Pairs Of Cranial Nerves Research Articles

G. A. Klyachkin. Materials for scholarship about the origin and central movement of V, VI, VII, IX, X, XI and XII pairs of cranial nerves. - Diss. Kazan. 1897

The author, using the Marhci method, studied the central passage and the origin of the above cranial nerves on cats and dogs. In relation to the trigeminal nerve, the author comes to the conclusion that this nerve appears in the region of the middle part of the bridge in the composition of the two main roots - motor and sensory.

The Different Stages of Vestibular Neuritis from the Point of View of the Video Head Impulse Test.

Vestibular neuritis (VN) is one of the most common causes of acute vestibular syndrome (AVS). Quantifying the vestibulo-ocular reflex (VOR) gain by the video Head Impulse Test (vHIT) could provide useful information to diagnose VN. This study aims to retrospectively evaluate the VOR gain values during the acute and subacute stages of the VN and to correlate these values with the patients’ dizziness-related handicap. Medical record of 28 patients with VN were reviewed. Patients were assigned to two groups according to the time since the acute vestibular syndrome (AVS). One group with patients assessed within seventy-two hours since the AVS (AVSg) and one group with patients evaluated from four days to six weeks since the AVS (PAVSg). VOR gain was evaluated in all selected patients and correlated to Dizziness Handicap Inventory (DHI). Significant differences were found in the between-subjects analysis in DHI score (p = 0.000) and in the ipsilesional hVOR gain values (p = 0.001). The correlation analysis showed significant results (p = 0.017) between DHI score (40 ± 16.08) and ipsilesional VOR gain (0.54 ± 0.09) in the PAVSg. Patients evaluated within 72 h since the AVS showed anticompensatory saccades (AcS) turning the head toward the contralesional side. Patients with unilateral Superior VN (SVN) could have dissimilar hVOR gain values and DHI score according to the damage of the VIII pair of cranial nerves. AcS in the contralesional side is a sign of acute phase in patients with unilateral SVN.

Neuroman: Voxel Phantoms from Surface Models of 300 Head Structures Including 12 Pairs of Cranial Nerves.

For a precise simulation of electromagnetic radiation effects, voxel phantoms require detailed structures to approximate humans. The phantoms currently used still do not have sophisticated structures. This paper presents voxel and surface models of 300 head structures with cranial nerves and reports on a technique for voxel reconstruction of the cranial nerves having very thin and small structures. In real-color sectioned images of the head (voxel size: 0.1 mm), 300 structures were segmented using Photoshop. A surface reconstruction was performed automatically on Mimics. Voxel conversion was run on Voxel Studio. The abnormal shapes of the voxel models were found and classified into three types: thin cord, thin layers, and thin parts in the structures. The abnormal voxel models were amended using extended, filled, and manual voxelization methods devised for this study. Surface models in STL format and as PDF files of the 300 head structures were produced. The STL format has good scalability, so it can be used in most three-dimensional surface model software. The PDF file is very user friendly for students and researchers who want to learn the head anatomy. Voxel models of 300 head structures were produced (TXT format), and their voxel quantity and weight were measured. A voxel model is difficult to handle, and the surface model cannot use the radiation simulation. Consequently, the best method for making precise phantoms is one in which the flaws of the voxel and surface models complement each other, as in the present study.

Facial nerve paralysis

Abstract The facial nerve, the seventh pair of cranial nerves, has an essential role in non-verbal communication through facial expression. Besides innervating the muscles involved in facial expression, the complex structure of the facial nerve contains sensory fibres involved in the perception of taste and parasympathetic fibres involved in the salivation and tearing processes. Damage to the facial nerve manifested by facial paralysis translates into a decrease or disappearance of mobility of normal facial expression. Facial nerve palsy is one of the common causes of presenting to the Emergency Room. Most facial paralysis are idiopathic, followed by traumatic, infectious, tumor causes. A special place is occupied by the child’s facial paralysis. Due to the multitude of factors that can determine or favour its appearance, it requires a multidisciplinary evaluation consisting of otorhinolaryngologist, neurologist, ophthalmologist, internist. Early presentation to the doctor, accurate determination of the cause, correctly performed topographic diagnosis is the key to proper treatment and complete functional recovery.

