Functional and morphological evaluation of the trapezius muscle after spinal accessory nerve transfer to brachial plexus nerves.

INTRODUCTION: The main innervation of the trapezius muscle is provided by the spinal accessory nerve. Several studies describe the contributions of cervical plexus roots to the trapezius muscle innervation, either directly or through connections with the spinal accessory nerve. There is no adequate understanding of how the trapezius muscle is affected after using the spinal accessory nerve in nerve transfer procedures with the usual technique, preserving at least 1 branch for the upper trapezius. METHODS: We evaluated 20 patients with sequelae of traumatic brachial plexus injury who underwent surgical procedures for brachial plexus repair or free muscle transfer, which included the spinal accessory nerve transfer technique and were followed for a minimum of 1 year. The three portions trapezius muscle were evaluated by physical examination, magnetic resonance imaging (analysis of fatty degeneration) and electromyography. RESULTS: In all evaluation methods, the middle and lower portions of the trapezius muscle showed more significant morphological and/or functional impairment than the upper portion, in most cases. There was a statistically significant difference in all the complementary exams results, between the affected side (with sacrifice of the nerve) versus the normal side, in the middle and lower portions of the trapezius muscle. CONCLUSIONS: Physical examination alone is not sufficient to determine the residual functionality of the trapezius muscle. Magnetic resonance imaging and electromyography are useful tools to assess both morphological involvement of the trapezius muscle and nerve conduction impairment of the trapezius muscle, respectively. The results suggest that the middle and lower portions of the trapezius muscle are affected by previous SAN transfer and should be considered with caution for further muscle transfer procedures.

Extracranial hypoglossal neurofibroma with a variant ansa cervicalis: a case report.

PURPOSE: This case report aims to explore a rare combination of findings in a cadaver donor: variant ansa cervicalis, vagus (CN X) and hypoglossal (CN XII) nerve fusion, and extracranial hypoglossal neurofibroma. BACKGROUND: The type of ansa cervicalis variation presented in this report has been documented in less than 1% of described cases. The CN X-CN XII fusion has been reported in one prior study. Additionally, hypoglossal neurofibromas are benign neoplasms of the peripheral nerve sheath. There are only two known cases of extracranial hypoglossal neurofibroma described in the literature. CASE REPORT: The study investigated a swelling of the right CN XII in a 90-year-old female cadaver donor. Detailed dissection, examination of the region, and histopathological analysis of the mass followed. The entire course of CN XII and other cranial nerves were examined to exclude concurrent pathology. A fusiform enlargement of the right CN XII was observed in the submandibular region, measuring ~ 1.27 × 1.27 cm. The superior portion of the right CN XII was fused to the right CN X, exiting the jugular foramen. The superior root of ansa cervicalis, normally a branch of CN XII, was found to arise from CN X on the right side. The left CN XII and CN X were unremarkable. Histopathological examination revealed benign neurofibroma. CONCLUSION: The anatomical variation and rare location of the tumor necessitate further investigation to better understand pathogenesis, clinical correlation, and surgical implications. This study furthers knowledge of this condition and contributes to the currently limited body of research.

Delineation and histological examination of the intramuscular innervation of the platysma: Application to botulinum neurotoxin injection.

This study aimed to identify the whole innervation pattern of the platysma using the Sihler's staining, and the axonal composition profile of the sensory-motor anastomosis identified by immunofluorescence assays. The findings provide a comprehensive understanding of the neural anatomy of the platysma and facilitate efficient and safe manipulation for neurotoxin injection. Ten fixed and two fresh hemifaces were included in this study. Sihler's staining was used to the study 10 fixed hemifaces and two fresh hemifaces were used for immunofluorescence assays. In all cases, the cervical branch of facial nerve (Cbr) broadly innervated the platysma, and the marginal mandibular branch of facial nerve (MMbr) provided supplementary innervation to the uppermost part of the platysma. The transverse cervical nerve (TCN), great auricular nerve (GAN), and supraclavicular nerve (SCN) were observed in the lower half of the platysma. In 30% of all cases, there was a communicating loop between the Cbr and TCN. In 20% of all the cases, a communicating branch joined between the Cbr and GAN. For successful esthetic rejuvenation procedures, a clinician should consider the Cbr distribution to the overall platysma and additionally innervation by individual nerves (MMbr, GAN, TCN, and SCN) to the middle and lower portions of the platysma muscle.

