Anatomical diversity of inferior belly of the omohyoid muscle - Anatomical, physiological and surgical paradigm.

Omohyoid muscle is one of the infrahyoid muscles of the neck which consists of two bellies combined at an angle by an intermediate tendon. The inferior belly is a flat, narrow band, which inclines forwards and upwards in the lower part of the neck. It generally originates from the upper border of the scapula, medial to scapular notch. The present case showed unilateral anomalous attachment of the inferior belly of the omohyoid on the medial part of clavicle on left side. Inferior belly was 2.2cm lateral to left sternoclavicular joint with 3.2 and 1.5cm in length and breadth, innervated by ansa cervicalis. Only 3% of this type of variation has been observed until now according to previous literature. Anterior and posterior triangles of neck on both sides of the cadaver were dissected during routine dissection for undergraduate teaching. There was no scapular attachment of inferior belly of the omohyoid on the left side. It was directly originating from the upper surface of the medial side of the left clavicle. Variation in the attachment of inferior belly can have a direct impact on the internal jugular vein and brachial plexus during neck surgeries or trauma due to its close relation to the mentioned structures. This variation should also be taken care during infrahyoid myocutaneus flap extraction for reconstruction surgery of tongue in cases of lingual carcinoma.

Sternocleidohyoid muscle: an unreported variant of cleidohyoid muscle.

Sternohyoid, sternothyroid, omohyoid, and thyrohyoid muscles are collectively known as infrahyoid muscles. These muscles frequently show variations in their attachments. Here, an extremely rare variant muscle belonging to this group has been presented. During cadaveric dissection for undergraduate medical students, an additional muscle was found between sternohyoid and superior belly of omohyoid muscles bilaterally in a male cadaver aged approximately 70 years. This muscle took its origin from posterior surface of the manubrium sterni, capsule of the sternoclavicular joint and the posterior surface of the medial part of the clavicle. It was inserted to the hyoid bone between the attachments of sternohyoid and superior belly of omohyoid muscles and was supplied by a branch of ansa cervicalis profunda. There is no report on such a muscle in the literature and it could be named as "sternocleidohyoid muscle". Knowledge of this muscle could be useful in neck surgeries.

Absent Posterior Belly of Digastric Muscle.

OBJECTIVE: Report a unique case of absent posterior belly of digastric muscle, with a literature review and discussion of its clinical importance. METHODS: Present a case report and review the current literature including PUBMED search terms; "absent posterior digastric", "digastric muscle", "posterior belly". RESULTS: While there were multiple reports of accessory anterior and posterior bellies and absence of anterior belly, there is a paucity of literature on absence of posterior belly of digastric muscle. CONCLUSION: To our knowledge, this is the first report of an absent posterior belly of the digastric muscle. The posterior belly of the digastric muscle is an important landmark in neck dissection, and its absence makes knowledge of other anatomic landmarks critically important. Laryngoscope, 131:1501-1502, 2021.

Positional anomaly between the brachial plexus and the scalene muscles, concomitant with an anomalous path of the musculocutaneous nerve: case report and clinical implication / Anomalía posicional entre el plexo braquial y el músculo escaleno anterior, concomitante con un trayecto anómalo del nervio musculocutáneo: reporte de un caso e implicancia clínica

Anatomical variations of the scalene muscles are frequent, as are those of the brachial plexus and its terminal nerves. Nonetheless, these variations are reported separately in the literature. The aim of this work is to present a variation of scalene muscles, concomitant with an abnormal path of the musculocutaneous nerve. During a routine dissection of the cervical region, axilla and right anterior brachial region in an adult male cadaver, a supernumerary muscle fascicle was located in the anterior scalene muscle, altering the anatomical relations of C5 and C6 ventral branches of the brachial plexus. This variation was related to an anomalous path of the musculocutaneous nerve that did not cross the coracobrachialis muscle. It passed through the brachial canal along with the median nerve. It then sent off muscular branches to the anterior brachial region and likewise, communicating branches to the median nerve. The concomitant variations of the brachial plexus and scalene muscles they are not described frequently. Knowledge of these variations improves diagnosis, enhancing therapeutic and surgical approaches by reducing the possibility of iatrogenesis during cervical, axillary and brachial region interventions.

