VASCULARISATION OF PECTORALIS MAIOR MYOCUTANEOUS FLAP-ANATOMICAL STUDY IN HUMAN FETUSES AND CADAVERS

Pectoral major fl ap is one of most frequently used fl aps in head and neck reconstruction. Th e wide attractiveness of this fl ap is based on secure vascular stalk made from pectoral branch of thoracoacromial artery. Th e aim of study was to analyze the variations in vascular supply of pectoral major muscle. Th e investigation was performed on  fetuses from  to  gestation week both gender. For determining vascular network the samples injected with barium sulphate were subjected to Spalteholtz technique, and on  fresh cadavers where and we performed injection of Metilen blue  in pectoral branch of thoracoacromial artery. In  we found one pectoral branch and in   two branches for pectoral muscle were found. Before entering the muscle, pectoral branch is dividing in two terminal branches (). In all cases lateral part of pectoral muscle is supplied by branch of lateral thoracic artery. Th e average area of dyed skin was  x  cm in region between III and VI rib and from parasternal line to anterior axillar line. Th e average distance of most distal part of dyed skin to midclavicular point was  cm. Th e pectoral branch of thoracoactomial artery obtains main blood supply for pectoral major muscle mass and despite of anatomical variations can be defi ned as main pedicle for musculocutaneous fl ap. Dyed skin confi rms that pectoral major fl ap has defi ned skin territory suffi cient for reconstructions in head and neck area.


Introduction
Soft tissue and skin defects in head, neck and thoracic region may be caused by tumor removal, thermal and other injuries or develop after infections.Pectoral major (PM) fl ap is one of the most used fl aps in reconstruction of soft tissue defects in head and neck region.Th e fl ap is introduced by Ariyan  for reconstruction of soft tissue defect in head and neck region, and opened new era in reconstructive surgery (, ).Th e fl ap is designed in anterior chest mostly as myocutaneous fl ap.Oval shaped skin incision is located in parasternal region and goes through subcutaneous tissue reaching pectoral fascia.When the lateral edge of pectoral major muscle is reached, the posterior aspect of muscle is explored and main fl ap pedicle found.Next step is cutting out the muscle around Skin Island and creating a strip of muscle bringing the pedicle in direction of middle of clavicle.Th is part of muscle is a protective muff bringing the vessels.All muscle fi bers of pectoral major muscle laterally from pedicle must be mandatory cut because if we leave part of muscle, the fi brosis could cause fl ap necrosis.Th e fl ap is transposed in defect and sutured in layers.Suction drainage is obligatory.Donor region is closed primarily.Current reports present the use of different modification of pectoral major flap and broad indications for its use (, , ).The prerequisite for secure use of muscle as myocutaneous flap is well defined and sufficient blood vessel as fl ap pedicle.Th e wide attractiveness of PM fl ap is based on secure vascular stalk made from pectoral branch of thoracoacromial artery.Thoracoacromial artery (TA) is the second branch of axillar artery (AA) arising from anterior aspect in - cm from its beginning.After passing through clavipectoral fascia this artery reach upper edge of small pectoral muscle it gave  terminal branches: pectoral, clavicular, acromial and deltoid.Pectoral branch goes between pectoral major and minor muscle and supplies them.Despite the pectoral major muscle has a pectoral branch of thoracoacromial artery as main stalk; more two vascular pedicles supply the muscle: lateral thoracic and perforating braches of internal thoracic artery ().Th e aim of study based on seldom clinical use of pectoral major fl ap is to contribute the understanding of vascular supply and vascular stalk of pectoral major fl ap in human fetuses and adult cadavers.We analyzed the arising of pectoral branch of thoracoacromial artery, its course, topographic relations with surrounding tissues, as well as the vascular network in pectoral muscle.In next step we had to defi ne the area vascularised by pectoral branch.

