Minor Muscle Research Articles

Muscle Compensation Strategies to Maintain Glenohumeral Joint Stability in Rotator Cuff Tears: A Cadaveric Study.

Superior translation of the humeral head is often identified in large and massive rotator cuff (RC) tears. However, the ability of the remaining RC muscles to compensate for the forces causing such superior translation in RC tears remains unclear. The purpose of this study was to investigate the impact of compensatory forces exerted by the remaining RC muscles on humeral head translation using a progressive RC tear model. Eight fresh-frozen cadaveric shoulders (mean donor age, 57 years) were tested using a custom shoulder testing system. In addition to an intact RC model, 3 RC tear models were created: a supraspinatus tear (Tear I); combined supraspinatus and infraspinatus tears (Tear II); and combined tears of the supraspinatus, infraspinatus, and superior one-third of the subscapularis (Tear III). Compensatory conditions were simulated by increasing the loading of the remaining RC muscles in each RC tear model. Humeral head translation was measured at different abduction and neutral rotation angles in each condition with normal and high deltoid muscle loading. Significant superior translation of the humeral head was observed in Tears II and III (but not Tear I), compared with the intact state, under high loading of the deltoid during abduction and during rotation. In Tear II, compensatory conditions involving increased loading of the teres minor and subscapularis muscles effectively reduced superior translation, so that no significant differences were observed compared with the intact state, even under high deltoid muscle loading. However, in Tear III, significant superior translation was still observed, regardless of the compensatory conditions. ompensation by the remaining RC muscles, particularly the teres minor and subscapularis, effectively reduced superior translation of the humeral head in the posterosuperior RC tear model, whereas this compensatory strategy was insufficient if tears also involved the superior one-third of the subscapularis. Patients with posterosuperior RC tears may find conservative treatment focusing on strengthening the remaining RC muscles, especially the subscapularis and teres minor, to be beneficial. Conversely, patients with repairable massive RC tears also involving the subscapularis tendon may benefit from surgical interventions aimed at primarily repairing the subscapularis tendon to restore the transverse force couple. Massive tears deemed not to be repairable should be evaluated for arthroplasty or other procedures.

Reversal of Denervation Changes in Infraspinatus Muscle After Operative Management of Paralabral Cysts: An MRI-Based Study.

Paralabral cysts at the spinoglenoid notch are rare disorders that can potentially lead to compressive suprascapular neuropathy. Given their infrequency, a standard treatment protocol has not yet been established. This study aimed to assess changes in the infraspinatus muscle using magnetic resonance imaging (MRI) and to compare the outcomes of 2 different surgical methods. It was hypothesized that surgical intervention could alleviate compressive neuropathy, with comparable outcomes between the 2 surgical approaches. Cohort study; Level of evidence, 3. This retrospective review encompassed 43 patients undergoing arthroscopic labral repair for a paralabral cyst at the spinoglenoid notch, with cyst decompression (27 patients; labral repair with cyst decompression [LRCD] group) or without cyst decompression (16 patients; labral repair only [LRO] group). Preoperative MRI focused on evaluating the condition of the infraspinatus and teres minor muscles. Electromyography (EMG) was conducted on 36 patients (21 in LRCD and 15 in LRO) to assess suprascapular nerve function. Postoperative evaluations were performed in 35 patients at postoperative 1 year, excluding those lost to follow-up. Postoperative MRI findings (24 patients in LRCD and 11 patients in LRO) and functional outcome scores including recovery of external rotation power were compared with preoperative status in both groups. Preoperative MRI revealed denervation changes or atrophy of the infraspinatus in 26 of the 43 patients (60.4%). Among the 36 patients who underwent preoperative EMG, 21 patients (58.3%; 13 patients in LRCD and 8 patients in LRO) showed evidence of suprascapular neuropathy. A discrepancy between EMG and MRI findings was noted in 10 patients, with 5 patients showing suprascapular neuropathy according to EMG despite normal muscle status on MRI scans, and the remaining 5 vice versa. Notable atrophy of the infraspinatus was seen in 6 patients and teres minor hypertrophy in 5 patients, all of whom exhibited concurrent infraspinatus atrophy. Postoperatively, cyst disappearance was observed in all cases in both LRCD (24 patients) and LRO (11 patients) groups. Denervation changes in the infraspinatus were resolved in all patients. In patients with infraspinatus atrophy, some improvement was noted. Teres minor hypertrophy persisted in 2 of 4 patients. Improvements were similar in both groups (all P > .05). External rotation power improved postoperatively in both groups (from 39.1 ± 18.6 to 50.6 ± 17.7 N in LRCD, P < .001; from 45.1 ± 16.0 to 54.2 ± 10.7 N in LRO, P = .025). Both LRCD and LRO surgical approaches appear to be effective for paralabral cysts at the spinoglenoid notch. Suprascapular neuropathy can be successfully addressed by both methods. However, conditions with severe infraspinatus atrophy and teres minor hypertrophy warrant further investigation in larger series.

