Summary: We examined the entire array of branches and the state of ramification of each branch of 144 subclavian arteries (Su) in 72 Japanese adults, and obtained the following findings.(1) The incidence of Type I -A(1) was 13.2%, the highest among the entire Su ramification. This was followed by Type I -B(1) at 9.0%, then Type I -A(2) at 6.9%, indicating considerable variation in the morphology of Su ramification. (2) Ontogenetic factors were implicated because of the existence of cases in which Su traversed the scalenus anterior muscle anteriorly (Type III : 0.7%), or was transfixed (0.7%). (3) Type 1-c was the form of thyrocervical trunk (Tic) observed with the highest incidence of 31.3%. In addition, inferior thyroid artery, and those in which another branch was included in this common trunk: 88.9%) be called Ttc.(4) The most common type of transverse cervical artery (Tc), which is formed from a common trunk consisting of highest incidence of 61.8%. Some of the superficial branches to the upper portion of the trapezius muscle that were independently from Su. We concluded that the sites at which Tc and Ss originate are the positions at which they traverse the brachial plexus (superior, transfixed to the plexus). (6) In cases in which the supreme intercostal artery (Is) and the deep cervical artery (Cp) were separate, (Types d-i excluding Type g: 31.9%), Is branched from a more proximal position than Cp.Formation of the human subclavian artery to an almost adult condition occurs in about 7 weeks of embryonic development.5, 6, 10, 26) There have been numerous reports of substantial individual and racial differences in the position of arterial branches and the nature of their ramifications as a result of various factors that have an influence on morphosis.7, 12, 13, 17, 21, 27, 29, 33, 35, 44) However, there are almost no reports of studies that have attempted to characterize and classify the ramification and positions of the entire array of branches arising from the subclavian artery. The only relevant reports in Japan were those by Adachi (28)1) and Ouchi ('63)3°), who described the subclavian artery ramification in Japanese adults, and that by Mori (P41)28), who described Japanese fetuses. However, these reports did not explain the entire subclavian artery ramification, nor determined the most common type of ramification or its incidence among the Japanese population.With recent increase in the use of CT, MRI and angiography, it has been pointed out that an accurate understanding of the morphology of the normal subclavian artery32) and detailed information about the ramification and course of arteries that branch from the subclavian artery12. 22) are essential prerequisites for accurate diagnosis by these techniques of pathogenic changes in the upper limbs. Furthermore, sternocleidomastoid muscle and trapezius muscle are frequently used as a musculocutaneous flap in reconstructive surgery, but despite the fact that the nutrient artery which supplies these muscles is a branch of the subclavian artery, reports ...

In the following, we report our findings obtained as a result of injecting an acrylic pigment in the arteries supplying the pectoralis minor muscle in 50 lateral chests of 26 Japanese adults (15 males and 11 females). In the pectoralis minor muscle, the muscular bundle near the terminal is supplied by A. processus coracoideris (Pc, Sato-Takafuji, '85) or A. coracobrachialis (Cb, Sato, '80) of A. axillaris (Ax), while its middle upper and lower peripherals are supplied by A. thoracoacromialis (Ta) and A. partis abdominalis (Pab, Sato, '76), respectively. Further, the upper and lower peripherals at its origin are supplied by A. thoracica suprema (Ts) and A. thoracica lateralis (Tl), respectively. Pc, Cb, Pab and Ts may occasionally be absent. Arteries supplying this muscle are classified according to their origins and routes of distribution, as follows. Type I-a: Pc or Cb, Ta, Pab, Ts and Tl are present, 32%; Type II-a: Ts is absent from Type I-a, 14%; Type III-a: Pb and Pc are absent from Type I-a, 20%; Type IV-a: Cb, Pc and Ts are absent from Type I-a, 10%. Type b is Type a without Pab. The rates of appearance of Type I-b, II-b, III-b and IV-b were all 6%. The ratios of distribution in area a were as follows, in order of decreasing ratio: 37.6% for Pab (37 cases), 32.4% for Tl (49 cases), 30.2% for Ta (49 cases), 10.8% for Ts (32 cases), 7% for Cb (9 cases), and 6.37% for Pc. In the pectoralis minor muscle, the major supplying arteries are Pab, Tl and Ta, and where Pab was absent, this was compensated for by a branch of Ta. The total number of supplying arteries in this muscle was two to five, with the majority, or 36%, having four arteries. As for sex differences in the incidence of each type, Type I-a appeared more often in males (40%) than in females (20%). The rates according to the ribs of origin were 46%, 36%, 16%, and 2% for types 2.3.4.5, 3.4.5, 2.3.4, and 2.3.4.5.6, respectively. It was interesting that all Type II and Type IV cases without Ts corresponded to Type 3.4.5 without the muscular bundle arising from the second rib, as it suggests the process of degeneration of the pectoralis minor muscle in Homo.(ABSTRACT TRUNCATED AT 400 WORDS)

