Unique variation of digastric muscle: a confusing landmark for head and neck surgeons

An anatomical variation of the left digastric muscle was found during the functional neck dissection of a patient with laryngeal carcinoma. This variant of the digastric muscle had three bellies including an accessory posterior belly. The anterior and posterior bellies had normal origin and course and were linked to each other by an intermediate tendon, whereas the accessory posterior belly took its origin from the mastoid notch of the temporal bone, together with the original posterior belly, sloped inferiorly and anteriorly, and inserted to the lateral border of the strap muscles by an evident tendon. This unique variation has not been reported in the literature. Presentation of this variation will guide surgical procedures, as well as anatomical dissections and medical imaging of the neck.     

Unique variation of digastric muscle: a confusing landmark for head and neck surgeons

An anatomical variation of the left digastric muscle was found during the functional neck dissection of a patient with laryngeal carcinoma. This variant of the digastric muscle had three bellies including an accessory posterior belly. The anterior and posterior bellies had normal origin and course and were linked to each other by an intermediate tendon, whereas the accessory posterior belly took its origin from the mastoid notch of the temporal bone, together with the original posterior belly, sloped inferiorly and anteriorly, and inserted to the lateral border of the strap muscles by an evident tendon. This unique variation has not been reported in the literature. Presentation of this variation will guide surgical procedures, as well as anatomical dissections and medical imaging of the neck.     

The applied anatomy of the periosteal flap composed of submental artery and dgastric muscle]

OBJECTIVE: To provide anatomical basis for a new style operation using periosteal flap composed of submental artery, anteroventral portion of digastric muscle and submental artery for the renovation of laryngotrachea. METHODS: The anatomical structures correlative with submental artery, submental vein, anteroventral portion of digastric muscle and mandibular periosteum in 23 (46 sides) cephalocervical samples were measured. RESULTS: The periosteal flaps had shown many advantages inculding large transfer capacity, rich blood supply, flexibility. CONCLUSION: It is feasible that the periosteal flap composed of submental artery, anteroventral portion of digastric muscle and mandibular periosteum is useful laryngotracheal renovation.     

颏下动脉二腹肌前腹为蒂下颌骨膜瓣的解剖

目的为应用颏下动脉二腹肌前腹为蒂的下颌骨骨膜瓣转位修复喉、气管提供解剖学依据。方法对２３例（４６侧）头颈部标本的颏下动脉、颏下静脉、二腹肌前腹的相关结构进行观测。结果颏下动脉为面动脉的恒定分支,走行于下颌下腺与下颌骨下缘之间,恒定分支供应二腹肌前腹和下颌骨骨膜,并与对侧有广泛的吻合支。二腹肌前腹以３０°角附着于骨膜,肌腹横截面积明显小于附着的骨膜面积。结论带颏下动脉二腹肌前腹蒂的下颌骨膜瓣有转移范围大、血供丰富、应用灵活等优点。颏下动脉二腹肌前腹为蒂的下颌骨膜瓣修复喉气管具有可行性。     

Contributions of individual muscles to the submental surface electromyogram during swallowing.

Submental surface electromyographic recordings are commonly used in the investigation of swallowing disorders. The measured electromyography is thought to reflect the actions of floor-of-mouth muscles. Although this is a reasonable assumption, to date there have been no investigations to delineate which muscles contribute to this surface recording. The primary goal of this experiment was to determine which muscles contribute most to the submental surface. Electromyography was recorded simultaneously from the submental surface as well as from five individual muscles: mylohyoid, anterior belly of the digastric, geniohyoid, genioglossus and platysma. Three analysis methods were performed to estimate individual muscle contributions: correlation, numeric, and analytic. For the numeric and analytic analyses, a linear model was defined and used to represent the relationship between the surface and intramuscular recordings. Muscles that received a high correlation, numeric and/or analytic value were considered to be primary contributors to the submental recording. Regardless of analysis approach, the primary contributions to the submental surface recording were the mylohyoid, anterior belly of the digastric, and the geniohyoid muscles. Contributions from the genioglossus and the platysma muscles were minimal. Contributions as a function of bolus volume and viscosity are also discussed.     