Quantitative anatomy of the infraspinatus muscle in the human fetus.

The study presents one of the six scapulohumeral muscles, which occupies most of the osteofibrous infraspinatus compartment. Along with the supraspinatus, teres minor and subscapularis muscles, the infraspinatus muscle contributes to the rotator cuff. It protects the posterior aspect of the articular capsule of the shoulder joint, adducts and externally rotates the arm. The aim of the study was to perform the quantitative analysis of the infraspinatus muscle in human fetuses and to elaborate growth dynamics for its morphometric parameters. Using anatomical dissection, digital image analysis (NIS Elements AR3.0) and statistics (Student's t-test, regression analysis), the vertical, transverse and oblique diameters, muscle circumference and projection surface area of the infraspinatus muscle were measured in 36human fetuses of both sexes (17♂, 19♀) aged 18-30weeks. The infraspinatus muscle revealed neither sex nor laterality differences. All examined morphometric parameters of the infraspinatus muscle increased commensurately in accordance with the following linear functions: y=-4.024 + 0.903×Age ± 0.621 (R²=0.96) for transverse diameter, y=-3.089 + 1.321×Age ± 0.897 (R²=0.97) for vertical diameter, y=-1.161 + 0.632×Age ± 0.444 (R²=0.97) for oblique diameter, y=-13.575 + 3.851×Age ± 1.938 (R²=0.98) for muscle circumference and y=-293.512 + 23.228×Age ±19.650 (R²=0.95) for projection surface area.

Effectiveness of Retraction 30 over Gross Stretch For Relieving Pectoralis Minor Tightness Among College Students

Background: The Pectoralis minor muscle originates from different 3 ribs and converges into one attachment point. Pectoralis minor shortening can contribute to many syndromes and impairments, especially at the shoulder. Some of them are impingement of the soft tissues, adhesive capsulitis etc. The prevalence of pectoralis minor tightness is very high in college-going students. The gross stretch is the stretching procedure that increases the length of the pectoralis minor muscle. This shoulder position produces tension in the muscle insertion in a posterior direction in conjunction with the scapular motion that is performed at flexion and elevation in the scapular plane, thereby lengthening the muscle. Retraction 30 is stretching with scapular retraction at 30 degrees of shoulder flexion; the flexion angle at 30 degrees can lengthen the muscle along the muscle fiber direction in the coronal plane. 30 degrees of flexion is considered to be more comfortable than a higher angle of flexion, as well as the angle is closest to the line of force Objectives of the study: To compare the effectiveness of gross stretch and retraction 30 in relieving pectoralis minor muscle tightness which can be co-operated in further treatment protocols. Study Design: Comparative Study Methodology: Two group pre–test–post–test design was used with purposive sampling. Selected subjects were allocated to two groups. Fourty subjects (20 males and 20 females) who fulfilled inclusion and exclusion criteria were recruited for the study. The independent variables are gross stretch and retraction 30 whereas the dependent variables were PMI (pectoralis minor index), pectoralis minor length test and Cervical Curvature. Result: This study results imply that retraction 30 is better when compared to gross stretch for correcting pectoralis minor tightness. Hence should be included as an inevitable part of stretching treatment. Practicing clinicians should continue to use evidence-based decisions when treating pectoralis minor tightness.

Description and Outcomes of an Ultrasound-Guided Technique for Catheter Placement in the Canine Quadratus Lumborum Plane: A Cadaveric Tomographic Study and Clinical Case Series.

