Division Of Muscle Research Articles

Per Oral Pyloromyotomy for Treatment of Gastroparesis in a Pediatric Patient

Per Oral Pyloromyotomy for Treatment of Gastroparesis in a Pediatric Patient

Tip Droop Prevention in Rhinoplasty: Dynamic Effect of Strut Graft on Smiling versus Depressor Muscle Release.

Background:Aesthetic rhinoplasty is one of the most challenging procedures performed by aesthetic surgeons. Tip droop, especially on smiling, may not be noted by the surgeon postoperatively but can be concerning to patients. Our aim was to determine if the division of the depressor septi nasi or its combination with a columellar strut graft during rhinoplasty produce a measurable reduction in nasal tip droop on smiling.Methods:A retrospective casenote and photograph review was conducted on patients who had undergone aesthetic endonasal rhinoplasty, performed by a single surgeon between 2015 and 2019. In total, 29 patients had release of the depressor septi nasi muscle, whilst 11 had release of the muscle along with a strut graft. Lateral smiling photographs were taken postoperatively. Tip droop was measured as a variation of the nasolabial angle from rest to smiling using the Frankfurt line.Results:Photographs were taken at a mean of 14 months postoperatively. In the group who had muscle release only, a mean increase in nasolabial angle of 3.66 degrees was seen when smiling when compared with rest. In the group who had muscle release combined with strut graft, a mean increase of 2.27 degrees was seen. When using a columellar strut along with muscle release, tip droop on smiling was reduced.Conclusions:This study demonstrates that columellar strut grafting in combination with muscle release can alleviate drooping of the tip better than muscle division alone after rhinoplasty. The columellar strut graft provides tip stability and can therefore be used to enhance dynamic outcomes after rhinoplasty.

Partial Division of Puborectalis Muscle with Lateral Internal Sphincterotomy: A Novel Surgical Technique for Management of Anal Hypertonia‐Associated Anismus

Treatment of anismus usually starts with biofeedback therapy and injection of botulinum toxin in the puborectalis muscle (PRM). Patients refractory to conservative treatment may require surgery. The present cohort study aimed to assess a combined technique of partial division of PRM and tailored lateral internal sphincterotomy (LIS) in treatment of anismus. Patients with anismus who failed conservative treatments were assessed clinically and with high-resolution anal manometry (HRAM), EMG, defecography, and underwent combined partial division of PRM on one side and tailored LIS on the contralateral side. Main outcome measures were improvement in symptoms and quality of life, changes in HRAM and defecography postoperatively, complications, and patient satisfaction. A total of 73 patients (61 male) of a mean age of 37 years were included to the study. In total, 89% of patients showed a significant improvement in symptoms at 12 months postoperatively. The mean modified Altomare score decreased significantly (p < 0.0001) from 16.4 ± 1.7 to 6.6 ± 1 at 12 months postoperatively. There was a significant increase in the mental and physical components of quality of life at 12 months postoperatively. The numbers of patients with positive findings of anismus in postoperative defecography, EMG, and balloon expulsion test were significantly less than before surgery. The mean total satisfaction score was 86.5 ± 8.7. Five (6.5%) patients developed minor complications. Partial division of puborectalis muscle combined with LIS is an effective technique in the management of anal hypertonia-associated anismus with satisfactory results and low incidence of complications.

Functional properties of single motor units in the human medial pterygoid muscle: Thresholds.