Acute Trigeminal Nerve Neuritis in German Shepherd

Background: Trigeminal nerve is composed by ophthalmic, maxillary and mandibular portion, presenting sensory and motor functions. Its most common conditions include vascular, neoplastic, infectious and inflammatory causes. Neuritis is an inflammation caused by a primary nerve injury that can progress to demyelination and even degeneration of nerve fibers. The present report aims to describe an unusual case of a female dog, German Shepherd breed, with acute manifestation of trigeminal nerve neuritis whose etiology may be associated with erlichiosis, since infection with Ehrlichia spp. through serological test was verified.Case: A 3-year-old female German Shepherd , weighing 26.8 kg and not neutered, was attended at Veterinary Hospital Dr. Halim Atique - UNIRP, São José do Rio Preto, SP, Brazil presenting apathy, sialorrhea and polydipsia for seven days. The tutor reported an episode of foamy and yellowish vomit three days ago and ixodidiosis last week. Physical examination revealed flaccid open-mouthed posture, with mild bilateral masseter and moderate temporal muscle atrophy. Water was offered to the animal and it was observed that it could not properly seize, confirming a false polydipsia. The neurological examination revealed a slight decrease in head sensitivity, difficulty in chewing and seizure of food. It was not observed alterations in the other pairs of cranial nerves or other neurological parameters (postural reactions and spinal reflexes), and the diagnose of bilateral dysfunction of the trigeminal nerve was based on the affected neuroanatomic region. On neurological examination, other lesions of the nervous system were ruled out, suggesting an isolated manifestation of the trigeminal nerve. CBC revealed anemia, intense thrombocytopenia and leukocytosis by neutrophilia. Radiographic examination ruled out the possibility of trauma due to the absence of mandible fracture and also temporomandibular joint alterations. Masseter and temporal muscle biopsy were performed, and myositis or other masticatory muscle alterations were discarded among the diagnostic possibilities. Serological tests showed non-reactive results for toxoplasmosis and neosporosis, but reagent for Erlichia spp.Discussion: Idiopathic trigeminal neuritis (ITN) has an unknown etiology, but is not related to signs of systemic disease, and is usually not associated with deficits in other cranial nerves. The main clinical sign related to this condition is acute jaw paralysis, with inability to close the mouth, and in some cases is observed sensitivity deficits in face, as observed in the dog of this report during the neurological examination. In the patient of the present report, no justifiable causes were found for the presented symptoms, except the presence of erlichiosis. The treatment was based on the use of prednisone, doxycycline, antioxidants and vitamin complex. Response to treatment was satisfactory after seven days, and complete remission of clinical signs occurred nine days after its onset. Although cranial nerve neuritis is an uncommon clinical manifestation of erlichiosis, the patient in this study presented a good response to the treatment instituted, suggesting that erlichiosis is an important differential diagnosis for neuritis.

Nervi terminalis (“0” pair of cranial nerve) revisited from fishes to humans

According to classical teaching in medical colleges and institutes, there are 12 pairs of cranial nerves, attached to the brain. They are numbered in Roman numerals from I to XII in the craniocaudal order of their attachment on the brain. In fact, there are 13 pairs of cranial nerves, the one which is not taught is the nervus terminalis (NT), i.e., “0” pair of cranial nerve. It is attached rostral to all other cranial nerves. Although it has been clearly identified as an additional nerve in the vertebrate species including humans for more than a century, its functional role is also understood to some extent. Still, it could not find its place in the standard textbooks of anatomy. It has also been given different names, viz., nerve of Pinkus, NT, cranial nerve “0,” cranial nerve nulla, terminal nerve, and cranial nerve XIII.

Manifestations of herpes zoster ophthalmicus

The article reviews the main ocular features of Herpes Zoster Ophthalmicus (HZO) including Ramsay-Hunt and Tolosa-Hunt syndromes that involve III, IV and VI pairs of cranial nerves and I branch of the trigeminal nerve, and describes treatment methods of its active manifestations and postherpetic neuralgia, as well as herpes zoster vaccination practices.

