650 



ARTERIA INNOMINATA. 



more particularly the point of division of the 

 vessel,* which will also correspond nearly to the 

 centre of a line drawn from the anterior superior 

 spinous process of the ilium to the umbilicus.f 



The practicability and success of these ope- 

 rations have been so long established that they 

 do not now require to be insisted upon. 



When the external iliac has been tied below 

 the origin of the epigastric and circumflex ilii 

 branches, the circulation of the limb is main- 

 tained through the communications of the 

 branches of the internal iliac with those of the 

 femoral, of which the principal have been 

 ascertained by Sir A. Cooper]: to be the gluteal 

 with the external circumflex, the obturator with 

 the internal circumflex, and the ischiatic with the 

 profunda, and through those of the circumflex 

 iliac with the same. (See FEMORAL ARTERY.) 

 When the ligature has been applied above the 

 origin of these branches, the circulation is esta- 

 blished also through their communications with 

 the internal iliac, the internal mammary, the 

 inferior intercostal and lumbar arteries. 



The ligature of the internal iliac artery can 

 cause little interruption of the supply of blood 

 to the parts to which it is distributed ; its com- 

 munications are so numerous and free, exter- 

 nally and inferiorly with the external iliac and 

 femoral arteries ; inward with that of the other 

 side, and upward with the aorta through the 

 middle sacral and hemorrhoidal arteries, that 

 the obstruction of the main trunk can affect it 

 but little. 



When the primitive iliac has been tied the 

 circulation must be restored by means of the 

 communication which exists between the arte- 

 ries of the upper and lower extremities through 

 the internal mammary and epigastric arteries, 

 of that between the aorta and the iliac arteries, 

 through the intercostal, lumbar, middle sacral, 

 hemorrhoidal, and the branches of the latter, and 

 of that between the iliac arteries of both sides. 



For BIBLIOGRAPHY, see ANATOMY and ARTERY. 

 ( B. Alcock.) 



ARTERIA INNOMINATA, (in human 

 anatomy) Fr. Tronc brachio-ccphalique. 



The innominata or brachio-cephalic artery is 

 situated to the anterior and right side of the 

 thorax, extending from the arch of the aorta to 

 the sterno-clavicular articulation. 



Of the three large vessels proceeding from 

 the arch of the aorta, the innominata is the 

 most anterior, the shortest, but of the largest 

 calibre ; it takes its origin at a point corres- 

 ponding and very nearly parallel to, the upper 

 edge of the cartilage of the second rib almost 

 immediately from that part of the arch of the 

 aorta where it alters its direction from the right 

 towards the left side, or rather from the com- 

 mencement of what is termed the transverse 

 portion of the arch, and hence the cause of its 

 being at this point not only to the right side 

 but also anterior and rather superior to the 

 other two, which arise from the remainder of 



* Guthrie. 



t Harrison. 



t Medico-Chirurgical Transactions, vol. iv. 



the transverse division of the arch, the left 

 carotid and subclavian arteries. It imme- 

 diately ascends obliquely upwards, outwards, 

 and very slightly backwards, to opposite the 

 right sterno-clavicular articulation, where it 

 divides into the right sub-clavian and carotid 

 arteries, the latter of which, although the smal- 

 lest in diameter, appears from direction to be 

 its continuation. The innominata, therefore, 

 is but a short trunk, rarely exceeding from an 

 inch and a half to two inches in length. Ne- 

 vertheless instances are upon record in which 

 it has attained above two inches and a half; 

 but these may be considered more in the light 

 of anomalies than regular occurrences. 



We now proceed to consider the various re- 

 lations which this vessel bears to the several 

 important organs in its neighbourhood, and we 

 shall then the more readily be able to account 

 for the many distressing symptoms usually 

 accompanying its enlargement. At its origin, 

 it lies upon the trachea and at its division cor- 

 responds, although at a considerable distance, 

 to the longus colli muscle separated from it by 

 glands and cellular tissue. Internally, or on 

 its left side from below upwards, are the com- 

 mencement of the left carotid artery and the 

 trachea, the latter, however, lying upon a plane 

 posterior to the artery, a quantity of cellular 

 tissue and glands being usually met with 

 between them. Externally or to its right 

 the relations are more complicated and consist 

 of parts of very great importance. It is here 

 connected to the right pleura and the middle 

 and inferior cardiac branches of the great sym- 

 pathetic nerve; the internal jugular vein lies 

 above it and on its right side, whilst the right 

 brachio-cephalic vein is to its right but some- 

 what anterior. Behind this vein and crossing 

 the subclavian artery at right angles very close 

 to its origin, we find the pneumo-gastric nerve 

 entering the thorax and giving back its recur- 

 rent branch which winds round the subclavian 

 artery; still more externally is the phrenic 

 nerve conducted into the thorax upon the an- 

 terior border of the anterior scalenus muscle, 

 and between the two latter the internal mam- 

 mary branch of the subclavian artery. The 

 parts covering the vessel are studied with 

 greatest advantage from the integuments back- 

 wards ; and the best method of effecting this is 

 as follows, as it enables us at the same time to 

 take a clear view of the attachment of the 

 various layers of the cervical fascia to the first 

 bone of the sternum and the inter-clavicular 

 ligament. 



Having placed the subject with a block 

 underneath the shoulders, and the head hanging 

 down, thus drawing the vessel as much as 

 possible out of the thorax, carry an incision 

 of about five inches upwards, commencing at 

 the middle of the sternum opposite the carti- 

 lage of the second rib. Through this incision 

 carry another of the same length at right angles, 

 commencing at the left sterno-clavicular arti- 

 culation, and extending along the right clavicle 

 as far as its centre. This crucial incision 

 should merely divide the skin, the triangular 

 flaps of which are next to be raised and re- 