In 1976, the authors reported that the abdominal part artery (Pab) supplying the abdominal part of the pectoralis major muscle usually originates from the axillary artery (Ax). The findings in the present study show that the type of origin of this artery most frequently encountered is type 2-a (44.0%) in which the Pab, as an independent branch (type a), branches out of the second part of the Ax (type 2). The second and third most frequently encountered types are type 2-b (17.0%), where the Pab has a common trunk with the thoracoacromial artery, and type 2-c (10.0%), where it has a common trunk with the lateral thoracic artery. By classification according to the supplying areas, 67% was type I-B, supplying the lower part of the pectoralis minor muscle and the abdominal part of the muscle. In 5% the branch as type I-A courses down to the sternocostal part. In most cases (types A and B in 91%), this artery originates from the Ax proximal to the ansa mediana of the brachial plexus; however, in 4% providing the superficial brachial artery, the Pab branches out from the superficial brachial artery. Based on those findings, the authors would propose that the artery be named the arteria partis abdominalis or Pab.

The distribution of the arterial supply and innervation of skeletal muscle in the whole human body has been being researched in our laboratory. The results obtained on the biceps brachii from 25 bodies (50 sides) are reported here. Generally, in this muscle, A. coracobrachialis (Cb, SATO, 1980), a branch of A. axillaris (Ax), is distributed at the upper muscle bundles of the short head after running parallel to N. musculocutaneus (Nmc) and supplying M. coracobrachialis. The main artery (Ma), which is a branch of A. brachialis (Br), is distributed at the upper and middle parts of both heads, and the point where Ma enters the muscle bundles almost coincides with the point where R. brachialis (Rb) branches from Nmc. R. biceps brachii (Rbi), which is distributed only at this muscle and Om, the common trunk to other muscles, is distributed at the lower part of the muscle bundles. The arterial supply of this muscle was classified as follows according to the conditions of origin and its distribution. Type I: Ax(Cb) was distributed to the upper part of the muscle bundle. Type II: The absence of Ax(Cb) in the upper part of the muscle bundle. Type A, a and 1: Ma.Br(Om) supplying the long, short and both heads of the biceps brachii. Type B, b and 2: Ma.Br(Rbi) supplying the long, short and both heads of the biceps brachii. In the long head, Type II-A accounted for 62.0%, Type II-B for 30.0%. In the short head, Type I-a was 62.0%, Type I-b 28.0%. In both heads, Type I-1 was 62.0%, Type I-2 28.0%. There were significant differences in the distribution of the nutrient arteries between the long and short heads. A. brachialis superficialis (Bs) was recognized in 3 of these cases (2 cases of Type III and 1 case of Type VII by Adachi's classifications), which were rare cases. In these cases, arterial branches other than Cb branching from A. brachialis profunda are branches of Bs. This means, judging from ontogeny, that Bs, the blood vessels in the superficial layer, supplies this muscle, which belongs to the superficial layer of the brachium.