the use of transradial ( tr ) access for coronary intevention has been associated with lower rates of vascular complications , including reduced bleeding181011 ) , reduced mortality91315 ) , earlier ambulation5 ) , and improved patient satisfaction6 ) compared with transfemoral catheterization ( tfc ) . in addition , early mobilization is another key advantage , especially in older patients2 ) . the diameter of the radial artery ( ra ) is significantly smaller than that of the femoral artery ( fa ) , and transradial catherization ( trc ) can be more challenging due to anatomical issues and tortuosities in the vasculature . this may limit the ability to adopt a radial approach in patients with severe systemic atherosclerosis or in those with concomitant femoral artery stenosis . because there are limited data on the use of trc in neurointerventional surgery , the aim of this study was to understand the anatomic characteristics of the ra , brachial ( bra ) , and subclavian arteries ( sca ) and their branches to facilitate the safe use of a transradial neuroendovascular approach . as the use of this approach to evaluating and treating non - coronary vascular disorders is quite rare , our data may help to build a foundation for performing neurointerventional surgery . this will be especially beneficial for a vertebral approach using radial and brachial routes , because there are no other direct pathways to the vertebral artery . the study was performed with 10 formalin - fixed korean adult cadavers , nine male and one female , with a mean age of 67.3 years ( range : 2887 years ) . the specimens , which were obtained from the anatomical department of our university , were placed in a supine position , the upper limbs were abducted to 90 , and their elbow and wrist joints were extended to straighten the arteries . both of the upper limbs of each cadaver were dissected from the axillary region down to the hand including the arm , cubital fossa , forearm , wrist , and palmar areas . the skin and fasciae of the dissected regions were incised and reflected to expose the deep structures . both the pectoralis major and minor muscles were dissected to expose the axillary vessels and branches of the brachial plexus . the biceps muscle was also retracted laterally to follow the course and branching pattern of the axillary and brachial arteries and their surrounding nerves . the course and the branches of the ra in the forearm and palm were carefully dissected , and their morphology and variations were recorded . in addition , any variant in course , distribution , or branching patterns was measured . the landmarks used for measurement were anatomical points on the radial styloid process ( rsp ) , the medial epicondyle of the humerus ( me ) ( fig . 1a , b ) , the sternoclavicular joint ( scj ) , and the vertebral artery orifice ( vao ) ( fig . vascular diameters were also studied in radial artery puncture site ( raps ) , the bra puncture site ( braps ) , the axillary artery at the humerus head ( aa ) , the subclavian artery ( sca ) at the va bifurcation , and the vao . the distances from the rsp to the raps and median nerve ( mn ) and from the me to the mn and braps were measured ( fig . the same measurements were made between the scj and the vao at the shoulder level . in addition , the average angle between the vao and the sca was measured ( fig . there were no bilateral length differences between the raps and the brab ( 206.9719.84 mm vs. 209.3611.76 mm , p>0.05 ) and vao ( 566.5042.61 mm vs. 564.8955.73 mm , p>0.05 ) . the length of the ra between the raps and the vao was also studied ( 565.6948.13 mm ) , and no bilateral differences were found . the average length between the radial styloid process ( rsp ) and the raps was 13.412.19 mm , and the rsp was 26.852.47 mm from the mn . the mean length between the medial epicondyle ( me ) and the bra puncture site ( braps ) was 44.235.47 mm . the mean distance between the me and the mn was 42.234.77 mm , and the mn was located about 2 mm to the medial of the braps ( table 1 ) . the mean length between the braps and the brab was 33.257.38 mm , whereas the mean length between the braps and vao was 327.9740.14 mm . the mean length between the braps and the brab was 33.257.38 mm , whiereas the mean length from the braps to the vao was 327.9740.14 mm . the mean diameters of the ra ( 1.770.48 mm ) , bra ( 3.190.75 mm ) , aa ( 4.790.97 mm ) , sca ( 6.441.53 mm ) , and vao ( 2.931.02 mm ) were also measured . the diameters of the ra , bra , aa , sca , and vao did n't significantly differ between sides ( p>0.005 ) . no palmar arch ( 78% vs. 78% , p<0.05 ) or thyrocervical trunk ( with an average number of 2.500.61 ) anatomical differences were found between right and left sides ( 2.220.44 vs. 2.780.66 , p>0.05 ) . the average vao - to - sca angle ( 70.946.12),and