARACTERISTIS OF MDCT IN NASOPHARYNGEAL CARCINOMA

Objectives: Imaging characteristis of MDCT in nasopharyngeal carcinoma. Subject and methods: Cross- sectional study in 51patients with nasopharyngeal carcinoma by MDCT at Danang Cancer Hospital from January 2013 to July 2014. Results: The findings reveal that the tumor in lateral wall (66.7%), diameter > 2cm (64.7%), hypodensity (98%), contrast- enhanced CT (62.7%). Blunting of fossa of Rosenmuller (96.1%), invasion of parapharyngeal space (62.7%), destruction of pterygoid bone (19.6%), invasion of skull base (17.6%), destruction of sphenoid bone (9.8%). Lymph nodes metastasis (96.1%), diameter (> 1- 3cm) is 58.8%. T-staging by CT showed T1 (35.3%), T2 (37.3%), T3 (17.6%) and T4 (9.8%). N- staging by CT showed N2 (66.7%), N3a- N3b (19.6%). Staging of Nasopharyngeal carcinoma: stage II-III (60.8%), stage IVA-IVB (23.5%) and stage IVC (11.8%). Conclusions: MDCT with a thinner slice thickness and high quality images is able to detect lymph nodes metastasis with small size and those in deep neck area and assess comprehensively the invasion of the tumor. Key words: Nasopharyngeal carcinoma, MDCT

Zygomatic Implant Placement With Flapless Computer-Guided Surgery: A Proposed Clinical Protocol

The aim of the present report is to describe a procedure for zygomatic implant placement using image-guided implant surgery. This is an innovative technique and includes a new clinical approach to provide the direction to guide drilling. The ethical committee of the University of Genoa approved the study. All patients had clinical indications of severe maxillary atrophy (Class 4 Cadwood-Howell). A total of 25 implants were placed, of which 17 were in the premaxilla, 7 in the zygomatic area, and 1 in the pterygoid bone. The treatment was performed in 2 phases. The first phase included cone-beam acquisition to exclude sinus disease and evaluate the anatomy of the residual premaxillary bone in 3 dimensions. The success of osseointegration achieved by the primary implants (PIs) was confirmed after temporary loading and before proceeding with the second phase, in which all patients were scheduled for zygomatic implants. A total of 3 or 4 regular platform MK III implants (17 in all) were placed in the premaxilla using conventional implant surgery. A model within the analogs of the PIs was prepared (master model), taking a conventional impression. Next, a radiologic template was prepared on the same master model and stabilized on the PIs, using dedicated prosthetic components. The guide was screwed onto the PIs during computed tomography acquisition to determine a fixed and repeatable position of the guide. In the second phase, after routine planning, a mucosa-supported stereolithographic SurgiGuide with sleeves for the zygomatic implants and the corresponding stereolithographic model, including the mucosa, were received from the manufacturers. The guide was repositioned on the master model to replace the sleeves for the PIs in the same position. With an original customized surgical kit, including an innovative intrasinus device, we next simulated surgery on the stereolithographic model to determine and control the direction of the osteotomies and the final depth of drilling. The SurgiGuide was anchored onto the PIs before the zygomatic osteotomy, after which flapless surgery was performed to place the zygomatic implants according to the plan. Two PIs in the premaxillary area failed (and were replaced before the zygomatic step). No zygomatic implants failed. The follow-up examinations at 4 to 39 months showed good esthetic, phonetic, and functional results. The results of the proposed surgical procedure appear to be encouraging. Although it is difficult to achieve the correct driven angle of osteotomies for zygomatic implants, in all patients we achieved correct zygomatic positioning, in agreement with previous planning. Additional research and randomized clinical trials are needed to assess the predictability of the procedure.

Transposition of the Pterygopalatine Fossa during Endonasal Endoscopic Transpterygoid Approaches

Introduction: The endoscopic transpterygoid approach classically involves sacrificing the vidian nerve to drill the base of the pterygoid bone. If it is necessary to remove pterygoid plates to access the infratemporal fossa, the greater palatine nerve and the descending palatine artery are usually transected.