Little is known regarding the functional properties of single motor units (SMUs) in the medial pterygoid muscle (MPt) during jaw movements. The aims are (a) to report the thresholds of onset of MPt SMUs during 4 goal-directed jaw movement tasks, and (b) to determine whether the threshold of onset of SMU activation varies with the velocity of jaw movement and the location within the muscle. Intra-muscular electrodes were inserted in the right MPt of 18 participants performing ipsilateral (right), contralateral, protrusive and opening-closing jaw movements recorded at 2 velocities. Task phases were as follows: BEFORE, OUT, HOLDING, RETURN and AFTER. SMU onset thresholds were determined from the displacement (mm) of the lower mid-incisor point. Electrode location within 4 arbitrary muscle divisions was determined with computer tomography. Statistical tests: Spearman's correlations, Kruskal-Wallis tests; significance accepted at P<.05. A significant inverse relation occurred between velocity and threshold for the RETURN of the ipsilateral movement (n=62 SMU thresholds), while a significant positive relation occurred for the OUT of the contralateral movement (n=208); there were no significant associations for the protrusive (n=131) and opening-closing (n=58) tasks. Significant threshold differences occurred across the 4 muscle divisions only during the OUT of the contralateral and protrusive movements. Some evidence was provided for gender differences in MPt SMU properties. The absence of a significant inverse relation between velocity and SMU threshold for most recorded movements suggests the MPt acts as a stabilizer of the jaw in horizontal and opening-closing jaw movements.

Anatomy of the thoracic limb muscles of wild boars (Sus scrofa, Artiodactyla: Suidae).

The study of the muscular anatomy of wild boar(Sus scrofa) is important, because it allows the understanding of the locomotor and evolutionary aspects, besides the improvement of surgical techniques used by veterinarians in swine. Thus, the objective of this study was to describe the morphology and disposition of the shoulder and arm muscles of S. scrofa. Twelve young specimens of hybrid S. scrofa, six males and six females were fixed and dissected following usual anatomy techniques. The bones of two specimens were prepared to analyze the fixation points of the muscles. The shoulder muscles presented fixation at the scapula and humerus, in distinct bone accidents, and were divided on lateral and medial faces. On the lateral face, the deltoid (divided in acromial and scapular parts), supraspinatus, infraspinatus (divided in cranial and caudal parts) and teres minor (deep to the caudal part of the infraspinatus) muscleswere found. In the medial face, the subscapular, coracobrachialis and teres majormuscles were observed. The arm muscles were arranged essentially around the humerus and were seen largely on its medial face, namely biceps brachii (originated by a single tendon), brachialis, tensor fasciae antebrachii (fused with the long head of the triceps brachii), triceps brachii (divided in lateral, long and medial heads) and anconeus (located mostly on the lateral side) muscles. Thus, it can be concluded that the S. scrofa presented seven muscles in the shoulder region and six muscles in the arm region, all with morphological similarities to domestic and some wild animals. Some differences werefound, for the most part, in the shape, division and fixation points of certain muscles.

Carotid endarterectomy remains safe in high-risk patients

ObjectiveCarotid endarterectomy (CEA) is a proven intervention for stroke risk reduction in symptomatic and asymptomatic patients. High-risk patients are often offered carotid stenting to minimize the risk and optimize the outcomes. As a referral center for high-risk patients, we evaluated and analyzed our experience with high-risk CEA patients. MethodsWe retrospectively reviewed consecutive patients who had undergone CEA at a tertiary referral center. The demographics, indications for surgery, physiologic and anatomic risk factors, intraoperative surgical management, perioperative complications, morbidity, and mortality were analyzed. The high-risk physiologic factors identified included an ejection fraction <30%, positive preoperative stress test results, and compromised pulmonary function test results. The high-risk patients included those requiring home oxygen, those with a partial pressure of oxygen of <60 mm Hg, and patients with a forced expiratory volume in 1 second of <30%. The high-risk anatomic factors identified included previous head and/or neck radiation, a history of ipsilateral neck surgery, contralateral nerve palsy, redo CEA, previous ipsilateral stenting, contralateral occlusion, contralateral CEA, nasotracheal intubation, and digastric muscle division. After propensity score matching, patients with and without high-risk physiologic and anatomic factors were compared. The primary outcomes were a composite of stroke, myocardial infarction, and 30-day mortality. The secondary outcomes were cranial injury and surgical site infection. ResultsDuring a 10-year period, 1347 patients had undergone CEA at the Cleveland Clinic main campus. Of the 1347 patients, 1152 met the criteria for analysis. Propensity score matching found adequate matches for 424 high-risk patients, with 173 patients having at least one physiologic high-risk factor and 293 at least one anatomic high-risk factor. No significant differences were found in the primary composite outcome or any of its components. Overall, the stroke rate for the standard-risk and high-risk patients was 1.9% and 1.4%, respectively. The high-risk patients were significantly more likely to have experienced a cranial nerve injury, although most were temporary. When patients with one or multiple risk factors were analyzed, no significant difference was found in the primary composite outcome or any of its components. Patients with two or more risk factors were significantly more likely to have experienced a cranial nerve injury, with most being temporary. ConclusionsIn our large series, CEA remained a viable and safe surgical solution for patients with high-risk anatomic and physiologic risk factors, with acceptable stroke, myocardial infarction, and 30-day mortality rates.

