Clinical Anatomy of the Maxillary Artery

Home , Buccal artery, Deep temporal arteries, Inferior alveolar artery, Infraorbital artery, Maxillary artery, Sphenopalatine artery

Okajimas CnlinicalFolia Anat. Anatomy Jpn., 87 of(4): the 155–164, Maxillary February, Artery 2011155

Ippei OTAKE1, Ikuo KAGEYAMA2 and Izumi MATAGA3

1 Department of Oral and Maxilofacial Surgery, Osaka General Medical Center (Chief: ISHIHARA Osamu) 2 Department of Anatomy I, School of Life Dentistry at Niigata, Nippon Dental University (Chief: Prof. KAGEYAMA Ikuo) 3 Department of Oral and Maxillofacial Surgery, School of Life Dentistry at Niigata, Nippon Dental University (Chief: Prof. MATAGA Izumi)

–Received for Publication, August 26, 2010–

Key Words: Maxillary artery, running pattern of maxillary artery, intraarterial chemotherapy, inner diameter of vessels

Summary: The Maxillary artery is a component of the terminal branch of external carotid artery and distributes the blood flow to upper and lower jawbones and to the deep facial portions. It is thus considered to be a blood vessel which supports both hard and soft tissues in the maxillofacial region. The maxillary artery is important for bleeding control during operation or superselective intra-arterial chemotherapy for head and neck cancers. The diagnosis and treatment for diseases appearing in the maxillary artery-dominating region are routinely performed based on image findings such as CT, MRI and angiography. However, validations of anatomical knowledge regarding the Maxillary artery to be used as a basis of image diagnosis are not yet adequate. In the present study, therefore, the running pattern of maxillary artery as well as the type of each branching pattern was observed by using 28 sides from 15 Japanese cadavers. In addition, we also took measurements of the distance between the bifurcation and the origin of the maxillary artery and the inner diameter of vessels. These findings thus obtained could contribute to knowledge of improved accuracy of image diagnosis as an index for embolization and for knowledge of an adequate superselective intra-arterial chemotherapy.

Introduction Subjects and Methods

The maxillary artery along with the superficial tem- Subjects poral artery is a terminal branch of the external carotid We studied 28 sides of symmetrically dissected heads artery. Its branches extended into the deep parts of the of 15 Japanese cadavers (21 sides in 11 men and 7 sides face, including the maxilla, mandible, cerebral dura mater, in 4 women) in which the maxillary artery could be and the nasal cavity. Clinically, the maxillary artery plays closely examined and measured. All the cadavers were an important role in superselective intra-arterial infusion preserved at Department of Anatomy, the Nippon Dental chemotherapy for head and neck cancers1, 2), arterial University School of Life Dentistry at Niigata. The mean embolization therapy for vascular lesions such as arte- age was 69.1 ± 16.9 years (range, 22 to 90). riovenous malformation and refractory nasal bleeding3–7), and reconstruction after tumor resection8, 9). Methods Studies of the maxillary artery have a long history, The coronoid process was transected, and the tem- dating back to reports by Thomson10), Lauber11), Adachi12), poral muscle was turned superiorly to expose the infra- Fujita13), and Lasker14). Recently, Japanese researchers temporal fossa. After confirming the relation between such as Sashi15) and Tsuda16–18) have evaluated the maxil- the lateral pterygoid muscle and the maxillary artery, the lary artery angiographically, whereas Kitsuta et al. (19) lateral pterygoid muscle was removed, and the maxillary have macroscopically studied anatomic characteristics. artery, its branches, and the surrounding nerves were We macroscopically studied the origins, courses, branch- photographed and sketched in detail. The region extending patterns, and the luminal diameters of the maxillary ing from the origin of the maxillary artery to the point artery and its branches in Japanese cadavers. of entry into the pterygopalatine fossa was carefully removed. The distances between each of the branches and the luminal diameters of the main branches were

Corresponding author: Ippei Otake, Osaka General Medical Center, Sumiyoshi-ku, Osaka, 558-8558 Japan. E-mail: [email protected] 156 I. Otake et al.