Las variaciones anatómicas de los músculos escalenos son frecuentes, así como también las del plexo braquial y sus nervios terminales. Sin embargo la literatura científica las presenta por separado. El propósito de este trabajo es presentar una variación de los músculos escalenos concomitante con un trayecto anómalo del nervio musculocutáneo. Disección de rutina de región cervical, axila y región braquial anterior derechas realizada en un cadáver adulto de sexo masculino. Se encontró un fascículo muscular supernumerario para el músculo escaleno anterior que alteraba las relaciones anatómicas de los ramos ventrales C5 y C6 del plexo braquial. Esta variación estaba acompañada por un trayecto anómalo del nervio musculocutáneo, el cual no atravesaba al músculo coracobraquial y transitaba por el conducto braquial acompañando al nervio mediano. Desde allí enviaba a la región braquial anterior ramos musculares y al nervio mediano ramos comunicantes. Las variaciones conjuntas del plexo braquial y los músculos escalenos no se presentan con frecuencia. Conocerlas enriquece la capacidad diagnóstica, terapéutica y quirúrgica. Reduciendo la posibilidad de iatrogenia al intervenir en las regiones cervical, axilar y braquial.

The effectiveness of a novel surgical approach for the treatment of congenital muscular torticollis.

The outcomes of surgical treatment for congenital muscular torticollis (CMT) are poor in many cases, primarily from surgeon's fear of damage to important blood vessels in the carotid sheath. The current research aimed to establish a novel, safer and more effective surgical approach for the treatment of CMT based on the anatomic relationship between the fascial sheath of the sternocleidomastoid muscle and the carotid sheath.A total of 12 formalin-fixed cadaveric specimens (including 9 males and 3 females with average age of 48.1 years at the time of death) were used to observe the anatomical integrity and the compactness of the sternocleidomastoid fascial sheath and its relationship with the carotid sheath. From January 2013 to December 2015, 22 patients with CMT were treated surgically, including 12 males and 10 females with an average age of 13 years (range: 6-28 years). All patients underwent surgical treatment using the novel approach designed by the author, that is, separation of the fascial sheath of the sternocleidomastoid and the carotid sheath was performed.The fascial sheath of the sternocleidomastoid muscle is easily isolated from the carotid sheath in all specimens. All procedures were successfully completed. The space between the fascial sheath of the sternocleidomastoid muscle and the carotid sheath can be accessed in all patients. Carotid sheath contracture was identified in 1 patient and divided successfully. The average follow-up period was 19 months (range: 5 to 43 months). No postoperative lateral band was noted in the neck in any of the patients. Satisfaction regarding cosmetic and functional outcomes was considered excellent in 13 patients, good in 7 patients, and fair in 2 patients.The fascial sheath of the sternocleidomastoid muscle is easily isolated from the carotid sheath. This anatomical feature is the basis of division of the sternocleidomastoid muscle and can improve the safety and effectiveness of surgical treatment for CMT in patients older than 6 years old.

Músculo elevador de la clavícula / The levator claviculae muscle

No disponible

Variation of the sternocleidomastoid muscle: a case report of three heads and an accessory head.

PURPOSE: Anatomical variations of the sternocleidomastoid muscle (SCM) have been observed to occupy multiple origins and insertion points and have supernumerary heads, sometimes varying in thickness. METHODS: An 85-year-old Korean male cadaver was dissected and a SMC with unilateral supernumerary heads was identified. RESULTS: Three heads and an accessory belly of the sternal head were recorded on the left side. There were two clavicular heads, one lateral and one medial. The sternal head originated inferior to the manubrium of the sternum. A small belly arose from the sternal head and merged to the lateral clavicular head on the C5 vertebrae level. These bellies inserted into the mastoid process of the temporal bone. CONCLUSIONS: These variants may be problematic during surgical approaches to the upper neck and occipital, and should thus be appreciated by the clinician.