Development of Pterygoquadrate Complex in the Embryogenesis of Sand Lizard, Lacerta Agilis (Reptilia, Squamata)

Development of Pterygoquadrate Complex in the Embryogenesis of Sand Lizard,Lacerta Agilis(Reptilia, Squamata)Serial sections of 15L. agilisembryos on the successive developmental stages, stained with hematoxylin-eosin or alcian blue and hematoxylin-eosin, were examined. It was found that cartilaginous pterygoquadrate complex ofL. agilisconsists of four parts: quadrate cartilage, pterygoquadrate cartilage, pterygoid process, and processus ascendens. Pterygoquadrate cartilage and pterygoid process are reduced in prenatal ontogenesis, but not earlier than underlying pterygoid bone is developed. The processus ascendens becomes the first cartilaginous parts of this complex, and then the other elements undergo chondrification. Basipterigoid process is formed by two independent parts: aboral part of cranial trabeculas and basipterigoid cartilage. Meniscus pterygoideus is an independent structure, but not a rudiment of the pterygoid process. A previously unrecorded cartilage was revealed and a name basipterigoid cartilage is proposed for it.

The constrictor dorsalis musculature and basipterygoid articulation in Sphenodon

The constrictor internus dorsalis (CID) trigeminal muscles in vertebrates lie between the braincase and the palatoquadrate bar, and in reptiles they are believed to function in the relative movements between braincase and maxillary segment known as kinesis. In amniote taxa, the presence of a synovial basipterygoid articulation (BPA) correlates with presence of the CID. Previous descriptions of the CID in the tuatara Sphenodon (Rhynchocephalia) are inconsistent regarding presence, size and direction, particularly of the m. protractor pterygoidei. The Sphenodon skull is reported to be akinetic. The CID was investigated in Sphenodon by examination of sectioned embryonic and hatchling material, and by dissection of fixed specimens. Osteological correlates of CID muscles and morphology of the BPA were examined on disarticulated skulls and on CT scan images. The vectors of action of these muscles in relation to the BPA were projected onto CT images. Mm. levator bulbi and levator pterygoidei are found to be similar to most previous descriptions, but m. protractor pterygoidei was found in a different position, lying entirely medial to the palatoquadrate bar. The insertions of mm. levator pterygoidei and protractor pterygoidei are visible on the disarticulated pterygoid bone. The BPA is mobile only by rotation around the horizontal axis of the joints themselves; metakinesis is not possible in the Sphenodon skull. M. protractor pterygoidei appears to either resist or recognize lateral displacement of the BPA. M. levator ptergyoidei is placed to resist dorsal displacement of the braincase at the BPA, or torsion of the braincase around its longitudinal axis. The BPA appears to be a means to direct compressive stress via the base of the braincase and occipital condyle to the cervical spine in Sphenodon, and probably in its direct ancestors. Metakinesis may never have been a feature of the lepidosaur skull.

Morphology of the cranial system of Platyclarias machadoi: interdependencies of skull flattening and suspensorial structure in Clariidae

The African catfish Platyclarias machadoi stands out from other clariid species by its extremely dorsoventrally flattened skull. This paper focuses on the spatial constraints and consequent functional interde- pendencies in this very low skull (average skull height of 27.5±3.0% skull length); such as the medial position of the retroarticular process on the lower jaw, the hori- zontal position of the suspensorium, the lateral tilting of the pterygoid bones and the anterior part of the quad- rate with regard to the suspensorial transverse long axis. These characteristics can be presumed to have major influences on the capacity of suspensorial adduction, influencing the feeding and respiratory mechanisms. A comparison with other clariid species showed that one of the apomorphies is the presence of an extra muscle (musculus adductor mandibulae A3¢¢ pars levator tend- inis) in the adductor mandibulae complex. This extra muscle lifts the tendon complex of the adductor man- dibulae, resulting in a higher moment on the lower jaw. Some comments on the original species/genus descrip- tions are given.

