Arterial Distribution in the Region of the Floor of the Mouth of the Rat by Plastic Injection Method

Okajimas Folia Anat. Jpn., 56(1) : 45-66, May 1979

HARUYOSHI OTSUKA

The 2nd Department of Oral Anatomy, Josai Dental University, Sakado, Saitama 350-02, Japan (Director : Professor H. Hanai) (With one table, two textfigures and 16 figures in 4 plates) -Received for Publication, November 1, 1978-

Key Words : Floor of mouth, Artery, Corrosion cast, Comparative anatomy

Summary. The arterial distributions in the region of the floor of the mouth in the rat were studied by means of the acryl plastic injection method. 1. The region and its related tissues were supplied mainly by branches of the sublingual artery of the facial, and partly by branches of the tonsillar of the facial and branches of the ascending palatine of the lingual. 2. Branches of the sublingual artery were the submandibular lymph node branch, the muscular branches, the submental branch, the mandibular transversal branches, the mucous branch, the genioglossal branches, the preincisive branch, the retroincisive branch and the alveolar branch. 3. Branches of the tonsillar artery were the mucous branch and the mylohyoid branches. 4. A forward branch and small twigs of the ascending palatine were distributed to the posterior small part of the region. 5. Between the above-mentioned branches and the lingual artery, any marked anastomoses were not observed.

Preface structed, and that, therefore, the sufficient observation has been difficult by using It is very important to survey the the common dissection method. arterial distribution in the oral region in This paper was undertaken to reveal the rat since this animal is the most the detailed arterial distribution and commonly used in many kinds of ramification of the distributing arteries medico-dental research. Nevertheless, in the region of the floor of the mouth little has been reported on the subject. and its related tissues (except the This may be due to that the arterial tongue) in the rat, using the acryl plastic branches in the region are much smaller corrosion method. and every organs are intricately con-

45 46 H. Otsuka

between the mylohyoid and the digastric Materials and Methods where it turns the direction horizontally. 50 adult rats were used for this study. It next proceeds forward about 4 mm They were injected with colored acryl beneath the mylohyoid onto the mandi- plastic through the aorta into the arterial bular transversal (Greene) beyond the system of the head by the plastic injection anterior end of the mylohyoid, crossing method of Taniguchi et al. ('52, '55) after the digastric branch of the mylohyoid exsanguination. Most of the injected nerve lateral to it. The artery passes heads were macerated in 20% NaOH further about 3 mm long over the man- solution to make corrosion casts, and dibular transversal lateral to the genio- some of them were embalmed in 10% hyoid and reaches inferior to the posterior formalin for dissection. The observation end of a crista (incisive ridge) which was made under the binocular magnifier. lies near the anterior end of the superomedial edge of the mandibular body Observations between the originating tendon of the geniohyoid and the inner surface of the The region of the floor of the mouth mandible to become three kinds of and its related tissues are supplied mainly termini. by branches of the sublingual artery of The terminal branches are as follows : the facial, and partly by branches of the (a) Preincisive branch—Passing for- tonsillar of the facial and branches of ward or forward and downward the ascending palatine of the lingual. through the lower part of the The facial artery (Fig. 2), after its symphysis and emerging in front origin from the external carotid, runs of the lower incisors. anteroinferiorly first medial to the (b) Retroincisive branch — Ascending mandibular angle and then between the posterior to the symphysis and masseter muscle and the digastric. It emerging into the gingiva behind comes next to the level of the lower the lower incisors. border of the anterior superficial part (c) Alveolar branch—Entering a for- (Greene '68) of the masseter where it amen on the inner surface. of the swings anterosuperiorly showing a down- jaw near the posterior end of the ward arch. The artery emerges lateral incisive ridge, not reaching the to the mandibular body across the incisive portion. inferior margin of the mandible obli- (a) and (b) are commonly unilaterally quely to continue onto the face. observed either on the right or left, but (c) bilaterally. In cases in which both I. Sublingual artery of the facial of (a) and (b) exist on the same side, (c) The artery (0.30-0.45, M. 0.39 mm) is observed commonly as a branch of (Figs. 2-4) originates forward and supero- (a) or leaves posterior to the divergency medially from the superior or superomedi- from the sublingual (Fig. 5). These al wall of the facial between the lower three termini are observed in type of surfaces of the anterior superficial part several combinations in every individuals. of the masseter and of the digastric Accordingly, the following 5 types about 9 mm distal to its origin. (Type I-V) are recognized (Fig. 1). The artery passes first forward and As shown in the table, the cases in superomedially about 4 mm long between which left sublingual divides into the both muscles mentioned above and comes preincisive and retroincisive branches Arterial Distribution in Mouth Flood of Rats 47 account for 56% totally. The cases in 1. Submandibular lymph node branch (R. which the left sublingual extends as the ln. submandibularis) retroincisiue branch far to the incisive The branch (0.20-0.35, M. 0.28 mm) (figs. region are observed in 70%, being 2, 7) is the largest among branches of nearly twice more than the cases in the sublingual and is observed in 72 which the right sublingual does so. The cases of 100 halves of all examples ob- fact suggests that the sublingual artery served. The branch arises from the of the rat on the left side is much inferior or inferomedial wall of the stronger and has a wider supplying sublingual within 1.5 mm from its origin territory than that on the right side. and runs backward along the inferopo- sterior border of the masseter, crossing medial to the facial artery, to be distributed to the submandibular lymph nodes. It extends backward far to the major sublingual and parotid glands to supply part of each gland.

