Ramus Mandibularis Research Articles

The northernmost occurrence of non-karaurid salamanders (Lissamphibia, Caudata) in the Mesozoic

Isolated incompete salamander dentaries from the Lower Cretaceous Teete locality in Yakutia (Eastern Siberia, Russia) represent the northernmost occurrence of non-karaurid salamanders in the Mesozoic and are evidence that small-sized salamanders lived in high latitudes (paleolatitude estimate of N 62°–66.5°) in the Northern Hemisphere in the Early Cretaceous. These gracile and lightly built dentaries are characterized by the presence of numerous slender and closely spaced pedicellate teeth, a sharp ridge along the ventral edge of the postsymphyseal region, numerous neurovascular foramina that open into parallel longitudinal grooves on the labial surface, and a complex neurovascular system. The neurovascular system, which consists of a large longitudinal canal for the ramus mandibularis internus of the trigeminal nerve associated with smaller lateral canals and an entirely separate anterior part of the alveolar canal for the branches of the ramus alveolaris of the facial nerve, is similar to that of the long-lived Juro-Cretaceous small-sized non-karaurid salamanders of the genus Kiyatriton. The Teete faunal association “relic karaurid stem salamander—small-sized non-karaurid salamander” is characteristic for the “Great Siberian refugium” for Jurassic vertebrate relicts that covered the vast northeastern part of the Asiatic continent during the Early Cretaceous.

Mandibular Fractures Admitted to the Emergency Department: Data Analysis from a Swiss Level One Trauma Centre.

Mandibular fracture is a common occurrence in emergency medicine and belongs to the most frequent facial fractures. Historically road traffic injuries (RTIs) have played a prominent role as a cause for mandibular fractures. We extracted data from all patients between August 2012 and February 2015 with “lower jaw fracture” or “mandibular fracture” from the routine database from the emergency department. We conducted a descriptive analysis at a Swiss level one trauma centre. 144 patients were admitted with suspected mandibular fractures. The majority underwent CT diagnostic (83%). In 7% suspected mandibular fracture was not confirmed. More than half of all patients suffered two or more fractures. The fractures were median or paramedian in 77/144 patients (53%) and in other parts (corpus, mandibular angle, ramus mandibularis, collum, and temporomandibular joint) in 100/144 (69%). Male to female ratio was 3 : 1 up to 59 years of age; 69% were younger than 40 years. 72% of all patients presented during daytime, 69% had to be hospitalized, and 31% could be discharged from the ED after treatment. Most fractures were due to fall (44%), followed by interpersonal violence (25%) and sport activities (12%). Falls were a dominant cause of fracture in all age groups while violence and sport activities were common only in younger patients. Comparisons to other studies were difficult due to lack of standardization of causes contributing to the injuries. In the observed time period and setting RTIs have played a minor role compared to falls, interpersonal violence, and sports. In the future, standardized documentation as well as categorization of causes for analytic purposes is urgently needed to facilitate international comparison of studies.

The jaw adductor muscle complex in teleostean fishes: evolution, homologies and revised nomenclature (osteichthyes: actinopterygii).

The infraclass Teleostei is a highly diversified group of bony fishes that encompasses 96% of all species of living fishes and almost half of extant vertebrates. Evolution of various morphological complexes in teleosts, particularly those involving soft anatomy, remains poorly understood. Notable among these problematic complexes is the adductor mandibulae, the muscle that provides the primary force for jaw adduction and mouth closure and whose architecture varies from a simple arrangement of two segments to an intricate complex of up to ten discrete subdivisions. The present study analyzed multiple morphological attributes of the adductor mandibulae in representatives of 53 of the 55 extant teleostean orders, as well as significant information from the literature in order to elucidate the homologies of the main subdivisions of this muscle. The traditional alphanumeric terminology applied to the four main divisions of the adductor mandibulae – A1, A2, A3, and Aω – patently fails to reflect homologous components of that muscle across the expanse of the Teleostei. Some features traditionally used as landmarks for identification of some divisions of the adductor mandibulae proved highly variable across the Teleostei; notably the insertion on the maxilla and the position of muscle components relative to the path of the ramus mandibularis trigeminus nerve. The evolutionary model of gain and loss of sections of the adductor mandibulae most commonly adopted under the alphanumeric system additionally proved ontogenetically incongruent and less parsimonious than a model of subdivision and coalescence of facial muscle sections. Results of the analysis demonstrate the impossibility of adapting the alphanumeric terminology so as to reflect homologous entities across the spectrum of teleosts. A new nomenclatural scheme is proposed in order to achieve congruence between homology and nomenclature of the adductor mandibulae components across the entire Teleostei.

