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Thoracic outlet: assessment with MR imaging in asymptomatic and symptomatic populations.

PURPOSE: To compare the dynamic modifications of the thoracic outlet in asymptomatic volunteers and symptomatic patients and assess the presence and location of vasculonervous compressions in these two populations. MATERIALS AND METHODS: Thirty-five healthy volunteers and 54 patients with clinical symptoms of thoracic outlet syndrome (TOS) underwent magnetic resonance (MR) imaging of the thoracic outlets with their arms alongside their bodies and after a postural maneuver. Measurements were obtained at the interscalene triangle (thickness of anterior scalene muscle, interscalene angle), at the costoclavicular space (minimum costoclavicular distance, distance between inferior border of subclavius muscle and the anterior chest wall, maximum thickness of subclavius muscle, angle between first rib shaft and horizontal), and at the retropectoralis minor space (distance between posterior border of pectoralis minor muscle and posterior lining of axilla at the passage of the axillary vessels, thickness of pectoralis minor muscle). The presence and location of vasculonervous compressions were also assessed. Group data were analyzed with the Student t test. RESULTS: Patients with TOS had a smaller costoclavicular distance after the postural maneuver (P <.001), a thicker subclavius muscle in both arm positions (P <.001), and a wider retropectoralis minor space after the postural maneuver (P <.001) than did volunteers. Venous compressions after the postural maneuver were observed in 47% of volunteers and 63% of patients at the prescalene space, in 54% of volunteers and 61% of patients at the costoclavicular space, and in 27% of volunteers and 30% of patients at the retropectoralis minor space. Arterial and nervous compressions, respectively, were seen in 72% and 7% of patients. No arterial or nervous compression was seen in volunteers. Except for venous thrombosis, vasculonervous compressions were demonstrated only with arm elevation. Only three thoracic outlet measurements differed significantly in both populations. CONCLUSION: MR imaging appeared helpful in demonstrating the location and cause of arterial or nervous compressions.

Adult↗

Protein turnover of breast muscle in germ-free and conventional chicks.

The effect of the gut microflora on protein turnover in pectoral muscle (M. pectoralis profundus) was studied by means of dietary infusion of L-[U-14C]phenylalanine and of massive dose injection of L-[4-3H]phenylalanine in chicks fed on a semi-purified casein-gelatin (SCG) diet until 19 d of age, and in those subsequently given either a nitrogen-free (NF) diet or NF supplemented with methionine and arginine (MA) for a further 9 d. Time-course changes in radioactivity released in expired carbon dioxide during the 8 h infusion period showed that isotopic equilibrium was reached in 4 h with the SCG diet and in 5 h with the MA diet. However, with the protein-deprived chicks given the NF diet, isotopic equilibrium was not achieved since radioactivity in CO2 increased linearly throughout. On feeding the NF diet, fractional protein synthesis rate and the absolute amount of protein synthesized in chick breast muscle were reduced. These reductions were partially alleviated by supplementing the NF diet with methionine and arginine. The fractional degradation rate of breast muscle was increased in chicks given the NF diet, while the absolute amount of protein degraded was decreased. The addition of methionine and arginine counteracted these changes brought about by protein starvation. Generally speaking, the presence of the gut microflora had little, if any, effect on protein turnover rate in chick-breast muscle.

Animals↗

Growth characteristics of selected broiler muscles as affected by age and experimental pen design.

Broilers were grown in conventional pens and in pens modified with barriers and ramps extending across their width. The purpose of these modifications was to increase the use (exercise) of specific muscle groups and measure changes in muscle growth. The breast (pectoralis, supracoracoideus, and gastrocnemius pars externa muscles) from birds reared in conventional pens grew at a more rapid rate than the total body weight of the live bird. Increased growth rates of the breast, pectoralis, supracoracoideus, gastrocnemius pars interna, and femorotibialis muscles were found in birds raised in pens with single ramps. The double-ramp treatment resulted in increased growth in peroneus longus and femorotibialis. Barriers in pens resulted in slower growth rates in gastrocnemius pars externa and iliotibialis, double ramps resulted in slower growth rates in gastrocnemius pars externa, and single ramps resulted in slower growth rates in gastrocnemius pars externa and semitendinosus. Modification of conventional pens caused changes in weight and measurements of many of the muscles studied. Pectoralis muscles from birds reared in pens with barriers were 12.6% heavier after 3 wk exposure than those from birds in conventional pens. The pectoralis muscle of birds after 4 wk exposure to single ramps was 7.1% heavier and the femorotibialis muscle was 19.8% heavier than respective muscles from birds grown in conventional pens. Changes in muscle dimensions showed that conformation of the muscle could be altered by pen modification.