Clinical diagnosis and treatment of chronic dizziness

Chronic dizziness is defined as a complex of symptoms lasting months or years, including oscillopsia, nystagmus, and postural instability. Diagnostic search includes peripheral vestibulopathy - chronic unilateral vestibulopathy resulting from vestibular neuronitis, schwannoma of the 8th pair of cranial nerves, medical or surgical ablation of the labyrinth, and bilateral vestibulopathy; central vestibulopathy - syndromes accompanied by central vertical nystagmus, small vessel disease in patients with chronic cerebral ischemia; general somatic diseases, peripheral polyneuropathy, side-effects of medications as well as persistent postural-perceptual dizziness. Often, when collecting an anamnesis, it is not possible to identify specific features of dizziness and instability, therefore, clinical and instrumental examination of the patient is of particular importance. In the otoneurological examination, the greatest attention is paid to static/coordination tests, oculomotor tests aimed at identifying signs of damage to the vestibulo-ocular reflex. The principles of treatment depend on the diagnosed cause of dizziness and instability and can, to varying degrees, combine pharmacotherapy, vestibular rehabilitation and psychotherapy, as well as correction of therapy for the underlying disease that caused vestibulopathy.

Medial axis segmentation of cranial nerves using shape statistics-aware discrete deformable models.

We propose a segmentation methodology for brainstem cranial nerves using statistical shape model (SSM)-based deformable 3D contours from T2 MR images. We create shape models for ten pairs of cranial nerves. High-resolution T2 MR images are segmented for nerve centerline using a 1-Simplex discrete deformable 3D contour model. These segmented centerlines comprise training datasets for the shape model. Point correspondence for the training dataset is performed using an entropy-based energy minimization framework applied to particles located on the centerline curve. The shape information is incorporated into the 1-Simplex model by introducing a shape-based internal force, making the deformation stable against low resolution and image artifacts. The proposed method is validated through extensive experiments using both synthetic and patient MRI data. The robustness and stability of the proposed method are experimented using synthetic datasets. SSMs are constructed independently for ten pairs (CNIII-CNXII) of brainstem cranial nerves using ten non-pathological image datasets of the brainstem. The constructed ten SSMs are assessed in terms of compactness, specificity and generality. In order to quantify the error distances between segmented results and ground truths, two metrics are used: mean absolute shape distance (MASD) and Hausdorff distance (HD). MASD error using the proposed shape model is 0.19 ± 0.13 (mean ± std. deviation) mm and HD is 0.21mm which are sub-voxel accuracy given the input image resolution. This paper described a probabilistic digital atlas of the ten brainstem-attached cranial nerve pairs by incorporating a statistical shape model with the 1-Simplex deformable contour. The integration of shape information as a priori knowledge results in robust and accurate centerline segmentations from even low-resolution MRI data, which is essential in neurosurgical planning and simulations for accurate and robust 3D patient-specific models of critical tissues including cranial nerves.

Method of preoperative labeling of lymph nodes affected by thyroid cancer metastases to facilitate their intraoperative identification

Objective. In surgical treatment of thyroid cancer, the appropriate resection of lymph nodes affected by metastases is mandatory. Minimally invasive inter­vention for metastatic process in thyroid cancer is alternative method of treatment in case of solitary neck metastases. The specific complications associa­ted with surgical trauma occur in cases of repeated interventions, namely the damage of Х, ХІ, and ХІІ pairs of cranial nerves, motor and sensory fibers of the cervical and brachial plexus, lymphorrhea. Complications associated with dissection of lymph drainage collectors lead to prolongation of post­operative stay in hospital. Thus, the need to minimize surgery risk and to increase efficacy of lymp­ha­den­e­ctomies in primary and repea­ted neck dissections emerges. The aim is to develop method of preoperative la­­beling of lymph nodes affected by thyroid cancer metastases to facilitate their intraoperative identi­fication. Materials and methods. The methylene blue dye for biological tissue labeling was used. In preoperative period, 24 hours before surgery FNAP was performed under the ultrasonography control with the purpose of metastatic lesion verification and then the 1 % solution of methylene blue dye was injected directly to affected node. During the dissection the labeled node was identified by its blue color. Results and discussion. Lymph nodes of different collector groups were labeled in 10 patients. The visual intraoperative identification of lymph node was feasible in all patients. The operation time was shortened in 9 patients (90 %). The mean decrease of operation time was 31.2 ± 7.6 min (p ≤ 0.05). The consecutive patho­logical investigation of all removed labelled lymph nodes confirmed the presence of metastatic thyroid cancer. Conclusion. The preoperative labeling of affected lymph nodes 24 hours ahead surgery is efficient, easy to use and cost-saving method of visualization which allows to mitigate excessive surgical traumatization during the lymph neck dissection and to decrease the operation time.