A New Pterosaur from the Jurassic of Cuba

Cacibupteryx caribensis gen. et sp. nov. is a new pterosaur of the family Rhamphorhynchidae found in western Cuba, in rocks of the Jagua Formation (Middle–Upper Oxfordian). The holotype, a skull and part of the left wing, is one of the few Jurassic pterosaurs that is well preserved in three dimensions. The new taxon shares characters with early and late Jurassic pterosaurs, and is one of the few late Jurassic taxa from western Laurasia and Gondwana. Furthermore, Cacibupteryx joins Nesodactylus hesperius Colbert from Cuba, and Sordes pilosus Sharov, from Kazakhstan as the most complete pterosaur recorded from the Middle–Upper Oxfordian. Cacibupteryx caribensis is one of the largest Jurassic pterosaurs known, and its skull possesses several distinct characters, including relatively broad roof elements (mainly frontal and parietal bones), a jugal with a prominent recess, occipital table trapezoidal in shape with the maximum width between the quadrate bones, and a small fenestra located in the posterior part of the pterygoid bones. In the Oxfordian, the Caribbean Corridor separated Laurasia and western Gondwana. The diversity of the marine herpetofauna found in the Jagua Vieja Member (Jagua Formation), and of teleostean fish, confirms that the corridor was an effective seaway over which flew at least Nesodactylus and Cacibupteryx.

Osteological variation and taxonomic affinities of bottlenose dolphins, Tursiops spp., from South Australia

Skulls and skeletons of 84 cranially mature bottlenose dolphins collected from South Australia were studied to distinguish morphological groups. The dataset comprised 38 skull measurements, 5 tooth counts/measurements, 6 coded skull features and 2 vertebral counts. There was no significant difference between sexes. Agglomerative, heirarchical cluster analyses performed on all variables and a dataset refined by eliminating those with high partial correlations produced two clear groups of skulls but with some differences in group membership between the statistical treatments. Size was an important factor in distinguishing groups, especially when categorical variables were excluded. Groups produced by cluster analysis of all variables were aligned with Tursiops truncatus and T. aduncus. In general, Tursiops truncatus was distinguished by a wide band (3-9 mm) of cancellous bone on the premaxillae, a distinct supraoccipital crest, raised naso-frontal complex, the almost complete lack of bone resorption on the pterygoid bones, a relatively wider rostrum, generally larger skull size (condylobasal length >465 mm versus <476 mm, except two skulls of 445 and 448 mm), and more than 60 vertebrae. This species was collected from open ocean coasts and sometimes stranded in groups. Tursiops aduncus generally had a narrow or no band of cancellous bone (0-5 mm), an indistinct or no supraoccipital crest, a naso-frontal complex that was not markedly raised, moderate to extensive bone resorption on the pterygoids, relatively narrow rostrum, fewer than 63 vertebrae and was collected mainly from the large gulfs. There was no significant difference between tooth diameter of T. aduncus and T. truncatus from South Australia.

In reply:

We know very well that mucoceles do not exist intraosseously but are intracavitary lesions. Sphenoid bone can occasionally be hollow,1 or sphenoid sinus can be unilateral and can unilaterally be enlarged and/or extend into pterygoid bone.2 We presume that in the present case the sphenoid bone was hollow and the mucocele arose in this cavity.

Use of the ‘shark-fin’ osteotome in separation of the pterygomaxillary junction in Le Fort I osteotomy: a clinical and computerized tomography study

Le Fort I osteotomy fails in many cases to completely separate the pterygomaxillary junction and often results in fractures of the pterygoid bone and the tuberosity, which subsequently can cause complications. The objectives of this study were to describe the specifically developed Laster ‘shark-fin’ osteotome and to compare its use to other methods of pterygomaxillary dysjunction. Pterygomaxillary dysjunction was performed in 10 adult patients requiring Le Fort I osteotomy. In one randomly chosen side of the maxilla, the Obwegeser osteotome was used, while the Laster ‘shark-fin’ osteotome was used on the opposite side. A postoperative computerized tomography of the separation at the pterygomaxillary junctions revealed that in all sites treated with the Laster ‘shark-fin’ osteotome, a complete or almost complete separation was obtained, whereas the use of the Obwegeser osteotome resulted in five sites with fractures of the maxillary tuberosity and three with high-level fractures of the pterygoid plates (P< 0.001). Comparing these findings with the literature, we concluded that the Laster ‘shark-fin’ osteotome is preferable for separating the pterygomaxillary junction in Le Fort I osteotomy.