This study aimed to describe an ultrasound-guided technique for implanting catheters for local anesthetic administration into the quadratus lumborum (QL) inter-fascial plane in canine cadavers and assessing the spread along the vertebral bodies (VBs) by computed tomography (CT). Phase 1: eight canine cadavers received one catheter per hemiabdomen, followed by injection of contrast media solution [low volume (LV) 0.3 mL kg-1 or high volume (HV) 0.6 mL kg-1]. Phase 2: postoperative pain of five dogs was managed by injecting 0.3 mL kg-1 of ropivacaine 0.5% through QL catheters every eight hours, up to 72 h after abdominal surgery. Pain was assessed using the Short Form of the Glasgow Composite Measure Pain Scale, and methadone 0.2 mg kg-1 was administered intravenously when the pain score was ≥6. The number of VBs stained by the contrast solution between the QL and psoas minor muscles was significantly higher in group HV than group LV. The catheter tip was visualized in the retroperitoneal space in 1/16 and 2/10 hemiabdomens in phases 1 and 2, respectively. Rescue analgesia was required in 3/5 dogs during the postoperative period. The QL catheter placement technique appears feasible and may be included in a multimodal analgesic approach for dogs undergoing abdominal surgeries.

Relationship Between Posterior Tibial Artery Blood Flow And Lower Leg Flexibility Among Collegiate Runners

Purpose: Understanding relationships between blood flow and muscle inflexibility in the lower leg can support improved healthcare competency. Sports medicine practitioners might use the reference ranges and knowledge of relationships among these variables to support effective health screenings among their competitive runners. These variables have been linked in other areas of the body where inflexibility in the pectoralis minor and scalene muscles have been associated with diminished blood flow to the upper limb. No studies, however, have examined the relationship between vascular and mobility characteristics in the lower legs of runners. Therefore, the purpose of this study was to examine the relationship between blood flow in the posterior tibial artery and ankle range of motion (ROM) among competitive runners. Methods: Blood flow in the posterior tibial artery and ankle ROM were measured bilaterally on twenty-five, asymptomatic collegiate track athletes (15 males, 10 females, age = 20.0±1.2 years, height = 171.5±10.2 cm, mass = 66.7±13.7 kg) using diagnostic ultrasound and standard goniometry, respectively. Pearson correlation analysis was used to analyze the relationship between blood flow in the posterior tibial artery and ROM of the ankle joint. Results: Findings revealed no significant relationship between blood flow in the dominant leg’s posterior tibial artery and dorsiflexion (r=.14, P=.52, CI95% = -0.27 – 0.51) or plantarflexion (r=-.32, P=.12, CI95% = -0.63 – 0.09) and no significant relationship between blood flow in the non-dominant leg’s posterior tibial artery and dorsiflexion (r=-.02, P=.93; CI95% = -0.41 – 0.38) or plantarflexion (r=-.02, P=.92; CI95% = -0.41 – 0.38). Conclusion: While muscle inflexibility is associated with compromised blood flow in other body regions, findings of this study demonstrated no relationship between the variables within the lower legs of a sample of competitive runners. Sports medicine practitioners should consider these findings in their efforts to predict, prevent, and manage potential vascular and musculoskeletal adaptations among clients/patients who are competitive runners.

A Cadaveric Study of the Rotator Cable: Interrogating the Suspension Bridge Model.

Purpose The objective of this cadaveric study was to describe the anatomical relationships between the rotator cuff muscles and the rotator cable. Methods In 30 formaldehyde-fixed shoulders from 20 cadavers, the rotator cuff and rotator cable were dissected and the glenohumeral joint opened. The orientation and attachments of the rotator cable to the rotator cuff muscles were described, and the severity of any osteoarthritis, labral pathology, and rotator cuff pathology present was documented. The width and thickness of the infraspinatus attachments to the rotator cable were measured. Results The infraspinatus muscle was noted to be more loosely adherent to the rotator cable, while the supraspinatus and teres minor were tightly adherent to the cable. Specifically, the superior-most portion of the infraspinatus was found to be less tightly adherent than the inferior-most portion in 26 of the 30 shoulders studied. The thickness/width ratio of the inferior-most portion of infraspinatus was significantly different in shoulders with more-than-minimal osteoarthritis and labral pathology (p=0.048 and p=0.041, respectively). Conclusion While the supraspinatus and teres minor muscles were tightly adherent to the cable in all shoulders, the degree of attachment of the superior-most portion of the infraspinatus muscle was notably less in 26 of the 30 shoulders studied. This could mean that only the inferior portion of the infraspinatus participates in stress shielding through the cable or be a compensatory response to increased load on the tendon. This work is expected to provide insight into the function of the rotator cable and the different functions of the infraspinatus.

