研究目的

第一部分：为明确额部主要动脉在不同的软组织层中的分布特点，并基于这些特点对额部动脉分布进行分型，以满足额部皮瓣手术对精细解剖结构的需求，为额部的填充注射提供指导，从而提高手术操作的安全性并改善术后效果。

第二部分：应用吲哚菁绿血管造影术（indocyanine green angiography, ICGA）联合SPY荧光成像系统（ICGA-SPY）探测额部血管，观察额部动脉和静脉灌注期，分析额部血管的分布特点、规律并进行分型。

第三部分：探讨以不同血管为蒂的多种类型额部皮瓣的特点，包括适应证、优点、缺点，以优化额部皮瓣在面颈部缺损修复中的应用。

研究方法

第一部分：本研究采用新鲜的人体头颈标本，按照表皮层、真皮层、皮下脂肪层、额肌-帽状腱膜层、骨膜层的顺序，对额部进行分层解剖。观察、测量并分析额部动脉的分布范围、走行层次、与周围组织的关系等解剖特点。

第二部分：2022年6月至2023年9月，应用ICGA对102例行面颈部手术的患者进行额部血管探测，观察并记录不同动脉的显影顺序和分布范围，测量动脉显影的荧光度。观察并记录显影静脉的位置、分布及与额部动脉的关系。

第三部分：回顾2004年3月至2024年1月应用不同类型的额部皮瓣修复面颈部不同部位软组织缺损的患者资料，分析不同额部皮瓣的特点，总结手术技巧、适应证及优缺点。

研究结果

第一部分：共计解剖11例头颈部标本，额部主要由滑车上动脉（supratrochlear artery, STA）、眶上动脉（supraorbital artery, SOA）和颞浅动脉额支（frontal branch of the superficial temporal artery, FBSTA）供血；旁正中动脉（paracentral artery, PCA）、正中动脉（central artery, CA）出现率较低，参与额中下部供血。STA的额肌穿出点位于眶上缘水平上方10.2 ± 4.5 mm、至额中线平均距离为14.9 ± 2.1 mm处；SOA的额肌穿出点位于眶上缘水平上方21.4 ± 2.4 mm、至额中线平均距离26.4 ± 1.3 mm处。额部血管的分布特点分为三种类型：Ⅰ型为SOA浅支缺如，额肌的浅面主要由STA浅支供血、深面主要由STA和SOA深支及骨膜支供血（68.2%，15/22）；Ⅱ型为SOA浅支存在，额肌的浅面主要由STA和SOA的浅支供血、深面主要由STA和SOA的深支和骨膜支供血（27.3%，6/22）；Ⅲ型表现为SOA缺如，STA仅存在深支，额肌的浅面主要由PCA供血，深面由STA深支和骨膜支供血（4.5%，1/22）。

第二部分：共102例患者接受额部ICGA检测，所有病例额部两侧均能观察到STA显影（100%，102/102，），88例额部两侧均出现FBSTA显影（86.3%，88/102），21例额部两侧均出现SOA显影（20.6%，21/102）、10例额部仅一侧出现SOA显影（9.8%，10/102）。额部动脉共存在3种分布类型：I型为STA和FBSTA可同时或先后显影，FBSTA进入额部后沿发际线走行（61.8%，63/102）；II型为STA和FBSTA可同时或先后显影，FBSTA在颞嵴中下部进入额部（24.5%，25/102）；III型为额部未见颞浅动脉分支，可见STA显影（13.7%，14/102）。在每一种类型中，SOA可显影或不显影。两侧STA、两侧FBSTA在显影强度方面存在显著性差异。在I型和II型中，一种为同侧STA、FBSTA显影强度均较对侧强，或显影范围均较对侧更大（56.8%, 50/88）；另一种为同侧STA、FBSTA仅一支血管的显影强度较强或显影范围较对侧大（43.2%, 38/88）。ICGA观察到在额中线的两侧存在两支滑车上静脉（supratrohclear vein, STV）、位于STA的内侧，滑车上动、静脉伴行不紧密；未观察到明显的眶上静脉（supraorbital vein，SOV）显影。