Variations of the digastric muscle and accessory bellies - A study of gross anatomic dissections.

OBJECTIVE: Variations of the bellies of the digastric muscle is reported for a long time and is not uncommon. However, there is still not a full consensus about the classifications and many different types of variations. The aim of this study was to examine the variations of the digastric muscle on cadaver dissections and to create a pictorial collection of variations related to present-day by combining with existing knowledge. METHOD: In the present study, a total of 40 formalin-fixed cadavers and head specimens' digastric muscles were analyzed bilaterally. RESULTS: Previous results were utilized for classification of the variations. Anterior belly, intermediate tendon, and posterior belly variations were evaluated according to unilateral, bilateral and unclassified types. 10 variations were identified in the digastric muscle of 40 cadavers. Thus, five of the variations were unilateral and rest of them were bilateral. Two of the variations were residing in the central area. One accessory muscle bundle was found obliquely residing between the left and right sides of the anterior bellies. Remaining variation was the crossing of the accessory anterior belly of digastric muscle fibers at the central line. Intermediate tendon variation as piercing the stylohyoid muscle was observed in only one case. Posterior belly exhibited no variation. CONCLUSION: Reporting the abnormalities and variations of the digastric muscle is very important in surgical attempts and evaluation of the lymphadenopathy of the submental area and in the floor of the mouth tumors, numerous clinically significant esthetic surgeries for head and neck surgeons, radiologists and plastic surgeons.

Anatomical variations of the anterior belly of the digastric muscle / Variaciones anatómicas del vientre anterior del músculo digástrico

A routine dissection of the digastric muscle reflected that it originated by two muscle bellies namely. the anterior and posterior belly which are connected by an intermediate tendon (IT). These bellies originated from the mastoid process of the temporal bone and the digastric fossa of the mandible respectively. The digastric muscle serves as an important surgical landmark in surgical interventions involving the submental area however, accessory bellies may interfere with surgical intervention in this area. Therefore, this study aimed to document the occurrence of the anatomical variations in the anterior belly of the digastric muscle (ABDM) in a selected number of cadaveric samples. Ten bilateral adult cadaveric head and neck specimens (n = 20) were macro-dissected in order to document the morphology of the digastric muscle. The accessory bellies in the ABDM was observed in 60 % of the specimens. Unilateral and bilateral variations were observed in 20 % and 30 % of the specimens, respectively. These accessory bellies originated in the digastric fossa, ABDM, IT and hyoid bone, and inserted into the mylohyoid raphe, mylohyoid muscle and hyoid bone. In addition, an anomalous main ABDM was observed in 10 % of the specimens inserting through a transverse tendon into the hyoid bone. Variations in the digastric muscle are common especially the accessory bellies, therefore, a comprehensive understanding of these anatomical variations could be of clinical importance to the surgeons during head and neck radiological diagnosis and surgical interventions.