Drug-induced hearing loss as a manifestation of drug-induced ototoxicity

The ability of drugs to have an ototoxic effect has been studied for a long time, however, the true prevalence of this undesirable phenomenon is unknown, which is due to the use of various audiological protocols, a wide range of reactions to drugs in different ethnic groups, and most importantly, the lack of caution with regard to otological symptoms due to their reversibility or lack of immediate threat to life. Drug-induced ototoxicity is a functional disorder of the inner ear (cochlea and/or vestibular apparatus) or eighth pair of cranial nerves. Pharmacotherapy, associated with the development of ototoxic drug reactions, may remain undervalued for a long time, often until irreversible hearing impairment is formed. The most frequently prescribed drugs that cause ototoxic phenomena include anticancer drugs, antibacterial drugs of the aminoglycoside group, loop diuretics, calcium channel blockers, non-steroidal anti-inflammatory drugs, antimalarial drugs, salicylates, etc. Monitoring the degree of hearing impairment before and during therapy is important in preventing the development of drug-induced ototoxicity and makes it possible to consider alternative treatment regimens in a timely manner. It is in this connection that the role of participation in the appointment of rational pharmacotherapy to patients with a potential risk of developing otological phenomena of a clinical pharmacologist and audiologist undoubtedly increases.

Cranial Pair II: The Optic Nerves.

The optic nerves (ONs), one of the 12 pairs of cranial nerves (Pair II), together with the olfactory and the cochlear nerves, are devoted to transmit sensory inputs. In particular, ONs convey visual information from the retina to the brain. In mammals, the ONs are bilateral structures that extend from the optic disc to the optic chiasm containing glial cells and retinal ganglion cells (RGCs) axons. RGCs are the only retinal neurons able to collect visual information and transmit it to the visual centers in the brain for its processing and integration with the rest of sensory inputs. During embryonic development, RGCs born in the retina extend their axons to exit the eye and follow a stereotypic path outlined by the transient expression of a wide set of guidance molecules. As the rest of central nervous system structures, the ONs are covered with myelin produced by oligodendrocytes and wrapped by the meninges. ON injuries or RGCs degenerative conditions may provoke partial or complete blindness because they are incapable of spontaneous regeneration. Here, we first review major advances on the current knowledge about the mechanisms underlying the formation of the ONs in mammals. Then, we discuss some of the human disorders and pathologies affecting the development and function of the ONs and finally we comment on the existing view about ON regeneration possibilities. Anat Rec, 302:428-445, 2019. © 2018 Wiley Periodicals, Inc.

Amaurosis and contralateral cranial nerve pairs III and VI paralysis after peribulbar block - case report

Peribulbar anesthesia has emerged as a safer option compared with intraconal retrobulbar block. Still, peribulbar anesthesia may not be considered without risk. Numerous complications have been described when performing this technique. This report aims to describe a rare case of amaurosis and contralateral paralysis while attempting to perform a peribulbar anesthesia. Male patient, 75-year old, physical status ASA II, undergoing cataract surgery by phacoemulsification with intraocular lens implantation. Sedated with fentanyl and midazolam and subjected to peribulbar anesthesia. There were no complications during surgery. After finishing the procedure, the patient reported lack of vision in the contralateral eye. Akinesia of the muscles innervated by the cranial nerve pairs III and VI, ptosis, and medium-sized pupils unresponsive to light stimulus were observed. Four hours after anesthesia, complete recovery of vision and eyelid and eyeball movements was seen in the non-operated eye. During peribulbar anesthesia, structures located in the intraconal space can be accidentally hit leading to complications such as described in the above report. Following the technical guidelines and using appropriate size needles may reduce the risk of such complication, but not completely.

