Search

The soft-tissue reconstruction and associated osteology of the North American therizinosaurian Nothronychus mckinleyi is updated. The cranial nerve topology is revised, bringing it more in line with coelurosaurs. The trunk of the trigeminal nerve is very short, with an incompletely intracranial trigeminal ganglion, an ophthalmic branch diverging anteriorly first, with later divergences of the maxillomandibular branches, following typical pathways. The facial nerve has been re-evaluated, resulting in a very typical configuration with an extracranial geniculate ganglion. The single foramen leading to the cochlea probably transmitted the vestibulocochlear nerve, along with some fibers of the facial. This configuration is reduced from the more standard three foramina (vestibular, cochlear, and facial) and may be apomorphic for therizinosaurs. Some alteration is proposed for the dorsiflexive musculature. The insertion point for m. transversospinalis capitis is partially changed to extend onto the parietal, along with a proposed functional difference in the moment arm. The expansion of the basicranial pneumatic system is limited to the paratympanic system, enhancing low frequency sound sensitivity. There is little expansion of the median pharyngeal and subcondylar sinuses. Ossification of the surrounding epithelium may provide some information on the embryology of the theropod skull. It may be associated with a reduced stress field, or the general similarity of the basicranium with anterior cervical vertebrae may reflect activation of a cervical vertebral (Hox) gene regulating ossification of the pneumatic sinuses. This might be a local, selectively neutral, fixed gene in the basicranium reflecting embryological regulation of cervical vertebrae development., Competing Interests: The authors have declared that no competing interests exist.

For accurate interpretation of magnetic resonance (MR) images of the equine brain, knowledge of the normal cross-sectional anatomy of the brain and associated structures (such as the cranial nerves) is essential. The purpose of this prospective cadaver study was to describe and compare MRI and computed tomography (CT) anatomy of cranial nerves' origins and associated skull foramina in a sample of five horses. All horses were presented for euthanasia for reasons unrelated to the head. Heads were collected posteuthanasia and T2-weighted MR images were obtained in the transverse, sagittal, and dorsal planes. Thin-slice MR sequences were also acquired using transverse 3D-CISS sequences that allowed mutliplanar reformatting. Transverse thin-slice CT images were acquired and multiplanar reformatting was used to create comparative images. Magnetic resonance imaging consistently allowed visualization of cranial nerves II, V, VII, VIII, and XII in all horses. The cranial nerves III, IV, and VI were identifiable as a group despite difficulties in identification of individual nerves. The group of cranial nerves IX, X, and XI were identified in 4/5 horses although the region where they exited the skull was identified in all cases. The course of nerves II and V could be followed on several slices and the main divisions of cranial nerve V could be distinguished in all cases. In conclusion, CT allowed clear visualization of the skull foramina and occasionally the nerves themselves, facilitating identification of the nerves for comparison with MRI images., (© 2015 American College of Veterinary Radiology.)

Objective: To investigate the anatomical structures of cranial nerves in the cerebellopontine angle region to offer anatomical data for clinical operation., Method: A total of 52 adult cadaveric heads fixed in 10% formalin were used for this study. After cutting cerebellum and meningeal between transverse and sigmoid sinus, simulate operating method of retrosigmoid approach to observe the cranial nerves., Result: External diameter and length of left V, VII, VIII, IX cranial nerves are (2.54 +/- 0.84) mm and (6.79 +/- 2.51) mm, (1.18 +/- 0.31) mm and (9.89 +/- 2.66) mm, (2.17 +/- 0.52) mm and (9.92 +/- 2.61) mm, (0.77 +/- 0.24) mm and (10.34 +/- 3.12) mm respectively. External diameter and length of right V , VII, VIII, IX cranial nerves are (2.52 +/- 0.86) mm and (6.91 +/- 2.66) mm, (1.14 +/- 0.31) mm and (10 +/- 2.96) mm, (2.13 +/- 0.63) m and (10.09 +/- 2.93) mm, (0.790.29) mm and (10.17 +/- 3.06) mm. intermedius nerve locate between facial nerve and acoustic nerve, external diameter of intermedius nerve is (0.47 +/- 0.91) mm (left) and (0.37 +/- 0.07) mm (right). Length of vagal nerve is (10.44 +/- 2.57) mm (left), (9.91 +/- 2.91) mm (right), rootlets of f vagal nerve is 6.37 +/- 2.26 (left) and 6.33 +/- 2.38 (right). external diameter of accessory nerve is (0.76 +/- 0.16) mm (left) and (0.81 +/- 0.19) mm (right)., Conclusion: This study provide anatomical data for retrosigmoid approach in the cerebellopontine angle region.

