Shoulder Joint Flexion Research Articles

Exploring whole-body kinematics when eating real foods with the dominant hand in healthy adults.

Despite the importance of eating movements to the rehabilitation of neurological patients, information regarding the normal kinematics of eating in a realistic setting is limited. We aimed to quantify whole-body three-dimensional kinematics among healthy individuals by assessing movement patterns in defined phases while eating real food with the dominant hand in a seated position. Our cross-sectional study included 45 healthy, right-hand dominant individuals with a mean age of 27.3 ± 5.1 years. Whole-body kinematics (joint angles of the upper limb, hip, neck, and trunk) were captured using an inertial sensor motion system. The eating motion was divided into four phases for analysis: reaching, spooning, transport, and mouth. The mean joint angles were compared among the phases with Friedman's analysis of variance. The maximum angles through all eating phases were 129.0° of elbow flexion, 32.4° of wrist extension, 50.4° of hip flexion, 6.8° of hip abduction, and 0.2° of hip rotation. The mean shoulder, elbow, and hip joint flexion angles were largest in the mouth phase, with the smallest being the neck flexion angle. By contrast, in the spooning phase, the shoulder, elbow, and hip flexion were the smallest, with the largest being the neck flexion angle. These angles were significantly different between the mouth and spooning phases (p < 0.008, Bonferroni post hoc correction). Our results revealed that characteristic whole-body movements correspond to each phase of realistic eating in healthy individuals. This study provides useful kinematic data regarding normal eating movements, which may inform whole-body positioning and movement, improve the assessment of eating abilities in clinical settings, and provide a basis for future studies.

Clinical Study on the Effects of Electroacupuncture Combined with Extracorporeal Shock Wave in the Treatment of Periarthritis of Shoulder

Abstract: Objective: To investigate the clinical effects of electroacupuncture combined with extracorporeal shock wave in the treatment of periarthritis of shoulder. Methods: 136 patients with periarthritis of shoulder admitted to our hospital from September 2018 to September 2019 were randomly divided into two groups by double-blind method. 68 patients in the control group were treated with extracorporeal shock wave; 68 patients in the observation group were treated with electroacupuncture combined with extracorporeal shock wave. The shoulder joint pain, joint function and activities of daily living were compared between the two groups. Results: The VAS score of shoulder joint pain in the observation group after treatment (1.92±0.24) was lower than that in the control group (3.51±0.32), and the UCLA score of shoulder joint function (31.28±1.96) was higher than that of the control group (27.42±2.36), the differences were statistically significant (P&lt;0.05). After treatment, the active degree of forward flexion and extension of shoulder joint in the observation group was higher than those of the control group, and the activities of daily living was higher than that of the control group, with statistically significant differences (P&lt;0.05) Conclusion: Electroacupuncture combined with extracorporeal shock wave treatment for periarthritis of shoulder has achieved ideal effects, safety and non-invasiveness, and can quickly restore the functions of shoulder joints.

Mid-term effectiveness of manipulation under anesthesia combined with arthroscopic capsular release and subacromial debridement for primary frozen shoulder

To evaluate mid-term effectiveness of manipulation under anesthesia combined with arthroscopic capsular release and subacromial debridement for primary frozen shoulder. Between January 2013 and December 2017, 33 patients of primary frozen shoulder were treated with manipulation under anesthesia combined with 360° arthroscopic capsular release and subacromial debridement. There were 10 males and 23 females, aged from 37 to 65 years, with a mean age of 50.9 years. The affected shoulder on left side in 17 cases and on right side in 16 cases. The disease duration was 6-13 months (mean, 8.4 months). Before and after operation, the visual analogue scale (VAS) score was used to evaluate the shoulder joint pain, Constant score was used to evaluate the shoulder joint function, and the flexion, abduction, and external rotation of shoulder joint were recorded. The internal rotation function was assessed based on the vertebral plane that the thumb could reach after internal rotation of the affected shoulder joint (the rank of internal rotation vertebra). X-ray film was taken to measure the distance of the subacromial space. There was no fracture or labrum tear in all patients, and all the incisions healed by first intention. All the 33 patients were followed up 20-31 months, with an average of 24.1 months. During the follow-up, there was no complication such as wound infection and nerve injury. At last follow-up, the range of motion of shoulder flexion, abduction, and external rotation, the rank of internal rotation vertebra, the VAS score, Constant score, and subacromial space were significantly improved when compared with preoperative ones ( P<0.05). Manipulation under anesthesia combined with arthroscopic capsular release and subacromial debridement can achieve a good mid-term effectiveness without complication for primary frozen shoulder.