Visual status of patient with syndrome of Moebius

PurposeTo analyze functional state of visual status in a patient with Moebius syndrome during 16 years of follow‐up.MethodsRetrospective analysis of clinical course of Moebius syndrome in a patient in the age 0.5 ‐ 16 years.ResultsParents appealed to the Institute because of unusual state of the child (lack of facial expressions and eye mobility). After the ophthalmologic and neurological examination, a diagnosis was made: Moebius syndrome. Underdevelopment of VII, IX, XII pairs of cranial nerves. Myopic astigmatism. At 10 years old facial asymmetry, exotropy with vertical component, positive traction test on both sides and lagophthalmus 3 mm at downgaze were noted. Best corrected visual acuity of both eyes is 0.2. Perimetry both eyes: concentric narrowing up to 40º from temporal and nasal sides, up to 20º from above and from below. Optic discs are pale, there are pigmentless sections of retinal dystrophy on the periphery and near the optic discs. Pleoptoortoptic treatment was carried out. As a result of regular courses of electrostimulation of extraocular muscles, by the age of 16, a tendency to insignificant motility of the eyes upwards appeared. Convergence was absent. Best corrected visual acuity decreased to 0.1 in both eyes. Significant help in diagnosis was provided by computer pupillography [Bushuyeva NN et al., 2003], which accurately records and measures pupil area. The initial size of the pupil area was: on the right eye 17.9 sq mm, and on the left eye 13.1 sq mm. After the flash, the pupil of the left eye narrowed to 3.7 sq mm and the right eye ‐ to 15.2 sq mm.ConclusionsPupillography allows evaluating vegetative nervous system status in Moebius syndrome patients. Electrostimulation of extraocular muscles allows slightly improving ocular motility of these patients. Obtained data needs further investigations on larger number of patients

The experience with the surgical treatment of glomus tumours

glomus tumours of the temporal bones rank second after neurinomas of the VII-th pair of cranial nerves among the pathological conditions that are likely to cause hearing mpairment. Being extensively vascularized locally invasive neoplasms, glomus tumours constitute a serious challenge for the surgeon because of their localization in the vicinity of the vitally important vascular and neural structures of the lateral skull base. To characterize some peculiar features of the surgical interventions and postoperative management of the patients presenting with different types of glomus tumours. our experience is based on the surgical treatment of 15 patients with glomus tumours of the temporal bones of varying extent and localization. It is concluded that the magnitude and extent of the surgical intervention and of the follow-up examination depend on the spread of the neoplasm. The treatment of the B, S, D - type tumours implies the necessity of pre-operative embolization of the vessels feeding the neoplasm.

Magnetic resonance imaging of optic nerve.

Optic nerves are the second pair of cranial nerves and are unique as they represent an extension of the central nervous system. Apart from clinical and ophthalmoscopic evaluation, imaging, especially magnetic resonance imaging (MRI), plays an important role in the complete evaluation of optic nerve and the entire visual pathway. In this pictorial essay, the authors describe segmental anatomy of the optic nerve and review the imaging findings of various conditions affecting the optic nerves. MRI allows excellent depiction of the intricate anatomy of optic nerves due to its excellent soft tissue contrast without exposure to ionizing radiation, better delineation of the entire visual pathway, and accurate evaluation of associated intracranial pathologies.

Dysregulation of the descending pain system in temporomandibular disorders revealed by low-frequency sensory transcutaneous electrical nerve stimulation: a pupillometric study.