This study reports a review of the literature on the structural anatomy of the Vth, VIIth, VIIIth, IXth, and Xth cranial nerves, known to harbor dysfunction syndromes in humans. Because these dysfunctions are hypothesized to be caused by neurovascular conflicts at the root entry/exit zone and the transitional zone between central and peripheral myelinization, this investigation focused on the study and description of this junction. All the cranial nerves, except the optic and olfactory nerves, which are considered to be more a direct expansion of the central nervous system, have a transitional zone between central myelin (coming from oligodendrocytes) and peripheral myelin (produced by Schwann cells). The human studies reported in the literature argue in favor of a dome-shaped transitional zone directed to the periphery. It seems that this junctional region is situated more peripherally in sensory nerves than in motor nerves. The transitional zone is situated very peripherally for the cochlear and vestibular nerves, and on the contrary very close to its exit from the brain stem for the facial nerve.

This article discusses the upper cranial nerves (I, III-VIII) and their anatomy as it pertains to intra-axial nuclei and tracts, cisternal portions, and extracranial portions. In addition, the most common pathologic processes affecting the upper cranial nerves are discussed and illustrated. Because the evaluation of small structures requires imaging techniques that provide high resolution and contrast, MR imaging is the examination of choice. CT still plays a limited but important role in the evaluation of intraosseous portions of some cranial nerves.

Knowledge of the nuclear origins and the normal course of the cranial nerves, and their functional components, is important in any evaluation of cranial neuropathy. MR imaging allows detailed evaluation of cranial nerve anatomy and pathology. Newer MR sequences allow more sensitive methods of detecting pathology and determining the cause of cranial neuropathy. The correlation of clinical findings with MR images will allow for more definitive evaluation.

Four areas of the brain which receive primary projections from chemical senses ([1] olfactory bulb, [2] gustatory area including facial and vagal lobes), the eye ([3] optic tectum), and mechanosensory, and-hair-cell based systems i.e. the lateral line, vestibular and auditory systems ([4] trigeminal and octavolateral regions) have been studied and relative size differences used to make deductions on the sensory preferences of 35 fish species living on or near the bottom of the deep sea. Furthermore the relative volumes of the telencephalon and the corpus cerebelli were determined. Two evaluation modes were applied: (1) the relative mean of each system was calculated and species with above-average areas identified; (2) a cluster analysis established multivariate correlations among the sensory systems. The diversity of sensory brain areas in this population of fish suggests that the benthic and epibenthic environment of the abyss presents a rich sensory environment. Vision seems to be the single most important sense suggesting the presence of relevant bioluminescent stimuli. However, in combination the chemical senses, smell and taste, surpass the visual system; most prominent among them is olfaction. The trigeminal/octavolateral area indicating the role of lateral line input and possibly audition is also well represented, but only in association with other sensory modalities. A large volume telencephalon was often observed in combination with a prominent olfactory system, whereas cerebella of unusually large sizes occurred in species with above-average visual, hair-cell based, but also olfactory systems, confirming their role as multimodal sensorimotor coordination centers. In several species the predictions derived from the volumetric brain analyses were confirmed by earlier observations of stomach content and data obtained by baited cameras., (Copyright 2001 S. Karger AG, Basel)