Dynamic and static nasolabial muscle anatomy of unilateral cleft lip adult patients based on magnetic resonance imaging data.

This study aims to obtain a three-dimensional reconstruction model based on magnetic resonance imaging (MRI) data of patients with different degrees of unilateral cleft lip and analyze the anatomy and changes in multiple groups of nasolabial muscles under dynamic and static conditions. One normal person and four adult patients with unilateral cleft lip were included, and MRI was performed under static (upper and lower lips closed naturally) and dynamic (pout and grin) conditions. 3D Slicer software was used to reconstruct the model and draw the anatomic morphology of nasolabial muscles. The distance between the junction (where the muscle merges into the orbicularis oris) of the levator muscle, zygomaticminor muscle, and zygomatic major muscle to the median sagittal plane, the starting point to the junction point, the dynamic and static junction points, and the angle between the connection of dynamic and static junctions and the horizontal plane were measured under three kinds of movements, and the ratio was calculated. In all patients, under dynamic and static conditions, the distance from the muscle junction to the median sagittal plane, their ratios of the cleft side to the non-cleft side were all greater than 1. While the ratio of the distance from the starting point of the muscle to the junction point is less than 1. At static conditions, the two ratios of the same muscle increased gradiently with the severity of the cleft, and the ratio of the zygomatic minor muscle was prominent in the same patient. The ratio of the cleft side to the non-cleft side was greater than 1, and the value for comparison was the angle of the line from the static to the dynamic junction and the horizontal plane. The symmetry of the insertion site of the orbicularis oris and the linear distance of both sides of the muscle are related to muscle and cleft types. The angle of muscle contraction on the cleft side is greater than that on the non-cleft side.

ADAR1 Promotes Myogenic Proliferation and Differentiation of Goat Skeletal Muscle Satellite Cells.

As one of the most important economic traits for domestic animal husbandry, skeletal muscle is regulated by an intricate molecular network. Adenosine deaminase acting on RNA (ADAR1) involves various physiological processes and diseases, such as innate immunity and the development of lung adenocarcinoma, breast cancer, gastric cancer, etc. However, its role in skeletal muscle growth requires further clarification. Here, we explored the functions of ADAR1 in the myogenic process of goat skeletal muscle satellite cells (MuSCs). The ADAR1 transcripts were noticeably enriched in goat visceral tissues compared to skeletal muscle. Additionally, its levels in slow oxidative muscles like the psoas major and minor muscles were higher than in the fast oxidative glycolytic and fast glycolytic muscles. Among the two common isoforms from ADAR1, p110 is more abundant than p150. Moreover, overexpressing ADAR1 enhanced the proliferation and myogenic differentiation of MuSCs. The mRNA-seq performed on MuSCs' knockdown of ADAR1 obtained 146 differentially expressed genes (DEGs), 87 upregulated and 59 downregulated. These DEGs were concentrated in muscle development and process pathways, such as the MAPK and cAMP signaling pathways. Furthermore, many DEGs as the key nodes defined by protein-protein interaction networks (PPI), including STAT3, MYH3/8, TGFβ2, and ACTN4, were closely related to the myogenic process. Finally, RNA immunoprecipitation combined with qPCR (RIP-qPCR) showed that ADAR1 binds to PAX7 and MyoD mRNA. This study indicates that ADAR1 promotes the myogenic development of goat MuSCs, which provides a useful scientific reference for further exploring the ADAR1-related regulatory networks underlying mammal skeletal muscle growth.

The other face of facioscapulohumeral muscular dystrophy: Exploring orofacial weakness using muscle ultrasound.