Una disección de rutina del músculo digástrico refleja que se éste originaba por dos vientres musculares, anterior y posterior conectados por un tendón intermedio (IT). Estos vientres se originaban a partir del proceso mastoide del hueso temporal y de la fosa digástrica de la mandíbula, respectivamente. El músculo digástrico sirve como un hito quirúrgico importante en las intervenciones que involucran el área submental. Sin embargo, los vientres accesorios pueden obstaculizar la intervención quirúrgica en esta área. Por lo anterior, este estudio tuvo como objetivo documentar observaciones de las variaciones anatómicas en el vientre anterior del músculo digástrico (VAMD) en un número seleccionado de cadáveres. Las muestras consistieron en 10 cabezas y cuellos cadavéricos de individuos adultos, estudiadas bilateralmente (n = 20). Estas muestras fueron disecadas para documentar la morfología del músculo digástrico. Los vientres accesorios en el VAMD se observaron en el 60 % de los casos. Se observaron variaciones unilaterales y bilaterales en el 20 % y el 30 % de las muestras, respectivamente. Estos vientres accesorios se originaban en la fosa digástrica, VAMD, IT y hueso hioides, y se insertaban en el rafe milohioideo, el músculo milohioideo y el hueso hioides. Además, se observó un VAMD principal anómalo en el 10 % de las muestras que se insertaban a través de un tendón transversal en el hueso hioides. Las variaciones en el músculo digástrico son comunes, especialmente los vientres accesorios, por lo tanto, un conocimiento completo de estas variaciones anatómicas podría ser de importancia clínica durante el diagnóstico radiológico de cabeza y cuello y en las intervenciones quirúrgicas de la región.

Duplicate Omohyoid Muscle Causing Progressive Dysphagia and Dyspnea: A Case Report.

INTRODUCTION: Duplicate omohyoid muscles are uncommon anomalies and exceedingly rare causes of progressive clinical symptoms. The goals of this case report are to describe the clinical characteristics, cross-sectional imaging, intraoperative findings, and curative treatment of our patient, to develop a differential diagnosis for this condition, and to review the pertinent literature regarding this particular type of anomalous omohyoid muscle as one among many variations. CASE PRESENTATION: A 20 year-old man presented with progressive limited neck range of motion followed by dysphagia and then dyspnea caused by his duplicate omohyoid muscle. He underwent curative surgery in 2015 at our tertiary care center. DISCUSSION: Although rare, a duplicate omohyoid muscle should be considered in the differential diagnosis of dysphagia and dyspnea with concurrent central neck deformity. We report the first case, to our knowledge, of an anomalous omohyoid that caused significant progressive clinical symptoms. Direct excision of the restrictive anomalous tissue proved curative.

Bilateral supernumerary clavicular heads of sternocleidomastoid muscle in a Korean female cadaver.

Many anatomical variants on the sternocleidomastoid muscle have been reported. In this study, supernumerary clavicular heads of sternocleidomastoid muscle in a Korean female cadaver were bilaterally displayed. The observed supernumerary heads were classified as follows: one sterno-mastoid, one cleido-occipital and one cleido-mastoid on the right side, and one sterno-mastoid-occipital, four cleido-occipitals, and one cleido-mastoid on the left side. The sterno-mastoid and sterno-mastoid-occipital and the cleido-occipital made the superficial layer of the sternocleidomastoid muscle, while others made deep layer. We discussed clinical relevance and developmental basis of these muscular variations important for clinicians and anatomists.

Unilateral asymmetrical anterior bellies of the digastric muscle in coexistence with accessory muscle bundles in the submental triangle: A rare case report.

A three-headed anterior belly of the digastric muscle (ABDM) on the right side of a 54-year old Greek male cadaver coexisted with two accessory muscle bundles (AMB) in the submental region. The left ABDM was typical. Typical ABDM was attached to the digastric fossa, while the accessory right anterior bellies to the lower border of the mandible. A muscle bundle arising from the attachment of the left ABDM to the hyoid bone was also observed fusing with the AMB of the ipsilateral side. It is of extreme importance to be aware of the submental region anatomical variations during surgery, imaging interpretation or differential diagnosis of neck masses.

Bilateral clavicular attachment of omohyoid muscle.