ECA: external carotid a. ST: superficial temporal a. Mx: maxillary a. MM: middle meningeal a. AM: accessory meningeal a. IA: inferior alveolar a. PT: posterior deep temporal a. B: buccal a. AT: anterior deep temporal a. PSA: posterior superior alveolar a. IO: infraorbital a. SP: sphenopalatal a. TM: temporal m. LP: lateral pterygoid m. MP: mesial pterygoid m. ATN: auriculotemporal n. IAN: inferior alveolar n. LN: lingual n. BN: buccal n. FO: foramen ovale FS: foramen spinosum (a.: artery, m.: muscle, n.: nerve)

Fig. 1. Measuring points.

measured. The following examinations and measurements were performed.

1) Levels of maxillary artery branches The distance between the origin of the maxillary artery and the superior margin of the external auditory canal was measured along a line parallel to the axis of the body (Fig. 1). The height of the origin of the maxillary artery was distinguished from the height of the bifurcation of the common carotid artery was classified into 3 groups as described in the following by Ito et al.20): a higher than average bifurcation, located near the region from the 2nd to 3rd cervical vertebrae; a standard bifurcation, located near the region from the 3rd to 4th cervical vertebrae; and a lower than average bifurcation, located near the region from the 4th to 5th cervical vertebrae.

2) Course of the main trunk of the maxillary artery The course of the main trunk of the maxillary artery was classified as following with respect to the lateral pterygoid muscle: with an external course pattern, if the main trunk ran superficial to the lateral pterygoid muscle; or with an internal course pattern, if the main trunk ran deep to the lateral pterygoid muscle (Fig. 2). The positional relation between the maxillary artery and the mandibular nerve was classified as described by Fujita (Fig. 3). Fig. 2. Positional relationship between Mx and lateral pterygoid. Cnlinical Anatomy of the Maxillary Artery 157

Fig. 3. Positional relationship between Mx, lateral pterygoid, and mandibular nerve

3) Orders of branches arising from the maxillary artery fossa was regarded as 100%, the relative distances of the The orders of the branches arising from the maxillary origins of each of the branches from the main trunk of artery were classified as described by Ikakura21). In Type the maxillary artery were calculated. I, after arising from the external carotid artery the maxillary artery gives off branches in the following order: the 5) Luminal diameters of the main trunk of the maxillary middle meningeal artery, the inferior alveolar artery, the artery and its branches posterior deep temporal artery, the buccal artery, the ante- The following 9 arteries were studied: the main trunk rior deep temporal artery, the posterior superior alveolar of the maxillary artery, the middle meningeal artery, artery, the infraorbital artery, the descending palatine the inferior alveolar artery, the posterior deep temporal artery, and the sphenopalatine artery. In Type II, the order artery, the buccal artery, the anterior deep temporal artery, of the middle meningeal artery and the inferior alveolar the posterior superior alveolar artery, the infraorbital artery is reversed. In Type III, the buccal artery is absent. artery, and the sphenopalatine artery. A section 1 mm in If the posterior superior alveolar artery and infraorbital width was cut 1 cm distal to the origin of each branch. artery arise from a common trunk, each type is classified Each specimen was cut open parallel to the course of the as type Ia, type IIa, and type IIIa, respectively (Fig. 4). vessel and mounted on a slide glass. The length between the two ends was measured with the use of a stereo- 4) Distances of the branches from the main trunk of the microscope (Stereo Photo SMZ-10, Nikon Co., Tokyo maxillary artery Japan) and a digital vernier caliper (Digimatic Caliper The distance from the main trunk of the maxillary 500–110, Sankin Co., Ltd., Tokyo, Japan) to derive the artery to each of its branches was measured as described lumen diameter. The same site was measured 3 times, by Shimada et al.22) A silk thread was placed along the and the mean value was calculated. If branches arose course of the vessel and extended in a straight line to from a common trunk, the site 1 cm distal to the origin measure the distance from the main trunk to each branch. of the common trunk was measured. The Wilcoxon rank- The proportional distance from the origin of the maxil- sum test was used for statistical analysis. lary artery to the point of entry into the pterygopalatine 158 I. Otake et al.