第三部分：共计94块额部皮瓣被用于修复面颈部不同部位的软组织缺损，其中以STA为血管蒂的额部皮瓣22块，以SOA为血管蒂的额部皮瓣6 块，以双侧FBSTA为血管蒂、以皮肤蒂形式转移的额部皮瓣26块，以单侧FBSTA为血管以皮肤蒂形式转移的额部皮瓣30块，以单侧FBSTA为血管蒂、以皮下蒂形式转移的额部皮瓣10块。术后1例皮瓣出现部分皮瓣坏死，5例远端静脉回流不畅，经换药后皮瓣最终成活。术后常需实施修整手术，其中，49 例行瘢痕修整术，29例行激光脱毛治疗，16 例行皮瓣修薄术。术后随访时间平均为14（8.2, 33.7）月，皮瓣颜色、质地与周围组织相似。

结论

第一部分：额部的血管分布存在深、浅两套系统，分别为额肌的深层和浅层组织供血，可指导进行额部皮瓣手术，以提高手术安全性和改善术后效果。

第二部分：ICGA检测额部血管，存在显影顺序、范围及强度的差异，提示动脉在额部两侧存在相对优势和劣势之分。应用ICGA可定位额部的动脉和静脉，辅助额部皮瓣的个性化设计和安全切取。

第三部分：额部血供丰富，不同类型的额部皮瓣具有各自的适应证及优缺点，选择合适的皮瓣有助于提高治疗效果，减少潜在的并发症。

Objective

Part I：This study aims to clarify the distribution characteristics of major arteries in different soft tissue layers in the forehead, and classify the distribution of the arteries based on these characteristics. The goal is to meet the demand for presice anatomical structures in forehead flap surgery, provide guidance for filling injections in the forehead, thereby improving the safety of surgical procedures and enhancing postoperative outcomes.

Part II：This study aims to gain a deep understanding of the vasculature in the forehead. Indocyanine green angiography (ICGA) with the SPY fluorescence imaging system (ICGA-SPY) was utilized to detect the forehead vessels, observe the perfusion phase of frontal arteries and veins, analyze the distribution characteristics, patterns and classifications.

Part III：The study aims to explore the characteristics of various types of forehead flaps based on different vessels. Through the development of a systematic and comprehensive treatment strategy, the goal is to optimize the application of forehead flaps in reconstruction of facial and cervical defects.

Methods

Part I：In this study, twenty-two hemifaces from 11 fresh cadavers were utilized to systematically perform layered dissection of the forehead, following the sequence of the epidermal layer, dermal layer, subcutaneous fat layer, frontalis muscle-galea aponeurotica layer, and periosteum layer. The anatomical characteristics of the forehead arteries, including their distribution, course, anastomoses, and relationships with surrounding soft tissues, were measured and analyzed.

Part II：From June 2022 to September 2023, ICGA was applied to detect forehead vessels in 102 patients undergoing reconstruction of the facial and cervical defects. The visualization sequence and distribution range of different arteries were observed and recorded, and the fluorescence intensity of arterial visualization was measured. Additionally, the location, distribution, and relationship of the veins with the arteries were observed.

Part III：This study conducted a retrospective analysis of patients who received different types of forehead flap surgery for reconstruction of facial and cervical defects at various locations between June 2022 and September 2023. The characteristics of different forehead flaps were analyzed, and surgical techniques, indications, advantages, and disadvantages were summarized.