Musculoskeletal deformities after thoracic surgery in children: An observational long-term follow-up study

PurposeThis study reports the incidence, severity, and predictors of musculoskeletal deformities (MD), including scoliosis and chest wall anomalies, following thoracic procedures in children. MethodsChildren younger than 14 years who had thoracic surgery between 1997 and 2012 and had no other predispositions to MD, underwent longitudinal follow-ups with dedicated musculoskeletal examination performed in an esophageal atresia, orthopedic, or research clinic. Incidence of MD was calculated, and logistic regression methods were used to determine independent predictors, including sex, gestational age, age at procedure, serratus anterior muscle division, and chest tube placement. ResultsThe study cohort consisted of 104 patients followed for a median of 10.8 years (range 3–21). A total of 56 MD developed in 41 patients (39%), including scapular winging (24; 23%), scoliosis (17; 16%), and chest wall anomalies (15; 14%). The majority of MD were subclinical, with only 8 patients [8% (6 thoracotomies, 2 thoracoscopies)] requiring intervention. Among patients who underwent thoracotomies (93, 89%), serratus anterior muscle division was the only significant predictor of the development of MD [OR 8.9; 95% CI 2.8–32.6]. ConclusionMusculoskeletal deformities develop in a significant proportion of children following thoracic surgery, but most are subclinical. A muscle-sparing technique decreases the incidence of these deformities. Type of StudyProspective Cohort Study. Level of EvidenceLevel II.

Surgical Strategies for Cervical Deformities Associated With Neuromuscular Disorders.

Neuromuscular disorders (NMDs) are diseases involving the upper and lower motor neurons and muscles. In patients with NMDs, cervical spinal deformities are a very common issue; however, unlike thoracolumbar spinal deformities, few studies have investigated these disorders. The patients with NMDs have irregular spinal curvature caused by poor balance and poor coordination of their head, neck, and trunk. Particularly, cervical deformity occurs at younger age, and is known to show more rigid and severe curvature at high cervical levels. Muscular physiologic dynamic characteristics such as spasticity or dystonia combined with static structural factors such as curvature flexibility can result in deformity and often lead to traumatic spinal cord injury. In addition, postoperative complication rate is higher due to abnormal involuntary movement and muscle tone. Therefore, it is important to control abnormal involuntary movement perioperatively along with strong instrumentation for correction of deformity. Various methods such as botulinum toxin injection, physical therapy, muscle division technique, or intrathecal baclofen pump implant may help control abnormal involuntary movements and improve spinal stability. Surgical management for cervical deformities associated with NMDs requires a multidisciplinary effort and a customized strategy.

Sublabial Approach to Tip Rhinoplasty: A Cadaver Model

Objectives The main objective of this study was to investigate the utility of the sublabial approach in gaining proper exposure for tip rhinoplasty maneuvers in a cadaver model. Additional objectives included identifying types of grafts that can be placed sublabially and whether these methods can be translated successfully to human subjects. Methods Ten (N = 10) fresh-preserved cadavers were dissected at our academic institution from August 18, 2019 through February 5, 2020. Photographs of the cadavers were taken with permission from the anatomy laboratory manager using an iPhone 10 (Apple Inc., Cupertino, CA). Standard rhinoplasty views were taken of all ten cadavers. Results Grafts were harvested and designed from septal (80%), auricular (50%) and rib cartilage (40%). The division of depressor septi muscle was accomplished in all ten (100%) cadavers to address tip ptosis. Placement of the columellar strut and shield grafts resulted primarily in the improvement of nasal projection as well as rotation in all (100%) cadavers. Premaxillary augmentation was not always indicated but helped to improve an acute, retrodisplaced nasolabial angle in three (30%) cadavers. Lateral osteotomies via this approach addressed the nasal bony pyramid in all ten (100%) cadavers. The swinging door technique enabled correction of the caudal septum in six (60%) cadavers. Conclusions Several rhinoplasty techniques can be successfully performed on cadavers via the sublabial approach and we hope this work can be translated to human subjects.