Age Factors↗

The anatomy of the pectoral nerves and their significance in brachial plexus reconstruction.

Twenty-nine brachial plexuses from 13 embalmed and 5 fresh cadavers were examined under x3.5 loupe magnification to collect systematic and topographic anatomical data regarding the lateral and medial pectoral nerves. Additionally, nerve biopsy specimens were harvested in 5 fresh cadavers to obtain histomorphometric data. In all dissections the pectoral nerves exited at the trunk level as 3 distinct nerves. The superior pectoral nerve (from the anterior division of the superior trunk) commences just distal to the suprascapular nerve and courses laterally to innervate the lateral clavicular portion of the pectoralis major muscle (PM) with 2 to 4 branches. The middle pectoral nerve (from the anterior division of the middle trunk) courses distally and enters the infraclavicular fossa with 2 constant branches. The superficial branch terminates in the medial clavicular and upper sternal parts of the PM. The deep branch always forms a plexus with the medial pectoral or inferior pectoral nerve (from the anterior division of the inferior trunk), which courses at a right angle around the the lateral thoracic artery. From this plexus several branches terminate in the Pm. The branch to the lower aspect of the PM pierces the pectoralis minor muscle in two thirds of cases, whereas it passes its inferior border to reach the lower aspects of the PM with an average length of 15 cm in one third of cases. Knowledge of the detailed anatomy of the pectoral nerves, as outlined in this study, clarifies the obscure anatomic relationship of the lateral and medial pectoral nerves and allows easy intraoperative location of the medial pectoral nerve at the exit of the lateral thoracic artery. The length of the inferior pectoral nerve, the number of motor axons, and the anatomical proximity of this nerve make it an expendable but powerful source of reinnervation to the musculocutaneous nerve in upper brachial plexus injuries.

Adult↗

Total mastectomy with complete axillary dissection.

A technique for total mastectomy with complete axillary dissection, which uses division of the insertion of the sternal portion of the pectoralis major muscle, preservation of its innervation, reconstruction after completion of the dissection and resection of the pectoralis minor muscle has been evaluated for 115 consecutive procedures. This modification facilitates a thorough axillary dissection, while preserving the cosmetic and functional benefits of the Patey operation.

Adult↗

Abdominal part artery of axillary artery: proposed term for the artery supplying the abdominal part of the musculus pectoralis major.

In 1976, the authors reported that the abdominal part artery (Pab) supplying the abdominal part of the pectoralis major muscle usually originates from the axillary artery (Ax). The findings in the present study show that the type of origin of this artery most frequently encountered is type 2-a (44.0%) in which the Pab, as an independent branch (type a), branches out of the second part of the Ax (type 2). The second and third most frequently encountered types are type 2-b (17.0%), where the Pab has a common trunk with the thoracoacromial artery, and type 2-c (10.0%), where it has a common trunk with the lateral thoracic artery. By classification according to the supplying areas, 67% was type I-B, supplying the lower part of the pectoralis minor muscle and the abdominal part of the muscle. In 5%, the branch as type I-A courses down to the sternocostal part. In most cases (types A and B in 91%), this artery originates from the Ax proximal to the ansa mediana of the brachial plexus; however, in 4% providing the superficial brachial artery, the Pab branches out from the superficial brachial artery. Based on those findings, the authors would propose that the artery be named the arteria partis abdominalis or Pab.

Adult↗

Sternalis muscle: importance in surgery of the breast.