A Comparison of Muscle Activity Depending on Shoulder Joint Flexion Angle When Conducting Kettle Bell Swing

Background/Objectives: The kettle bell exercise is effective in improving the strength and physical strength of the whole body as a popular exercise for modern people. The purpose of this study was to compare the muscle activity of Biceps femoris, Vastus medialis oblique, Erector spine and Anterior deltoid depending on shoulder joint flexion angle when conducting kettle bell swing.Method/Statistical Analysis: The kettle bell exercise is effective in improving the strength and physical strength of the whole body as a popular exercise for modern people. The purpose of this study was to compare the muscle activity of Biceps femoris, Vastus medialis oblique, Erector spine and Anterior deltoid depending on shoulder joint A total of 30 healthy men and women who agreed to participate in the study were the subjects. All of the kettle bell swing starting positions were conducting with flexion knee about 50° and the whole body. The shoulder flexion angle was set 90°, 140°, 180° and the end position was the same as the starting position. For comparison of the muscle activity depending on shoulder joint angle, One-way Repeated ANOVA was used and Bonferroni method for post-test.Findings: Biceps femoris showed significant differences at all degrees(P .05). There was no significant difference in the spinal erector muscle (p>.05).Improvements/Applications: Therefore the muscle activity degree for each muscle was clearly different depending on the shoulder angle.

Surgical Outcomes after Arthroscopic Single Row Anchor Repair for Subscapularis Tears Concomitant with Injury of the Long Head of the Biceps Tendon.

ObjectiveTo analyze the clinical effects of single row anchor in repairing tears of the subscapularis muscle combined with the long head of the biceps tendon (LHBT) injury under arthroscopy.MethodsFrom June 2016 to June 2017, the clinical data of 32 patients with subscapularis combined with biceps tendon injury were retrospectively analyzed. Preoperative MRI examination of the shoulder joint was performed to evaluate tendon injuries, and the subscapularis muscle was repaired with single row anchor under arthroscopy, and tenotomy or tenodesis was performed on the long head tendon of the biceps humerus in the intertubercular groove. The range of motion and the functional score of the shoulder joint before and after the operation were evaluated. All patients were followed up for at least 24 months.ResultsThe mean follow‐up period was 28.8 months (range, 24–34 months). No infections occurred during the follow‐up period. The patients’ follow up exams showed significant improvement in postoperative shoulder joint flexion, external rotation, and internal rotation (P < 0.01), and the postoperative shoulder function American Society of Shoulder and Elbow Surgery Shoulder Joint Score (ASES; 80.6 ± 7.6) was significantly higher than the preoperative score (P < 0.01). The visual analog scale score (1.8 ± 0.8) was significantly lower than that before surgery (P < 0.01). The constant score (80.5 ± 7.4) was significantly higher than preoperation (P < 0.01). There was no significant difference in shoulder joint score between the tenotomy and tenodesis groups (P > 0.05). Preoperative and postoperative scores were, respectively: visual analog scale score (1.7 ± 0.9 vs 1.8 ± 0.0.8) ASES score (81.3 ± 7.9 vs 80.1 ± 8.0) and constant score (80.9 ± 8.0 vs 80.1 ± 6.9).ConclusionUsing single row anchor under arthroscopy to repair subscapularis combined with long head of biceps tendon injury yielded good results and high tendon healing rates were obtained.

Autonomic nervous activity of patient with schizophrenia during Pepper CPGE-led upper limb range of motion exercises

Healthcare for the increasing senior population is a significant challenge. To address this problem, the use of healthcare robot is increasingly being recognized to have strong potential in addressing older adult and psychiatric patients' healthcare and welfare needs. The purpose of this preliminary study is to evaluate the changes in the autonomic nervous activity of an elderly patient with schizophrenia during upper limb range of motion (ROM) exercises led by Pepper (SoftBank Robotics) with the application program of Care Prevention Gymnastics Exercises (Pepper-CPGE) made by Xing Company in Japan. A Pepper-CPGE-led three-minute radio gymnastics program (Radio Exercises #1, consisted of three types of exercises) and instructions were developed. The normal aging 69-year old schizophrenic subject followed instructions from Pepper throughout the intervention. Electrocardiography (ECG) records, heart rate, acceleration score, and ROM exercises of upper limb were collected and analyzed using the GSM's Bonaly Light instrument and Image-J analysis. (1) The high-frequency (HF) (indicative of parasympathetic nervous activity), and low-frequency (LF)/HF ratio (indicative of sympathetic nerve activity) were increased in reference from the baseline data before the exercise stretching the chest. (2) The momentum decreased as the ROM of shoulder joint flexion declined. Declines in both parasympathetic and sympathetic nervous activity were observed. Also, (3) when the exercise "bend the body forward" was performed, the HF and LF/HF also decreased. Evaluation of robot-based rehabilitation exercise program effectiveness by the ROM exercises image analysis and autonomic nervous activity is essential for the futurist programming of ROM exercise among patients with schizophrenia.