Is Routine Postoperative Anticoagulation Necessary in All Patients after First Rib Resection for Paget-Schroetter Syndrome?

Definitive treatment of Paget-Schroetter syndrome (PSS) involves first rib resection (FRR), division of the anterior scalene muscle, and resection of the subclavius muscle. This is a single-institution experience with PSS, according to a treatment algorithm of preoperative venogram (accompanied by lysis and percutaneous mechanical thrombectomy as needed) followed by transaxillary FRR. In the later period of this experience, patients have often been discharged on aspirin only, with no plan for anticoagulation postoperatively. We sought to evaluate outcomes in light of this experience and these practice patterns. Between 2007 and 2018, 125 transaxillary FRRs were performed in 123 patients. All patients presented with documented venous thrombosis, underwent diagnostic venography and-if indicated-lysis and percutaneous mechanical thrombectomy (VPT) before FRR. The patient was not offered FRR if the vein could not be crossed with a wire and patency was not re-established during percutaneous treatment. The experience was divided into early (before 2012, n=50) and late (n=75) periods. Mean patient age was 28.4 (12-64years) years. Of the cohort, 33 were high-level competitive athletes, 13 presented with documented pulmonary embolism in addition to local symptoms, and 3 had a cervical rib fused to the first rib. Patients underwent FRR a median of 50 (4 days to 18 years) days after their initial symptoms, and a median of 22 (1 day to 9 months) days after their percutaneous intervention. Postoperative VPT was required in 23 patients and performed a median of 5 (1-137days) days postoperatively; in 19 of these patients, postoperative VPT was required for postoperative re-thrombosis, whereas in 4 patients, postoperative VPT was planned before FRR due to vein stenosis or residual thrombus. All these patients were prescribed postoperative anticoagulation. No operative venous reconstruction or bypass was performed. Median follow-up time after FRR was 242days; at last follow-up, 98.4% (123/125) of axillosubclavian veins were patent by duplex ultrasound (and all those patients were asymptomatic). Postoperative anticoagulation was less frequently prescribed in the late experience, with no difference in the rate of early re-thrombosis or follow-up patency. This experience demonstrates 98.4% patency at last follow-up with standard preoperative percutaneous venography and intervention, transaxillary FRR, and postoperative endovascular re-intervention only in cases with persistent symptoms, stenosis, or re-thrombosis. Patients presenting with both acute and chronic PSS did not require surgical venous reconstruction. In the later experience, patients frequently have not been anticoagulated postoperatively. Advantages of this algorithm include the following: (1) the cosmetic benefits of the transaxillary approach, (2) the preoperative assessment of the ability to recanalize the vein to determine which patients will benefit from surgery, (3) the capacity to use thrombolysis preoperatively, and (4) potential elimination of the risk and inconvenience of postoperative anticoagulation.

Lateral internal sphincterotomy (LIS)—still top gun in chronic anal fissure treatment?