The communication between the auriculotemporal and the facial nerves, i.e. the communicating auriculotemporal nerves (CATN), was studied in 55 facial sides from Thai cadavers. CATN only joined the temporofacial (upper) division of the facial nerve. CATN patterns were classified as follows: (1) the facial nerve was joined by 1 CATN (20.7%), (2) by 2 separate CATN branches (60.4%), (3) by 3 separate CATNs (15.1%); (4) several CATNs ran parallel to the zygomatic and buccal nerves to the muscles of facial expression (3.8%). The 4 types of CATN pattern showed further variations according to the site of union with the facial nerve. The superficial temporal artery was crossed by CATN branches anteriorly in 47.1%, posteriorly in 18.9%, and anteriorly and posteriorly in 34.0% of the cases. The facial nerve branches that were joined by CATNs were observed to supply the upper muscles of facial expression, i.e. frontalis, orbicularis oculi and zygomaticus major. Some offshoots from CATNs were seen to innervate orbicularis oculi. On the basis of our results we suggest that CATNs may convey proprioceptive impulses from orbicularis oculi.

Electroreception evolved in the catfishes probably as a specialization of the mechanosensory lateral line system. Fibers of the anterior lateral line nerve in catfishes innervate electrosensory ampullary organs and mechanosensory neuromasts of the head lateral line system. The purpose of this study is to determine the projection patterns of the major principal branches of the ALLN and to investigate the topography within the various nuclei of the terminal fields of these different branches. Fibers of the superficial ophthalmic, buccal and hyomandibular branches of the anterior lateral line nerve terminate in a somatotopic fashion within medullary and cerebellar nuclei. These fibers project to, and terminate within, several discrete nuclei in the medulla and cerebellum, notably the electrosensory lateral line lobe, the medial and caudal octavolateralis nuclei, and portions of a nuclear complex in the cerebellum called the eminentia granularis. Furthermore, the dorsoventral somatotopy in the medullary electrosensory nucleus is a reversed or 'mirror' image of that in the mechanosensory nucleus. This reversed map is similar to that observed in other electrosensory systems and suggests that there may be a common mechanism for the copying and preservation of spatial information as new systems are evolved from primitive sensory pathways.

On 119 brain stem halves the nerve root fasciculi of the intermediary nerve were examined in respect of their position relative to the facial and vestibulocochlear nerves. The following variants were seen: 1.) the intermediary nerve lies between the facial and vestibulocochlear nerves as stated in the textbooks, in 32.9% of the cases; 2.) in 18.5% of the cases it is entirely apposited to the vestibulocochlear nerve from the beginning and branches off from that nerve only later; 3.) part of the nerve root fasciculi are apposited to the vestibulocochlear nerve and the others originate between the facial and vestibulocochlear nerves. This was seen in 49.6% of the cases.

The course of the seventh to twelfth cranial nerves in the posterior fossa is described. The relation between the nerves and the cranial vessels, as well as their importance in practical medicine are discussed.

The topographic relationships of the superficial roots and ganglia of the anterior lateral line nerve (NLLa) to each other and to cranial nerves V, VII and VIII were studied, in the smooth dogfish Mustelus canis, by dissection of Sudan Black B stained specimens. NLLa consists of four branches: namely, superficial ophthalmic, buccal, otic and external mandibular. Each branch carriers lateral line neurons exclusively and forms a dorsal root and a ventral root which enter the anterior lateral line lobe and posterior lateral line lobe of the medulla respectively. It is estimated that slightly more than 50% of the fibers of the superficial ophthalmic, approximately 60% of the fibers of the buccal, at least 35% of the fibers of the otic and about 20% of the fibers of the external mandibular constitute the dorsal root. The ventral root is comprised of less than 50% of the fibers of the superficial ophthalmic, 40% of the fibers of the buccal, at least 50% of the fibers of the otic, and 80% of the fibers of the external mandibular. These results are correlated with the peripheral distribution and central termination of NLLa and it is concluded that the dorsal root carries axons from ampullary receptors and the ventral root carries fibers that innervate ordinary lateral line sense organs.