The Great Auricular Nerve Trigger Site: Anatomy, Compression Point Topography, and Treatment Options for Headache Pain.

BACKGROUND: Peripheral nerve decompression surgery can effectively address headache pain caused by compression of peripheral nerves of the head and neck. Despite decompression of known trigger sites, there are a subset of patients with trigger sites centered over the postauricular area coursing. The authors hypothesize that these patients experience primary or residual pain caused by compression of the great auricular nerve. METHODS: Anatomical dissections were carried out on 16 formalin-fixed cadaveric heads. Possible points of compression along fascia, muscle, and parotid gland were identified. Ultrasound technology was used to confirm these anatomical findings in a living volunteer. RESULTS: The authors' findings demonstrate that the possible points of compression for the great auricular nerve are at Erb's point (point 1), at the anterior border of the sternocleidomastoid muscle in the dense connective tissue before entry into the parotid gland (point 2), and within its intraparotid course (point 3). The mean topographic measurements were as follows: Erb's point to the mastoid process at 7.32 cm/7.35 (right/left), Erb's point to the angle of the mandible at 6.04 cm/5.89 cm (right/left), and the posterior aspect of the sternocleidomastoid muscle to the mastoid process at 3.88 cm/4.43 cm (right/left). All three possible points of compression could be identified using ultrasound. CONCLUSIONS: This study identified three possible points of compression of the great auricular nerve that could be decompressed with peripheral nerve decompression surgery: Erb's point (point 1), at the anterior border of the sternocleidomastoid muscle (point 2), and within its intraparotid course (point 3).

Dissecção do plexo cervical na formação médica: aplicabilidades clínicas e cirúrgicas / Dissection of the cervical plexus in medical training: clinical and surgical applicabilities

A Anatomia da região cervical é de particular importância para os clínicos e cirurgiões de diversas especialidades médicas. Em se tratando da organização nervosa presente na região anterolateral do pescoço, encontra-se o plexo cervical, formado pelos ramos anteriores dos nervos cervicais C1 a C4, cuja função é promover a sensibilidade da pele anterolateral cervical, torácica anterossuperior e do couro cabeludo posterior, na cabeça, além de controlar a musculatura infra-hióidea e diafragmática. Logo, lesões a essa estrutura nervosa e aos seus ramos podem causar graves complicações ao corpo humano. Esse trabalho objetivou utilizar a dissecção da região anterolateral do pescoço como uma ferramenta pedagógica para o estudo das relações anatômicas dos nervos do plexo cervical observados durante essa prática, assim como relatar algumas de suas importâncias clínicas e cirúrgicas. O presente estudo é caracterizado como qualitativo/descritivo. A dissecção foi realizada semanalmente, durante o segundo semestre de 2018 e o primeiro semestre de 2019, com a supervisão do professor responsável e auxílio do técnico de laboratório, no Laboratório de aulas práticas da Universidade Estadual de Londrina (UEL). Considera-se que a dissecção da região anterolateral do pescoço permitiu a visualização de diversos nervos cutâneos e musculares do plexo cervical, assim como de alguns de seus ramos e suas relações anatômicas. Também contribuiu para o conhecimento da topografia em que se encontravam tais estruturas e sua organização em camadas. Esse conhecimento anatômico é essencial para a prática médica, tanto clínica quanto cirúrgica.(AU)

The anatomy of the cervical region is of particular importance for surgeons and physicians of different medical specialties. The cervical plexus can be found in the anterolateral region of the neck, formed by the anterior branches of the cervical nerves C1 to C4, whose function is to promote the sensitivity of the cervical anterolateral skin, anterosuperior thoracic skin, and posterior scalp, on the head, in addition to controlling the infrahyoid and diaphragmatic muscles. Therefore, injuries to this nervous structure and its branches may cause serious complications to the human body. This work aimed at using the dissection of the anterolateral neck region as a pedagogical tool for the study of the anatomical relationships of the cervical plexus nerves observed during this practice, as well as to highlight some of its clinical and surgical importance. This is a qualitative/descriptive study. The dissection was performed weekly, during the second semester of 2018 and the first semester of 2019, with the supervision of the professor in charge and the assistance of the laboratory technician at the Laboratory of Practical Classes at the State University of Londrina (UEL). It is considered that the dissection of the anterolateral neck region allowed the visualization of several cutaneous and muscular nerves present in the cervical plexus. It also contributed to the knowledge of the topography in which these structures were found and their organization in layers. This anatomical knowledge is essential for both clinical and surgical medical practice.(AU)