Fig. 4. Classification on the derivative order of branches of Mx.

Results Table 1. Distance between superior margin of external auricular me- atus and origin of Mx 1) Height of the origin of the maxillary artery (n = 28/mm) The vertical height of the origin of the maxillary Right Left artery from the superior margin of the external auditory Male 24.3 ± 5.6 23.2 ± 3.6 canal ranged from 15.4 mm to 32.7 mm (mean, 23.4 ± (15.4~32.7) (17.4~28.7) 5.1 mm) on the right side and from 12.5 mm to 28.7 mm Female 21.2 ± 3.2 20.2 ± 7.3 (mean, 22.6 ± 4.5 mm) on the left (Table 1). The height (18.4~28.7) (12.5~26.8) of the bifurcation of the common carotid artery was stan- Average 23.4 ± 5.1 22.6 ± 4.5 dard in 15 patients (53.5%), high in 9 (32.2%), and low (15.4~32.7) (12.5~28.7) in 1 (3.6%) (Table 2).

2) Course of the main trunk of the maxillary artery Table 2. Pattern of bifurcation level of the common carotid artery In the present study, 27 (96.4%) of the 28 sides stud- Right Left Total ied had an external course pattern, and only 1 (3.6%) had an internal course pattern. Examples of the external Higher bifurcation 4 (14.3%) 5 (17.9%) 9 (32.2%) and internal course patterns are shown in Figs. 5 to 8, Standard bifurcation 9 (32.1%) 6 (21.4%) 15 (53.5%) Lower bifurcation 1 ( 3.6%) 0 1 ( 3.6%) respectively. The positional relation between the maxil- Unknown 1 ( 3.6%) 2 ( 7.1%) 3 (10.7%) lary artery and the mandibular nerve was classified as described by Fujita13). Type A was most common, present n = 28 in 22 sides (78.6%), followed by type B in 5 (17.8%) and type C in 1 (3.6%). No side was type D or type E (Table 3). in 7 (25.0%) of 28 sides, type Ia in 12 (42.9%), type II in 2 (7.1%), type IIa in 0 (0%), type III in 3 (10.7%), and 3) Order of branches arising from the maxillary artery type IIIa in 1 (3.6%). Type Ia was most common. The The order of branches arising from the maxillary standard patterns of type I or type Ia were found in 19 artery according to Ikakura’s classification21) was type I subjects (67.9%) (Table 4). Three sides were difficult to Cnlinical Anatomy of the Maxillary Artery 159

Fig. 5. Lateral Type. Fig. 6. Lateral type of the Maxillary Artery.

Fig. 7. Medial Type. Fig. 8. Medial type of the Maxillary Artery.

classify because of reversed orders of branches or dupli- lows: the middle meningeal artery, 9.4 ± 5.2 mm; the cate branches. inferior alveolar artery, 17.3 ± 4.4 mm; the posterior deep temporal artery, 29.0 ± 5.7 mm; the buccal artery, 48.7 4) Distances of branches from the main trunk of the max- ± 10.6 mm; the anterior deep temporal artery, 55.4 ± 6.2 illary artery mm; the posterior superior alveolar artery, 64.1 ± 8.0 The mean bilateral distances from the origin of the mm; and the infraorbital artery, 66.8 ± 9.2 mm. The dis- maxillary artery to the following branches were as fol- tance between the origin of the maxillary artery and the 160 I. Otake et al.