Anal fissure is one of the most common proctological complaints. If the fissure persists for more than 6–8 weeks, it is termed a chronic fissure and will most likely need surgical intervention. Surgical partial transection of the internal sphincter muscle, lateral internal sphincterotomy (LIS), is still seen as the gold standard procedure for chronic anal fissure in many parts of the world, especially in the Anglo-American community. In contrast, the German-speaking surgical community favors fissurectomy ± application of Botox, as some studies report high postoperative incontinence rates after LIS. This paper aims to give an overview of the literature on LIS and its outcomes and answer the question, “Is LIS still the gold standard surgical approach for chronic anal fissure?” A literature search for “sphincterotomy,” “internal sphincter,” and “anal fissure” was performed in PubMed. For the purpose of this overview article, randomized controlled trials (RCTs), meta-analyses, up-to-date guidelines, and retrospective cohort studies were taken into account. LIS produces excellent rates of fissure healing (~95%), quick symptom relief, and high patient satisfaction. Incontinence after LIS is mostly described as mild and transient. In the authors’ view, open LIS is therefore rightfully still the gold standard procedure for treatment of chronic anal fissure in the majority of patients. A conservative approach with limited division of internal sphincter muscle is preferred. For patients with preexisting sphincter weakness and an increased risk of incontinence, further preoperative diagnostic assessment (anal manometry, endoanal ultrasound) is recommended. In this high-risk group, alternative surgical options might be preferred.

Comparison between the 4K ultra-high definition (UHD) and high definition (HD) endoscopic systems for transoral endoscopic thyroidectomy.

The transoral endoscopic thyroidectomy vestibular approach (TOETVA) is the most recently introduced method of minimally invasive thyroid surgery. To our knowledge, no studies have compared TOETVA outcomes using different laparoscopic systems. This study compared outcomes of TOETVA using conventional high definition (HD) and ultra-high definition (UHD) equipment. Medical data and surgery videos of 62 patients who randomized to undergo thyroid lobectomy by TOETVA using an HD or UHD system from August 2018 to April 2019 were retrospectively reviewed. Endoscopic procedures were divided into four phases: flap creation to isthmectomy (phase I); strap muscle division to upper pole ligation (phase II); trimming recurrent laryngeal nerve (phase III); and ligation of Berry's ligament to complete resection (phase IV). Of the 62 patients, 28 underwent TOETVA using an HD device and 34 using a UHD device. The clinical characteristics of the two groups were not different. Mean operating time for lobectomy was similar in the HD and UHD groups (44.19±9.94 versus 43.47±12.19 min, P=0.825). The times required for phases I (15.02±5.33 versus 13.67±5.44 min, P=0.397); II (12.89±2.84 versus 13.17±5.22 min, P=0.816); III (9.85±4.36 versus 9.98±4.55 min, P=0.918); and IV (6.43±3.69 versus 6.65±3.45 min, P=0.840) were also similar in the HD and UHD groups. The numbers of retrieved lymph nodes did not differ significantly in the HD and UHD groups (3.26±2.62 versus 3.45±2.81, P=0.807). Applying a UHD system in TOETVA resulted in outcomes similar to those observed with a conventional HD system. Operation time tended to be lower, especially for flap dissection, and numbers of harvest lymph nodes tended to be higher in the UHD group. Large-scale studies are needed to assess the advantages of the UHD system.

The Transaxillary Subcutaneous Endoscopic Sternocleidomastoid Muscle Division as an Approach for the Surgical Treatment of Congenital Muscular Torticollis in Children.

Traditionally congenital muscular torticollis is treated with a neck incision which results in a neck scar. The purpose of this study was to evaluate the effectiveness of the transaxillary subcutaneous endoscopic sternocleidomastoid muscle division for the treatment of congenital muscular torticollis. This is a prospective study of 7 children with torticollis treated surgically by the transaxillary endoscopic approach in the department of Pediatric Surgery between 2014 and 2018. The age at operation ranged from 5.5 to 9years, mean 7.3 (SD ± 1.3) years. The mean operation time was 65min. The complete muscular release was successfully completed using the endoscopic approach. There were no major complications. All patients improved in gaze angle, lateral tilt and range of motion. There was no cosmetically unacceptable scar visible at the surgical sites in all patients during follow up. All families were pleased with the cosmetic outcome. The transaxillary subcutaneous endoscopic technique can be applied as a surgical approach for children with muscular torticollis an alternative to traditional open methods. It is a technically feasible procedure in children, provides excellent cosmesis and moreover avoids scarring on the neck.