Classification of the patterns of the emerging branches of the superficial cervical plexus / Clasificación de los patrones de las ramas emergentes del plexo cervical superficial

SUMMARY: The cutaneous branches of the superficial cervical plexus (SCP) emerge at variable points, from beneath the posterior margin of the sternocleidomastoid muscle and from this point radiate like "spokes of a wheel" antero-inferiorly and postero-superiorly. This study aimed to classify the emerging points of the branches of the superficial cervical plexus in relation to their location on the sternocleidomastoid muscle. In order to classify the emerging points of the superficial cervical plexus, the sternocleidomastoid muscle was first measured from mastoid process to clavicle; subsequently each branch of the superficial cervical plexus was measured from the mastoid process to their exit points. The emerging points of the superficial cervical plexus branches were classified according to Kim et al. (2002) seven categories: Type I (32 %); Type II (13 %); Type III (35 %); Type IV (13 %); Type V, VI, VII (2 %). The order in which the superficial cervical plexus branches emerged from the posterior margin of the sternocleidomastoid muscle remained constant, i.e. lesser occipital, great auricular, transverse cervical and supraclavicular nerves. Knowledge of emerging points may assist in the effective anaesthesia to all branches of the superficial cervical plexus during surgical procedures of the neck, viz. carotid endarterectomy and thyroid surgery.

RESUMEN: Las ramas cutáneas del plexo cervical superficial (SCP) emergen en puntos variables, desde el margen pos- terior del músculo esternocleidomastoideo y desde este punto inferior irradian como "radios de rueda" anteroinferior y postero-superior. Este estudio tuvo como objetivo clasificar los puntos emergentes de las ramas del plexo cervical superficial en relación a su ubicación en el músculo esternocleidomastoideo. Para clasificar los puntos emergentes del plexo cervical superficial, primero se midió el músculo esternocleidomastoideo desde el proceso mastoides hasta la clavícula; posteriormente se midió cada rama del plexo cervical superficial desde el proceso mastoideo hasta sus puntos de salida. Los puntos emergentes de las ramas del plexo cervical superficial se clasificaron según Kim et al. (2002) en siete categorías: Tipo I (32 %); Tipo II (13 %); Tipo III (35 %); Tipo IV (13 %); Tipo V, VI, VII (2 %). El orden en el que las ramas del plexo cervical superficial emergían del margen posterior del músculo esternocleidomastoideo se mantuvo constante, es decir, los nervios occipital menor, auricular magno, cervical transverso y supraclavicular. El conocimiento de los puntos emergentes puede ayudar a la anestesia eficaz de todas las ramas del plexo cervical superficial durante los procedimientos quirúrgicos del cuello, a saber, endarterectomía carotídea y cirugía de tiroides.

A quantitative analysis of the dimensions and content of the vertebral triangle.

PURPOSE: The vertebral triangle (VT) located in the root of the neck most commonly contains the vertebral artery (VA), cervical sympathetic chain and certain roots of the brachial plexus. Although other structures have been reported, few studies have reported on the overall content of this space. Based on the current literature, there is a general paucity of anatomical information pertaining to the dimensional anatomy of the VT and specifically the structures related to it. Therefore, this study aimed to quantitatively analyze the size, position, content, and anatomical structures in relation to the vertebral triangle in a South African sample. METHODS: Forty-three VTs were dissected on bodies donated to science. Measurements taken include the dimensions of the triangle, as well as distances between prominent structures and landmarks of the VT. Observations were made on the presence/absence of the varying neurovascular structures within the VT. RESULTS: Mean height was 30.1 ± 1.51 mm (R) and 32.9 ± 1.78 mm (L). Mean width was 18.3 ± 0.74 mm (R) and 19.3 ± 0.98 mm (L). The C8 spinal nerve was found on average approximately halfway [16.4 ± 0.74 mm (R) and 15.9 ± 0.95 mm (L)] in the VT. The VA was present in the VT in 100% of the sample and the C7 spinal nerve and inferior sympathetic ganglia were present in more than 80% of the sample. CONCLUSION: Understanding the VT and the content is of the utmost importance and of great interest to neurosurgeons, to avoid these important neurovascular structures and prevent iatrogenic complications during surgery.