Table 3. Positional relationship between Mx, the lateral pterygoid, and Table 5. Distance between branches of Mx the mandibular nerve Diameter (mm) Frequency Lateral type Medial type MMA 2.7~20 ( 9.4 ± 5.2) 3.8~24.7 (12.1 ± 6.8) A B C D E IA 8.9~28.5 (17.3 ± 4.4) 12.4~35.3 (22.0 ± 5.2) PTA 8.9~36.7 (29.0 ± 5.7) 12.4~49.5 (37.3 ± 6.6) Male Right 9 (32.1%) 2 ( 7.1%) 0 0 0 BA 21.9~66.9 (48.7 ± 10.6) 28.6~76.7 (62.3 ± 11.3) Left 9 (32.1%) 2 ( 7.1%) 1 (3.6%) 0 0 ATA 42.5~68.0 (55.4 ± 6.2) 61.7~80.4 (70.5 ± 4.7) Female Right 3 (10.8%) 0 0 0 0 PSA 51.2~78.7 (64.1 ± 8.0) 72.4~96.9 (81.3 ± 6.4) Left 1 ( 3.6%) 1 ( 3.6%) 0 0 0 IFA 48.2~87.9 (66.8 ± 9.2) 73.9~96.9 (85.2 ± 6.2) Pterygoid Fo. 61.3~99.3 (78.5 ± 9.3) 100 Total 22 (78.6%) 5 (17.8%) 1 (3.6%) 0 0 Min~Max (average ± SD) n = 28