2. Muscular branches (Rr. musculares) They (0.10-0.25, M, 0.14 mm) (figs. 2, 3, 8), 3 or 4 in number, leave the sublingual as it travels inferior to the mylohyoid muscle. They are divided into two groups. One of them consists of 1 or 2 lateral branches which run superolaterally beneath the mylohyoid and are distributed to the lower half to third of the muscle and the middle part of the geniohyoid. The other group consists of 1 or 2 medial branches which run medially or anteromedially between the digastric ( a ) Preincisive branch and the mylohyoid and are distributed ( b ) Retroincisive branch to the anterior and middle part of the ( c ) Alveolar branch digastric and the inferomedial part of the mylohyoid. When well-developed, Table. Frequencies of appearence the branches extend as far as the of the types. mandibular transversal muscle to supply it.

3. Submental branch (R. submentalis) The branch (0.10-0.25, M. 0.20 mm) (figs. 2, 10) exists unilaterally either on the right or left side, that is, on the left in 27 cases of 50 examples observed, on the right in 20 cases. In remaining 3 cases the branch originates bilaterally and The sublingual sends the following joins each other in the median where branches in its course. one branch originates T-shapedly for-

48 H. Otsuka

Fig. 1. Schematic illustration of patterns of the terminal branches of the sublingual artery. Arterial Distribution in Mouth Floor of Rats 49

ward as the submental branch. The sublingual 1-2 mm distal to the origin branch arises from the medial wall of of the submental branch opposite the the sublingual 4-6 mm distal to its origin. anterior border of the mylohyoid. After After passing once medially or antero- the origin, they pass forward through medially between the anterior belly of the origin of the mandibular transversal the digastric and the mylohyoid as far muscle, giving several twigs to the as the anterior border of the latter, the muscle. The branches extend anteriorly branch descends vertically in the median as far as adjacent to the mental symphysis between the anterior bellies of the to supply the periosteum and the muscles digastric on both sides and emerges into in this portion. The branches release the subcutis through the platysma. additionally 2 or 3 twigs. They enter Next it proceeds forward tortuously in nutrient foramina located in a fossa for the subcutis to the chin, giving twigs the origin of the mandibular transversal to the area, to supply the skin and the muscle and bore the alveolar wall of the platysma in the submental region. The lower incisor to join the periodontal branch anastornoses with branches of the plexus (Boyer '62) which is formed inferior labial adjacent to the lower mainly by the peripheries of the inferior border of the mandible or the chin. In alveolar (fig. 9). Sometimes these twigs 2 cases of all examples observed the arise independently from the sublingual. branch is well-developed and compensates for the preincisive branch which is weak 5. Mucous branch (R. mucosus) in the cases. The branch (0.10-0.20, M. 0.15 mm) (figs. 2-5, 11-14, 16, 17), arises from the 4. Mandibular transversal branches (Rr. superior or superolateral wall of the m. trasversus mandibularis) sublingual 0.5-2.0 mm distal to the origin The branches (0.08-0.15, M, 0.13 mm) of the branches to the mandibular trans- (figs. 2, 3, 5, 8, 9, 11), 1 or 2 in number, verse muscle below the lower second originate from the inferior wall of the molar. The branch runs first forward

