Anatomical Study Of Infrahyoid Myocutaneous Flap

Objective:This research uncovers the mechanism of myocutaneous flap necrosis by using technologies like lead oxide modified angiography, fresh specimens of anatomy, 3D software reconstruction to study the characteristic of blood supply of infrahyoid myocutaneous flap and infrahyoid muscles, thyroid gland arteriovenous, and their positional relationship,etc.Methods:(1) Lead oxide latex whole-body perfusion 8 cases of fresh adult specimens,6 males,2 females,Between the ages of 20 to 70,1 case within 20-30 years old,3 case 30-40 years old,1 case 40-50 years old,3 case 50-70 years old.Femoral arteriovenous cutting operation in latex-lead oxide mixed suspension.systemic perfusion,within 48 h after death onset.Observation of perfusion,when acra、facia、sclera shows perfusate color dot or patching, stop perfusion, and frozen specimens。(2) Radiography and body spiral CT scanningCT scanning requirements: scanning With 64 row general/partial helical CT whole body scan:Width 512,Height 512; Pixel Size 0.5mm,Slice Increment 0.5mm;120kv,300.00 mAs.Width,Height,kv,mAs datas are for reference only.Different machines and Specimens of parts May not be the same.(2) Specimens anatomy, photography and related data collection and analysisIn the process of stratified anatomy,using a digital camera records the anatomy of the process successively,Observing epidermis perforating branches.Detailed records on the superior thyroid artery and its branches of anatomical features,and records superior thyroid artery starting-point with superior thyroid starting-point on the location of the relationship. Getting the infrahyoid muscles flap after the anatomy finished and tiled,take x-ray films to comprehend vascular distribution characteristicsd and anastomoses.Gather positional relationship date of superior thyroid starting point and superior vein thyroid converging point in clinic operation, and compared with related data of Specimens.(4) Mimics 3D reconstruction of the neck vesselsPuting the CT data into Mimics software. Application of fast direct volume rendering(volume rendering, VR) and three-dimensional reconstruction of trunk vessel, smaller arterial branches and vascularized image.Result:(1) Effectiveness evaluation of specimen overall perfusionThe perfusion is sufficient and well-distributed. Main arteries and their branches develop well. Three-dimensional reconstruction renderings of neck vessels is clear.(2) Blood supply of infrahyoid myocutaneous flap surface skinDissection shows that blood supply of suface skin comes from tiny skin perforating branch(0.1-0.5mm), which number is not content, and the otherness is rather big, no stable perforating branch,these tiny skin perforting branch starting points mainly distributes from the following thyroid pole, nearing the cricoid cartilage, and found during the dissection of these small perforating branches of the superior thyroid artery branches-cricothyroid branch(muscular branches) issued, accounting for 15/16 side; from the superior thyroid artery branch-glandular branches(anterior branch) issued, accounting for 1/16 side. And found only oneperforator in 16 side specimens, which diameter is about 5mm.And issued by the thyroid gland artery branch.In addition, the other most important nutrientsbranch is the sternocleidomastoid branch(branch of the superior thyroid artery) skin perforator. It emits near sternocleidomastoid intersection supraomohyoid abdomen. It can be divided into upstream branch, medial branch and descending branch. Medial branch can enter the surface of the skin from the muscle flap flap outer boundary.(3) The hyoid muscles blood supplyThe study found sternohyoid and sternal thyroid muscle blood supply primarily from the cricothyroid branch(muscular branches). It can be divided into three types.Type Ⅰ : vessels between sternohyoid sternum thyroid muscle, accounting for 8/16 side;Type Ⅱ: Vascular issued two branches surrounding the hyoid muscles and sternum sternum thyroid muscle from the side, accounting for 7/18 side;Type Ⅲ: it has a direct line to go between thyroid and sternum thyroid muscle, accounting for 1/16 side. In addition, the thyroid artery branch line to walk between the thyroid gland and sternal thyroid muscle, it also issued under a lot of small branches up nutrition hyoid muscles. Other branches of the superior thyroid artery, such as the hyoid bone and the lower branch sternocleidomastoid branch also nutrition hyoid muscles.(4) Anatomical points on thyroid arteryStudy found that thyroid artery can be divided into two types: type I arched forward lower deck was shaped like an "S" shape, accounting for 10/16 side; Down-shaped front was another type, like an inverted "L", accounting for 6/16 side; all thyroid artery from the issue point to the pole of the thyroid actual distance is greater than the straight line distance between two points.(5) Thyroid venous anatomy classificationStudy found that thyroid vein independent dry form directly into the internal jugular vein, accounting for 14/16; and surface veins and other vein common trunk into the internal jugular vein, accounting for 2/16; loop reflow mode, accounting 0.In addition, according to the distance between thyroid artery and thyroid vein, it can be divided into three types, A type: upper thyroid artery point higher than thyroid vein into points, accounting for 13/16 side; B type: thyroid artery. point lower than the thyroid vein into points, accounting for 2/16 side; C type: both at the same height, representing 1/16 side.Conclusion:(1) Diameter of nutrient vessels of infrahyoid myocutaneous flap is small, the number of which is not constant, distributed below thyroid upper pole and around cricoid. Pay attention to protect myocutaneous flap during preparation process. Meanwhile preserving the sternocleidomastoid muscle flap branch can help to strengthen the blood supply. And carrying on a part of the thyroid upper pole(hat) can help to improve security of flap.(2) According to localization, thyroid superior artery are divided into two types: type I arched down forward, shaped like an "S", and the other type goes down forward, shaped like an inverted "L". Thyroid vein directly flows into the internal jugular vein by independent trunk form, or by having co-trunks with facial vein and other veins to reflux.(3) According to the distance between superior thyroid artery and superior thyroid vein, it can be divided into three types, A type: superior thyroid artery starting point is higher than thyroid vein converging point; B type: superior thyroid artery starting point is lower than thyroid vein converging point; C type: uperior thyroid artery starting point and thyroid vein converging point are at the same height.