Table 4. Derivative order of branches of the maxillary artery Table 6. Luminal diameter of branches of Mx and maxillary artery Type Right Left Total (%) Right Left Total (mm) I 4 (14.3%) 3 (10.7%) 7 (25.0%) MA 1.7~2.3 (1.9 ± 0.2) 1.6~5.6 (2.2 ± 1.0) 1.6~5.6 (2.1 ± 0.7) Ia 7 (25.0%) 5 (17.9%) 12 (42.9%) MMA 0.8~1.9 (1.3 ± 0.3) 0.7~1.6 (1.2 ± 0.2) 0.7~1.9 (1.2 ± 0.2) II 0 2 ( 7.1%) 2 ( 7.1%) IAA 0.5~1.0 (0.6 ± 0.1) 0.5~0.9 (0.6 ± 0.1) 0.5~1.0 (0.6 ± 0.1) IIa 0 0 0 PTA 0.5~1.0 (0.7 ± 0.1) 0.6~1.1 (0.8 ± 0.2) 0.5~1.1 (0.7 ± 0.1) III 2 ( 7.1%) 1 ( 3.6%) 3 (10.7%) BA 0.3~0.7 (0.5 ± 0.1) 0.3~0.9 (0.6 ± 0.2) 0.3~0.9 (0.6 ± 0.2) IIIa 0 1 ( 3.6%) 1 ( 3.6%) ATA 0.4~1.5 (0.7 ± 0.3) 0.5~0.9 (0.7 ± 0.1) 0.4~1.5 (0.7 ± 0.2) Others 1 ( 3.6%) 2 ( 7.1%) 3 (10.7%) PSA 0.7~1.1 (1.0 ± 0.2) 0.6~1.3 (1.0 ± 0.2) 0.7~1.3 (1.0 ± 0.2) IFA 0.7~2.2 (1.0 ± 0.4) 0.7~1.3 (1.0 ± 0.2) 0.7~2.2 (1.0 ± 0.3) n = 28 SPA 0.7~1.7 (1.2 ± 0.3) 1.0~1.6 (1.3 ± 0.2) 0.7~1.7 (1.2 ± 0.2) Min~Max (average ± SD) point of entry into the pterygopalatine fossa was 78.5 ± 9.3 mm. When this value was regarded as 100%, the relative mean distances until each branch were as follows: artery. The maxillary artery is distributed to the maxilla the middle meningeal artery, 12.1 ± 6.8; the inferior and mandible and is the most important artery supplying alveolar artery, 22.0 ± 5.2; the posterior deep temporal soft and hard tissue in the maxillofacial region. The max- artery, 37.3 ± 6.6; the buccal artery, 62.3 ± 11.3; the illary artery arises from the external carotid artery pos- anterior deep temporal artery, 70.5 ± 4.7; the posterior teriorly and inferiorly to the neck of the mandible, runs superior alveolar artery, 81.3 ± 6.4; and the infraorbital anteriorly to the inner surface of the mandibular ramus, artery, 85.2 ± 6.2 (Table 5). and enters the pterygopalatine fossa, ending in the pterygopalatine artery. The maxillary artery can be divided 5) Luminal diameters of the main trunk of the maxillary into the mandible, the pterygoid, and the pterygopalatine artery and its branches portions, each of which gives off branches. The courses The mean bilateral luminal diameters of the maxillary of the maxillary artery are subject to considerable indi- artery and its branches were as follows: the main trunk of vidual variation, such as running externally or internally the maxillary artery, 2.1 ± 0.7 mm; the middle meningeal to the lateral pterygoid muscle. artery, 1.2 ± 0.2 mm; the inferior alveolar artery, 0.6 ± 0.1 Takarada23) and Ikakura21) classified the origin of the mm; the posterior deep temporal artery, 0.7 ± 0.1 mm; maxillary artery with respect to the posterior border of the buccal artery, 0.6 ± 0.2 mm; the anterior deep tempo- the ramus of the mandible. Both found that the maxillary ral artery, 0.7 ± 0.2 mm; the posterior superior alveolar artery arose from two fifths above the posterior border of artery, 1.0 ± 0.2 mm; the infraorbital artery, 1.0 ± 0.3 the ramus of the mandible in about 80% of subjects. In mm; and the sphenopalatine artery, 1.2 ± 0.2 mm. There contrast, Ito et al.24) used the point corresponding to the were no statistical significant differences in the mean eye-ear plane of the superficial temporal artery for refer- luminal diameter between the left and right sides (Table ence. A Teflon tube was inserted into the artery at that 6). point, and the distance until the origin of the maxillary artery was measured. The mean distance to the origin of the maxillary artery was 30.9 ± 19.7 mm on the right side Discussion and 31.1 ± 1.3 mm on the left. Shintani et al.25) measured the distances between the auricular point and each of its Courses of the maxillary artery branches and reported that the mean distance to the origin The maxillary artery and the superficial temporal of the maxillary artery was 32.0 ± 9.0 mm. In the present artery are both terminal branches of the external carotid study, we used the superior margin of the external audi- Cnlinical Anatomy of the Maxillary Artery 161 tory canal as a reference point and measured the distance In our series, only 1 (3.6%) of 28 sides had an internal to the origin of the maxillary artery. The mean distance course pattern; all others had an external course pattern. was 23.4 ± 5.1 mm on the right side and 22.6 ± 4.5 mm In the subject with an internal course pattern, the