One of the most distinct clinical features of facioscapulohumeral muscular dystrophy (FSHD) is facial weakness. It leads to diminished facial expression and functional impairments. Despite its clinical relevance, little else is known about orofacial muscle involvement. We therefore evaluated orofacial muscle involvement in a sizeable cohort of FSHD participants with muscle ultrasound. Muscle ultrasound images of the following orofacial muscles were scored visually and quantitatively: depressor anguli oris (DAO), orbicularis oris (OO), buccinator, temporalis, masseter, digastric, zygomaticus major and minor bilaterally, and the geniohyoid. Reliability analyses of both visual and quantitative evaluations were performed. Ultrasound results were correlated with other measures: the FSHD clinical score, facial weakness score, and facial function scale. We included 107 FSHD participants (male 54%; age 52 ± 14 years), of whom 92% showed signs of facial weakness. The reliability of visual ultrasound analysis varied widely (κ 0.0-1.0). Quantitative ultrasound reliability was high (intraclass correlation analysis ≥ 0.96). The DAO, buccinator, OO, temporalis, and zygomaticus minor muscles were affected most often (15%-39%). The digastric, geniohyoid, zygomaticus major, and masseter muscles were least often affected (<5%). The ultrasound compound score correlated weakly to moderately with other outcome measures used (ρ = 0.3-0.7). This study adds to the understanding of orofacial weakness in FSHD, confirming the involvement of the muscles of facial expression in FSHD using ultrasound. We showed that orofacial muscle ultrasound is feasible and reliable when quantitatively assessed. Future studies should evaluate orofacial muscle ultrasound longitudinally, alongside clinical and patient-reported facial weakness outcome measures, to assess their potential as outcome measures.

Partial agenesis of the pectoralis major and minor muscle: A cadaveric case report.

The pectoralis major and minor muscles, located in the anterior chest wall, are crucial for upper limb movements. Their nonsyndromic absence is rare but significant for surgical procedures involving the axillary and pectoral regions. Ultrasound can confirm the diagnosis and delimit the extent of the muscular abnormality, detect abnormalities of the costal cartilages, among others. This descriptive, cadaveric case report involves a formalin-fixed 57-year-old North American male, with no clinical or family history of similar conditions. The study was conducted at the Human Anatomy Laboratory of the School of Medicine of the Universidad Finis Terrae in Santiago, Chile, in August 2022. We present a cadaveric case of bilateral partial agenesis of the pectoralis muscles discovered during routine dissection. The pectoralis major muscle exhibited only the clavicular portion, with the sternocostal and abdominal portions absent and replaced by a thin layer of connective tissue bilaterally. The pectoralis minor muscle showed partial muscle fibers only in the most distal and inferior portions bilaterally. This case report is significant due to the rarity of this condition without accompanying anatomical variations. Understanding this variant is valuable for clinical situations involving the shoulder and thorax region, such as trauma to the proximal third of the humerus, clavicular region, suprascapular region, and anterior chest wall. It may complicate conservative and/or surgical treatments due to different functional and irrigation patterns in the area and is also important for educating future professionals.

Fibrotic Contracture of the Infraspinatus Muscle with or without Contracture of the Teres Minor Muscle: A Retrospective Study in Eight Dogs.

(1) Background: Fibrotic contracture of the canine infraspinatus muscle (FCIM) is considered an uncommon musculotendinous condition mainly affecting hunting dogs. After an acute onset of a painful non-weight-bearing lameness over a period of one to four weeks, a characteristic circumducted gait is developed in the affected thoracic limb. (2) Methods: Eight client-owned dogs of varying breeds, both sexes, aged 4-9 years old, and weighing 14-26 kg participated in the study. The duration of lameness prior to their first consultation ranged from 10 to 450 days. All participants were thoroughly examined clinically, orthopedically, and radiographically. (3) Results: The dogs underwent infraspinatus tenotomy, resulting in improved limb function. In three cases, a teres minor muscle contracture was revealed intraoperatively and resolved via a tenotomy at its insertion. The findings showed that 15 days post-operation, all dogs returned to full activity. The results obtained confirm and reinforce the literature data around FCIM and describe the first recorded condition of the simultaneous contracture of the infraspinatus and teres minor muscles. (4) Conclusions: In every case of shoulder lameness, contractures of all shoulder muscles should be included in the differential diagnosis and patients should be assessed for concurrent contractures even if infraspinatus contracture is identified.