Material and Methods
Th e investigation of vascular network of pectoral major fl ap we performed in  human fetuses.We used fetuses both gender, gestation age  to  gestation week and performed dissection on both sides.All fetuses were medico legally provided from the Clinic of Gynecology and Obstetrics of the Faculty of Medicine in Nis, and were without anatomical deformities and systemic pathology.*Fetuses were previously fi xed in  formalin and their blood vessels were injected with Micropaque solution (barium sulphate).Th e technique of macro and micro dissection with surgical microscope "Olympus" is performed.Th e incision is made along the clavicle, midsternal region and lateral thoracic region.Th e skin and subcutaneous tissue were removed and the humeral insertion of pectoral major muscle detached.Th e thoracoacromial artery is defi ned and its pectoral branch analyzed.For later studies we used whole pectoral major muscle.Samples were prepared as transluminiscent specimens by Spalteholtz technique.Th e digital camera on microscope was used for documentation.The other part of investigation is performed bilaterally in  human cadavers both gender, age  to  years.All cadavers were necropsied in Department for Pathology and Forensic Medicine at Faculty of Medicine Nibs.We performed horizontal incision of skin and subcutaneous tissue along the middle of clavicle in length of  cm.Th e attachment of deltoid muscle is raised from the clavicle and structures in subclavicular region were blunt dissected, and the origin of thoracoacromial artery found.We investigated sceletopic relation of origin of thoracoacromial artery and measured its diameter by micrometer in .mm scale.Th e arteriotomy of pectoral branch of thoracoacromial artery was performed and an intravenous canula placed in.Th e position of canula and prevention of leaking is obtained making ligature with a surgical stitch.Metilen blue dying is injected in amount of  ml .Th e most distal part of colored skin from the clavicle is measured as well as the length and width of colored skin.

Results
Th oracoacromial artery in  originates one stalk in right angle ( fetuses) from axillary artery, than goes forward through clavipectoral fascia above the upper edge of pectoral minor muscle and divides in terminal branches.In only  ( fetus)  Th e area of skin dyed in cadavers was from x cm to x cm.Th e average area dyed was  x  cm. ( Figure  a,b,c).In all cadavers we found that skin from rd to th rib and from parasternal line to anterior axillary line was colored.Th e distance from the midpoint of clavicle to most distal point of colored skin was  to  cm.Th e average distance was  cm and that distance can be defi ned as the arc of rotation of pectoral major fl ap.

Discussion
The  () in their studies pointed that vascularisation of pectoral major muscle arise from three arteries: pectoral branch of thoracoacromial artery, lateral thoracic artery and perforators from internal mammary artery.The main vascular supply is obtained by pectoral branch of thoracoacromial artery and it was found in all our cases.But in  we found two pectoral branches of TAA for pectoral major muscle.Moreover pectoral branch is dividing in two branches before reaching the muscle and form rich arterial network inside.
In one dissection () we found that two arteries arise from axillar artery, first giving acromial and deltoid branch and later artery goes strait same as pectoral branch.
Park and al. () in . cases found that the pectoral branch arise from TAA but in rest of cases arise from medial or lateral roof of thoracoacromial artery.Freeman and Walkers () refers in  of dissections that a. thoracic supreme is a branch of TAA.We did not found this variation in our investigation.We found that TAA gives branch for pectoral minor muscle in  of cases.Th e same is found by Little ().
The route of pectoral branch is arc-like shaped and runs from the middle of clavicle along medioclavicular line and turns medially approaching xyphoid processus by the line connecting acromial part of scapula and xyphoid.The same rout of pectoral branch is described by other authors (,,,).
In our study we found in  that TAT arises from anterior aspect of axillar artery in the middle of the clavicle and very rare laterally or medially from that point.Park and all () refer that in right side TAA arise laterally of midclavicular point in all cases but at the left side in  TAA arises medially from midclavicular line.Our study with injections of metilen blue in TAA confi rm that the pectoral branch of thoracoacromial artery is constant and detectable vascular pedicle of pectoral major muscle and supply sternocostal part of muscle and pectoral skin from rd to th rib and from parasternal to anterior axillar line.According to referred data, the vascular pedicle of pectoral major fl ap is defi ned (pectoral branch of thoracoacromial artery), extent of fl ap's skin and muscle territory (x to x  cm -average  x  cm) as well as the arc of fl ap rotation (,).
Yung and all refers that pectoral branch supplies ,of pectoral major, lateral thoracic artery , and  of muscle parenchyma is supplied by perforator branches of internal mammary artery ().Th ey advocate that the almost half of the muscle mass is supplied by internal mammary artery and that is the main cause of fl ap loss.Th e anatomical vascular network is important for fl aps with additional blood supply and it could be described as: primary vascular territory (main pedicle), secondary territory (anastomotic network with additional blood supply) and tertiary territory supplied by additional pedicle (in this case it is internal mammary artery) Th e anastomotic network in pectoral major fl ap is rich and obtains proper fl ap survival rising the fl ap on pectoral branch of TAA.