Fig. 2. Schematic illustration of arterial distribution in the region of the mouth . (Legends of the abbreviations are shown on p. 58) 50 H. Otsuka and superolaterally in a short distance sublingual gland giving glandular twigs and turns upward and backward, forming to it, and then reach the gingival margin a forward loop. It then runs backward opposite the lower molars through the or upward and backward, after crossing mucous membrane. They anastomose the lateral side of the submandibular here with fine alveolar twigs coming duct, in or deep to the minor sublingual upward in the periodontal membrane to gland which is located under the form a vascular network and are dis- mucosa and above the mylohyoid muscle tributed to the greater part of the lingual in the alveolingual district. In this part gingiva and mucosa in the molar portion. the branch lies 1.5-2.5 mm below the The gingival branches join one another gingival margin of the lower molars. in their course to form many upward Finally it anastomoses below the lower small loops (fig. 14). third molar with the mucous branch of the tonsillar artery coming from behind 2) Submandibular ductal branches (Rr. (in 63 cases of 90 halves) or with a for- ductuum submandibulares) ward branch of the ascending palatine The branches (0.05-0.08, M 0.06 mm) artery out of the lingual (in 27 of 90 (figs. 2, 4, 12) are 2 or 3 in number and halves). Thus the mucous branch forms arise within 2 mm distal to the origin of an upward arch in the alveolingual the mucous branch. The anteriormost district. one of them proceeds forward along the The arch shows three kinds of forms duct to supply the adjacent portion of as follows : it. Others being larger than this pass a) Taking a comparatively straight backward along the duct and are dis- course. (in 60 of 90 halves) (figs. 4, tributed to part of the duct which lies 11) on the mylohyoid muscle. b) Taking a wavy course. (in 21) (figs. 13, 17) 3) Twigs to the minor sublingual gland c) Forming a simple network partly. They (figs. 4, 14) arise richly from the (in 9) (fig. 3) arch and from the gingival branches to In 24 of 90 cases, the arch forms a supply the gland, surrounding it in a small islet (fig. 14) in its course. cage-form. From the arch, the following branches are given off : 4) A twig entering a„.foramen 1) Gingival branches (Rr. gingivales) The twig (fig. 2) leaves near the origin They (0.05-0.1, M. 0.07 mm) (figs. 2-4, of the mucous branch and ascends on 13, 14), 4 or 5 in number, leave upward the medial surface of the mandible from the superior wall of the arch. The giving 1-3 twigs to the superoanterior anteriormost one of them runs forward small part of the mylohyoid muscle, to and upward and anastomoses below the enter a minute foramen which is located gingival margin of the lower first molar on the medial surface of the mandible with a branch of the angular artery of below the first molar to be distributed the mouth, which comes over the diastema to the bone tissue in the area. of the mandible (figs. 4, 11). One or two twigs out of the anteriormost branch 6. Genioglossal branches (Rr. genioglossi) are distributed to the sublingual duct The branches (0.08-0.15, M. 0.10 mm) in this part. Other gingival branches (figs. 2, 4, 12, 17), 2 or 3 in number, ascend tortuously first in the minor originate 1-2 mm distal to the origin of Arterial Distribution in Mouth Floor of Rats 51 the mucous branch from its superior branch passes forward between the wall. They run upward and forward to genioglossus muscle and the medial be distributed to the anterior parts of surface of the mandible ; in the other the genioglossus muscle and of the sub- group it passes forward inferomedial to mandibular duct. the genioglossus and nearer the midline. In either case, the branch ascends be- 7. Preincisive branch (R. preincisivus) tween the orifices of the submandibular The branch (0.10-0.25, M. 0.15 mm) (figs. glands on both sides along the posterior 2, 4-6, 12) is observed unilaterally on the margin of the symphysis. On reaching left side in 37 of 48 examples observed, the posterior end of a small projection on the right side in 11. After its origin, located just posterior to the lower it passes forward and downward along incisor, it bifurcates in a Y-shape. Each the anterior margin of the intermandi- of them runs forward in a shallow bular ligament which stretches between groove on the projection in the lingual the anterior ends of the jaws of both gingiva, showing a lateral arch. Finally sides, under the origins of the genioglossus they reunite in the gingiva