Quantitative assessment of rotator cuff injuries using synthetic MRI and IDEAL-IQ imaging techniques

PurposeTo evaluate synthetic magnetic resonance imaging (SyMRI) and iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL-IQ) imaging for a comprehensive evaluation of rotator cuff injuries (RCI). MethodsNinety-seven patients with RCI were classified into four groups based on the arthroscopic results: (grade II), partial tear (grade III), complete tear (grade IV), and controls (grade I). T1 (Transverse Relaxation Time 1), T2 (Transverse Relaxation Time 2), proton density (PD), and fat fraction (FF) were evaluated using SyMRI and IDEAL-IQ. Measurement reliability was assessed using intraclass correlation coefficients (ICC). The diagnostic potential for grading RCI was evaluated using ordinal regression and ROC analyses. ResultsA high measurement reliability (ICC > 0.7) was observed across subregions. T1 and T2 significantly varied across grades, particularly T2 in the lateral subregion between grades III and IV (P < 0.001) and the central subregion between grades II and III (P < 0.001). ROC analyses yielded valuable diagnostic accuracy, including T2 in the lateral subregion with an AUC of 0.891, distinguishing grade I from grade IV. Positive correlations were found between T2 values in specific shoulder subregions and injury grade (r = 0.615 for lateral, r = 0.542 for medial, both P < 0.001). In grade IV, FF was notably increased in the supraspinatus, infraspinatus, and subscapularis muscles compared with grades I-III. There were no significant FF variations in the teres minor muscle among grades. ConclusionsQuantitative MRI parameters from SyMRI and IDEAL-IQ, especially T2 and FF, may classify and assess RCI severity. The results could help improve the accuracy of diagnosing different grades of RCI, offering clinicians additional tools for improving patient outcomes through personalized medicine.

Which muscle is the external rotation compensator after superior capsular reconstruction?

BackgroundSuperior capsular reconstruction (SCR) is a surgical option for massive irreparable rotator cuff tears, particularly involving the supraspinatus and infraspinatus. In this procedure, the torn infraspinatus is not repaired or reconstructed. However, an improvement in postoperative external rotation (ER) angle and strength is observed. There is a lack of studies explaining how ER is restored after SCR. The aim of this study is to identify the ER compensator by assessing the muscle volume of the posterior deltoid and teres minor. MethodsSixty-eight patients with massive rotator cuff tears underwent SCR during 2016-2021. Of these patients, 28 who met the following inclusion criteria were retrospectively reviewed: (1) massive rotator cuff tears including the supraspinatus and infraspinatus; (2) severe muscle atrophy and fatty change; (3) intact or reparable subscapularis tendon; (4) Hamada of grade 3 or lower. Posterior deltoid and teres minor volume were measured by using an open-source medical image processing software preoperatively and 1-year postoperatively. The percentage of the posterior deltoid and teres minor muscle volume change was compared between patients with 1-year postoperative ER manual motor testing (MMT) of grade 5 and of grade < 5. The relationship between grade of fatty change, percentage of the muscle volume change, and ER angle and strength were evaluated. ResultsThere was a significant increase in the 1-year postoperative teres minor volume compared with the preoperative volume (24.6±10.3 cm³ versus 20.9±8.3 cm³, p<0.000), while the posterior deltoid volume remained unchanged (178.1±48.3 cm³ versus 178.8±47 cm³). Patients with ER MMT of grade 5 had a greater teres minor volume compared to those with an ER MMT grade of less than 5 (22.3% versus 9.4%), although this difference was not significant (p=0.074, 95% CI=-1.3–27.0). The posterior deltoid volume showed no significant change. The percentage of teres minor volume change had a weak positive correlation with ER strength (r=0.308, p=0.055, 95% CI=-0.02–1.0). There was a significant negative correlation between ER strength and the severity of both preoperative and postoperative fatty changes in the teres minor (r=-0.258, p=0.065, 95% CI=-1.0–-0.042 and r=-0.323, p=0.028, 95% CI=-1.0–-0.113, respectively). The pre- and postoperative fatty changes in the teres minor were negatively correlated with the percentage of teres minor volume change (r=-0.298, p=0.062, 95% CI=-1.0–0.031 and r=-0.413, p=0.015, 95% CI=-1.0–-0.1, respectively). ConclusionThe teres minor may serve as a potential compensator for ER in patients with massive rotator cuff tears following SCR.

Unusual Multiple and Bilateral Combinations of Arterial and Neural Variations in the Axillae of Single Cadaver

Nerve During the dissection of the axillae and upper limbs of an 80-year-old male donor, multiple vascular and neural variations were encountered. On the right side, the thoracoacromial artery and the lateral thoracic artery were absent. On the left side the subscapular artery was absent, and the posterior cord of the brachial plexus gave branch to two upper subscapular nerves and then divided into radial nerve and a common stem that branched into thoracodorsal nerve, lower subscapular nerve, nerves to teres major and minor muscles and the axillary nerve. Additionally, in the left arm there was a variant communication between the musculocutaneous nerve and the median nerve. Although the existence of these variations is well documented in the literature as individual entities or few combinations, the occurrence of such multiple variations in a single cadaver in a limited area of the body involving vessel and nerves is not common. A multitude of variations in a small area of the body such as this can be a source of diagnostic and imaging interpretation errors. Unpredictable iatrogenic injuries can also occur during various procedures in the area such as during preparation of muscle flap, mastectomy with axillary lymph node dissection, reconstructive and aesthetic plastic surgery of the breast and other clinical procedures including shoulder arthroplasty.