Submental surgery. A graduated approach to the aging neck

Adequate aesthetic contouring of the aging neck often presents a difficult surgical challenge to the facial plastic surgeon. The apparent failure of the classic rhytidectomy to achieve acceptable results in the submental region has encouraged previous surgeons to develop surgical techniques specifically addressing this area. Definitive procedures were developed to treat the excess skin, fat, or muscle. Aesthetic results have progressively improved with the introduction of liposuction, judicious muscle rearrangement, and more conservative submental skin violation. This article describes our experience with these concepts and presents a useful classification devised to serve as an operative guide in the management of the aging neck.     

Quantitative contributions of the muscles of the tongue, floor-of-mouth, jaw, and velum to tongue-to-palate pressure generation

PURPOSE: The purpose of this investigation was to evaluate the relationship between tongue-to-palate pressure and the electromyography (EMG) measured from the mylohyoid, anterior belly of the digastric, geniohyoid, medial pterygoid, velum, genioglossus, and intrinsic tongue muscles. Methods Seven healthy adults performed tongue-to-palate pressure tasks at known percentages of their maximum pressure while intramuscular EMG was recorded from the muscles stated above. Multiple regression analysis was performed. RESULTS: Predictors of pressure included the posterior fibers of the genioglossus, mylohyoid, anterior belly of digastric, medial pterygoid, and intrinsic tongue. CONCLUSIONS: Increasing tongue-to-palate pressure coincides with increased muscle activity. Activation of the floor-of-mouth, tongue, and jaw closing muscles increased tongue-to-palate pressure. These findings support the use of a tongue-press exercise to strengthen floor-of-mouth muscles, tongue, and jaw-closing muscles.     

Neonatal dermoid cyst of the floor of the mouth extending to the midline neck.

We describe a male neonate who presented at birth with a compressible dermoid cyst that extended from the floor of the mouth to the midline of the neck. Ultrasonography revealed a fluid-filled sublingual mass. Magnetic resonance imaging performed when the patient was 1 week old demonstrated a 2-cm, cystic, left-sided, sublingual mass that crossed the midline without extension inferior to the mylohyoid muscle. At 3 months of age, the patient developed a 1-cm, solid, submental mass. At the time of surgery, the lesion had a fibromembranous tract that extended through the myolohyoid muscle to a 1-cm cyst in the submental region. Histologic sections depicted 2 dermoid cysts and a connecting fistula. This case represents the first report (to our knowledge) of a dermoid cyst presenting in a neonate as a mass in the floor of the mouth with extension to the midline of the neck.     

Severe posterior epistaxis-endoscopic surgical anatomy

OBJECTIVE: To describe the anatomy of the sphenopalatine foramen (SPF) region and possible anatomical variations. STUDY DESIGN: Prospective study accomplished from September, 2006, to January, 2007. METHODS: The sphenopalatine foramen (SPF) of 61 cadavers were carefully dissected. Presence of the ethmoidal crest, location of sphenopalatine and accessory foramens, and the number of arterial branches emerging through foramens were observed. Data were analyzed in relation to gender, racial group, and symmetry of the cadaver. Prediction of the presence of accessory foramen was evaluated. RESULTS: Mixed race cadavers prevailed in 122 nasal fossae dissected (75% males). Ethmoidal crest was present in 100% of the cadavers, being anterior to the SPF in 98.4% of the cases. The most frequent SPF location was the transition of the middle and superior meatus (86.9%). Mean distance from the SPF and accessory foramen to anterior nasal spine was 6.6 cm and 6.7 cm, respectively. Accessory foramen was present in 9.83% of the cases. A single arterial stem emerged through the SPF in 67.2% of the cases, and 100% through accessory foramens. The prevalence analyses showed no differences that were statistically significant (P > 0.05) between gender and racial group. The symmetry analyses showed a strong conformity (P < 0.01) between nasal fossae in relation to the SPF location. There was no statistically significant conformity between nasal fossae and accessory foramen (P = 0.53). None of the variables of interest presents any statistically significant (P > 0.05) association with the presence of the accessory foramen. CONCLUSIONS: There are anatomical variations in the lateral nose wall that should be considered for successful endoscopic surgical treatment of severe epistaxis.     