between the and the geniohyoid muscles and, passing incisors forming a vascular network to through the lower part of the symphysis, anastomose with the ascending periphery emerges in front of the symphysis where of the preincisive branch. Therefore, an it usually divides into two branches ; one arterial spindle-shaped islet is formed in running forward, the other running the lingual gingiva (figs. 15, 16). Fine backward. The former being larger than twigs ascend from the anterior end of the latter reaches the labial gingiva in the islet toward the surface of the the region of the incisors, giving several interincisive gingiva. Rarely a small branches toward both sides in the secondary islet formation is recognized gingiva, and usually anastomoses with at the spindle-shaped islet on its one the periphery of the retroincisive branch, side. In two cases in which the retro- which will be mentioned below, in the incisive branches exist bilaterally, larger gingiva between two central incisors. one forms the spindle-shaped islet and The latter, smaller, ends in the adjacent the other joins it just posterior to the tissue. The preincisive branch is distri- bifurcation. buted to the symphysis, the labial gingiva The retroincisive branch is distributed of the lower incisors and adjacent to the lingual gingiva in the region of mucosa, and muscles in the mental the incisors, the anterior portion of the region. The branch anastomoses laterally submandibular and sublingual ducts and with branches of the inferior labial the adjacent mucosa. artery and inferoposteriorly with the peripheries of the submental branch. 9. Alveolar branch (R. alveolaris) The branch (0.08-0.15, M. 0.10 mm) is 8. Retroincisive branch (R. retroinci- the smallest among the three terminal sivus) branches of the sublingual. In 32 cases This branch (0.10-0.20, M. 0.16 mm) of 100 halves of all examples observed (figs. 2-5, 12, 16) is observed unilaterally the sublingual artery continues directly on the left side in 33 of 48 examples to the alveolar branch. It enters a small observed, on the right side in 15. It may foramen which is located on the inner be divided into two groups according to surface of the mandible adjacent to the its course. In one group of them the posterior end of the incisive crest to be 52 H. Otsuka distributed to the alveolar wall of the branch is distributed to the mucosa on incisor root and to join the periodontal the lingual side posterior to the lower plexus of it. molar and its vicinity and the posterior In addition to the above-mentioned part of the mylohyoid muscle. branches, the sublingual artery sends indefinite twigs to the certain tissues 2. Mylohyoid branch (R. mylohyoideus) and the bone which lie near the course The branch (0.10-0.25, M. 0.18 mm) of the artery. Distinct anastomosis be- (figs. 2-4, 14, 17) is one of the terminal tween branches of the sublingual and branch of the tonsillar artery and larger those of the lingual is not recognized. than the mucous branch. It passes anterosuperiorly beneath the mylohyoid II. Tonsillar artery of the facial muscle in the gap bounded medially by The artery (0.25-0.35, M. 0.30 mm) (figs. the inferolateral surface of the muscle 2-6, 17) originates from the superior and laterally by the inner surface of the wall of the facial just distal to the origin mandibular body. After giving off twigs of the submandibular glandular branch to the superior part of the muscle, it medial to the point where the submandi- enters a foramen which is located on bular duct crosses medial to the facial the lingual surface of the mandibular artery. The main stem of the artery body opposite the root of the lower passes anterosuperiorly between the second molar to supply its alveolar wall. anterior margin of the lower part of the Any marked anastomosis between these medial pterygoid muscle and the posterior two branches and branches of the lingual margin of the mylohyoid and enters the artery is not observed. medial pterygoid to supply it. Among branches of the tonsillar artery the III. A forward branch and small twigs following two are distributed to the of the ascending palatine artery of region of the floor of the mouth. the lingual 1. Mucous branch (R. mucosus) In approximately 80% of all examples The branch (0.10-0.20, M. 0.15 mm) (figs. observed the ascending palatine arises 2-6, 13, 14, 17) is given off from the from the lingual ; in the remainder from superior wall of the tonsillar artery the facial or directly from the external nearly 2 mm distal to the origin of it. carotid. The branch first follows forward