the median length between the scj and the vao ( 60.308.48 mm ) were also calculated and they were also similar on both sides ( p<0.05 ) . there were no bilateral length differences between the raps and the brab ( 206.9719.84 mm vs. 209.3611.76 mm , p>0.05 ) and vao ( 566.5042.61 mm vs. 564.8955.73 mm , p>0.05 ) . the length of the ra between the raps and the vao was also studied ( 565.6948.13 mm ) , and no bilateral differences were found . the average length between the radial styloid process ( rsp ) and the raps was 13.412.19 mm , and the rsp was 26.852.47 mm from the mn . the mean length between the medial epicondyle ( me ) and the bra puncture site ( braps ) was 44.235.47 mm . the mean distance between the me and the mn was 42.234.77 mm , and the mn was located about 2 mm to the medial of the braps ( table 1 ) . the mean length between the braps and the brab was 33.257.38 mm , whereas the mean length between the braps and vao was 327.9740.14 mm . the mean length between the braps and the brab was 33.257.38 mm , whiereas the mean length from the braps to the vao was 327.9740.14 mm . the mean diameters of the ra ( 1.770.48 mm ) , bra ( 3.190.75 mm ) , aa ( 4.790.97 mm ) , sca ( 6.441.53 mm ) , and vao ( 2.931.02 mm ) were also measured . the diameters of the ra , bra , aa , sca , and vao did n't significantly differ between sides ( p>0.005 ) . no palmar arch ( 78% vs. 78% , p<0.05 ) or thyrocervical trunk ( with an average number of 2.500.61 ) anatomical differences were found between right and left sides ( 2.220.44 vs. 2.780.66 , p>0.05 ) . the average vao - to - sca angle ( 70.946.12),and the median length between the scj and the vao ( 60.308.48 mm ) were also calculated and they were also similar on both sides ( p<0.05 ) . this study investigated the anatomical basis of the ra , bra , and sca in the korean population to determine an optimal direction and configuration and to reduce complications when a transradial approach to neurointerventional surgery is adopted . the major branch of the axillary artery becomes the bra at the distal border of the teres major tendon . the bra ends close to the distal elbow joint at the neck of the radius by dividing into the radial and ulnar arteries4 ) . the bra frequently divides more proximally and may also trifurcate into radial , ulnar , and common interosseous arteries . such variations are related to the termination of a short segment the bra , which may occasionally divide into two trunks in the proximal segment , which may then reunite4 ) . ectodermal - mesenchymal interactions and extracellular matrix components within the developing limb bud interact with inductive factors in the mesenchyme3 ) . in anatomical - based studies , high ra origin was the most common arterial variation in the upper limb , and its incidence varied from 4.17% to 15.6% in cadavers and embryos12 ) . however , there were differences between races : an axillary ra origin was seen in 5% of africans but in only 2.7% of caucasians7 ) . the incidence of high - origin ra varied from 5.9% to 12.1% among caucasians , but it was lower in korean cadavers , at only 2.3%17 ) . however , in singaporean chinese cadavers , high - origin ra was found in even fewer patients , with only a 0.33% prevalence18 ) . although the differences in the ra origin among races have no clear explanation , racial differences are of great importance in clinical practice . although it involved a small number of cadavers , this study did not detect high - origin ra . although the incidence of high - origin ra is relatively low in koreans , such anatomic variations may cause transradial cathetherization failure . therefore , this should be considered during any interventional , cardiac , or vascular manipulations . in this study , all subjects were adult cadavers with a mean age of 63.7 years ; however , our subjects were mainly male ( 90% ) , and height and weight could not be measured . however , the lengths , angles , and vascular diameters did not differ between the sides of the 10 cadavers . the number of thyrocervical trunks on the right ( 23 ) seemed to be lower than that on the left ( 24 ) , but this may be due to the formalin fixation process performed on these cadavers . the results of this study show that the mean raps - to - vao length was 565.6948.13 mm . the average vao - to - sca angle was 70.946.12 , and the median length between the scj and the vao was 60.308.48 mm . therefore , the optimal catheter for a transradial approach to neurointerventional surgery should be chosen according to these lengths and angles . today trc is mainly prefered in patients with vascular anatomical diffuculties and in neuroendovascular practice several guiding catheters are used depending on the anatomy , including a 5 fr simmons type ii and type i catheter ( cook , bloomington , in , usa ) , h1 ( cook