A comprehensive review of the great auricular nerve graft.

The great auricular nerve (GAN) is a superficial branch of the cervical plexus that innervates parts of the mandible, auricle, and earlobe. Over the past 30 years, the GAN has become the nerve graft donor of choice for many surgeons for reconstructing injured facial nerves. In this review, we discuss the anatomy and function of the GAN, while focusing on surgical landmarks and the characteristics that make it a suitable nerve graft donor. In addition, we present and summarize published case reports on use of the GAN for grafting. We hope that this review will provide surgeons with an up-to-date and concise reference.

In-Depth Look at the Anatomical Relationship of the Lesser Occipital Nerve, Great Auricular Nerve, and Spinal Accessory Nerve and Their Implication in Safety of Operations in the Posterior Triangle of the Neck.

BACKGROUND: Migraine surgery is an increasingly popular treatment option for migraine patients. The lesser occipital nerve is a common trigger point for headache abnormalities, but there is a paucity of research regarding the lesser occipital nerve and its intimate association with the spinal accessory nerve. METHODS: Six cadaver necks were dissected. The lesser occipital, great auricular, and spinal accessory nerves were identified and systematically measured and recorded. These landmarks included the longitudinal axis (vertical line drawn in the posterior), the horizontal axis (defined as a line between the most anterosuperior points of the external auditory canals) and the earlobe. Mean distances and standard deviations were calculated to delineate the relationship between the spinal accessory, lesser occipital, and great auricular nerves. RESULTS: The point of emergence of the spinal accessory nerve was determined to be 7.17 ± 1.15 cm lateral to the y axis and 7.77 ± 1.10 caudal to the x axis. The lesser occipital nerve emerges 7.5 ± 1.31 cm lateral to the y axis and 8.47 ± 1.11 cm caudal to the x axis. The great auricular nerve emerges 8.33 ± 1.31 cm lateral to the y axis and 9.4 ±1.07 cm caudal to the x axis. The decussation of the spinal accessory and the lesser occipital nerves was found to be 7.70 ± 1.16 cm caudal to the x axis and 7.17 ± 1.15 lateral to the y axis. CONCLUSION: Understanding the close relationship between the lesser occipital nerve and spinal accessory nerve in the posterior, lateral neck area is crucial for a safer approach to occipital migraine headaches, occipital neuralgia, and new daily persistent headaches and other reconstructive or cosmetic operations.

Platysma muscle additionally innervated by a variant anterior branch of the great auricular nerve.

Damage to the great auricular nerve, with consequent clinical deficits, is a common surgical complication in facial aesthetic and in head and neck procedures such as parotidectomy, neck dissection, rhytidectomy and platysma flap operations. Hence, a thorough knowledge of nerve anatomy, particularly its potential variations, is critical in reducing the associated operative morbidity. Accordingly, we report an unusual variation of the anterior branch of the great auricular nerve noted in an 81-year-old female cadaver. The nerve was observed to course into the submandibular region anterior and superficial to the internal jugular vein, communicating with the cervical branch of the facial nerve, while independently innervating the platysma muscle. Although several anatomical variations of the branches of the cervical plexus have been documented, our report describes unique innervation of the platysma muscle by the great auricular nerve, which provides a new insight on the motor component of the nerve.

Sternothyroid receives a supplementary innervation separate to the ansa cervicalis: a case report of a variation.