on the The ascending palatine is derived medial surface of the lower border of within 1 mm from the origin of the the medial pterygoid and then comes to lingual and ascends S-shapedly in the lie on the superomedial surface of the lateral wall of the fauces to the soft mylohyoid muscle beyond its posterior palate. One or two small twigs out of border. Next it proceeds forward in it run forward and downward beyond the submucosa of the alveolingual district the anterior margin of the medial ptery- and finally anastomoses with the poster- gold and are distributed to the posterior iorly running mucous branch of the sub- small part of the alveolingual district. lingual artery opposite the lower molars In 27 cases of 90 halves, one additional to join in the formation of an arterial branch (0.10-0.17, M. 0.14 mm) (figs. 2, 18) arch. Usually the branch releases a small proceeds forward beyond the anterior twig near the posterior end of the, margin of the medial pterygoid to mylohyoid to the mucosa posterior to participate in the formation of the the lower posteriormost molar. The arterial arch in place of the mucous Arterial Distribution in Mouth Floor of Rats 53 branch of the tonsillar artery. The which arises from the sublingual and branch originates from the lateral or extends in the superficial part of the anterolateral wall of the ascending submental region to the chin. palatine nearly 2 mm distal to its origin The sublingual and submental arteries at the first curve of its S-shaped course. have different sources according to After passing forward medial to the animal species. The sublingual in the middle of the medial pterygoid muscle, dog, cat and guinea pig arises from the it comes to lie superomedial to the facial, the submental from the sub- mylohyoid beyond its posterior margin lingual [Miller ('64) in the dog, HUTH- and finally anastomoses with the mucous mann ('12) in the cat and Shively ('74) branch of the sublingual to form the in the guinea pig]. Accordingly this arterial arch upward and to be distributed originating pattern may be called to the mucosa and substance in the "carnivora type" for convenience . While posterior part of the alveolingual district. the sublingual in the rabbit, goat, cattle and man arises from the lingual, the Discussion submental from the facial [Okano ('60) in the rabbit and goat, Bugge ('68) and A. Sublingual and submental arteries Craigie ('48) in the rabbit, Sato ('59) in § Origin and course the goat, Kato ('74) in the cattle and Greene ('68) described in his textbook Gray ('69) in man]. So the pattern may that the submental artery leaves the be called "human type". Accordingly the external maxillary and passes between pattern in the rat belongs to the the anterior belly of the digastricus and carnivora type. mylohyoid supplying both to reach the The course of the sublingual from the transversus mandibularis, platysma and origin itself to the origin for the sub- integument of the submental region. By mental branch in the rat is similar to the present observation Greene's sub- the submental artery seen in the rabbit, mental artery, after passing forward cattle and man. below the mylohyoid, emerges superior Greene did not describe on the present to the transversus mandibularis and author's sublingual artery coming to the proceeds as far as the incisive region as floor of the mouth, but he illustrated a the principal vessel of the region of the branch out of the sublingual coming floor of the mouth. onto the transversus mandibularis muscle. In reviewing previous reports, it is This branch, indeed, is the main trunk evident that the artery which is dis- of the sublingual artery. tributed to the region of the floor of the According to Bugge's description and mouth, the musculature and substance in figure, there are some close similarities the region has been termed "sublingual" in the branching feature and course of artery whatever may arise, and that the sublingual between the rabbit and submental artery is considered to pass rat. Besides he described that the sub- superficially forward inferior to the lingual artery on one side continues for- mylohyoid muscle as far as the subment- ward through the symphysis to the al region, without coming onto the facial gingiva opposite the lower incisor. muscle. Therefore, that artery to the This anterior part of the sublingual ap- floor of the mouth should be termed pears to correspond to the preincisive "sublingual" artery , while the name branch of the rat. "submental" should be given to a branch It is interesting that the terminal 54 H. Otsuka