Using computerized pupillometry, our previous research established that the autonomic nervous system (ANS) is dysregulated in patients suffering from temporomandibular disorders (TMDs), suggesting a potential role for ANS dysfunction in pain modulation and the etiology of TMD. However, pain modulation hypotheses for TMD are still lacking. The periaqueductal gray (PAG) is involved in the descending modulation of defensive behavior and pain through μ, κ, and δ opioid receptors. Transcutaneous electrical nerve stimulation (TENS) has been extensively used for pain relief, as low-frequency stimulation can activate µ receptors. Our aim was to use pupillometry to evaluate the effect of low-frequency TENS stimulation of μ receptors on opioid descending pathways in TMD patients. In accordance with the Research Diagnostic Criteria for TMD, 18 females with myogenous TMD and 18 matched-controls were enrolled. All subjects underwent subsequent pupillometric evaluations under dark and light conditions before, soon after (end of stimulation) and long after (recovery period) sensorial TENS. The overall statistics derived from the darkness condition revealed no significant differences in pupil size between cases and controls; indeed, TENS stimulation significantly reduced pupil size in both groups. Controls, but not TMD patients, displayed significant differences in pupil size before compared with after TENS. Under light conditions, TMD patients presented a smaller pupil size compared with controls; the pupil size was reduced only in the controls. Pupil size differences were found before and during TENS and before and after TENS in the controls only. Pupillometry revealed that stimulating the descending opioid pathway with low-frequency sensory TENS of the fifth and seventh pairs of cranial nerves affects the peripheral target. The TMD patients exhibited a different pattern of response to TENS stimulation compared with the controls, suggesting that impaired modulation of the descending pain system may be involved in TMD.

Patología de los pares craneales

There are 12 pairs of cranial nerves (CN). The central involvement may be due to multiple causes and other commonly associated injury CN and long routes. In peripheral lesions predominate as causal agents extrinsic compression, trauma or microisquemia and associated involvement of other CN at points where they share a common path. Damage to the oculomotor CN produces ophthalmoparesis, diplopia, ptosis and pupillary abnormalities. There are facial and oropharyngeal sensory impairment and masticatory injury paresis CN V. The CN VII palsy causes the affected facial expression muscles, sometimes associated with xerophthalmia, hyperacusis or dysgeusia. Hearing loss, tinnitus and vertigo result from injury VIII CN. Involvement of CN IX cause dysphagia, and X CN also associated cardiorespiratory dysphonia and vegetative disturbances. The trapezius and sternocleidomastoid paralysis due to injury CN XI and lingual muscles of CN XII.

ВОЗМОЖНЫЕ ПУТИ ОПТИМИЗАЦИИ ДИАГНОСТИЧЕСКОЙ ПОМОЩИ БОЛЬНЫМ С СИМПТОМАТИЧЕСКОЙ ЭПИЛЕПСИЕЙ НА ФОНЕ ХРОНИЧЕСКОГО ГЕРПЕСВИРУСНОГО ЭНЦЕФАЛИТА

The aim of our research was search of possible ways to optimize the diagnostic care for patients with symptomatic focal epilepsy with chronic parainfectious encephalitis associated with viruses of the family Herpes viridae. Materials and Methods. The study included 180 patients (107 women and 73 men) aged 18 to 50 years. Diagnostic methods include analysis of objective and subjective neurological symptoms, video-EEG monitoring, multimodal evoked potentials, brain MRI, laboratory methods (hemogram, immunogram, antibody titers of IgG and IgM to antigens of viruses HSV-1, HSV-2, CMV, VZV, HHV-6 and EBV, antibody avidity). Results. Relapsing course labial / facial herpes with subacute course was recorded in 93.1% of patients without epilepsy versus 95.7% patients with epilepsy (φ=0,764, p>0.05). Patients had a combined lesion of the central and peripheral nervous system involvement in the pathological process of II and VIII of the pairs (usually), V and VII pairs of cranial nerves (rarely), and the presence of chronic diseases of the paranasal sinuses in the form of chronic hyperplastic sinusitis. Patients with epilepsy, the total concentration of the major classes of immunoglobulins was smaller compared with uncomplicated encephalitis (IgA – 1,12 g/l vs. 1,5 g/l; IgG – 10,3 g/l vs. 13.8 g/l). This indicates a highly probable functional deficiency of B-lymphocytes and is manifested in the reduction antiteloproduktsii that promotes slow accumulation of specific antibodies, chronic process, an increase in viral load and associated complications. Reduced visual afferentation was 65.5% cases of encephalitis without epilepsy vs. 62.4% encephalitis with epilepsy. Reduced hearing afferentation observed less frequently (24.1% vs. 26.9%, respectively). Changes in cognitive evoked potentials identified in 28.7% cases of encephalitis without epilepsy vs. 53.8% encephalitis with epilepsy. Conclusions. Possible ways to optimize the diagnostic care for patients with symptomatic epilepsy parainfectious include a multidisciplinary approach (neurologist, neuroscientist, epileptologist, immunologist, otolaryngologist, ophthalmologist, psychotherapist), immune status, serum antibodies to herpesviruses, video-EEG monitoring, multimodal evoked potentials, neuropsychological testing, brain MRI with contrast, MR spectroscopy mediobasal (limbic) parts of brain.