We report on an additional innervation to the sternothyroid that, to our knowledge, has not been previously described. During a cadaveric neck dissection, we found an aberrant nerve to the sternothyroid in addition to the normal innervation. The classical innervation to the sternothyroid is through the ansa cervicalis (C1-C3), and the sternothyroid muscle is important for depression of the thyroid cartilage that is involved with swallowing and speech. The cervical plexus is difficult and time consuming to elucidate in fixed cadavers, which limits knowledge of variations from this source. Branches of the plexus are delicate and can be damaged during operations on the neck. Awareness of variations in innervation during operation reduces the chance of damage to nerves and prevents functional changes postoperatively.

A Review of the History, Anatomy, and Development of the C1 Spinal Nerve.

The C1 spinal nerve is a fascinating anatomic structure owing to its wide range of variations. Throughout history, understanding of the cranial and spinal nerves has probably influenced the current conception of this nerve among anatomists. Located at the craniocervical junction, the C1 spinal nerve contributes to the motor innervation of deep cervical muscles through the cervical (anterior) and Cruveilhier's (posterior) plexuses. Sensory functions of this nerve are more enigmatic; despite investigations into its dorsal rootlets, a dorsal root ganglion, and the relationships between this nerve and adjacent cranial and spinal nerves, there is still no consensus regarding its true anatomy. In this article, we review the available literature and discuss some of the developmental models that could potentially explain the wide range of variations and functions of the C1 nerve.

Morphohistometric study of the ligamentum flavum in cervical, thoracic and lumbar vertebrae: comparative approach

Anatomic characterization and fine structure of the human ligamentum flavum (LF), especially at different spinal levels, represent an attractive focus for the scientific and surgical application. Descriptive anatomical and structural study of LF at the cervical, thoracic and lumbar levels of the vertebral column in human cadavers is carried out here. The aim of the work is to clarify the anatomical features and fine structural differences in the human LF at different vertebral levels (cervical, thoracic and lumbar). Specimens of vertebral column were obtained from 34 human preserved cadavers. Their average age ranged between 56 and 69 years. Morphometric parameters including height, width and thickness of the ligament flavum at the midlevels of cervical, thoracic and lumbar regions were measured. Sections obtained from different levels were stained with different stains. Morphometric measurements involved the relative elastic area, relative collagen area, elastic area and collagen area% were measured.The results of the height, width and thickness of the LF at different spinal levels showed gradual increase in their mean values respectively. The LF midline gaps were found in the cervical, thoracic and lumbar regions. The morphometrical measurements showed that the average elastic area was highest in the cervical region and lowest in the thoracic region. In the lumbar region, the percentages of both elastic area and the collagen area were nearly the same. The characterization of morphological and histological aspects of the LF at different spinal levels will be of great importance for applications in spinal surgery, biomechanical and physical rehabilitation of vertebral column

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The Greater Occipital Nerve and Obliquus Capitis Inferior Muscle: Anatomical Interactions and Implications for Occipital Pain Syndromes.

BACKGROUND: The compression/injury of the greater occipital nerve has been identified as a trigger of occipital headaches. Several compression points have been described, but the morphology of the myofascial unit between the greater occipital nerve and the obliquus capitis inferior muscle has not been studied yet. METHODS: Twenty fresh cadaveric heads were dissected, and the greater occipital nerve was tracked from its emergence to its passage around the obliquus capitis inferior. The intersection point between the greater occipital nerve and the obliquus capitis inferior, and the length and thickness of the obliquus capitis inferior, were measured. In addition, the nature of the interaction and whether the nerve passed through the muscle were also noted. RESULTS: All nerves passed either around the muscle loosely (type I), incorporated in the dense superficial muscle fascia (type II), or directly through a myofascial sleeve within the muscle (type III). The obliquus capitis inferior length was 5.60 ± 0.46 cm. The intersection point between the obliquus capitis inferior and the greater occipital nerve was 6.80 ± 0.68 cm caudal to the occiput and 3.56 ± 0.36 cm lateral to the midline. The thickness of the muscle at its intersection with the greater occipital nerve was 1.20 ± 0.25 cm. Loose, tight, and intramuscular connections were found in seven, 31, and two specimens, respectively. CONCLUSIONS: The obliquus capitis inferior remains relatively immobile during traumatic events, like whiplash injuries, placing strain as a tethering point on the greater occipital nerve. Better understanding of the anatomical relationship between the greater occipital nerve and the obliquus capitis inferior can be clinically useful in cases of posttraumatic occipital headaches for diagnostic and operative planning purposes.