Anatomical study of jugular foramen in the neck

IntroductionThe anatomical complexity of the jugular foramen makes surgical procedures in this region delicate and difficult. Due to the advances in surgical techniques, approaches to the jugular foramen became more frequent, requiring improvement of the knowledge of this region anatomy.ObjectiveTo study the anatomy of the jugular foramen, internal jugular vein and glossopharyngeal, vagus and accessory nerves, and to identify the anatomical relationships among these structures in the jugular foramen region and lateral-pharyngeal space.MethodsA total of 60 sides of 30 non-embalmed cadavers were examined few hours after death. The diameters of the jugular foramen and its anatomical relationships were analyzed.ResultsThe diameters of the jugular foramen and internal jugular vein were greater on the right side in most studied specimens. The inferior petrosal sinus ended in the internal jugular vein up to 40 mm below the jugular foramen; in 5% of cases. The glossopharyngeal nerve exhibited an intimate anatomical relationship with the styloglossus muscle after exiting the skull, and the vagal nerve had a similar relationship with the hypoglossal nerve. The accessory nerve passed around the internal jugular vein via its anterior wall in 71.7% of cadavers.ConclusionAnatomical variations were found in the dimensions of the jugular foramen and the internal jugular vein, which were larger in size on the right side of most studied bodies; variations also occurred in the trajectory and anatomical relationships of the nerves. The petrosal sinus can join the internal jugular vein below the foramen.     

The effects of taste and consistency on swallow physiology in younger and older healthy individuals: a surface electromyographic study.

Recent studies done on healthy older individuals have demonstrated elevated taste thresholds for sweet, sour, and salty taste. At suprathreshold levels, such individuals have also shown less ability to discriminate between different intensities of the same tastant. This study was designed to provide information on swallow timing and muscle contraction intensity variables in healthy older people during swallowing of liquid and cottage cheese consistencies in 3 taste conditions (sweet, salty, and sour). Taste and consistency were incorporated in the design of this study to determine not only the effect of taste and consistency independently, but also the effects of taste and consistency in combination. Surface electromyography (EMG) at 3 sites--the orbicularis oris inferior region, submental muscle region, and infrahyoid muscle region--were included in the study. Results revealed that the start of submental muscle activation was significantly later in older participants than in younger participants. The 3 taste conditions had higher EMG levels and shorter activation times than the no-taste condition, although different taste conditions and different muscle sites were affected differently. With thicker consistency, substantially increased EMG amplitude and duration were noted for all three sites. A more pronounced effect of taste was manifested as earlier submental or infrahyoid muscle activation when the three tastants were added to a thicker consistency. Interaction of taste, consistency, and age was also noted for onset time at the submental and infrahyoid sites.     

电生理法对豚鼠副嗅球功能分区的显示

目的 :探讨豚鼠副嗅球 (AOB)是否存在多个功能分区。方法 :在豚鼠副嗅球矢状位切片上 ,将双钨电极插入副嗅球前部或后部的犁鼻神经纤维层 (VNL ) ,以单个方波刺激传入神经纤维 ,用玻璃微电极记录 AOB前部或后部外橄状层 (EPL)细胞外场电位。结果 :电刺激 VNL,可在 EPL 记录到典型的衰减性场电位 ,且后 EPL记录到的场电位的持续时间较前部分明显延长。刺激前 VNL 仅在前 EPL 记录到场电位 ,而刺激后 VNL 只在后EPL 记录到场电位。结论 :豚鼠副嗅球可分为前后两个亚区 ,两区存在解剖学上的差异 ,说明在犁鼻系统中至少存在两个不同的传入 -传出通路。     

Innovations in platysma rhytidectomy

Cervical and submental deformities are the major complaints of many patients who have had rhytidectomies. Unfortunately, traditional rhytidectomy techniques have failed to provide satisfactory and lasting results in this region. During recent years, the superficial muscular aponeurotic system has been described and multiple platysma surgical techniques introduced. Our technique emphasizes a youthful cervical and submental region. It involves an anterior submental incision, total surgical excision of the anterior platysma bands, conservative submental lipectomy, routine rhytidectomy dissection, submandibular and mandibular fat contouring, and division and rotation of platysma flaps. This technique has been used for two years on 94 patients. There have been no complications specifically related to this technique.     

Submental flap for reconstruction of anterior skull base,orbital, and high facial defects

Purpose

Large anterior skull base, orbital, and high facial defects can present a challenging reconstructive problem. Limited data exists in the literature on the use of a submental flap for reconstructing such defects. We aimed to describe the feasibility, success, and advantages of using variations of the submental flap for reconstruction of anterior skull base, orbital, and high facial defects.

