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At least 19 recordsLinked to original sources
PubMed2002

Consequences of deltoid muscle elongation on deltoid muscle performance: a computerised study.

BACKGROUND: The deltoid muscle plays an important role in normal shoulder function. Knowledge of the position of the glenohumeral rotational centre and of the deltoid muscle length is essential to understand optimal placement of a total shoulder prosthesis. OBJECTIVE: This study is designed to analyse the effect of deltoid muscle elongation on shoulder joint function. DESIGN: A three-dimensional model of the glenohumeral joint with deltoid muscle analysis in the scapular plane. METHODS: A geometrical three-dimensional ball-and-socket model of the shoulder joint was developed. From dry bones, the position of the origins and insertions of the three parts of the deltoid muscle relative to the calculated centre of rotation of the humeral head was defined. The position and the direction of the muscle force working lines relative to this humeral centre were calculated using former measurements and CT-data of the deltoid. Muscle length-tension data were applied to obtain angle-force relationships. The model was used to calculate the angle-force relationships, the moment arm and the moment of the deltoid muscle components for successive arm elevation angles in the scapular plane. These data were compared to those of a theoretical situation assuming a 10% elongation of the muscle. RESULTS: Muscle angle-force curves show a more favourable slope after moderate (10%) deltoid muscle elongation. Elongating the muscle by changing the distance between the humeral rotation point and the deltoid insertion along the humeral axis does not affect moment arms. The moments of the deltoid muscle forces themselves, however, seem more adapted to elevation in the scapular plane. The deltoid maximal moment exceeds the arm-weight moment by about 40% instead of being approximately equal, and that the maximum is situated around 100 degrees of elevation. CONCLUSIONS: From a biomechanical point of view, stretching the deltoid muscle by 10% seems to result in a significantly more favourable position in case of shoulder elevation at 90 degrees of abduction in the scapular plane in a centred glenohumeral joint. RELEVANCE: This model suggests that a 10% elongation of the deltoid muscle, the most important shoulder abductor, improves its ability to elevate the arm. If properly implemented, this observation can be very important in the treatment and early rehabilitation of rotator-cuff-insufficient shoulders treated by a specific total shoulder replacement design.

Adult↗
PubMed1975

Absorption and sedative effects of diazepam after oral administration and intramuscular administration into the vastus lateralis muscle and the deltoid muscle.

The absorption of diazepam 10 mg after oral administration and intramuscular administration into the vastus lateralis muscle or the deltoid muscle was compared in a double-blind cross-over study in eight healthy subjects. Serum diazepam concentrations were measured, and the presence of tiredness was noted 20, 40, 60, 90 and 150 min after the drug administration. Peak concentrations in serum were 209+/-49, 152+/-60 and 143+/-62 ng/ml ((means+/-SD) at 90, 60 and 60 min after oral, shoulder and thigh administration respectively. Absorption was more rapid after intramuscular than after oral administration, serum mean diazepam concentrations at 20 min after oral administration being only 26% of those after shoulder administration. The rapid rate of absorption from the shoulder was associated with a more rapid feeling of tiredness and a greater sedative effect than after oral or thigh administration. There was no evidence that diazepam induced its own metabolism after one or two administrations. The results suggest that, if rapid preanaesthetic medication with diazepam is needed, shoulder administration might be superior to oral or thigh administration.

Absorption↗
PubMed1998

The blood supply of the deltoid muscle. Application to the deltoid flap technique.

The major ruptures of the rotators cuff point out the problem of their surgical repair. Various techniques are described in the literature, among them the deltoid flap technique, described by Apoil and Augereau. This technique points out the problem of a few cases of flap early necrosis (Saragaglia). We studied the deltoid arterial blood supply on 40 cadaveric shoulder, after coloured injection into the subclavian artery. Our study included 40 macroscopic and 15 radiographic observations. The thoracoacromial artery gave off two collaterals to the anterior part of the deltoid muscle. The first one, called the deltoid artery, ran into the anterior part of the deltoid, near the deltopectoral line. In 53%, it gave off a first superior collateral branch, which ran at 3 cm under the clavicle. The second one, called the acromial artery, ran deep to the anterior part of the deltoid muscle, near the clavicle and the acromion. The posterior circumflex humeral artery was the most important artery. It supplied the posterior and middle parts of the deltoid muscle. The anterior circumflex humeral artery supplied the anterior part of the deltoid muscle in 63%. In ten cases, we dissected a deltoid flap. In all the cases, the acromial artery was cut near the acromion. When the deltoid artery gives off its superior collateral branch, it was always cut. Then, this flap was only vascularized by its inferior aspect. These results show that the flap is located in a poorly supplied area. Thus, the flap necrosis could be explained by an insufficient anastomotic network. An operative technique modification could avoid this complication.