Conclusion
Pectoral major fl ap for head and neck reconstructions is supplied by pectoral branch of thoracoacromial artery and variations of beginning route and branching of this artery may be hazardous for operative success of modifi ed pectoral fl aps (e.g.double island pectoral major fl ap brings high risk in cases when artery approach muscle without branching).Th e area of vascularised skin defi ned with color injection (av. x  cm) is suffi cient for reconstructions in head and neck defects.
we found that from axil-* All Clinics and Departments, as parts of the Faculty of Medicine in Niš, have integrated professional cooperation and internal ethical control.lary artery arise two arteries where the fi rst branch gave acromial and deltoid and the other gave pectoral branch.In  ( fetuses) we found  terminal branches of thoracoacromial artery (Figure .) and in  ( fetuses) the clavicular branch was not found.In all cases lateral part of pectoral major muscle is supplied by branch of lateral thoracic artery (Figure ).In  one pectoral branch is found but in  cases we found two pectoral branches (Figure ).In cases of two pectoral branches the first reaches muscle more proximally than later.(FIG) Pectoral branch divides in two terminal branches before the entering muscle belly in .In   we found that it reach muscle without branching and in  gives three terminals before entering muscle belly (Figure a).We found a lot of anastomoses between terminal branches in pectoral major muscle (Figure b).In all cadavers thoracoacromial artery arise from anterior aspect of axillar artery.TAT arises in  of cases ( cadavers) sharply in the middle of clavicle.In ,  ( cadavers) in arise  mm medially from the midpoint and in , of cases ( cadavers) arise  mm laterally from the middle of the clavicle.Th e length of TA artery from arising to branching vas  to  mm.Th e average length of TA was , mm (SD . mm and coeffi cient of variation ,) Th e diameter of TA artery was , to , mm.Th e average diameter of TA artery was , mm with SD , mm.In , of cases ( cadavers) TAA branching in  terminals, in ,  ( cadavers) we found fifth branch supplying pectoral minor muscle and in  ( cadavers)  terminal branches detected (clavicular branch did not found).
use of musculocutaneous flaps bringing well vascularised muscle mass and proper skin quality island presents advance in reconstructive surgery.Pectoral major myocutaneous flap is used for long time but investigation of its blood supply is attractive because of understanding partial flap necrosis despite of excellent surgical technique.The results of our anatomical study certainly define that main blood supply of pectoral major flap is thoracoacromial artery, what is contributed by other authors.(-) Nakajima and al. () And Pandey and al.
Nakajima and al. ()  refer similar results.Th ey discus about difference in both sides explaining in embryology: the right axillar artery develops from aortic arch but in left side from brachicephalic trunk.We did not fi nd the diff erence in the sceletopic relations of TAA.The average length of TAA was , mm, The average diameter of TAA in arising was ,mm (SD=,), but others refers diameter of , mm and diameter of pectoral branch  -, mm.()