Arteries of the Trunk. 



419 



Ramus posterior ^ ; Ramus spinalis 



N. lumbalis II 



M. sacrospinalis 



Processus 

 transversus 



vertebrae " 

 lumbalis III 



M. inter- 



traiisversarius- 



lateralis 



Aorta 

 abdomiiialis 



.A. meseuterica 

 inferior 



462. Branches of the arteriae lumbales dextrae. 



(A piece of the himbar spine with its mnscles, viewed from the right and somewhat from above.) 



A. Eanii riscerales: 1. Aa. broucliiales (see Fig. 461), 23, from the anterior wall 

 of the first part of the vessel, very frequently (especially on the right side) from the a. inter- 

 costalis in. They go forward to the right and left bronchus and along with these into the lungs. 



2. Aa. oesophageae (not illustrated), 3 7, from the anterior wall at different levels, for- 

 ward and ti) the right to the oi^sophagus ; the lowermost anastomoses with the a. gastrica sinistra. 



3. Rami pericardiaci (not illustrated), delicate, to the posterior wall of the pericardium. 



4. Rami inediastiuales (not illustrated), arising partly in common with the preceding, 

 slender, going to the contents of the spatium mediastinale posterius; the lowermost spread 

 out also upon the pars lumbalis of the diaphragm as the aa. phrenicae xuperiorcs (not illustrated). 



B. Rami parietales: Aa. intercostales (see also Fig. 461), fi-om the posterior wall 

 of the vessel, ten on each side for the 3^3 lltii intercostal space and the lower margin of 

 12^11 rib. The upper arteries run upward in a recurrent direction, the lower ones more horizon- 

 tally; those on the right side are the longer. All of them lie upon the lig. longitudinale anterius, 

 behind the n. sympathicus and behind the v. azygos or hemiazygos, the right also behind the 

 oesophagus and behind the ductus thoracicus. Each arrives at the lower margin of a capitulum 

 costae and there divides. 



a) Ramus posterior gives off a ramus spinalis, which goes through the foramen inter- 



vertebrale into the canalis vertebralis to the spinal cord and its surroundings. It 

 then goes backward, medianward from the lig. costotransversarium anterius, gives off 

 ra)ni miisculares, and divides into two branches. One of these runs between the 

 mm. semispinalis and longissimus, appears between two procc. spinosi and turns lateral- 

 ward to the skin (ramus cutaneus medialis) ; the other lies between the mm. longis- 

 simus and iliocostalis and goes often (especially in the lower segments) also to the 

 skin (ramus cutaneus lateralis). 



b) Ramus anterior runs forward in the spatium intercostale beneath the v. intercostalis 



(see p. 455), at first covered only by the fascia endothoracica and the pleura, then 

 also by the mm. intercostales interni or the m. subcostalis; it gives off a branch to 

 the upper margin of the next lower rib and also many rami miisculares. In front 

 it anastomoses with the corresponding ramus intercostalis of the a. mamraaria interna. 

 In the region of the digitations of origin of the m. obliquus abdominis e.xternus 

 rami cutanei laterales [pectorales et abdominalesj (not illustrated) go, some back- 

 ward (ramus posterior) to the lateral, some forward (ramus anterior) to the anterior 

 wall of the trunk : small rami mammarii laterales go from the latter to the mammary 

 gland. Only in the 4th 6''! intercostal space, as a rule, small branches pass to the 

 skin medial from the nipple (raini cutanei anteriores [pectorales et abdominalesj) 

 (not illustrated) and some to the mammary gland (rami mammarii mediales). 