Arytenoid motion evoked by regional electrical stimulation of the canine posterior cricoarytenoid muscle

Anatomical studies have demonstrated that the posterior cricoarytenoid muscle in the dog is composed of three bellies. These bellies are termed vertical, oblique, and horizontal on the basis of their orientation. The purpose of this study was to show whether each of these bellies can move the vocal fold in different ways. Ten anesthetized dogs underwent laryngectomies while paralyzed with curare. The posterior cricoarytenoid muscles were then exposed by dissecting the overlying esophageal mucosa. Electrical stimulation was applied to each belly, and the motion of the arytenoid cartilage was measured. Because the oblique belly overlies the vertical belly, they were usually stimulated together. It was found that the vertical and oblique bellies rock the arytenoid backwards while sliding it laterally, thus causing a maximal dilation of the airway. The horizontal belly caused a swiveling motion of the arytenoid. It is proposed that the vertical and oblique bellies normally cause vocal fold abduction during respiration, while the horizontal belly primarily is used to adjust finely the position of the vocal process during phonation. Because the human posterior cricoarytenoid is also composed of separate bellies it, too, may have distinct functions.     

舌骨上肌与喉内肌的同步肌电生理实验研究

目的对犬的舌骨上肌（二腹肌前腹、后腹,茎突舌骨肌,下颌舌骨肌和颏舌骨肌）与喉内肌（环杓侧肌和环杓后肌）进行同步肌电图研究。方法检测13只犬同步肌电图。结果①呼吸时环杓侧肌在呼气相放电,余各肌在吸气相放电。深呼吸时诸肌放电强度增加。②吞咽时诸肌和环杓侧肌呈同步放电。环杓后肌肌电抑制,间歇期可见肌电位发放。③发音时二腹肌前腹、后腹和环杓侧肌呈同步性密集型放电,环杓后肌在发音过程中持续放电,动作电位出现时间较迟。茎突舌骨肌和颏舌骨肌无明显肌电活动。结论①发音及吞咽时下颌舌骨肌与环杓侧肌同步且相似,可作为重建声门内收功能的备选肌肉;②吸气时颏舌骨肌与环杓后肌同步且相似,可作为重建声带外展功能的备选肌肉。     

The three bellies of the canine posterior cricoarytenoid muscle: Implications for understanding laryngeal function

The posterior cricoarytenoid (PCA) muscle is known to be active during phonation and respiration. The presence of muscle compartments (bellies) that might subserve these functions was investigated in the canine PCA by anatomical dissection and muscle fiber histochemistry. Five PCA muscles were microdissected and the origins and insertions of all muscle bundles were recorded. An additional six PCA muscles were frozen, sectioned, and stained for adenosine triphosphatase (ATPase) activity. The total number of fast- and slow-twitch fibers were counted and their proportion was determined for each region of the muscle. The PCA muscle was found to contain three distinct neuromuscular compartments. The vertical compartment is oriented at 24 degrees from true vertical, inserts on the lateral aspect of the muscular process of the arytenoid, and is composed of 65% type 2 (fast) muscle fibers. The oblique is oriented at 44 degrees from vertical, inserts on the top of the muscular process of the arytenoid, and is composed of 77% type 2 muscle fibers. The horizontal is oriented at 63 degrees from vertical, inserts on the medial aspect of the muscular process of the arytenoid, and is composed of 59% type 2 muscle fibers. The cricoarytenoid joint is capable of three arcs of motion and the physical arrangement of each compartment appears to correspond to each of these motions. Moreover, the histochemical profiles show that the activity of the three bellies is quite different. These results suggest that the different compartments of the PCA perform distinctive motions during phonation and inspiration.     

The intramuscular nerve supply of the posterior cricoarytenoid muscle of the dog.

The paired posterior cricoarytenoid (PCA) muscle has three separate muscle bellies that differ in muscle fiber type (percentage of fast vs. slow twitch) and electromyelographic activity, and, in addition, produce different movements of the arytenoids when stimulated. An investigation of the innervation of the muscle was undertaken to demonstrate the existence of separate functional units. The intramuscular nerve supply of the PCA from five sacrificed dogs were microdissected. The intramuscular nerves of three additional dogs were removed and stained for acetylcholinesterase, which differentiates axons bound for fast- and slow-twitch muscle, and sensory end organs. Three separate fascicles are described entering the PCA muscle from a single branch of the recurrent laryngeal nerve. The three fascicles differ in axon type composition and in sensory, autonomic, and motor percentages, with the ratio of fast twitch to slow twitch varying from 0.78 to 1.5 to 1.7 (P less than .05). This variation supports separate functional capabilities for the three muscle bellies of the PCA.