Results

Part I：A total of 22 hemifaces from 11 cadavers were dissected. The supratrochlear artery (STA) and the supraorbital artery (SOA) were the main blood supply of the forehead. The frontal branch of the superficial temporal artery (FBSTA) was located on the superior lateral margin of the forehead. The paracentral artery (PCA) and central artery (CA) primarily contributed to the blood supply of the middle and lower forehead. STA and SOA exhibited three types of courses: periosteal, superficial, and deep branches. The distance from where the STA piercing the frontalis to the supraorbital margin was 10.2±4.5 mm and to the midline of the forehead was 14.9±2.1 mm. The distance from where the SOA emerging from the frontalis muscle to the the supraorbital margin was 21.4±2.4 mm and to the midline of the forehead was 26.4±1.3 mm. Three types of vascular distribution patterns were classified. In type I, the superficial branch of SOA (sSOA) was absent, and the layer superficial to the frontalis was predominantly supplied by the superficial branch of STA (sSTA), while the layer deep to the frontalis was mainly nourished by the deep branch of STA and SOA (dSTA, dSOA) (15/22 cases). In type II, the sSOA was present, the layer superficial to the frontalis was supplied by sSTA and sSOA. The deep and periosteal branches of STA (dSTA, pSTA) and SOA (dSOA, pSOA) were distributed deep to the frontalis (6/22 cases). In type III, the SOA was absent, the layer superficial to the frontalis was primarily supplied by PCA, and the layer deep to the frontalis was nourished by dSTA and dSTA.

Part II：ICGA was performed in 102 patients. In all cases, STA was observed on both sides of the forehead (100%, 102/102). FBSTA was observed on both sides of the forehead in 88 cases (86.3%, 88/102). SOA was observed on both sides of the forehead in 21 cases (20.6%, 21/102), while it was observed on only one side in 10 cases (9.8%, 10/102). There existed three distinct distribution patterns of forehead arteries. In type I, visualization of STA and FBSTA were present, with FBSTA entering the forehead and coursing along the hairline (61.8%, 63/102). In type II, visualization of STA and FBSTA were present, with FBSTA entering the forehead horizontally from the lower part of the temporal crest (24.5%, 25/102). In type III, STA was observed with the absence of  branch of the suoerficial temporal artery entering the forehead (13.7%, 14/102). Significant difference existed in the fluorescence intensity of both STA and FBSTA on both sides, as well as between the dominant and nondominant sides of the same vessel. In Type I and II, either the ipsilateral STA and FBSTA exibited stronger fluorescence intensity or a larger range compared to the contralateral side (56.8%, 50/88), or only one of the STA or FBSTA exhibited stronger visualization intensity or a larger range compared to the contralateral side (43.2%, 38/88).  ICGA revealed the presence of supratrohclear vein (STV) on both sides of the midline of the forehead, both located medially to the STA. STV was located at some distance from STA. No visualization of the supraorbital vein (SOV) near the SOA was observed.

Part III：A total of 94 forehead flaps were utilized for the reconstruction of facial and cervical defects in various locations. There were 22 forehead flaps based on STA, 6 forehead flaps based on SOA, 26 bi-pedicled forehead flaps based on bilateral FBSTA, 19 scarless forehead flaps based on unilateral FBSTA, 11 interpolated forehead flaps based on unilateral FBSTA, and 10 island forehead flaps based on unilateral FBSTA. Postoperatively, partial flap necrosis occurred in one case, while venous congestion occurred in five cases. The average follow-up period was 14 (8.2, 33.7) months, the color and texture of the flap were similar to the adjacent tissue..

Conclusions

Part I：There existed two types of arterial systems, supplying the layer deep and superficial to the frontalis, respectively. Understanding of the features can guide surgical procedures, enhancing the safety and improving postoperative outcomes.

Part II：ICGA examination revealed that differences existed in visualization order, range, and fluorescence intensity among forehead vessels, suggesting the presence of relative dominant and nondominant arteries on both sides of the forehead. The application of ICGA allowed for the localization of forehead arteries and veins, assisting in the personalized design and safe harvest of forehead flaps.

Part III：The color and texture of the forehead were well matched to the other regions of the face and neck, with rich blood supply. Developing treatment strategies utilizing different types of forehead flaps for the reconstruction of facial and cervical defects can improve postoperative outcomes and reduce potential complications.

Key Words: Forehead flap, Tissue expansion, Indocyanine green angiography, Anatomical study, Flap surgery