The Great Auricular Nerve: Anatomical Study with Application to Nerve Grafting Procedures.

BACKGROUND: When it comes to autogenous nerve grafting, the sural and great auricular nerve (GAN) are the 2 nerves predominately used for trigeminal and facial nerve repair. Arising from the second and third cervical ventral rami, the GAN emerges from the posterior border of the sternocleidomastoid coursing superiorly and anteriorly toward the ear. METHODS: Eleven sides from 5 Caucasian and 1 Asian cadaveric heads (all fresh-frozen) were used. One man and 5 women were used with an age at death ranging from 57 to 91 years, with a mean of 80.3 years. Measurements were made from the inferior border of the ear to the GAN, the GAN to the external jugular vein, and the inferior border of the mastoid process to the GAN; the proximal, medial, and distal diameters of the GAN and the length of the GAN that was obtained from this exposure were also measured. RESULTS: The mean distance from the inferior border of the mastoid process to the GAN, inferior border of the ear to the GAN, and GAN to the external jugular vein was 27.71, 31.03, and 13.28 mm, respectively. The mean length of the GAN was 74.86 mm. The mean diameter of its distal, middle, and proximal portions was 1.51, 1.38, and 1.58 mm, respectively. CONCLUSIONS: The GAN is an excellent option for use in nerve grafting for repair of, for example, facial dysfunction. In this study, we review our measurements, techniques for identification, and dissecting techniques for the GAN. The proximity to the operative area and minimal complications associated with GAN grafting might contribute to improved patient satisfaction and better outcomes regarding functional restoration.

Ansa cervicalis - A new classification approach.

Normally, the inferior root of Ansa cervicalis passes around the internal jugular vein and runs in an anterior direction to meet the superior root ventral to the common carotid artery. However, anatomical variants of the Ansa cervicalis are as yet not well investigated and understood. To close this gap the present study was undertaken. The Ansa cervicalis was examined in 54 human formalin-fixed cadavers and preparations of the head and neck by conventional dissection. In 66% of the specimens the Ansa cervicalis displayed the typical course that was classified as "internal type" (located medial to the internal jugular vein inside the carotid sheath). The remaining 34% pertained to the "external type" of the Ansa cervicalis (lateral to the internal jugular vein). The distance of the Ansa cervicalis relative to the superior margin of the thyroid cartilage was measured in every specimen. The external type Ansa cervicalis was located significantly lower than the internal type relative to the superior margin of thyroid cartilage. Regarding its location relative to the internal jugular vein four variants of combinations of the external and internal types of Ansa cervicalis on the right and left sides were distinguished. Based on their distance from the superior margin of the thyroid cartilage three types of Ansa cervicalis were defined.

[Dissection and observation of a large unnamed nerve in the posterior cervical triangle].

OBJECTIVE: To characterize the anatomical features of a large unnamed nerve in the posterior cervical triangle and clarify its relationship with the lesser occipital nerve. METHODS: We dissected 31 adult formalin-fixed cadaver head and neck specimens (62 sides). The lateral cervical region, the anterior cervical region, the sternocleidomastoid region, and the occipital region were dissected to define the anatomical features of the unnamed nerve. RESULTS: This unnamed nerve was identified in the posterior cervical triangle in 96.8% of the specimens. The main trunk of the nerve had a diameter of about 3 mm with a length of around 10 cm. The nerve arose from the anterior branch of the second cervical nerve (C2, C2-3), entered the posterior cervical triangle at 1-3 cm above the accessory nerve, and continued to ascend along or in parallel with the posterior border of the sternocleidomastoid muscle. It passed between the attachments of the sternocleidomastoid and the trapezius to the occiput and divided into 3-5 branches, which innervated the skin area between the lesser and greater occipital nerves. CONCLUSIONS: We identified a large unnamed nerve in the posterior cervical triangle, for which we coined the name "long occipital nerve" based on its unique anatomical features. The discovery of this nerve can be important for local surgery and for diagnosis and treatment of related diseases.