contra- on the left. We also examined the positional relation be- lateral maxillary artery had an external course pattern; tween the bifurcation level of the common carotid artery the artery was thus asymmetrical. The prevalence of the and that of the maxillary artery for 25 sides in which maxillary artery passing through the belly of the lateral the bifurcation level of the common carotid artery could pterygoid muscle was reported to be 0.6% (2/331) by be evaluated. We had initially assumed that the bifurca- Adachi12), 1.9% (3/158) by Iwamoto et al.27), and 0.5% tion level of the maxillary artery was influenced by the (1/200) by Lurje28). In addition, Takemura et al.29), bifurcation level of the common carotid artery. Although Fujimura et al.30), and Tanaka et al.31) reported cases in we had the impression that a high bifurcation level of which the maxillary artery passed through the mandibu- the common carotid artery was slightly associated with a lar nerve, so-called type D of Fujita’s classification13). higher bifurcation level of the maxillary artery than was In our series, however, no subject had a type D pattern. a standard bifurcation level of the common carotid artery, Although Fujita’s classification has been used previously, there was no distinct relation between the bifurcation the prevalence of type D appears to be very low (Table 8). level of the common carotid artery and that of the maxil- Consistent with our results, most Japanese have lary artery. been reported to have an external course pattern of the The courses of the maxillary artery have been reported maxillary artery. The Gow-Gates technique for conduc- to be diverse. In previous studies conducted in countries tion of anesthesia in clinical dentistry32) is associated other than Japan, the prevalence of an internal course with a higher response rate (≥ 95%) than conventional pattern was reported to be 44.7% by Thomson10) in the mandibular foramen conduction anesthesia, with a low United Kingdom, 91.5% by Lauber11) in Australia, and risk of directly puncturing blood vessels (about 1%). 45.6% by Lasker14), who studied Caucasians in the United However, Toki33) reported that the Gow-Gates technique States. In Japan, a number of investigators, including had a response rate of only 75% in Japanese patients, Adachi12), Fujita13), Takarada23), and Ikakura21), reported lower than that in Australian subjects, as well as a higher that the main trunk of the maxillary artery usually runs rate of intravenous puncture (17%). These results are superficially to the lateral pterygoid muscle (the external attributed to differences in the courses of the maxillary course pattern). The prevalence of an internal course pat- artery between Japanese and Australian. Therefore, tern has been reported to be only 6.3% to 10.1%12, 13, 21, 23) techniques for anesthesia should not be selected solely (Table 7). In individual subjects, the courses of the left on the basis of the results of studies in Australian patients and right maxillary arteries are overwhelmingly sym- because inappropriate approaches can lead to a reduced metrical. The prevalence of different courses of the left rate of response and a higher risk of complications such and right of the maxillary arteries was reported to be as vascular puncture. 6.8% (3/47) by Takarada23) and 6.3% (5/80) by Ikakura21). Branches of the maxillary artery The main trunk of the maxillary artery usually extends Table 7. Comparison of individual observation on the medial type of into branches in the following order: the deep auricular Mx artery, the anterior tympanic artery, the middle meningeal artery, the inferior alveolar artery, the masseteric Authors Year n medial type (%) artery, the posterior deep temporal artery, the pterygoid Adachi 1928 331 21 ( 6.3) branch, the buccal artery, the posterior superior alveolar Fujita 1932 119 12 (10.1) artery, the infraorbital artery, the descending palatine Takarada 1958 120 11 ( 9.2) artery, the pterygoid canal artery, and the sphenopalatine Ikakura 1961 160 15 ( 9.4) 17, 21, 23) Iwamoto 1981 158 11 ( 7.0) artery . In the present study, we classified the order Tsuda 1991 339 22 ( 6.5) of 8 arteries arising from the maxillary artery (the middle Present study 2005 28 1 ( 3.6) meningeal artery, the inferior alveolar artery, the poste-