branch of the sublingual exists unilate- In Greene's publication he illustrated rally either on the right or left in the a branch corresponding to the present rabbit as well as in the rat. author's submandibular lymph node Yoshimura ('59) stated in human fetus branch, but did not describe on it. that the sublingual artery enters the The present study revealed that some bone tissue at the lower border of the branches of the sublingual and tonsillar lingual surface of the mandible to ana- enter the mandible through foramina on stomose with the inferior alveolar and its lingual surface and are distributed to supply the region of the anterior to the adjacent bone tissue. Huelke et teeth. This seems to correspond to the al. ('65) in a report on the blood supply alveolar branch in the present study. to the rat mandible, did not mention Fukuoka ('46) mentioned in man that such branches entering the bone. the lower alveolar mucosa on the lingual Miyata et al. ('65) stated in the guinea side is supplied by both the sublingual pig that a branch of the submental (the and submental arteries ; the mucosa on present author's sublingual artery) is the labial side merely by the submental. distributed to the submandibular lymph By the present observation the mucosa nodes in about half cases of all examples on both sides are supplied merely by the observed. In the rat the lymph nodes sublingual. Though by Hanai et al. ('75) are supplied in 72 cases of 100 examples the anterior periphery of the sublingual by the lymph node branch out of the in the crab-eating monkey is well- sublingual ; in remaining cases by a developed and extends to the lower lip branch of the facial. through the symphysis as the median The submental artery in man is bilate- inferior labial artery, and, however, in rally observed, however, the submental the rat the periphery of the sublingual branch in the rat arises commonly does not extend beyond the labial gingiva unilaterally. or the incisive region. Findings by Hanai et al. agree with the present study B. Tonsillar artery in that the periphery of the sublingual Greene described that the • name is recognized unilaterally and exists "tonsillar branch" has been retained for more on the left than on the right. this artery since its course and distribu- Hamano ('64) found in man that the tion correspond to those of the same sublingual artery which arises from the artery in man. The present author wishes lingual is lacked in 40--,50% and that in to term it "tonsillar" artery likewise, such cases one well developed branch as there is no reason to reject the term. out of the submental artery comes to Among branches of the tonsillar, two the sublingual region through the kinds of branches which is related to mylohyoid muscle to supply the region. the floor of the mouth and which Greene The present author considers such an has failed to describe, were recognized, abnormal submental artery to be identical that is, the mucous and the mylohyoid with the normally appeared sublingual branch. He, however, did not mention artery in the rat. about these branches, nor about that the artery contributes to the blood § Branches supply of the floor of the mouth. No detailed description on branches of Greene stated that the mylohyoid the sublingual and their nomenclature muscle is supplied by the sublingual in the rat have been seen previously. branch of the lingual artery and the Arterial Distribution in Mouth Floor of Rats 55 submental branch (sublingual artery by 4) Fukuoka, R.: On the vascular system of the present author). However, by the the mandible. J. Dent. 3 : 34-43, 1946. (in Japanese) present study the mylohyoid branch of the tonsillar is one of the major supply 5) Gray, H.: Gray's anatomy. 