Acromion↗
PubMed2003

Electromyographic validation of basic exercises for physical conditioning programmes. IV. Analysis of the deltoid muscle (anterior portion) and pectoralis major muscle (clavicular portion) in frontal-lateral cross, dumbbells exercises.

The electromyographic activity of the shoulder muscles deltoid--anterior portion (DA) and pectoralis major--clavicular portion (PMC) was tested on 24 male volunteers using a 2 channel TECA TE4 electromyograph and Hewlett Packard surface electrodes during the execution of four different modalities of frontal-lateral cross, dumbbells exercises. The results showed that all of the tested exercises developed high levels of action potential for both muscles. So, we justify the indication of all of them for physical fitness programmes for DA and PMC. Some suggestions to the use of the tested exercises are presented.

Action Potentials↗
PubMedDate not supplied

Electromyographic validation of basic exercises for physical conditioning programmes. I. Analysis of the deltoid muscle (anterior portion) and pectoralis major muscle (clavicular portion) in rowing exercises with middle grip.

The electromyographic activity of the shoulder muscles Deltoid--anterior portion (DA) and Pectoralis major--clavicular portion (PMC) was tested on 24 male volunteers using a 2 channel TECA TE4 electromyograph and Hewlett Packard surface electrodes during the execution of four different modalities of rowing exercises with middle grip. The results showed that rowing exercises are not appropriate for physical fitness programmes for PMC but some of them are significantly useful for DA. The authors present some suggestions to the use of the tested exercises.

Action Potentials↗
PubMed2002

Dynamic glenohumeral stability provided by three heads of the deltoid muscle.

The deltoid is a large bulky muscle, comprising approximately 20% of the shoulder muscles. Therefore, the function of the deltoid as a stabilizer is thought to be significant. The current authors quantified dynamic glenohumeral stability provided by three heads of the deltoid by a new biomechanical parameter, the dynamic stability index. The dynamic stability index considers not only the force vectors generated by individual shoulder muscle, but also the concavity compression mechanism. The higher the dynamic stability index, the greater the dynamic stability. The deltoid generated significant shear force and compressive force in the position of anterior shoulder instability. The deltoid provided dynamic stability with the arm in the scapular plane and only decreased the stability of the shoulder with the arm in the coronal plane. The mid and posterior heads should be strengthened vigorously in anterior shoulder instability in conservative and operative treatment, because they provide more stability generating higher compressive force and lower shear force than the anterior head. Scapular muscles should be balanced to avoid the vulnerable glenohumeral position where the arm is extended beyond the scapular plane. Anatomic reattachment of the detached labrum onto the glenoid rim in the anterior instability is important to enhance the effect of compressive force component generated by the muscles.

Aged↗
PubMed2006

Electromyogram and force patterns in variably timed manual muscle testing of the middle deltoid muscle.

OBJECTIVE: The objective of the study was to compare force curves and surface electromyogram from examiners and subjects during manual muscle testing with 3 examiner-identified variants of manual muscle testing (MMT)-examiner-started (ESMMT), patient-started (PSMMT), and undifferentiated/near-simultaneous (NSMMT). METHODS: Forty-two volunteer applied kinesiologist doctors tested 36 volunteer students, doctors, and spouses at a professional conference. Start-time difference between examiner and subject muscle contraction, peak force, time of peak force and duration of force was measured. Force and surface electromyogram from examiner and subject were recorded simultaneously during MMT of the middle deltoid muscle for each style of testing used in practice. RESULTS: The congruence between examiner label and timing was as follows: ESMMT, 39%; PSMMT 61%; and NSMMT 28% within 50 milliseconds of simultaneous. Mean subject/examiner start-time difference differed significantly between PSMMT (-0.116 seconds) and both ESMMT (-0.018 seconds) and NSMMT (-0.0053 seconds). No clear cutoff between styles was evident. Peak force ranged from 0.548 to 23.615 lb (mean, 8.806 lb; SD, 4.543 lb), and all styles were significantly different. Duration of force ranged from 0.325 to 3.490 seconds (mean, 1.338 seconds; SD, 0.576 seconds), with NSMMT significantly shorter than ESMMT or PSMMT. The shape of force curves did not differ between styles of muscle testing, but differed between facilitated vs inhibited tests. CONCLUSIONS: In this group of doctors, neither start-time difference nor the shape of force curves distinguished styles of MMT. Differences in peak force and test duration may account for differences in outcomes when examiners purposely vary their muscle testing style.