Table 8. Positional relationship between Mx, lateral pterygoid, and mandibular nerve Lateral type Medial type A B C D E Ikakura 122 (76.3%) 23 (14.4%) 11 (6.4%) 1 (0.6%) 3 (1.9%) Takarada 78 (75.0%) 17 (16.3%) 7 (6.7%) 1 (1.0%) 1 (1.0%) Fujita 67 (85.9%) 5 ( 6.4%) 5 (6.4%) 1 (1.3%) 0 Present study 22 (78.6%) 5 (17.8%) 1 (3.6%) 0 0 162 I. Otake et al. rior deep temporal artery, the buccal artery, the anterior site as, or proximal to, the middle meningeal artery in temporal artery, the posterior superior alveolar artery, about 20% of subjects. In the present study, the inferior the infraorbital artery, and the sphenopalatine artery) alveolar artery arose distal to the middle meningeal artery into 6 groups according to the Ikakura’s classification21). in 25 of 28 sides (89.3%) and proximal to the middle The combined prevalence of the standard types I and Ia meningeal artery in the 1 side with an internal course was 67.9%. In previous studies of Japanese subjects, the pattern and 2 sides in which the inferior alveolar artery prevalence of these standard types was reported to be arose from 2 sites. 63.9% by Takarada23), who studied 6 arteries from the If reconstruction is performed with a temporalis middle meningeal artery to the posterior superior alveolar muscle flap, the bifurcation sites and courses of the artery, 72.1% by Ikakura21), who studied 8 arteries from posterior and anterior deep temporal arteries should be the middle meningeal artery to the descending palatine carefully assessed37). In our series, the posterior deep artery, and 66.8% by Tsuda17), who studied 7 arteries temporal artery arose from the inferior alveolar artery in from the middle meningeal artery to the infraorbital 1 side with an internal course pattern, but from the main artery. These results suggest that the prevalence of stan- trunk of the maxillary artery in all others. The origin was dard types is about 70% in Japanese. distal to the inferior alveolar artery. The posterior deep An accessory middle meningeal artery, (i.e., a branch temporal artery did not arise proximal to the inferior of the middle meningeal artery) was found in 25 (89.3%) alveolar artery or from a common trunk in any subject. of 28 sides. We defined a branch arising from the main In 4 sides (14.4%) in our study, arteries were distributed trunk of the maxillary artery as an accessory middle to the temporalis muscle peripheral to the deep temporal meningeal artery and a branch arising from the middle artery. Miura et al.37) found similar arteries at a similar meningeal artery as an accessory branch of the middle prevalence (15.8%). meningeal artery, as reported by Kodama34). In our series The anterior deep temporal artery was present in 26 of 28 sides, an accessory middle meningeal artery was of 28 sides (92.9%). The anterior deep temporal artery found in 7 sides (25.0%), and an accessory branch of usually arises distal to the buccal artery, but arises from the middle meningeal artery was found in 18 (64.3%). the same site as, or proximal to, the buccal artery in some Baumel et al.35) reported that an accessory branch of the subjects. The frequencies of these patterns were respec- meningeal artery was found in 73 of 76 subjects (96%) tively reported to be 15.2% and 5.4% by Takarada23) and and that the branch arose from the main trunk of the 11.3% and 3.5% by Ikakura21). maxillary artery and from the middle meningeal artery The buccal artery was absent in 7 of 28 sides (25.0%), with similar frequency. Ikakura21) reported that accessory a higher prevalence than that reported by Takarada23) and branches of the meningeal artery arose from the main Ikakura21) (11.6% and 10.8%, respectively). trunk of the maxillary artery in about 5% of subjects, Takarada23) and Ikakura21) reported that the posterior similar to the frequency of accessory branches arising superior alveolar artery and the infraorbital artery arose from the middle meningeal artery. Yagishita36) found ac- from a common trunk in about 50% of subjects. In our cessory middle meningeal arteries on angiography in 21 series, 13 of 28 sides (46.4%) had a common trunk. In 1 of 30 subjects (70.0%), but did not distinguish whether of 15 sides (6.7%) without a common trunk, the positions the accessory arteries originated from the main trunk of of the posterior superior alveolar artery and infraorbital the maxillary artery or from the middle meningeal artery. artery were reversed. In this subject, the maxillary artery Tsuda17) similarly performed angiographic studies of 339 ran anteriorly and inferiorly after extending from the cadavers at through autopsies. An accessory branch of anterior deep temporal artery, turned anteriorly and supe- the middle meningeal artery was present in 316 subjects. riorly after giving off the buccal artery from the inferior Of the 316 subjects, 299 (94.6%) had an external course wall, giving off the infraorbital artery from the inferior pattern; in 231 (73.1%) the accessory branch arose from wall, and then traveled inferiorly