A CROSS-SECTIONAL CADAVERIC STUDY OF THE PREVALENCE AND MORPHOMETRY OF PSOAS MINOR MUSCLE IN WESTERN MAHARASHTRA

Introduction:The Psoas minor muscle is a long, elongated, spindle-shaped muscle thatis rarelypresent in the human body. Despite its relatively minor role in human biomechanics, understanding its prevalence and morphology can be crucial in certain surgical and diagnostic contexts. Aim:The primary aim of this cross-sectional cadaveric study is to investigate the prevalence and describe the morphometry of the Psoas minor muscle in a population from western Maharashtra. Materials and Methods:63 well-preservedformalin-fixed and soft-embalmed human cadavers were examined during routine dissection. The prevalence, sexual dimorphism, morphology, morphometry, and laterality of Psoas minor muscle were assessed.Digital vernier calipers and tape measure were used to measure the psoas minor muscle morphometry. Result:The study reveals a prevalence rate of 33.33% for the Psoas minor muscle in the studied population. The muscle was present in 21 cadavers out of 63 cadavers. It was bilateral in 17.46% (11/63) cadavers and unilateral in 15.87% (10/63) cadavers. In all the examined cases muscle took origin from a T12-L1 vertebra, and was distally connected to the iliopubic eminence.The muscle was found unilaterally in 05 males and 05 female cadavers, and bilaterally in 07 males and 04 female cadavers. Conclusion:The study provides valuable insights into the presence and anatomical characteristics of the Psoas minor muscle among the population of Western Maharashtra. The prevalence as well as morphometry and morphology of this muscle is of significant academic interest for anatomists, surgeons, radiologists, kinesiologists, and physiotherapists for diagnostic purposes.

Biomechanical effects of deltoid muscle atrophy on rotator cuff tissue: a finite element study

The deltoid muscle and rotator cuff tissue are structural components that maintain the dynamic stability of the shoulder joint. However, atrophy of the deltoid muscle may affect the stability of the shoulder joint, which in turn alters the mechanical distribution of rotator cuff tissue. Currently, the effect of muscle volume changes in the deltoid muscle on reducing the load on the rotator cuff tissue is still unknown. Therefore, this paper intends to analyze the mechanical changes of rotator cuff tissue by deltoid muscle atrophy through finite elements. Based on previously published finite element shoulder models, the deltoid muscle was modeled by constructing deltoid muscle models with different degrees of atrophy as, 100% deltoid muscle (Group 1), 80% deltoid muscle (Group 2), and 50% deltoid muscle (Group 3), respectively. The three models were given the same external load to simulate glenohumeral joint abduction, and the stress changes in the rotator cuff tissue were analyzed and recorded. In all three models, the stress in the rotator cuff tissue showed different degrees of increase with the increase of abduction angle, especially in the supraspinatus muscle. At 90° of glenohumeral abduction, supraspinatus stress increased by 58% and 118% in Group 2 and Group 3, respectively, compared with Group 1; In the subscapularis, the stress in Group 3 increased by 59% and 25% compared with Group 1 and Group 2, respectively. In addition, the stress of the infraspinatus muscle and teres minor muscle in Group 2 and Group 3 were higher than that in Group 1 during the abduction angle from 30° to 90°. Deltoid atrophy alters the abduction movement pattern of the glenohumeral joint. During glenohumeral abduction activity, deltoid atrophy significantly increases the stress on the rotator cuff tissue, whereas normal deltoid volume helps maintain the mechanical balance of the rotator cuff tissue.