By horseradish peroxidase (HRP) labelling the course and origin of the II-X cranial nerves are identified in the teleost fish Gnathonemus petersii. Roots as well as motor and sensory nuclei in the viscero- and somatomotor and somatosensory areas are localised. Earlier data of comparative and experimental anatomical observations are completed, partly confirmed or corrected.

Twenty-one rabbits received injection of Indian ink into the stylomastoid foramen. Observation of the serial sections of their temporal bones revealed Indian ink infiltration into the subarachnoid space, along the facial nerve, the auricular branch of the vagus nerve and the tympanic nerve. Along the acoustic nerve, the infiltration was found as far as the fundus of the internal auditory meatus. In some cases, however, Indian ink reached the subarachnoid space and infiltrated into the scala tympani, scala vestibuli and around the saccule by way of the cochlear aqueduct. These routes are suspected to be a course of spreading infection or tumor cells.

Nerve degeneration studies were performed to determine the central projections of the octavus nerve in the guitarfish. Rhinobatos sp. Most first-order octavus nerve afferents are confined to the ventral longitudinal column of the medulla, which consists of four octavus nuclei: the nucleus octavus anterior (NOA), nucleus octavus magnocellularis (NOM), nucleus octavus descendens (NOD); and nucleus octavus posterior (NOP). Central projections of the octavus nerve outside of the ventral octavus nuclear column are to the vestibulolateral lobe of the cerebellum, the large multipolar cells that lie deep to the cerebellar crest of nucleus intermedius, the reticular formation, and the nucleus octavolateralis efferens. In addition, the cytoarchitectural features of the four octavus nuclei have been analyzed: the NOA consists of large spindle-shaped neurons and medium-sized multipolar neurons; the NOM is a small nucleus consisting of very large multipolar neurons; the NOD contains several types of neurons including large spindle-shaped neurons, large multipolar neurons, and polymorphic small and medium-sized neurons; and the NOP contains small spherical and small multipolar neurons evenly distributed throughout the nucleus. On the basis of the morphology of the neurons, the NOA and NOD appear to have subdivisions suggesting a more complex organization of the octavus nuclear column than previously recognized.

Acousticolateral systems were examined by means of the horseradish peroxidase tracing method in a teleost (Sebastiscus marmoratus). The torus semicircularis projected bilaterally to the optic tectum, nucleus ventromedialis thalami of Schnitzlein ('62), and reticular formation; contralaterally to the torus semicircularis; and ipsilaterally to the nucleus preglomerulosus of Schnitzlein ('62) and the inferior olive. No topographic organization was detected between the torus semicircularis and the nucleus preglomerulosus. Ipsilateral inputs to the torus were from dorsal telencephalic areas (pars centralis, Dc; pars dorsalis, Dd; and the dorsal part of pars medialis, dDm) and the optic tectum. Contralateral inputs to the torus were from the torus semicircularis, a caudal part of the cerebellum, and a portion of the trigeminal complex. The torus also received bilateral input from the nucleus ventromedialis thalami, nucleus of lemniscus lateralis, nucleus medialis, anterior octaval nucleus, descending octaval nucleus, and the reticular formation. Retrogradely labeled cells in the octaval nuclei were seen predominantly subsequent to HRP injections in the medial torus, while cells in the nucleus medialis were retrogradely labeled following injections into the lateral torus. HRP injections into the nucleus preglomerulosus labeled cells in the superficial region of the torus, while injections into the nucleus ventromedialis thalami labeled cells in the deep region. The nucleus preglomerulosus received inputs bilaterally from the nucleus of the lemniscus lateralis and reticular formation and ipsilaterally from the dorsal telencephalic areas (Dc, Dd, and dDm) and the torus semicircularis. In turn the nucleus preglomerulosus projected to Dd and Dm. Fibers arising in the nucleus ventromedialis thalami ended in Dc, Dd, Dm, and area ventralis pars supracommissuralis (Vs). Homology between the nucleus preglomerulosus and the central thalamic nucleus in amphibians, the nucleus reuniens in reptiles, the nucleus ovoidalis in birds, and the medial geniculate body in mammals is discussed.