33rd Ed., London, 782-791, 1964. of the muscle in cooperation with the 6) Greene, E.C. : Anatomy of the rat. musclar brances of the sublingual and Hafner Publ. Co., N.Y., 31-253, 1968. the twigs from the mucous branch. 7) Hamano, F.: Studies on the blood vessels of the salivary glands of the human C. Ascending palatine artery fetus. 1. The nutrient arteries of the Greene described that the ascending salivary glands. J. Tokyo Dent. Coll. palatine artery in the rat may arise Soc., 65: 22-77, 1965. (in Japanese) from the external carotid artery with 8) Hanai, H., T. Hanai, H. Otsuka & A. the lingual or as a separate branch from Yamanaka : The arterial distribution of the external carotid. Wakida et al. ('74) the lips in the crab-eating monkey by also in the rat found the artery to plastic injection method. Okajimas Fol. originate from the lingual in 16 cases of anat. jap., 52: 85-102, 1975. 35 examples. However, the present 9) Huelke, D.F. & W.A. Castelli : The blood supply of the rat mandible. Anat. author recognized the ascending palatine Rec., 153: 335-343, 1965. to arise in nearly 80% from the lingual 10) Hiirlimann, R.: Die arteriellen Kopf- near its origin. It was observed that in gefasse der Katze. Intern. Mschr. Anat., 27 cases of 90 examples observed, a 29: 391-400, 1912. branch originating from the ascending 11) -Kato, Y.: Atlas of the comparative palatine near its origin extends forward anatomy of domestic animals. Yokendo as far as the mucosa in the alveolingual Publ. Co., Tokyo, 438-441, 1974. (in district and anastomoses with the mucous Japanese) branch of the sublingual to from an 12) Miller, M.E., G.C. Christensen & H.E. arterial arch and to supply the mucosa Evans : Anatomy of the dog. Saunders in the posterior part of the alveolingual Co. Phila., 288-300, 1964. 13) Miyata, T., K. Kamakura & S. Kaneko : district. Greene described neither such Distributing arterial branches of the sub- a branch nor such an arterial arch. mandibular lymph nodes in guinea pig. Okajimas Fol. anat. jap., 41: 221-225, Acknowledgement 1965. 14) Okano, H.: On the ramification of A. The author should like to express his lingualis and its fine distribution in some thanks to Professor H. Hanai for guid- mammals. Okajimas Fol. anat. jap., 34 : ance and encouragement shown to him. 233-297, 1960. 15) Sato, M.: The blood supply of the goat References mandible and teeth. J. Kurume Med. Assoc., 22 : 3497-3517, 1959. (in Japanese) 1) Boyer, C.C. & C.M. Neptune : Patterns 16) Shively, M.J. & J.E. Stump : The sys- of blood supply to teeth and adjacent temic arterial pattern of the guinea pig : tissues; J. Dent. Res. 41 : 158-171, 1962. The head, thorax, and thoracic limb. 2) Bugge, J.: The arterial supply of the Am. J. Anat., 139: 269-284, 1974. rabbit nose and oral cavity. Acta Anat. 17) Taniguchi. Y., Y. Ohta & S. Tajiri : 70: 168-183, 1968. New improved method for injection of 3) Craigie, E.H. : Bensley's practical ana- acrylic resin. Okajimas Fol. anat. jap., tomy of the rabbit. 8th Ed., Phila., 292- 24: 259-267, 1951. 295, 1948. 18) Taniguchi, Y., Y. Ohta, S. Tajiri, H. 56 H. Otsuka