Unsupervised low-intensity home exercises as an effective intervention for improving physical activity and physical capacity in the community-dwelling elderly.

[Purpose] The purpose of this study was to examine the effectiveness of unsupervised low-intensity home exercises in improving physical activity and physical capacity for daily activities among the community-dwelling elderly. [Participants and Methods] We included 24 female older participants and divided them into two groups: 14 in the resistance training group and 10 in the fast walking group. The resistance training group performed shoulder joint flexion and abduction exercises using a resistance tube twice daily (in the morning and afternoon). Participants in the fast walking group walked fast for 3,000 steps once daily. Both groups continued the exercise intervention for 6 months. We measured the forced vital capacity, respiratory muscle strength, physical activity, walking distance in the 6-min walk test, grip strength, and knee extension strength before and after the intervention. [Results] The forced vital capacity significantly increased in the resistance training group, whereas the moderate-intensity physical activity time significantly increased in both groups and the vigorous-intensity physical activity time increased in the fast walking group only. We observed no intergroup differences in respiratory muscle strength, 6-min walking distance, grip strength, or knee extension strength. [Conclusion] The results of this study suggest that low-intensity home exercises can improve pulmonary function and physical activity and should be recommended for promoting health in the community-dwelling elderly.

Reverse total shoulder arthroplasty for the treatment of old fracture of proximal humerus in elderly patients

To investigate clinical results of reverse total shoulder arthroplasty in treating old fracture of proximal humerus in elderly patients. From January 2012 to December 2017, 12 elderly patients with old proximal humeral fractures were treated with reverse total shoulder arthroplasty. There were 5 males and 7 females with an average age of 70.2 years old (ranged from 63 to 81 years old) and an average course of 12.3 months (ranged from 9 to 18 months). VAS score was used to evaluate the degree of pain relief of shoulder joint, Constant-Murley score was used to evaluate the improvement of shoulder joint function and observe the complications during and after operation. All the 12 patients were followed up with an average duration of 22.3 months (ranged from 15 to 56 months). At the latest follow-up, the VAS score was 1.9±1.4, and Constant-Murley score was 83.4±8.4. Among them, shoulder joint flexion was (92.5±7.7)°, abduction was (90.4±14.3)°, external rotation was(31.9±10.0)°, and internal rotation was(58.9±13.1)°. There was statistical significance before and after treatment(P<0.05). There were 2 cases with glenoid notch. The imaging findings were grade I and grade II respectively. No loosening was found during follow-up. No infection, acromial fracture, prosthesis loosening, axillary nerve injury and other complications occurred. Reverse total shoulder arthroplasty in treating old proximal humeral fractures in elderly patients can achieve satisfactory results, however, indications and complications should be noted.

The effect of manual inter-structural release on glenohumeral internal rotation range and gliding between the infraspinatus and posterior deltoid

Introduction: Shoulder pain in overhead athletes may be related to posterior tightness of the glenohumeral joint, which may be caused by the posterior deltoid, infraspinatus, and teres minor along with the capsule. One method of relieving posterior tightness is “sleeper stretch” in which the arm is inwardly rotated during shoulder joint flexion. However, adhesion may require a more direct intervention such as manual inter-structural release (ISR) to improve the durability of post-intervention effects. This study investigated the effects of ISR between the posterior deltoid and infraspinatus on the gliding behavior of the muscles as well as the range of motion.