Transaxillary left-sided minimally invasive approach for upper thoracic vertebral resection and reconstruction at T2–T3 levels: a case report

Surgical procedures of the upper thoracic spine are often challenging due to the anatomical topography of the thoracic spine. The most common approaches include the anterior supramanubrial, transmanubrial, and transsternal as well as the posterior approach with costotransversectomy. Recently, an infraaxillary right-sided thoracotomy was described for upper thoracic vertebral decompression and fusion at T2–T6 levels. In the current case, we report a transaxillary left-sided mini-thoracotomy for thoracic vertebral resection and reconstruction at T2–T3 levels. The incision enabled safe and uncomplicated surgery of the upper thoracic spine providing excellent exposure of the surgical site. Compared with the common incisions applied for surgery of the upper thoracic spine, surgical trauma is minimized without the need of sternotomy, division of the back muscles or resecting a rib. Moreover, anatomical critical structures such as the common carotid trunk, the jugular vein, or trachea are not encountered, hence increasing the safety of the procedure.

Evaluation of anterior versus posterior component separation for hernia repair in a cadaveric model.

Component separation remains an integral step during ventral hernia repair. Although a multitude of techniques are described, anterior component separation (ACS) via external oblique release (EOR) and posterior component separation (PCS) via transversus abdominis muscle release (TAR) are commonly utilized. The extent of myofascial medialization after ACS or PCS has not been well elucidated. We conducted a comparative analysis of ACS versus PCS in an established cadaveric model. Fifteen cadavers underwent both ACS via EOR and PCS via TAR. Following midline laparotomy (MLL), baseline myofascial elasticity was measured. Steps for ACS included creation of subcutaneous flaps (SQF), external oblique release (EOR), and retrorectus dissection (RRD). For PCS, steps included retrorectus dissection (RRD), transversus abdominis muscle division (TAD), and retromuscular dissection (RMD). Maximal advancement of anterior rectus fascia (ARF) was measured following application of tension to the fascia as a whole, and separately at upper, middle, and lower segments. Statistical analysis was performed with Mann-Whitney U test. Values are represented as average myofascial medialization in centimeters. Following MLL an average of 5.0 ± 0.9cm (range 3.4-6.0cm) of baseline medialization was obtained. Complete ACS provided 8.8 ± 1.2cm (range 6.3-10.7cm) of ARF advancement compared to 10.2 ± 1.7cm (range 7.6-12.7cm) with PCS, p = 0.046. In the upper and mid-abdomen, we noted increased ARF advancement with PCS versus ACS (8.1 ± 1.4cm vs. 6.7 ± 1.2cm and 11.4 ± 1.5 vs. 9.6 ± 1.4cm, respectively, p = 0.01). Similar levels of ARF advancement were observed in the lower abdomen, 9.1 ± 1.7cm versus 8.7 ± 1.8cm, p = 0.535. Component separation via both anterior and posterior approaches provide substantial myofascial advancement. In our model, we noted statistically greater anterior fascial medialization after PCS versus ACS as a whole, and especially in the upper and mid-abdomen. We advocate PCS as a reliable and possibly superior alternative for linea alba restoration for reconstructive repairs, especially for large defects in the upper and mid-abdomen.

A Quantitative Analysis of Animation Deformity in Prosthetic Breast Reconstruction.

Animation deformity is characterized by implant deformity with pectoralis contraction after subpectoral implant-based breast reconstruction. Extant methods to measure and analyze animation deformity are hampered by the paucity of objective, quantitative data. The authors endeavored to supplement subjective measures with an in-depth quantitative analysis. Patients undergoing subpectoral implant-based breast reconstruction were followed prospectively with video analysis of animation deformity. Nipple displacement and surface area of contour deformity in resting and contracted states were quantified using imaging software. Degree of animation was compared to breast size, body mass index, division of pectoralis muscle, complications, and radiation therapy. One hundred forty-five reconstructed breasts (88 patients) were analyzed. Mean nipple displacement was 2.12 ± 1.04 cm, mean vector of nipple displacement was 62.5 ± 20.6 degrees, and mean area of skin contour irregularity was 16.4 ± 15.41 percent. Intraoperative pectoralis division, smooth/round implants, and bilateral reconstructions were associated with greater deformity. A three-tiered grading system based on thresholds of 2-cm net nipple displacement and 25 percent skin contour irregularity placed 41.4 percent of breasts in grade 1, 35.9 percent in grade 2, and 22.8 percent in grade 3. Interrater variability testing demonstrated 89.5 percent overall agreement (kappa = 0.84). This study presents the first quantitative analysis of animation deformity in prosthetic breast reconstruction. Geometric analysis of nipple displacement vector and increasing animation with pectoralis division both implicate the inferior pectoralis myotome as a primary driver of animation deformity. A concomitant grading schema was developed to provide a standardized framework for discussing animation from patient to patient and from study to study.