Clinical anatomy of the cranial nerves

We are very happy to present this Special Issue on the cranial nerves to the readers of Clinical Anatomy. The history of the exploration of the cranial nerves and elucidation of their anatomy is ancient. Galen's classification of the cranial nerves (Table 1), notably excluding the olfactory nerves, was composed of seven pairs where it is interesting to note that the sixth pair included the glossopharyngeal, vagus and accessory nerves all travelling through the jugular foramen (Clarke and Jacyna, 1987). The cranial nerves were essentially identified, numbered and characterized based on the opening through which they exited the skull base. Our knowledge of the cranial nerves became more clearly discussed and disseminated by such medieval Middle Eastern and European scholars as Rhazes, Avicenna, Jorjani, Mundinus, Benedetti, Achillini, Massa and Berengario de Carpi (Shoja et al., 2007; Shaw, 1992). The Galenic seven-pair classification of the cranial nerves remained unchanged for more than a millennium until the celebrated German physician and anatomist, Samuel Thomas von Sömmerring, in 1778, implemented a novel classification scheme that is still used today (Squire et al., 2013). Niccolo Massa, an Italian physician and anatomist, was probably the first anatomist in Europe who challenged Galen's classification scheme by enumerating the olfactory nerves as the first pair of cranial nerves. Thomas Willis is notable for his work enumerating and illustrating nine cranial nerve pairs, including the olfactory nerves as the first pair and counting the trochlear, trigeminal and abducens nerves individually (Casey, 2007; Shaw, 1992). In this special issue of Clinical Anatomy, we have attempted to include a wide range of relevant articles with emphasis on their originality and clinical applications of the cranial nerves. The review article by Dr. Vilensky on cranial nerve 0 or the “neglected cranial nerve” is very informative. The special issue contains a landmark study by Dr. Tubbs and his colleagues, which represents “the largest study to date documenting the presence of a cranial root of the accessory nerve.” An article by Dr. Hendrix and colleagues (2014) on the arterial supply of the lower cranial nerves is one that needs specific mention. Skull base surgeons are often perplexed by the fact that following resection of a vestibular schwannoma, some patients develop facial nerve paralysis without their facial nerve being traumatized during the operation. The vast and complex anatomy of the cranial nerve blood supply may provide an explanation for this observation. Whether a proportion of patients with facial paralysis following tumor resection suffer from acute ischemic neuropathy secondary to arterial disruption needs further research. The first step in such research is to elucidate the anatomy of the arterial supply. The two articles on the anastomoses between lower cranial and upper cervical nerves (see Shoja et al., 2014a, 2014b) are products of an over three year review, which attempted to further elucidate the anatomy of the neural network formed by the lower cranial and upper cervical nerves and their branches. The reviews conclude that these nerves “with their extra-axial communications can be collectively considered a plexus.” The anatomy of this craniocevical nerve plexus needs to be revisited and appreciated in the anatomical literature. Ultimately, we hope that clinical anatomists from around the world will enjoy reading this issue and find its contents valuable in their teaching and research.