Tendon-associated bone features of the masticatory system in Neandertals

Masticatory or paramasticatory activities are often considered to have produced elevated stresses important in the evolution of the Neandertal face. Yet Neandertals were geometrically ill-equipped to produce absolutely great anterior bite forces due to their relatively long bite-force lever arms. To consider whether Neandertals might have had structurally different masticatory muscles capable of producing more force than modern human muscles, this study examines the form and frequency of bone features known to be associated with internal tendons (structure) of the masticatory musculature in four species of macaques (n=85), three geographically distinct samples of modern humans (n=111), and Neandertals (n=27). Neandertals present a mosaic of tendon-associated bone features compared with macaques and humans. The Neandertal deep masseter and anterior temporalis are inferred to be better defined and perhaps larger than in modern humans based on their better developed deep masseter fossae and presence of a postorbital ridge. Medial pterygoid bone features were not qualitatively different from those in some modern humans although the medial pterygoid tubercle is larger, on average, in Neandertals. These results imply the presence of moderately stronger masticatory muscles in Neandertals than in modern humans. A moderate increase in masticatory muscle strength is considered necessary in Neandertals to offset their relatively prognathic face. However, the differences are small enough that it remains unlikely that Neandertals could produce absolutely great anterior bite forces.

Biomechanics of cranial kinesis in birds: Testing linkage models in the white-throated sparrow (Zonotrichia albicollis).

Cranial kinesis in sparrows refers to the rotation of the upper jaw around its kinetic joint with the braincase. Avian jaw mechanics may involve the coupled motions of upper and lower jaws, in which the postorbital ligament transfers forces from the lower jaw, through the quadrate, pterygoid, and jugal bones, to the upper jaw. Alternatively, jaw motions may be uncoupled, with the upper jaw moving independently of the lower jaw. We tested hypotheses of cranial kinesis through the use of quantitative computer models. We present a biomechanical model of avian jaw kinetics that predicts the motions of the jaws under assumptions of both a coupled and an uncoupled mechanism. In addition, the model predicts jaw motions under conditions of force transfer by either the jugal or the pterygoid bones. Thus four alternative models may be tested using the proposed model (coupled jugal, coupled pterygoid, uncoupled jugal, uncoupled pterygoid). All models are based on the mechanics of four-bar linkages and lever systems and use morphometric data on cranial structure as the basis for predicting cranial movements. Predictions of cranial motions are tested by comparison to kinematics of white-throated sparrows (Zonotrichia albicollis) during singing. The predicted relations between jaw motions for the coupled model are significantly different from video observations. We conclude that the upper and lower jaws are not coupled in white-throated sparrows. The range of jaw motions during song is consistent with a model in which independent contractions of upper and lower jaw muscles control beak motion. © 1996 Wiley-Liss, Inc.

Observations on the ontogeny and homology of the pterygoid bones in Corydoras paleatus and some other catfishes

There has been much uncertainty in the past concerning the identity of the pterygoid bones in Siluroidei (catfishes). This confusion stems from the often increased number of pterygoid elements and their modified development, as compared with other teleosts. The ontogeny of the hyomandibula‐pterygoquadrate series in a 20‐day developmental sequence of Corydoras paleatus (Jenyns, 1842) embryos is described and supplemented with observations on a clariid and an ageniosid. A historical résumé of previous interpretations of siluroid pterygoid bone homologies is given together with our own which regards the metapterygoid as the central, densely ossified area of the pterygoquadrate, surrounded by the membranodermal ento‐ and ectopterygoids.

Ontogeny of architectural complexity in embryonic quail visceral arch muscles.