Visualization and Quantification of Digitally Dissected Muscle Fascicles in the Masticatory Muscles of Callithrix jacchus Using Nondestructive DiceCT.

The organization and length of a muscle's fascicles imparts its contractile properties. Longer fascicles permit increased muscle excursion, whereas changes in fascicle orientation relate to the overall vector of contractile force. Collecting data on fascicle architecture has traditionally involved destructive and irreversible gross dissection. In recent years, however, new imaging modalities have permitted muscles and their fascicles to be visualized nondestructively. Here, we present data from a primate (Callithrix jacchus), in which, for the first time, individual muscle fascicles are digitally "dissected" (segmented and reconstructed) using nondestructive, high-resolution diffusible iodine-based contrast-enhanced computed tomography (DiceCT) techniques. We also present quantitative data on the length and orientation of these fascicles within 10 muscle divisions of the jaw adductor and abductor musculature (superficial, deep, and zygomatic portions of temporalis and masseter; medial and lateral pterygoid; anterior and posterior digastric) and compare these digitally measured lengths to fascicular lengths measured using traditional gross and chemical dissection. Digitally derived fascicle lengths correspond well to their dissection-derived counterparts. Moreover, our analyses of changes in fascicle orientation across the adductor complex enable us to visualize previously uncharacterized levels of detail and highlight significant variation between adjacent muscle layers within muscle groups (e.g., between superficial, deep, and zygomatic portions of masseter and temporalis). We conclude that this technique offers great potential to future research, particularly for questions centered around the visualization and quantification of obscured and often-overlooked muscles such as the pterygoid and digastric muscles, and for deriving more accurate models of the masticatory system as a whole. Anat Rec, 302:1891-1900, 2019. © 2019 American Association for Anatomy.

Completely thoracoscopic surgical stabilization of rib fractures: can it be done and is it worth it?

Surgical stabilization of rib fractures (SSRF) is now a common operation at most high-volume trauma centers. Increased experience with the procedure has spawned a variety of technical modifications to minimize incision length, muscle division, scapular retraction, and general tissue trauma. The ultimate example of such a minimally invasive approach is completely thoracoscopic SSRF, which refers to using a video-assisted thoracoscopic surgery (VATS) technique to both reduce and fixate rib fractures in an intra-thoracic fashion. The benefits of thoracoscopic SSRF may be divided broadly into those that relate to the repair of the rib fractures themselves, and those that relate to adjuncts to rib fracture repair. With respect to the former, theoretical benefits include improved visualization of rib fractures (particularly in posterior and sub-scapular locations), minimization of trauma to overlying muscles and nerves, minimization of trauma to intra-thoracic structures, and elimination of palpable plates. With respect to the latter, theoretical advantages include evacuation of retained hemothorax, guided placement of loco-regional anesthesia and chest tubes, and identification and repair of associated, intra-thoracic injuries. A VATS may also aid in trainee education. Despite these theoretical benefits, early attempts at thoracoscopic SSRF have been limited by both user inexperience and inadequate instrumentation. Furthermore, there are currently no data comparing the efficacy of completely thoracoscopic SSRF to either contemporary, minimally-invasive, extra-thoracic SSRF or non-operative management.

Central and peripheral innervation patterns of defined axial motor units in larval zebrafish.