Non-feeding and feeding tadpoles in hemiphractine frogs: larval head morphology, heterochrony, and systematics of Flectonotus goeldii (Amphibia: Anura: Hylidae)

The Hemiphractinae (Hylidae) is group of neotropical egg-brooding frogs. It comprises species with different larval life history strategies. The larvae of Flectonotus hatch in an advanced stage of development. They are free-living but non-feeding. The putative sister taxon Gastrotheca includes species with feeding and free-living larvae, and others that undergo direct development. This study gives the first description of the skull of premetamorphic Flectonotus goeldii. Results are compared to the skulls of free-living Gastrotheca larvae. Some of the differences between the skulls can be explained as structural reductions of the larval feeding system in F. goeldii, due to the non-feeding mode of life: small and shallow branchial basket: simple ceratobranchialia; absence of branchial food traps, filter rows, ciliary cushions; only two open gill clefts; some branchial muscles weakly developed or missing. Many cranial structures appear to stop their differentiation and growth precociously in F. goeldii, compared to Gastrotheca: lack of commissura quadratoorbiialis anterior; short cornu trabeculae; persisting fenestrae parietales; and crista parotica without pronounced processus. The simplified feeding apparatus and the retarded features of the neurocranium can be accounted for by a heterochronic truncation of the larval developmental program in F. goeldii. Despite many structural differences, larvae of F. goeldii and Gastrotheca also share cranial features: similar eihmoidal region: lack of processus oticus; high cartilago orbitalis; intermediate suspensorium; large processus pterygoideus; copula anterior absent; musculus levator mandibulae externus and m. branchiohyoideus externus missing; m. levator mandibulae anterior lateralis not functionally differentiated before metamorphosis: ramus mandibularis (N.V) perforates m. levator mandibulae subexternus: rostral end of cornu trabeculae not conspicuously projecting laterally beyond cartilago labialis superior; and lateral rim of palatoquadrate curved dorsally and smooth. However, none of these shared character states is unique to the two taxa. They are also found in larvae of some other species of the Hylidae and Hyloidea and are probably symplesiomorphic for Gastrotheca and Flectonotus.

The Ba/Sr ratio, carious lesions, and dental calculus among the population buried in the church La Concepción (Tenerife, Canary Islands)

Certain trace elements may accumulate in bone in relation to dietary habits, so some of them are of interest in paleodietary analysis. This is the case with strontium (Sr) and barium (Ba), whose potential value as paleodietary indicators is enhanced by their relatively inert metabolic behaviour. The presence of carious lesions may indicate consumption of sugar and vegetables, whereas the etiology of dental calculus deposition is multifactorial, although some authors consider this as an indicator of protein consumption. Based on these facts we analysed (1) Ba, Sr, and calcium (Ca) content of inner cortical bone obtained from the ramus mandibularis, by atomic absorption spectrophotometry, (2) presence of teeth with carious lesions, and (3) presence of teeth with calculus deposition in 62 mandibles. All samples were obtained from the church La Concepción, an 18th century burial place in Tenerife. Gender was assessed by analysing genetic expression of amelogenin in some cases (14), and by inspection of pelvic bones when available (41 cases). We found (1) Carious lesions in 32 cases, and dental calculus, in 39; no association was observed between sex and presence of dental caries or calculus deposition, nor between the sex and the proportion of carious teeth nor the proportion of teeth with calculus deposition; (2) people buried near the altar (priests and individuals of the highest social class) showed a significantly higher proportion of teeth with dental calculus deposition ( χ 2 = 5.36, p = 0.021); (3) bone Sr and bone Ba were significantly higher than the values observed in a control group of 10 modern omnivorous individuals; the lowest Sr values were observed among people buried near the altar; and (4) the Ba/Sr ratio was directly related with the proportion of teeth with carious lesions. These data suggest that there were differences in dietary pattern among the individuals belonging to different social classes; overall, consumption of vegetables was widespread, as shown by the high proportion of carious lesions, in relation with raised Ba/Sr ratio, whereas consumption of marine products was scarce.