Adult↗
PubMed1997

Anatomical variant of the lateral pectoral nerve innervating the anterior portion of the deltoid muscle: a case report.

BACKGROUND: The deltoid muscle is innervated by the axillary nerve. There is no collateral nerve supply described for this muscle. Palsy of the axillary nerve is common in shoulder trauma due to its close relationship to the surgical neck of humerus. METHODS: A dissection of the pectoral and axillary regions of two female cadavers was performed bilaterally for a detailed analysis of the innervation of the deltoid muscle. RESULTS: A branch of the lateral pectoral nerve provided supplemental innervation to the anterior portion of the deltoid muscle bilaterally in both cadavers. CONCLUSION: A branch of the lateral pectoral nerve could provide collateral nerve supply to the deltoid muscle. The frequency of this anatomical variation requires further exploration.

Aged↗
PubMedDate not supplied

Dynamic stabilizing function of the deltoid muscle in shoulders with anterior instability.

BACKGROUND: The stabilizing role of the deltoid muscle has not been extensively studied. PURPOSE: To study the contribution of the deltoid muscle to anterior stability of the shoulder. STUDY DESIGN: Controlled laboratory study. METHODS: We used nine fresh cadaveric shoulders with the arm at 90 degrees of abduction and 90 degrees of external rotation. The position of the humeral head was monitored by an electromagnetic tracking device with 0 and 1.5 kg of anterior translation force; with 0, 1, 3, and 5 kg of force applied to each of the anterior, middle, and posterior portions of the deltoid muscle; and with the capsule intact, vented, and with a simulated Bankart lesion. RESULTS: With the capsule intact, anterior displacement was significantly reduced by application of load to the middle deltoid muscle. After the capsule was vented, load application to the anterior, middle, or posterior deltoid muscle significantly reduced anterior displacement. With a simulated Bankart lesion, effects of muscle loading were most apparent: anterior displacement was significantly reduced with loading of each muscle portion. CONCLUSION: The deltoid muscle is an anterior stabilizer of the glenohumeral joint with the arm in abduction and external rotation. CLINICAL RELEVANCE: The stabilizing function of the deltoid muscle takes on more importance as the shoulder becomes unstable.

Aged↗
PubMed1994

Changes in muscle fiber cross-sectional area and concentrations of Na,K-ATPase in deltoid muscle in patients with impingement syndrome of the shoulder.

Disturbances of the stabilizing musculature are an important factor in painful shoulders. The important changes in the rotator cuff muscles are well established, but less attention is put on possible disturbances of the deltoid muscle. This study investigated the effect of shoulder impingement on muscle fiber cross-sectional area and the Na,K-pump concentration of the deltoid muscle. The study included six patients with impingement syndrome. Biopsies were taken from the affected and unaffected sides. The muscle fiber cross-sectional area and the Na,K-ATPase concentration was measured. There were significant decreases (p < 0.05) in cross-sectional area of type 1 and type 2 fibers of the affected deltoid muscle of 25 and 18%, respectively. The Na,K-pump concentration of the affected muscles was reduced by 26.6% (p < 0.05).

Adult↗
PubMed2001

The fibrous frame of the deltoid muscle. Its functional and surgical relevance.

Black lines seen on magnetic resonance imaging in the middle part of the deltoid suggest the presence of fibrous bands. Anatomic study of 30 deltoid muscles was done. Eight half-cone shaped distal fibrous structures merged together into the distal tendon of the deltoid muscle. The middle part of the deltoid muscle contains four deep fibrous bands that glide inside the distal half-cones. The anterior and posterior parts of the deltoid muscle lacked such bands. Histologic study confirmed the presence of the bands and cones. In the middle part of the deltoid, muscle fibers are oblique between the bands or between the bands and the half-cones. This multipennate structure favors strength instead of range of excursion of the muscle. Because of its significant change of direction around the humeral head, at the onset of elevation of the arm, the deltoid muscle sustains forces that press the muscle against the head which then leads to deformation of the muscle. The fibrous bands make the muscle strong enough to support these forces. The middle part of the muscle is of greatest importance in comparison with the other parts. This should be considered during shoulder rehabilitation. The presence of the fibrous band originating from the anterior corner of the acromion may help create a strong repair after splitting the deltoid.

Aged↗
PubMed2001

Applied anatomy of the axillary nerve for selective neurotization of the deltoid muscle.