and medially and giving the middle meningeal artery. Among 22 subjects with an off the posterior superior alveolar artery from the lateral internal course pattern, the accessory branch arose from inferior wall. the maxillary artery in 14 cases (4.4%). These findings Most previous studies evaluating the distance from suggest that accessory branches of the middle meningeal the origin of the maxillary artery to each of its branches artery usually arise from the middle meningeal artery reported positional relations relative to the surround- in persons with an external course pattern and from the ing muscles and nerves. For example, Takarada23) and main trunk of the maxillary artery in persons with an Ikakura21) studied the positional relations between the internal course pattern. In the present study, however, an origin of the middle meningeal artery and the inferior accessory middle meningeal artery was not found in only border of the lateral pterygoid muscle, and between the one of the side of a symmetrically dissected head. inferior alveolar artery and the inferior border of the The inferior alveolar artery usually arises distal to lateral pterygoid muscle as well as the inferior alveolar the middle meningeal artery. Takarada23) and Ikakura21) nerve. However, when performing cannulation for intra- reported that the inferior alveolar artery arose at the same arterial infusion chemotherapy and arterial embolization, Cnlinical Anatomy of the Maxillary Artery 163 not only the courses of arteries, but also the distances nal nerve, the maxillary artery passed inside of the between branches are important factors. We therefore buccal nerve (type B and C) in 21.4% of the sides if measured the absolute distances from the main trunk of the symmetrically dissected heads. However, the max- the maxillary artery to the origin of each of its branches illary artery did not pass inside the inferior alveolar and calculated the relative distances of each branch from nerve in any subjects. Namely we could not observe the origin of the maxillary artery, regarding the length type D and E. from the origin of the maxillary artery to the point of 2. The vertical height of the origin of the maxillary entry into the pterygopalatine fossa to be 100%. The infe- artery from the superior margin of the external audito- rior alveolar artery and the anterior deep temporal artery ry canal was 23.4 ± 5.1 mm on the right side and 22.6 showed the smallest variations, the buccal artery showed ± 4.5 mm on the left. There was no relation between the largest. Miura et al.37) measured the distance from the bifurcation level of the common carotid artery and the origin of the maxillary artery to each of its branches that of the maxillary artery. and reported that the mean distance was 11.4 mm for the 3. As for the order that each branch arose from the middle meningeal artery, 15.6 mm for the inferior alveo- maxillary artery, 67.9% of all sides showed standard lar artery, 31.0 mm for the posterior deep temporal artery, patterns. and 53.7 mm for the anterior deep temporal artery. These 4. The inferior alveolar artery and the anterior deep results were similar to our findings. temporal artery showed the smallest variations when the site of the origin of each branch of the maxillary Luminal diameters of branches of the maxillary artery artery was expressed relative to the distance from the The diameters of cervical blood vessels used as feed- origin of the maxillary artery to the site of entry into ing arteries during vascularized free-flap grafting after the pterygopalatine fossa. malignant-tumor resection have been reported sporadi- 5. Among branches of the maxillary artery, the luminal cally38, 39). To our knowledge, however, no previous study diameter was largest for the middle meningeal artery has measured the luminal diameters of the main trunk (1.2 ± 0.3 mm) and smallest for the buccal artery (0.6 of the maxillary artery and its branches. We therefore ± 0.2 mm). measured the luminal diameters of branches of the maxillary artery. Recent technical and physical advances in angiography have allowed the external carotid artery and Acknowledgement its branches to be superselectively visualized by means of the Seldinger approach via the femoral artery by a On completion of this manuscript, we are deeply in- retrograde approach from the superficial temporal artery. debted to the donors and their families. We also thank the Superselective intra-arterial infusion chemotherapy1, 2) physicians of Department of Anatomy for their coopera- has become a standard treatment for malignant tumors. tion in performing this study. Intra-arterial infusion using the Seldinger approach car- ries the risk of causing embolism in the region of the internal carotid artery. To prevent such complications, re- References gurgitation of the injected medium used for embolization should be avoided. Our results may be useful for select- 1) Robbins KT, Fontanesi J, et al. 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