Omohyoid muscle present in cervical region is of particular importance to anatomists as it defines anteriorly the carotid triangle and divides the posterior cervical triangle. It has superior and inferior bellies and an intermediate common tendon. Like sternohyoid, sternothyroid and thyrohyoid muscles, omohyoid is also an infrahyoid muscle, but it differs from them in its course. The infrahyoid muscles are formed from a muscle primordium occurring in the anterior cervical area. Anderson (Anderson, 1881) theorized that the superior belly of the omohyoid muscle is a true infrahyoid muscle, whereas the inferior belly most likely shares a common embryology with the subclavius muscle. In the present study, during routine dissection in the neck region of an adult male cadaver of 50 years age, an anomalous origin of inferior belly of omohyoid with absence of intermediate tendon was observed bilaterally. It was arising from clavicle on both sides. Both the muscle bellies were measured from the lateral end of fascial sling. The inferior belly of omohyoid extending from the lateral margin of sling to clavicular surface was measured 3.3cm in length on left side and 3.6cm on right side. The omohyoid is important in neck dissections because it is considered as an ideal landmark for level III and IV lymph node metastases. Knowledge of variations of this muscle is very important for surgeries in neck region because of its close relation to the internal jugular vein and brachial plexus. Its crucial relationship to vascular structures in the neck makes it an important landmark during neck surgeries.

The Levator Claviculae Muscle Presenting as a Neck Mass.

The levator claviculae muscle is an uncommonly encountered muscle variant, occurring in 1% to 2% of the human population. Most accounts of the levator claviculae muscle have been reported in association with routine cadaveric examination and as an incidental finding by computed tomography (CT) and magnetic resonance (MR) imaging. We report a case of this variant muscle presenting as a soft-tissue mass within the neck of a young male. Furthermore, we discuss the embryologic origin, imaging features and clinical implication.

SEPN1-related myopathy in three patients: novel mutations and diagnostic clues.

UNLABELLED: Mutations in SEPN1 cause selenoprotein N (SEPN)-related myopathy (SEPN-RM) characterized by early-onset axial and neck weakness, spinal rigidity, respiratory failure and histopathological features, ranging from mild dystrophic signs to a congenital myopathy pattern with myofibrillar disorganization. We report on clinical and instrumental features in three patients affected with a congenital myopathy characterized by prevalent neck weakness starting at different ages and mild myopathy, in whom we performed diagnosis of SEPN-RM. The patients presented myopathic signs since their first years of life, but the disease remained unrecognized because of a relatively benign myopathic course. In two cases, myopathic features were stable after 2 years of follow-up, but respiratory involvement worsened. The muscle MRI and muscle biopsy showed a typical pattern of SEPN-RM. Molecular diagnosis revealed two novel homozygous mutations in SEPN1, c.1176delA and c.726_727InsTCC. CONCLUSION: This report underlines the clinical diagnostic clues of early neck and axial weakness to suspect a SEPN-RM and the usefulness of muscle MRI in conjunction with clinical features to achieve the diagnosis. Our data confirm the slow progression of respiratory involvement in spite of the relatively stable course of myopathy. We report two previously undescribed mutations in SEPN1. WHAT IS KNOWN: • Mutations in SEPN1 cause myopathy characterized by early-onset axial and neck weakness spinal rigidity and respiratory failure. • SEPN-related myopathies have been initially associated with four distinct histopathological entities that however appear more mixed in recently described cases. What is New: • SEPN-related myopathies can remain unrecognized because of the normal early motor development and relatively benign myopathic course of the disease. • Our study adds two novel homozygous mutations to the number of reported pathogenic SEPN1 variants.

Bilateral four heads of the sternocleidomastoid muscle.

The sternocleidomastoid muscle shows a wide range of variations including supernumerary muscular heads. We found a rare variation in the sternocleidomastoid muscle with bilateral supernumerary heads in a 67-year-old Korean male cadaver. Bilateral four muscle bellies were recorded: two sternomastoids, one cleido-occipital and one cleido-mastoid occipital on the right side, and one sternomastoid, one cleido-occipital and two cleido-mastoids on the left side. The variation of bilateral four heads on sternocleidomastoid muscle is important to surgeons and anesthetists for clinical using.