Okano & H. Hanai : Supplement to new branches in the rat. Bull. Josai Dent. improved method for injection of acrylic Univ., 3: 13-18, 1974. (in Japanese) resin. Okajimas Fol. anat. jap., 21: 401- 20) Yoshimura, K.: Studies on the blood 406, 1955. supply of the mandible in the human 19) Wakida, T., H. Hanai & H. Otsuka : On fetus. J. Kurume Med. Assoc., 22 : 3497- the external carotid artery and its 3517, 1959. (in Japanese) Arterial Distribution in Mouth Floor of Rats 57

PLATES 頓 ◎o

Explanation of Figures

Plate I

Figs. 3-6. Medial aspect of the lower jaw. Key to Abbreviations for Figs. 2-18. Fig. 3. The right side. General course of the distributing arteries D: M. digastricus gg : Genioglossal branches of the floor of the mouth is seen. The sublingual artery Gg : M. genioglossus 1: Submandibular lymph arisen from the facial passes forward as far as the behind of In : Lower incisor node branch the lower incisors, ending as the retroincisive branch. The LD : Sublingual duct : Lingual artery tonsillar artery arises from the facial posterior to the origin LY : Submandibular lymph node m1 : Mucous branch of the of the sublingual and passes forward and upward. The M: M. mylohyoideus sublingual tonsillar sends off the mucous branch and the mylohyoid MD : Submandibular duct m2 : Mucous branch of the branch ; the former anastomosing with the mucous branch P: M. pterygoideus medialis tonsillar S : Symphysis mh : Mylohyoid branch of the sublingual and the latter supplying the mylohyoid 幽} muscle. ca. x 3. 5 SLa : Major sublingual gland mt : Mandibular transversal 辱 )( SLi : Minor sublingual gland branch けの SM : Submandibular gland mu : Muscular branches 賃 Fig. 4. The right side. The sublingual shows Type I. The mucous 閑 branches of the sublingual and tonsillar anastomose with each T: M. transversus pi : Preincisive branch 笛 other in the alveolingual district to form an arterial arch mandibularis ri : Retroincisive branch ( ), showing a fairly straight couse. The arch sends off a: Arterial arch sd : Submandibular ductal the submandibular ductal branches, the gingival branches al : Alveolar branch branches taking a zigzag course, and twigs to the minor sublingual an : Angular artery of the sl : Sublingual artery gland. ca. x 4. 3 mouth sm : Submental branch ap : Ascending palatine artery sp : Spindle-shaped islet Fig. 5. The left side. The arterial arch is formed superior to ec : External carotid artery t: Tonsillar artery the mylohyoid muscle. The sublingual shows Type II and f: Facial artery tf : Twig of mucous branch the alveolar branch leaves the sublingual posterior to the fo : Forward branch of the entering a foramen divergency (/) of it. The preincisive branch reaches the ascending palatine artery ts : Twigs to the minor labial gingiva in the incisive region. ca. x3.5 g: Gingival branches sublingual gland Fig. 6. The right side. The sublingual shows Type III. The alveolar branch enters a small foramen on the inner surface of the mandible. ca. x3 59

Plate I

H. Otsuka 60 H. Otsuka

Plate II

Fig. 7. Medial aspect.

Figs. 8-10. Inferior aspect of the submental region.

Fig. 7. The right side. Medial aspect of the origin of the sublingual. Its first branch, the submandibular lymph node branch, arises near the origin of the sublingual and runs posteriorly to the submandibular lymph nodes. ca. x7

Fig. 8. The medial branches of the muscular branches supply the mylohyoid muscle. ca. x 5. 5

Fig. 9. Some of branches (\) of the mandibular transversal branches supplies the same named muscle and others enter the alveolar bone to join the periodontal plexus (\,). ca. x 20

Fig. 10. The submental branch is commonly observed on either side. In this example it originates from the left sublingual. It passes first anteromedially, turning anteriorly near the median, and next it runs anteriorly to the chin where it anastomoses with branches of the inferior labial ( ). ca. x 5. 5 61

Plate 11

H. Otsuka ゆ悼

Plate III

Figs. 11-14. Medial aspect of the lower jaw.

Fig. 11. The right side. The arterial arch showing a straight course sends off gingival branches, the anteriormost of which anastomoses with a branch of the angular artery of the mouth below the first molar ( ). The mandibular transversal branches enter the = bone through foramina located in a fossa for the origin of the mandibular transverse 雛 ( muscle. ca. x4.3 ) け m 露 Fig. 12. The left side. The origins of the mucous branch and the genioglossal branch are ズ麟 seen. The preincisive branch passes inferoanteriory through the symphysis. ca. x5.6

Fig. 13. The right side. The gingival branches arcend in a zigzag course from the arch which shows a wavy course. ca. x6

Fig. 14. The right side. The gingival branches form many upward small loops (fl with their twigs. The arterial arch forms a small islet in its course (1, ). Twigs to the minor sublingual gland are seen. ca. x8 63

Plate III

H. Otsuka 忠

、

Plate IV

Fig. 15. Supprior aspect of the incisive region.

Figs. 16-18. Medial aspect of the lower jaw.

Fig. 15. Superior aspect. The retroincisive branch on either side divides into two (/) and reunites (*--) between the lower incisors to form a spindle-shaped islet behind the = . incisors. ca. x 10 O g Fig. 16. The left side. The retroincisive branch and its islet formation (t ). ca. x5.6 奏餌 Fig. 17. The right side. The tonsillar artery sends the mucous and mylohyoid branches. The former forms the arch joinning with the mucous branch of the sublingual ; the latter passes under the mylohyoid muscle to supply it. ca. x8

Fig. 18. The left side. In 27 cases of 90 examples observed the ascending palatine sends a forward branch whlich anastomoses with the mucous branch of the sublingual, in place of the mucous branch of the tonsillar which is absent in these cases. ca. x3 65

Plate IV

H. Otsuka