HTNet for micro-expression recognition

Facial expression is related to facial muscle contractions and different muscle movements correspond to different emotional states. For micro-expression recognition, the muscle movements are usually subtle, which has a negative impact on the performance of current facial emotion recognition algorithms. Most existing methods use self-attention mechanisms to capture relationships between tokens in a sequence, but they do not take into account the inherent spatial relationships between facial landmarks. This can result in sub-optimal performance on micro-expression recognition tasks. Therefore, learning to recognize facial muscle movements is a key challenge in the area of micro-expression recognition. In this paper, we propose a Hierarchical Transformer Network (HTNet) to identify critical areas of facial muscle movement. HTNet includes two major components: a transformer layer that leverages the local temporal features and an aggregation layer that extracts local and global semantical facial features. Specifically, HTNet divides the face into four different facial areas: left lip area, left eye area, right eye area and right lip area. The transformer layer is used to focus on representing local minor muscle movement with local self-attention in each area. The aggregation layer is used to learn the interactions between eye areas and lip areas. The experiments on four publicly available micro-expression datasets show that the proposed approach outperforms previous methods by a large margin. The codes and models are available at: https://github.com/wangzhifengharrison/HTNet.

Accessory thoracic muscles in human fetuses.

Typically, the anterior thoracic wall musculature is composed of the pectoralis major and pectoralis minor. Embryologically, these two muscles are originated from a common pectoral muscle mass; therefore, disruption of the normal development and differentiation could give rise to an aberrant or accessory muscle. The main aim of this study is to demonstrate and classify the accessory muscles of the pectoralis region in human fetuses. Fifty spontaneously aborted human fetuses (25 male and 25 female, 100 sides) aged 18-38 weeks of gestation at death, and fixed in 10% formalin solution were examined. Following parental approval, the fetuses were donated to the Medical University anatomy program. The pectoralis major and minor muscle's morphology, the possible occurrence of accessory muscles of pectoral region and its morphology, their origins, and insertions, as well as the morphometric details, were assessed. The pectoralis major and minor were bilaterally found in all fetuses (100 cases). The accessory muscles of pectoral region were found in 16 cases (16%), and four types were differentiated. The Pectoralis Quartus muscle was the most common type of accessory muscles found in this study and occurred in 8 cases. The axillary arch muscle was observed in 3 cases. The chondrocoracoideus muscle was observed in 3 cases. The sternalis muscle occurred in 2 cases, and one of them was bifurcated. The thoracic region is characterized by a large amount of morphological variations, which are observed not only in adult population, but also among human fetuses. The pectoralis quartus was the most frequent variation in this study. Accessory structures like sternalis muscle, chondrocoracoideus muscle, pectoralis quartus muscle, or axillary arch muscle may have clinical implications, and knowledge about them is very useful for clinicians, especially plastic surgeons, thoracic surgeons, and orthopedics.

Intraoperative thoracic interfascial plane block with levobupivacaine versus levobupivacaine with dexmedetomidine for postoperative analgesia after modified radical mastectomy: A randomised controlled double-blinded trial.

Nearly half of the patients following breast cancer surgery experience postoperative pain. The interfascial plane for the pectoral nerve (PECS) block, along with dexmedetomidine, can alleviate this pain. After institutional ethics committee clearance and written informed consent, this randomised, double-blind study was conducted on 60, 18-60 years female patients, who were scheduled for modified radical mastectomy (MRM) under general anaesthesia. Patients were randomised into Group L (20 ml of 0.25% levobupivacaine) and Group DL (20 ml of 0.25% levobupivacaine with 0.5 µg/kg of dexmedetomidine). After resection of the tumour and securing haemostasis, under strict aseptic precaution, 10 ml of the study drug was injected under direct vision between the pectoralis major and pectoralis minor and 10 ml between pectoralis minor and serratus anterior muscles by the operating surgeon (direct PECS block). The primary outcome was to compare the duration of analgesia. Normally distributed variables were compared using Student's t-test, and non-normally distributed variables were compared using the Mann-Whitney U-test. Qualitative data were analysed using Chi-square/Fisher's exact test. Statistical significance was kept at P < 0.05. The median time of the first analgesic requirement was 8 [inter-quartile range (IQR): 6-8] h in Group L and 18 (IQR: 16-20) h in Group DL (W = 17.000, P < 0.001). The mean total opioid consumption of Group L was 12.53 [standard deviation (SD): 2.29] mg in the first 24 h and 6.93 (SD: 1.89) mg in Group DL. Adding 0.5 μg/kg dexmedetomidine to 20 ml of levobupivacaine enhances the duration of analgesia of direct PECS block in patients undergoing MRM.