Enhancing Soft-tissue Reattachment with Artificial Mesh in Joint Endoprosthetic Reconstruction for Bone Tumors

Objective: To investigate the operative method and clinical application of the BARD(®) Mesh in enhancing joint stability and function of endoprosthetic reconstruction for bone tumors. Methods: From Jan 2013 to Jun 2015, the clinical data of 51 patients aged (44.75±23.18) years underwent wide resection of tumor and endoprosthetic reconstruction using the BARD(®) Mesh were collected. Among them, 27 were male and 24 were female. The surgical treatments received by these patients included 5 shoulder arthroplasties, 12 elbow replacements, 12 hip replacements and 32 knee replacements (including 24 femoral tumors and 8 tibial tumors). According to the pathologic type, there were 12 metastatic tumors, 20 osteosarcomas, 7 chondrosarcomas, 5 malignant fibrous histiocytomas, 4 giant cell tumors of bone, 1 Ewing sarcoma, 1 leiomyosarcoma and 1 pigmented villonodular synovitis (pvns). These patients received extensive tumor resection, tumorous prosthesis replacement, preserved articular capsule and muscles repair with artificial mesh and endoprosthesis wrapping. The curative effect including joints range of motion and Musculoskeletal Tumour Society Scores (MSTS) were evaluated. Results: The median follow-up time was (19.75±8.17) months. The drainages were removed out on an average of 4 days after operation. The postoperative complications included 2 superficial incision infection, 1 deep incision infection and 1 osteofascial compartment syndrome, infection or dislocation of prosthesis wasn't observed. The mean active flexion of shoulder joint after replacement was (34.00±10.84)°, mean active abduction was (20.00±9.35)° and the mean MSTS was 19.80±9.54. The superior rate of shoulder flexion function was 0. The mean active flexion of elbow joint after replacement was (75.00±7.07)°, mean active abduction was (-5.00±7.07)° and the mean MSTS was 25.00±2.83. The superior rate of elbow flexion function was 50.0% (1/2). The mean active flexion of hip joint after replacement was (86.67±20.60)°, mean active abduction was (2.08±4.98)° and the mean MSTS was 25.42±1.78. The superior rate of hip flexion function was 83.3% (10/12). The mean active flexion of knee joint after replacement was (89.69±22.39)°, mean active abduction was (-0.63±1.68)° and the mean MSTS was 23.31±2.09. The superior rate of knee flexion function was 50.0%(16/32). Among them, the superior rate of femoral flexion function was 66.7% (16/24), the superior rate of tibial flexion function was 0. All of patients were satisfied with the curative effect of operation at the end of follow-up time. Conclusions: The BARD(®) Mesh may enhance the attachment of soft-tissue to endoprosthesis, improve the joint stability, decrease the endoprosthetic infection and dislocation, facilitate the attachment of tendon to endoprosthesis and recover the muscular motivation after endoprosthetic reconstruction. This plays an important role in joint stability and motivation reconstruction of soft-tissue impairment, effectively prevents surgical complications.

筋電信号による装着可能な軽量腕型外骨格パワーアシスト装置の開発

Electromyography (EMG) has been widely used as the driving signal for controlling powered exoskeletons. This study aims to develop a light and wearable upper extremity exoskeleton controlled by EMG signals to support the elbow and shoulder joints. This exoskeleton has four degrees of freedom, one for elbow joint and three for shoulder joint. The flexion and extension movements of elbow and shoulder joint are actively powered to support the wearer and other two DoFs of shoulder joints are freely passive. The structure, mechanism and the control system are developed. The movements of the prototype are verified by experiments.

Activation of the Shoulder Belt and Shoulder Muscles in Humans Providing Generation of “Two-Joint” Isometric Efforts

This review deals with the processes of coordination of central motor commands (CMCs) that arrive at human arm muscles in the course of realization of “two-joint” voluntary isometric efforts. The dependence of formation of such motor events on changes in the direction of the generated effort is described. Differences between patterns of co-activation of the studied arm muscles under conditions of isometric contractions are presented. Based on the obtained data, directions of the developed efforts are classified as coinciding and, correspondingly, easier for realization (flexion–flexion and extension–extension in both joints), and as discordant “inconvenient” (extension in the shoulder joint–flexion in the elbow joint and flexion in the shoulder joint–extension in the elbow joint). Programming of coactivation of flexors and extensors of the shoulder and elbow joints seems to be possible at the level of CMCs. Predominant sectors of the activity of separate functional muscle groups during realization of the studied efforts are estimated. We found that the orientation of such sectors depends, in most cases, on the orientation of the effort vector but not on the position of the limb within the horizontal plane.