Spinal motor neurons and the peripheral muscle fibers they innervate form discrete motor units that execute movements of varying force and speed. Subsets of spinal motor neurons also exhibit axon collaterals that influence motor output centrally. Here, we have used in vivo imaging to anatomically characterize the central and peripheral innervation patterns of axial motor units in larval zebrafish. Using early born "primary" motor neurons and their division of epaxial and hypaxial muscle into four distinct quadrants as a reference, we define three distinct types of later born "secondary" motor units. The largest is "m-type" units, which innervate deeper fast-twitch muscle fibers via medial nerves. Next in size are "ms-type" secondaries, which innervate superficial fast-twitch and slow fibers via medial and septal nerves, followed by "s-type" units, which exclusively innervate superficial slow muscle fibers via septal nerves. All types of secondaries innervate up to four axial quadrants. Central axon collaterals are found in subsets of primaries based on soma position and predominantly in secondary fast-twitch units (m, ms) with increasing likelihood based on number of quadrants innervated. Collaterals are labeled by synaptophysin-tagged fluorescent proteins, but not PSD95, consistent with their output function. Also, PSD95 dendrite labeling reveals that larger motor units receive more excitatory synaptic input. Collaterals are largely restricted to the neuropil, however, perisomatic connections are observed between motor units. These observations suggest that recurrent interactions are dominated by motor neurons recruited during stronger movements and set the stage for functional investigations of recurrent motor circuitry in larval zebrafish.

Three‐Dimensional Masticatory Muscle Fascicular Orientation in a Digitally Dissected Callithrix jacchus

Diffusible iodine-based contrast-enhanced computed tomography (DiceCT) has been increasingly used to study the functional morphology of soft-tissues. Where traditional CT is ineffective at allowing the differentiation of lower density structures, the iodine in the DiceCT process binds to myological carbohydrates, increasing their density and thus allowing clear visualization of muscles. When done carefully (i.e., with the right concentrations of iodine, for the right amount of time and with intermediate evaluation of diffusion rates), the DiceCT procedure can yield results that allow individual fascicles within specific sections of muscles to be isolated for analysis. Following these procedures, we studied a subset of muscle fascicles from each part of the mandibular adductors (superficial, deep and zygomatic portions of the masseter and temporalis as well as the two heads of medial pterygoid) and the lateral pterygoid of a common marmoset, Callithrix jacchus. We also segmented the skull and aponeuroses to which each of the masticatory muscles attaches. Because we segmented representative fascicles from throughout each muscle portion, we are able to show, for the first time, the angularity of these fascicles relative to each other in three dimensions. We also used traditional gross dissection of these same muscle divisions from the same specimen, followed by chemical dissection and traditional fascicle analysis (including sarcomere measurement). Comparison of these data demonstrates relative congruence between the physically and digitally measured fascicle lengths, with an average variance of 10% between the two techniques. Beyond this confirmation that these digital fascicle dissections yield comparable results to those achieved using traditional methods, this new fascicle-by-fascicle digital dissection reveals other important anatomical findings: 1) the majority of the fascicles are measurably curved when the jaws are at near occlusion. The sarcomeres of each of the adductors were also shorter than their optimal tension length. Thus, near occlusion, fascicles are compressed at both the gross and cellular level, and previous studies that have made assumptions about bite force based on these near occlusion fascicle lengths need to better account for the fact that these fascicles would need to be stretched to wider gapes prior to providing active bite force. 2) The visualization also clearly shows that superficial muscle portions have substantially different fascicle orientations than deeper muscle portions. Thus, it is not possible to physically slice apart muscles based on external appearance without slicing through fascicles, and all studies that have relied on that method have, therefore, almost certainly underestimated fascicle lengths. Lastly, 3) this approach has yielded the first clear visualization of the in situ fascicle orientation of the lateral pterygoid – a muscle that is so inaccessible to traditional gross dissection that it has been largely ignored by masticatory anatomists. However, this anterior translator is of great importance in some taxa, like this gouging C. jacchus, and its visualization may yield new and valuable functional insight. Support or Funding Information This project was supported by the NSF (IOS-15-57125). Fascicle-by-fascicle dissection of Callithrix jacchus masticatory muscles. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.