Mastectomy is a commonly performed surgery for carcinoma of breast. During surgery, pectoral fascia is removed and pectoralis major muscle is laid bare. Sternalis is a rare muscle encountered in the subcutaneous plane. We examined the operative records of 1,152 patients who underwent modified radical mastectomies between 1990 and 2000. Patients who underwent conservative breast surgery or radical mastectomy were excluded. Among 1,152 patients who underwent modified radical mastectomy, eight were identified as having sternalis, a subcutaneously placed muscle oriented craniocaudally. The thickness of the muscle varied. The muscle was spared in all patients. Sternalis is a rare muscle in the subcutaneous plane. It should not be mistaken for a mass on mammography. During surgery it is important to be aware of this rare entity and identify the muscle early so that the dissection plane is appropriate. The depth at which internal mammary nodes are irradiated may also vary in the presence of the muscle. In addition, it should not be mistaken for recurrence on follow-up.

Breast Neoplasms↗

Effect of resection of the sternum and manubrium in conjunction with muscle transposition on pulmonary function.

We recorded the changes in pulmonary function that occurred after removal of the sternum and manubrium and repair by pectoralis major muscle transposition in six patients. Of these patients, three had osteomyelitis of the manubrium and sternum, two had osteosarcoma of the sternum, and one had osteomyelitis and radionecrosis of the manubrium and sternum. Body plethysmography and the rebreathing, hypercapnic ventilatory response test with inductive plethysmographic recordings of chest-wall motion were performed preoperatively and postoperatively. Preoperatively, four of the six patients had evidence of mild to moderate chest-wall restriction. Pulmonary function was normal in the other two patients. Postoperatively, total lung capacity was unchanged but the vital capacity decreased 11.5% in the overall group. Static compliance, retractive force, and the steady-state diffusing capacity for carbon monoxide decreased modestly but significantly postoperatively. The expiratory flow rates and maximal voluntary ventilation remained unchanged. Preoperatively, the slope of the hypercapnic ventilatory response was less than that predicted. Postoperatively, the slope did not change. In three patients, however, increased dependence on the abdomen for breathing suggested a dynamic restriction of rib-cage motion. On the basis of our findings, we conclude that surgical removal of the sternum and manubrium in conjunction with muscle flap repair is a well-tolerated procedure. Any postoperative changes in pulmonary function are minor.

Adolescent↗

The thoracoacromial vessels as recipient vessels in microsurgery and supermicrosurgery: an anatomical and sonographic study.

The purpose of this study was to investigate the presence and the precise course of the pectoral branch of the thoracoacromial vessels on the underside of the pectoralis major muscle by anatomical dissection and by color Doppler ultrasound. A further goal was to determine whether these vessels were suitable as recipient vessels in microsurgery and supermicrosurgery for breast reconstruction. In 18 cadavers, the pectoral branch of the thoracoacromial vessels was followed caudally until the diameter of the artery diminished to 1 mm. The same examination was carried out in 40 young female volunteers by tracing the vessel course with color Doppler ultrasound. The 1-mm cutoff point of the artery was measured with reference to the manubrium, the midsternal line, the clavicle, and the upper border of the closest rib. In addition, in the cadavers, the 2-mm cutoff point was determined. At both cutoff points, the diameter of the accompanying vein was measured. The pectoral branch of the thoracoacromial vessels with the artery and concomitant veins could be detected on all 100 undersides of the pectoralis major muscle, anatomically and sonographically. In their course from the acromial region downward, the arteries reached a diameter of 1 mm at an average of 9.9 cm from the manubrium, horizontally 9.4 cm from the midsternal line, and vertically 4.0 cm from the lower border of the clavicle. The 1-mm reference point was situated on the upper border of the third rib in 85 percent of cases. The average distance between the 1-mm and the 2-mm cutoff points was 3.5 cm. At the 1-mm cutoff point, the diameter of the vein was 0.9 mm, and at the 2-mm cutoff point, it was 1.7 mm. Because of their central position at the anterior hemithorax, these vessels are easily accessible from mastectomy incisions, even in skin-sparing mastectomies; the donor-site morbidity is negligible; and as the diameters of the vessels gradually decrease along their caudal course, the recipient site can be chosen precisely according to the length and the diameter of the donor vessels and major mismatch can be avoided. Thus, the pectoral branches of the thoracoacromial vessels are well suited as recipient vessels for (super)microsurgery and are a very promising addendum to the thoracodorsal and internal mammary vessels.