The clinical effect of comprehensive rehabilitation therapy after arthroscopic rotator cuff repair using suture-bridge technique for full-thickness rotator cuff tears

Objective To evaluate and analyze the clinical effect of comprehensive rehabilitation therapy after arthroscopic rotator cuff repair using suture-bridge technique for full-thickness rotator cuff tears.Methods Forty-one patients (20 males,21 females; mean age 52.2 years) with full-thickness rotator cuff tears were treated with arthroscopic rotator cuff repair using suture-bridge technique between June 2010 and January 2012 in our hospital.After arthroscopic rotator cuff repair,the patients were randomly assigned to a treatment group (21 patients) or a control group (20 patients).The treatment group received systematic rehabilitation therapy including rehabilitation education,physical modalities treatment and rehabilitative training additionally,while the control group only accepted the routine rehabilitation therapy including stretching and muscle strength training.The outcome was evaluated at 6 months after surgery,by employing visual analogae scale (VAS),the range of motion (ROM) testing of shoulder joint flexion and rotation,the rating scale of University of California at Los Angeles (UCLA),and the shoulder index of American shoulder and elbow surgeons (ASES).Results The mean follow-up period was 15.6 months (8-24 months).Prior to intervention,there was no significant difference in any parameter between the two groups (P ＞ 0.05).Six months later,all scores of assessments changed:in treatment group VAS (1.7 ± 1.5),ROM [flexion (168.3±31.3)°,rotation (47.2±11.2)°],UCLA(30.7 ±4.13) and ASES (85.1 ±15.67); in control group VAS(3.8±2.2),ROM[flexion (121.2 ±53.6)°,rotation (32.9 ±14.9)°],UCLA(18.3 ±4.94) and ASES (36.4 ± 17.70).Significant changes occurred in both groups in all the parameters after treatment when compare to baseline (P ＜ 0.05).Conclusions Comprehensive rehabilitation therapy is an effective approach for improving motor ability of the shoulder in patients after arthroscopic rotator cuff repair with suture-bridge technique for their full-thickness rotator cuff tears. Key words: Arthroscopy; Rotator cuff; Suture bridge technique; Rehabilitation therapy

The Immediate Effect of Humerus Anatomical Neck-shaft Rotation on Glenohumeral Joint Contracture.

[Purpose] Elderly female patients with glenohumeral joint (GHJ) contracture, forced into prolonged immobility were examined. Range of motion exercises using humerus anatomical neck-shaft rotation were performed, and the immediate effect and adaptation were investigated. [Subjects and Methods] A total of ten individuals with a mean age of 79.4 ± 11.0 years were included in this study. The controlled intervention involved conventional range of motion exercises, and the experimental intervention involved humerus anatomical neck-shaft rotation. Each exercise was performed 30 times. Shoulder joint flexion and abduction and external rotation of the GHJ range of motion were measured with the scapula fixed. Each change in range of motion was compared using ANOVA; less than 5% was considered significant. [Results] After the experimental intervention, significant increases were seen in shoulder joint flexion, abduction, and external rotation ranges of motion. [Conclusion] Therefore, this method was effective as a means of improving the range of motion of the GHJ.

Effects of Vibration and Stretching Training on Range of Motion in Female

The purpose of this study was to investigate the acute and long term effects of vibration and stretching training on range of motion (ROM) of shoulder and hip joints in female elderly. Thirty female elderly (≧65 years of age) were participated in this study. The ROM was measured prior to training, then, randomly assigned to vibration-stretching (VT, n = 10), static-stretching (SE, n = 10) or control (CON, n = 10) groups. During the 6 weeks training session, VT group performed static stretching training with vibration (1.5 mm, 25 Hz, 3 × 30s, 7 exercises, 3 times/week) and SE group performed static stretching training (3 × 30s, 7 exercises, 3 times/week). The ROM was measured after completion of the first and 6 weeks training. The data was analyzed by statistical ANCOVA and significance was set at α = .05. The acute phase showed that only VT was significantly increased ROM of glenohumeral adduction (p ＜ .05). In addition, the long term phase showed that VT in ROM of shoulder joint (glenohumeral extension, flexion and rotation) and hip joint (hip extension and flexion) were significantly higher than SE and CON (p ＜ .05) groups, but SE showed significantly higher ROM only in of hip flexion than CON (p ＜ .05). The findings suggested that static stretching training combined with vibration on the improvement of ROM in female elderly was better than static stretching training.