Homologies of the adductor mandibulae muscles in Tetraodontiformes as indicated by nerve branching patterns

Homologies of the adductor mandibulae muscles in eight families of Tetraodontiformes were hypothesized from the branching patterns of ramus mandibularis trigeminus. Insertions of the muscles to the upper or lower jaw were weak indicators of homology, migrations of the sites occurring frequently in A1, A2α, A2β, and A3. In monacanthids, tetraodontids, and diodontids, A1 tended to be split into numerous subsections, whereas in aracanids and ostraciids, A3 was highly developed, comprising three or four subsections. In tetraodontids, A2β was found to be a composite of A1 subsection and A2β. The methods of and limits to applying nerve branching patterns to muscle homology are discussed. A new naming system that reflects both muscle homologies and insertions is proposed.

Aesthetic Indications for Botulinum Toxin Injection

A clinical trial was undertaken to evaluate the effects of commercially available botulinum toxin on 14 hyperactive corrugator muscles, 14 procerus muscles, one case of congenital aplasia of the depressor labii inferioris muscle, and one case of iatrogenic injury to the ramus mandibularis branch of the facial nerve with paralysis of the depressor labii and mentalis muscles. Of the 31 muscles injected, 28 were appropriately paralyzed with the initial injection. The desired results were obtained in the 3 remaining muscles following a second injection. The ability to frown was nullified in all subjects, resulting in the elimination of glabellar lines. Facial symmetry was achieved in both patients with muscle imbalance. The average duration of the paralysis was 8 weeks, with a range of 2 to 16 weeks. However, this period was prolonged in the latter part of the study with an adjustment of the toxin dose. Our results demonstrate that botulinum toxin injected into overactive facial muscles does produce a predictable and reversible paralysis and eliminates or ameliorates deep frown lines. We also illustrate its use in achieving facial symmetry in one patient with congenitally absent depressor labii inferioris and platysma muscles and in another with postrhytidectomy facial nerve paralysis.

The current surgical management of carotid body paragangliomas.

To determine if recent trends in evaluation and therapy have contributed to the successful surgical management of carotid body paragangliomas, we reviewed our experience over the past decade. Nineteen carotid body paragangliomas were identified in 17 patients. Eleven patients underwent complete, preoperative embolization of their afferent arteries with one complication. Calculated carotid body paragangliomas surface areas did not differ between the embolized 64.6 +/- 43.3 cm2 and nonembolized 63.0 +/- 57.9 cm2 lesions. Intraoperative blood loss was lower (p = 0.02) in the patients treated with embolization (372 +/- 213 ml) compared with their cohorts (609 +/- 564 ml). However, the operative times were equivalent 4.1 hours versus 4.5 hours in both groups. Intraoperative electroencephalographic (EEG) monitoring was used in 10 patients; in one patient the EEG indicated intraoperative thrombosis of the carotid artery, which was successfully treated by thrombectomy without complications. Two patients required carotid bifurcation resection and vascular reconstruction to remove the entire tumor; a late stroke manifested by contralateral hand weakness developed in one of these patients. The incidence of cranial nerve injury was low at 16%, with one transient ramus mandibularis paresis and two instances of vocal cord dysfunction. Two additional patients had a postoperative Horner's syndrome. We conclude that by diminishing intraoperative blood loss through complete and careful preoperative embolization and use of intraoperative EEG monitoring along with careful surgical technique, the complications associated with this challenging operation are facilitated and diminished.

The current surgical management of carotid body paragangliomas

To determine if recent trends in evaluation and therapy have contributed to the successful surgical management of carotid body paragangliomas, we reviewed our experience over the past decade. Nineteen carotid body paragangliomas were identified in 17 patients. Eleven patients underwent complete, preoperative embolization of their afferent arteries with one complication. Calculated carotid body paragangliomas surface areas did not differ between the embolized 64.6 ± 43.3 cm2 and nonembolized 63.0 ± 57.9 cm2 lesions. Intraoperative blood loss was lower (p = 0.02) in the patients treated with embolization (372 ± 213 ml) compared with their cohorts (609 ± 564 ml). However, the operative times were equivalent 4.1 hours versus 4.5 hours in both groups. Intraoperative electroencephalographic (EEG) monitoring was used in 10 patients; in one patient the EEG indicated intraoperative thrombosis of the carotid artery, which was successfully treated by thrombectomy without complications. Two patients required carotid bifurcation resection and vascular reconstruction to remove the entire tumor; a late stroke manifested by contralateral hand weakness developed in one of these patients. The incidence of cranial nerve injury was low at 16%, with one transient ramus mandibularis paresis and two instances of vocal cord dysfunction. Two additional patients had a postoperative Horner's syndrome. We conclude that by diminishing intraoperative blood loss through complete and careful preoperative embolization and use of intraoperative EEG monitoring along with careful surgical technique, the complications associated with this challenging operation are facilitated and diminished.