Adult↗

[The axillopectoral muscle].

Extending between the pectoralis major and latissimus dorsi muscles, the "pectoro-axillary" muscle, the principal anatomic variation of the axillary wall, forms and ectopic muscle band that can complicate axillary dissection. The origin and features of this supernumerary muscle related to Langer's arch are described with emphasis on its surgical applications.

Breast↗

Dynamic stabilization of winging scapula by direct split pectoralis major transfer: a technical note.

A new technique of split pectoralis major tendon transfer (sternal head) for symptomatic scapular winging is shown. Whereas other authors use a lengthening with autogenous grafts, we prefer a direct attachment of the split pectoralis major tendon. With the use of an anterior and a posterior incision, the tendon of the sternal head of the pectoralis major is mobilized and transferred directly to the inferior angle of the scapula. An anatomic study shows that the pectoralis major muscle usually seems to be suitable for this procedure. Direct transosseous fixation of the transferred split pectoralis major tendon appears to be an excellent operation for correcting winging scapula without the necessity of an autogenous graft and concern over stretching or tearing of the graft extension.

Cadaver↗

Vascular consideration in raising the pectoralis major flap.

Several types of musculocutaneous flaps, including that the pectoralis major, have been used for reconstruction following resection of malignant tumors in the head and neck region. Although several clinical studies have investigated the vascularity of such musculocutaneous flaps, the findings have been inconsistent. The present study examined the distribution of arteries in the pectoralis major muscle and surrounding subcutaneous tissue by macroscopic dissection and angiography. Based on the results of this examination, muscle layer and surrounding subcutaneous tissue appear to be supplied by different arteries and show different distribution patterns. However, evidence of penetrating branches from the muscle layer to the subcutaneous tissue layer suggests the existence of blood flow from the muscle layer to the subcutaneous tissue layer. Such arterial branches should be considered when raising the pectoralis major flap in order to prevent necrosis and improve the viability of the flap.

Angiography↗

Effect of genetic selection on MyoD and myogenin expression in turkeys with different growth rates.

Skeletal muscle development requires the ordered expression of specific myogenic regulatory factors, which include MyoD, Myf5, myogenin, and MRF4. The MyoD and Mrf5 factors are required for the determination of myoblasts, whereas myogenin and MRF4 play a pivotal role in terminal differentiation. In the current study, males and females of a turkey genetic line selected only for increased 16-wk BW (F line) and an unselected randombred control (RBC2 line) from which the F line was developed were used to investigate the developmental expression of MyoD and myogenin mRNA in embryonic pectoralis major muscle and myogenic satellite cells. Pectoralis major muscle was isolated at embryonic d (ED) 14, 16, 18, 20, 22, and 24. The mRNA levels of MyoD and myogenin were measured using a real-time quantitative polymerase chain reaction method. Both MyoD and myogenin expression declined during embryonic development. The decrease in MyoD expression started at ED 16 for the F line and at ED 18 for the RBC2 line for both sexes. Myogenin expression in both lines began to decline at ED 14. The F line males had lower myogenin expression at ED 14, 16, and 18 than the RBC2 line males, which was similar for the F line females compared with the RBC2 line females except there was no significant difference at ED 18. The RBC2 line males had greater expression than the females for myogenin at ED 16 and 18 for the RBC2 line. Proliferating myogenic satellite cells in both lines and sexes expressed low levels of MyoD and myogenin. After the initiation of differentiation in both lines and sexes, there was a sharp surge in MyoD expression at 24 h followed by a decrease at 48 h and then an increase in expression through 72 or 96 h of differentiation. There were line and sex differences in myogenin expression during the differentiation process. These data are suggestive of growth- and sex-related differences in the expression of myogenic regulatory factors key to muscle cell proliferation and differentiation, which will affect muscle growth rate.

Animals↗