Morphologic and internal topographic features of the axillary nerve were studied in 40 cadaveric shoulders to provide anatomic data for selective neurotization of the deltoid muscle in axillary nerve injury. The axillary nerve can be divided into three segments. Proximal to the subscapularis muscle, the axillary nerve is a single nerve trunk. Nerve fascicles to the deltoid muscle are identified at its lateral part. In front of the subscapularis muscle, the axillary nerve forms into the lateral and medial fasciculi groups. Distal to the subscapularis muscle, the nerve divides into anterior and posterior branches, which are continuations of the lateral and medial fasciculi groups, respectively. The anterior branch contains all fibers that innervate to the anterior and middle deltoid muscle. In 90% of cases, the posterior branch contains part or all nerve fibers to the posterior deltoid muscle. Nerve fibers to the teres minor and cutaneous sensory fibers are found in the posterior branch. In neurotization of the deltoid muscle, the best approach is to match the donor nerve to the lateral fasciculi group, which will give the highest percentage of reinnervation of the deltoid muscle.

Adult↗
PubMed1998

Contracture of the deltoid muscle: imaging findings in 17 patients.

OBJECTIVE: A retrospective review of the MR images and radiographs of 26 shoulders in 17 patients suffering from contracture of the deltoid muscle was used to establish the characteristic imaging findings. MATERIALS AND METHODS: Deltoid muscle contractures in 26 shoulders in 17 patients encountered over a 4-year period are reported. The history of intramuscular injection and clinical symptoms and signs are detailed. Imaging studies including routine radiographs (24 shoulders), MR images (25 shoulders), and computed arthrotomograms (two shoulders) were reviewed. On MR images, the winging angle of the scapula (angle between the axis of the scapular body and the coronal plane of the chest) and the diameter of the lesion were measured and compared with data derived from 24 age-matched control subjects. RESULTS: Diagnostic MR features of deltoid muscle contracture include fibrotic cord in the deltoid muscle, especially its middle portion, extending from the superior acromial surface to the deltoid tuberosity, and winging of the scapula (increased winging angle of the scapula). Characteristic radiographic features include abduction contracture, winging of the scapula, lateral down-sloping of the acromial process, and a superior acromial enthesophyte. CONCLUSION: MR images are sensitive and accurate in the diagnosis of contracture of the deltoid muscles. Characteristic features also allow accurate routine diagnosis on radiographs.

Arm↗
PubMedDate not supplied

The deltoid muscle origin. Histologic characteristics and effects of subacromial decompression.

The histologic characteristics of the deltoid muscle attachment to nine cadaveric acromia were studied using light microscopy. The deltoid muscle attaches to the anterior and lateral acromion primarily by direct tendinous attachment. The muscle attaches to the dorsal side of the acromion by periosteal fiber attachment. In the specimens studied, a hypothetical acromioplasty of 4 mm would release, on average, 41% of the direct fiber attachment, and a 6-mm acromioplasty would release 69% for all zones examined histologically. The functional and clinical effects of these findings are not known, but the deltoid muscle would be released by arthroscopic acromioplasty in areas where bone is removed.

Acromion↗
PubMed1991

Transfer of upper pectoralis major flap for functional reconstruction of deltoid muscle.

Since January 1984, functional reconstruction of the deltoid muscle using transfer of the upper part of the pectoralis major muscle has been performed in 7 patients with deltoid dysfunction. 5-20 months follow-up (average 11) revealed marked improvement in 6 patients. During the operation, the superior and inferior parts of the pectoralis major muscle were bluntly dissected and sectioned. The upper part of this muscle was turned over and transferred to the site normally occupied by the deltoid muscle. The transposed muscle contributed to both abduction and flexion of the shoulder. The efficacy of abduction was reinforced by the increased arm of action.

Adolescent↗
PubMed2005

Imaging findings of spontaneous detachment of the deltoid muscle as a complication of massive rotator cuff tear.

A tear at the origin of the deltoid muscle is uncommon and usually occurs as a complication of shoulder surgery. We report a case of spontaneous deltoid detachment as a complication of massive rotator cuff tear in a 70-year-old woman evaluated by standard radiographs, ultrasound, arthrography and MR-arthrography. We present the multimodality imaging findings with review of the literature. We found that ultrasound is an accurate modality in detecting and assessing spontaneous detachment of the deltoid muscle. As ultrasound is a noninvasive, low-cost, and universally available imaging modality we suggest using ultrasound as the first modality for evaluation of spontaneous detachment of the deltoid muscle.

Aged↗