肩関節屈曲、外転時の肩甲帯周囲筋群の起始・停止間距離の変化について

肩関節屈曲、外転時の肩甲帯周囲筋群の起始・停止間距離の変化について

Muscles within muscles: Coordination of 19 muscle segments within three shoulder muscles during isometric motor tasks

The aim of the present study was to determine how the intra-muscular segments of three shoulder muscles were coordinated to produce isometric force impulses around the shoulder joint and how muscle segment coordination was influenced by changes in movement direction, mechanical line of action and moment arm (ma). Twenty male subjects (mean age 22 years; range 18–30 years) with no known history of shoulder pathologies, volunteered to participate in this experiment. Utilising an electromyographic technique, the timing and intensity of contraction within 19 muscle segments of three superficial shoulder muscles (Pectoralis Major, Deltoid and Latissimus Dorsi) were studied and compared during the production of rapid (e.g. approximately 400 ms time to peak) isometric force impulses in four different movement directions of the shoulder joint (flexion, extension, abduction and adduction). The results of this investigation have suggested that the timing and intensity of each muscle segment’s activation was coordinated across muscles and influenced by the muscle segment’s moment arm and its mechanical line of action in relation to the intended direction of shoulder movement (e.g. flexion, extension, abduction or adduction). There was also evidence that motor unit task groups were formed for individual motor tasks which comprise motor units from both adjacent and distant muscles. It was also confirmed that for any particular motor task, individual muscle segments can be functionally classified as prime mover, synergist or antagonist – classifications which are flexible from one movement to the next.

Importance of Therapeutic Exercise for Compensation Movements during Primary Flexion of Shoulder Joint and Alignment of Scapula

Importance of Therapeutic Exercise for Compensation Movements during Primary Flexion of Shoulder Joint and Alignment of Scapula

Evaluation of the passive function of the biceps brachii muscle-tendon unit in limitation of shoulder and elbow joint ranges of motion in horses

To quantify the passive contribution of the biceps brachii muscle-tendon unit to the limits of elbow joint extension during shoulder joint flexion in horses. Normal right forelimb specimens from 6 Thoroughbred cadavers. Specimens included the scapula, humerus, radius-ulna, biceps brachii muscle-tendon unit, and stabilizers of the shoulder and elbow joints. Specimens were mounted to a rigid board by transfixation pins through the humerus and instrumented for mechanical manipulation of the limb and joint angle and load measurements. Flexion and extension limits of shoulder and elbow joint ranges of motion were measured in each joint separately, while the other joint was fixed. Measurements were made before and after transection of the biceps brachii muscle-tendon unit. The biceps brachii muscle-tendon unit limited elbow joint extension when the shoulder joint was fixed in flexion, limited shoulder joint flexion when the elbow joint was fixed in extension, and inhibited shoulder joint extension to a lesser degree when the elbow joint was fixed at midrange angles of 75 degrees to 90 degrees. Clinical manipulation of the elbow joint into hyperextension during shoulder joint flexion is indicative of biceps brachii injury.

MUSCLES WITHIN MUSCLES: ANATOMICAL AND FUNCTIONAL SEGMENTATION OF SELECTED SHOULDER JOINT MUSCULATURE

The objectives of this study were two-fold. Firstly we wished to investigate the segmental anatomy, geometry and gross innervation patterns of selected shoulder joint musculature (pectoralis major, latissimus dorsi and deltoid) to establish if these muscles could be anatomically subdivided according to predetermined criteria. We then wished to use this information to help determine if a segments activation pattern was reliant on an efficient line of action and a large moment arm for the intended movement. Surface electromyography was used for this purpose whilst manipulating the independent variable of contraction intensity (% MVC) during two shoulder joint flexion tasks. For the anatomical portion of the study the dissection of ten cadaveric shoulders revealed the deltoid to consist of seven segments whilst the pectoralis major and the latissimus dorsi were both ascribed six segments according to predetermined anatomical/functional criteria. Primary nerve branching was evident in each muscle but no apparent relationship existed between the designated anatomical segments and the primary nerve branches. Differences were evident in the geometry of each segment in regard to moment arms and orientations of each segments line of action. The functional portion of this study, which utilized miniature bipolar surface electrodes during the performance of a static shoulder joint flexion task at 75% and 25% MVC, showed significant differences (p&lt;0.05) in the activation patterns of active segments between the two tasks. Specifically, a "drop out" of segments with smaller flexion moment arms and more diverging lines of action in comparison to the movement plane was evident for all subjects in the 25% MVC task in comparison to the 75% MVC task.