Understanding the mechanisms of muscle pattern formation requires that the complete sequence of ontogenetic events be defined, particularly in the emergence of architectural complexity and in the spatial relations between muscles and skeletal elements. This analysis of visceral arch myogenesis in quail (Coturnix coturnix japonica) embryos identifies the location of premuscle condensations and subsequent segregation of individual muscles, documents the initial orientation of myofibers and changes in alignment associated with maturation, and describes the spatial and temporal relations between muscle development and the formation of connective tissues. Premuscle condensations form within the visceral arches on embryonic days 2-4, before skeletal elements make their appearance. Discrete muscles may form from the subdivision of a muscle mass after fiber orientations have been established (e.g., jaw adductor and hyobranchial muscles) or by the segregation of a mesenchymal cluster from the condensation prior to the appearance of oriented fibers (e.g., protractor, muscle of the columella). The rate and pattern of subsequent muscle maturation are closely associated with the development of the hard tissues. Myogenesis in 4-9-day embryos centers around the quadrate cartilage, the retroarticular process of the mandibular (Meckel's) cartilage, and the epibranchial cartilage. Muscles form attachments on these elements and remain without additional attachments until the appropriate elements (e.g., otic capsule, pterygoid bone) develop. No single description of myogenic events applies to all visceral arch muscles, nor is there an arch-specific pattern of ontogeny. Rather, each muscle has distinctive characteristics based on its spatial relations within the developing head.

Tongue Evolution in the Lungless Salamanders, Family Plethodontidae IV. Phylogeny of Plethodontid Salamanders and the Evolution of Feeding Dynamics

-Plethodontids, a monophyletic group, comprise about 60% of living salamanders. Many have a tongue that may be projected rapidly and for a distance up to half the body length. Previous studies have focused on the functional morphology of the projectile tongue and the comparative morphology of the feeding system in the family. Here we present a working hypothesis for the phylogeny of plethodontids and a scenario for the evolution of tongue feeding based on the phylogenetic hypothesis. Primitive and derived states are identified and transformation series proposed for 30 characters. Four alternative phylogenetic hypotheses are presented. Our choice of a preferred phylogenetic hypothesis is based on consideration of conflicting characters and tongue projection mechanics. The preferred hypothesis is not the most parsimonious, in a strict technical sense, because several homoplasious characters appear (on functional grounds) to be closely associated with attainment of tongue projectility, which itself has evolved several times. In our hypothesis the bolitoglossines and plethodontines are sister taxa. They in turn are the sister taxon of the hemidactylines, and this grouping is the sister taxon of the desmognathines. Within the bolitoglossines, Batrachoseps is the sister taxon of the Neotropical genera (supergenus Bolitoglossa). In our scenario for the evolution of tongue feeding, the ancestral plethodontid had an protrusible tongue. From this condition projectile have arisen at least three times within the family: in the ancestors of the hemidactylines; in the ancestors of Ensatina; and in the ancestors of the bolitoglossines. In turn, the projectile condition has given rise to projectile at least once within the hemidactylines and twice within the bolitoglossines. This scenario tends to maximize the number of times projectile and projectile have evolved in the family. [Plethodontidae; phylogeny; tongue; evolutionary morphology.] The lungless salamanders, family Plethodontidae, are distributed in North and Central America and northern South America in the New World, and two species of one genus occur in Europe. The family includes over 200 species, currently placed in 27 genera, which comprise about 60% of all salamander species. The family is characterized by a relatively high degree of terrestriality (Dunn, 1926; Wake, 1966) and, in addition, most plethodontids have a highly specialized feeding mechanism, usually extensive tongue projection. Plethodontids are a monophyletic group based on the presence of an opercularis muscle formed entirely or in part from the cucullaris and, in transformed adults, the presence of a nasolabial groove and the absence of an ossified pterygoid bone. In addition, all are lungless-a condition shared with a few derived species of other families. In this paper we add further synapomorphies from the structure of the feeding apparatus. For the past 50 years, the hyobranchial skeleton and musculature of the feeding system have been the major structural attributes used in considering plethodontid phylogeny. Thus, it is not surprising that most authors who have considered the phylogeny of plethodontids have also made at least passing reference to feeding evolution, if not considering it in detail. Of particular importance has been the perceived dichotomy attached tongues versus free tongues. Previous authors either