Extended neck dissection

From the time Crile described radical neck dissection in 1906, this surgical procedure became popular in the management of metastatic cancer in the neck. Over the past two decades, the modified neck dissection has been effectively utilized for conservation of function and cosmesis while achieving the same oncologic goals. However, there are several instances where the above standard procedures are not adequate for resection of malignant tumors. Although there is a definite trend toward conservation procedures, extended neck dissection is often necessary especially in patients with N2 and N3 disease. Apart from the standard structures removed in radical neck dissection, the other structures removed in extended neck dissection include skin, the digastric muscle, hypoglossal nerve, vagus nerve, sympathetic chain, ramus mandibularis, carotid artery, tracheo-esophageal nodes, etc. Over the past seven years, we have performed 40 extended neck dissections. All the patients had N2 or N3 disease in the neck. Nine patients had unknown primaries. Thirteen patients had their primary tumors in the oral cavity and 11 in the laryngopharynx. Five patients had primary tumor in the salivary glands and two patients had metastatic melanoma. Patients who underwent extensive skin excision had pectoralis myocutaneous flap reconstruction. All patients received postoperative radiation therapy. One patient died of cardiac problems 4 weeks after operation. Local control was achieved in 70%. The most difficult region for local control was the disease behind the mastoid process, and the most difficult problems were patients with involvement of the subdermal lymphatics. Our data suggests that there are definite situations where extended neck dissection is indicated with satisfactory local control of the nodal disease.

Excision of the submandibular gland: minimizing the risk of nerve damage.

Surgical texts do not clearly advise whether the ramus mandibularis should be identified in excision of the submandibular salivary gland for benign disease. An analysis of 74 patients was undertaken to assess the subsequent nerve function after submandibular salivary gland excision. Both glands were removed in two patients, making the total number of glands excised 76. In five cases the nerve was identified, in five patients the operative record did not clearly state whether the nerve was identified, and in the remaining 66 a non-identification technique was used. The subsequent analysis was unable to follow-up six patients fully. Seven patients had mild to moderate weakness in the early postoperative period, but all recovered, some taking up to 3 months to do so. Other complications were minor, except for two patients who had postoperative haemorrhage, one requiring a tracheostomy. As the majority of these patients had a non-identification technique, and because searching for the nerve is tedious and time-consuming, the former approach is recommended when operating for benign disease of the submandibular salivary gland.

Morphological evidence for a direct projection of trigeminal nerve fibers to the primary gustatory center in the sea catfish Plotosus anguillaris

The central projections of the ramus mandibularis were examined in the Japanese sea catfish, Plotosus anguillaris by using the technique of transganglionic tracing with horseradish peroxidase (HRP). This ramus receives fibers from both the trigeminal and facial nerves and supplies primarily the two mandibular barbels. Two pathways for a direct trigeminal projection to the facial lobe (FL) were found: one from the main descending root of the Vth nerve (MRDV) to the medial portion of the FL, approximately midway between the rostro-caudal axis of the FL and a second, from deep RDV to the intermediate nucleus (NIF), beneath the medial lobule of the FL. The facial fibers project exclusively onto the medial portion of the FL and the NIF. The results show that fibers of these two cranial sensory nerves supplying the mandibular barbels converge centrally on the medial portion of the FL, indicating that the FL of the Japanese sea catfish is a highly differentiated center for both gustation and somatosensation.

The cranial nerves of the teleost Trichiurus lepturus.