medical , bloomington , in , usa ) , or a berenstein ( boston scientific corporation , natick , ma , usa ) with a 0.035 inch glidewire ( terumo interventional systems ) . our data of vao - to - sca angles suggest that simmons type ii and type i catheter can be more safely used in the selection of vao . learning and implementing trc with novel techniques will cause widespread adoption and encourages neurointerventionists to perform this route more common . therefore understanding the anatomic characteristics of these vessels when performing trc , the location of the puncture site is also important for preventing nerve and tissue damage . in practice , trc is performed primarily via the right radial artery for the right internal carotid system and for brachiocephalic , right vertebral , and basilar therapeutic procedures and via the left radial artery for left subclavian and left vertebral v14 segment preocedures . however , data about the route and specifity of the catheters have been limited . in this study , the distance between the rsp and the raps was 13.412.19 mm , and the raps was 26.852.47 mm from the mn . the distance from the me to the braps was 44.235.47 mm , whereas the distance between the me and the mn was 42.234.77 mm . therefore , a transbrachial approach to catheterization may cause median nerve injury because the braps is close to the mn . the transradial approach has become more popular than the transfemoral or transbrachial approach because the ra has a superficially safe course for better haemostasis , is not surrounded by major veins or nerves , and has good collaterals1 ) . we also studied vessel diameters . as expected , the diameter of the ra ( 1.770.48 mm ) was smaller than that of the bra ( 3.190.75 mm ) . knowledge of ra diameter may help clinicians to cannulate various sheath sizes during transradial interventions . our data suggested that 5 fr ( 1.65 mm ) sheath can be more safely used for trc . but 6 fr ( 1.98 mm ) and 7 fr ( 2.31 mm ) sheath can be inserted on the braps . complications due to trc include radial artery intimal dissection or perforation , gross hematoma , pseudoaneurysm , arteriovenous fistula formation , and thrombosis . to prevent such complications , it is important to select a favorable catheter size , angle , and length . although the data in this study reflect the anatomical aspects of endovascular surgery , the results are limited due to the small sample and the formalin fixation process . so , we recommend that the selction of approaches , length and shape of catheters should be decided upon the angiographic characteristics during endovascular procedures compared with our cadaveric study datas . in conclusion we believe that the basic ra and bra anatomical information found in this study can help neurointerventionists adopt a transradial neuroendovascular approach . our data can help improving new techniques , selection of size and shape of catheters for trc . further understanding of the three - dimensional aspects of the blood vessel structures in the upper extermity increases the safety of trc in endovascular surgery .
objectivethe transradial catheterization ( trc ) is becoming widespread , primarily for neurointerventions . 
 therefore , the evaluation of radial artery puncture in clinical practice and a better understanding of the anatomy are important to improve the safety of neuroendovascular surgery.methodsten formalin - fixed adult korean cadavers were dissected to expose radial artery ( ra ) , brachial artery ( bra ) and subclvian artery ( sca ) , bilaterally . 
 vessel lengths and diameters were meaured using a caliper and distance between the specific point of vessels and the anatomical landmarks including the radial styloid process , the medial epicondyle of the humerus , the sternoclavicular joint , and the vertebral artery orifice were also measured.resultsthe average length between the radial ( raps ) and the bra puncture sites ( braps ) and between the vertebral artery orifice ( vao ) and the bra bifurcation ( brab ) did not differ between sides ( p>0.05 ) . 
 the average length between the radial styloid process ( rsp ) and the raps was 13.412.19 mm , and the rsp was 26.852.47 mm from the median nerve ( mn ) . 
 the mean length between the medial epicondyle ( me ) and the braps as 44.235.47 mm , whereas the distance between the me and the mn was 42.234.77 mm . 
 the average vao - sca angle was 70.946.12 , and the length between the sca junction ( scj ) and the vao was 60.308.48 mm.conclusionthis study provides basic anatomical information about the radial artery and the brachial route and can help improving new techniques , selection of size and shape of catheters for trc . 
 this can help neurointerventionists who adopt a transradial neuroendovascular approach and offers comprehensive and safe care to their patients .