The cranial nerves of the cutlassfish, Trichiurus lepturus, were described from their external brain origin to their most distal points. The nervus olfactorius, nervus opticus, nervus oculomotorius, nervus trochlearis, nervus abducens, nervus glossopharyngeus, and nervus vagus of Trichiurus are characteristic of teleosts. The cephalic autonomic nervous system also follows the general scheme for teleosts. Atypical patterns are exhibited by portions of the ramus mandibularis facialis, ramus mandibularis trigemini, nervus stato-acusticus, and nervus lineae later-alis. A cutaneous ramus mandibularis externus facialis arises from the ramus mandibularis; this cutaneous nerve has been recorded specifically in only certain siluroid catfish. A connection from the ramus mandibularis trigemini to the cutaneous ramus mandibularis externus facialis is present; an equivalent of this connection has been reported only in the silversides, Menidia, and the siluroid catfish Parasilurus. This nerve pattern probably represents an archaic arrangement. The nervus stato-acusticus of Trichiurus is typical for teleosts, except for a branch extending from the posterior part of the nerve; this branch sends connections to the nervus lineae lateralis and then exits the cranium via the vagus foramen. Connections between the nervus lineae lateralis and the nervus stato-acusticus have previously been reported in only the hatchetfish, Argyropelecus, and the bristle-mouth, Cyclothone. This condition may represent a specialized adaptation of certain mesopelagic teleosts having extreme vertical-migration capabilities.

The M. masseter of the Formosan monkey.

A study of the M. masseter was made bilaterally according to the technique of Yoshikawa et al. on a sample of 25 Macaca cyclopis.1) A classification into the M. masseter superficialis (lamina prima and secunda), intermedius (lamina prima and secunda), profundus (lamina prima and secunda) and profundissimus was possible on the basis of the site and condition of origin and insertion, course of muscle bundles, etc. These parts were all supplied by branches from the N. massetericus.2) The M. masseter superficialis lamina prima in many cases was found to show a formation corresponding to the pars reflexa of Rodentia.3) In rare cases, conditions presumed to be variations of the M. masseter profundus were found.4) The muscle located between the M. masseter and M. temporalis, with origin from the inner surface of the arcus zygomaticus and insertion into the lateral surface of the ramus mandibularis, which I called the M. masseter profundissimus is the part corresponding to the so-called M. zygomaticomandibularis of Toldt or the M. maxillomandibularis in the classification of Yoshikawa et al. The portion regarded as the M. zygomaticomandibularis by Yoshikawa et al. is an entirely different muscle from the M. zygomaticomandibularis of Toldt even though the nomenclature is the same and is a part of the M. temporalis.The nerve supply also indicated that these parts belong to the M. masseter, and there was no apparent need to separate these parts and give them independent names as being part of the improper masseter group.

The Skull of Hymenochirus curtipes.

Summary.The nasal capsule comprises a small tectum nasi, a septum nasi that is ossified posteriorly, a flat cartilago alaris and a long slender cartilago obliqua. The crista intermedia and its laminae are absent.The nasal cavities consist of three chambers which have been termed the cavum principale, the intermediate chamber and the recessus lateralis. Communicating with the latter is the organ of Jacobson, into the floor of which Jacobson's gland opens. There is no ductus nasolacrimalis or glandula intermaxillaris.The cranial nerves are discussed in connection with the lateral wall of the neurocranium. It is observed that there is a well‐marked preoptic root, but no distinct pila metoptica, the side wall between the foramen opticum and the foramen prooticum representing a combination of the pila metoptica and the pila antotica. It is considered that a prefacial commissure is present.The skull is strongly ossified. The nasals, the fused frontoparietals, the pterygoids and the parasphenoid are large. A small foramen parietale occurs in the fused fronto‐parietals. The pterygoids do not encircle the median Eustaehian aperture, which in section is seen to penetrate the exoccipitale. The sphenethmoicl region is cartilaginous and unpaired. There is no separate supra‐ethmoid or prevomer. The palatines and quadratojugals are lacking. The quadrate region is anteriorly situated. An ossified processus basalis of the quadrate is recognized. The processus pterygoideus is confluent with neighbouring parts, but the processus oticus forms a lateral cartilaginous wall between the pars media plectri and the middle ear.The musculus levator mandibulae anterior seems to be present, as the whole levator muscle occurs laterally and posteriorly to the ramus mandibularis V. The musculus depressor mandibulae consists of superficial and deep sections. Some of the fibres of the latter originate on the hinder process of the pars media plectri and on the posterior extremity of the ceratohyale.The hyobranchial skeleton consists of two completely separated parts. The copula and the ceratohyale are ossified.The affinities of Hymenochirus are discussed and some neotenie features are pointed out.