Introduction

The brachial artery, a continuation of the axillary, usually begins at the lower border of teres major muscle courses deep to the median nerve and ends at the level of the neck of the radius by dividing into ulnar and radial arter-ies (1). Variations occur in course of the artery in relation to the median nerve (2, 3), pattern and level of bifurca-tion (4-6). Variant anatomy is important in trans-radial percutaneous coronary angiography or when using ra-dial artery for coronary bypass grafts (7, 8). Complica-tions as a result of the variant pattern of this artery have been reported in surgical procedures (9). Knowledge of these variations is important to avoid complications of accidental intra-arterial injection of medication into su-perficial arteries that may lead to clinically important se-quelae such as to paraesthesias, severe pain, motor dys-function, compartment syndrome, gangrene, and limb loss (10). This study reports surgically relevant variants of the brachial artery in a black Kenyan population.

 

Materials And Methods

This was a dissection study carried out on 162 upper limbs from 81 cadavers of adult black Kenyans in the Department of Human Anatomy, University of Nairobi. Vertical incisions were made on the lateral and medial borders of the arm from the coracoid process and ax-illa proximally to the mid forearm. These incisions were joined by transverse ones and the skin flaps removed. The biceps brachii was sectioned in the middle, the ends retracted and the fascia split to expose the brachial artery in its entire extent from the axilla to the cubital fossa. The artery was traced proximally to its continuity with the axillary artery at the lower border of teres major and distally to its point of termination. The course in relation to the median nerve, level and pattern of termination were identified as follows; normal (classical pattern), an artery with a classical origin, course and branching pattern as described in Gray’s Anatomy (1). This artery originates from the lower border of Teres major muscle and coursed deep to the median nerve, terminating at the level of the radial tuberosity into the ulnar and ra-dial arteries. Superficial brachial artery described an ar-tery with a course superficial to the median nerve (3, 11, 12). Brachioradial artery described a proximal origin of the radial artery in the arm which courses superficial to the median nerve. Photographs of the representative pat- terns were taken using a Sony cybershot ® camera 14.1 mega pixels, 4x optical zoom. The results were analysed using the Statistical Programme for Social Scientists (SPSS) version 17 for Windows and presented in tables and macrographs.

 

Results

Brachial artery was present bilaterally in all 162 upper limbs studied. Variations were observed in course, level and pattern of termination. The usual anatomical de-scription of the brachial artery occurred in 72.2% (117 of the cases) of the cases. The artery was found to course superficial to the median nerve mainly as the brachiora-dial artery (12.3%) in which case the artery bifurcated in the arm, and the radial artery coursed superficial to the nerve. A superficial brachial artery existed in 6.1% of the cases.

 

Regarding the point of termination of the brachial ar-tery, 79% terminated at the radial neck (Fig. 1A). Twenty brachial arteries (12.3%) had a proximal bifurcation in which case the radial artery coursed distally at first medial to the median nerve then arching superficial to the median nerve from medial to lateral (Fig.1B). These proximal bifurcations occurred either in the proximal third of the arm, 18 cases, 11.1%, (Fig. 1B) or mid arm level 2 cases, 1.2% (Fig 1C). Fourteen brachial (8.6%) arteries took a longer course and terminated at the level of the radial tuberosity (Fig.1D). The mode of termi-nation observed in this study was either a bifurcation of the brachial artery into ulnar and radial arteries 146 (90.1%) or a trifurcation into the ulnar, radial and com-mon interosseous arteries 9.3% (Fig. 1D, E). In one case (0.6%), the brachial artery terminated in the arm as a trifurcation into the radial, ulnar and profunda brachii arteries (Fig. 1F).

 

Discussion

In the present study, 72.2% of the limbs displayed the classical pattern of the brachial artery. This is lower than the 82% reported (6) in an Indian population. The ex-istence of such variations of the upper extremity is clini-cally important. They may complicate intravenous drug administration as well as percutaneous brachial cath-eterization. For instance, in the present study, 10 (6.1%) brachial arteries coursed superficial to the median nerve, higher than 3.6% reported by Keen (1961) [Table 1] (2). Miller (1939) suggested the superficial brachial artery

 

Click to view table 1

 

Click to view table 2

 

was an atavistic feature as he considered a brachial artery passing anterior to the median nerve to be the usual arrangement in pri-mates (13). Such an artery may be mistaken for a vein. Its superficial course makes it more prone to injury, which may result in profuse bleeding. On the other hand, the superficial brachial artery could be used as a feeding artery to a free flap from medial arm skin (14). The brachial artery terminated proximal to the intercondylar line in 12.3% of the cases, in all cases, the radial artery being superficial to the median nerve. Our findings therefore indicate a proximal origin of the radial artery in 12.3 % of the cases. This is almost similar to the findings of Anson (1966) and Rodriguez-Niedenfuhr (2003) in American and Spanish populations respectively (12, 17). Previ-ous studies (2, 13, 18) have documented varying incidences of the proximal radial artery (Table 2).

 

 

The proximal radial artery is the commonest variation of the termi-nation of the brachial artery (4, 19). Knowledge of such variations is of clinical significance. For example, iatrogenic pseudo aneurysm of the radial artery in the arm may follow chronic hemodialysis (20). Anatomical variations of the radial artery have also been implicated in failures of the transradial approach for percutaneous coronary procedures (21).

 

Trifurcation into radial, ulnar and common interosseous arteries occurred in 9.3% of the cases. Trifurcation of the brachial artery has been previously observed, into; ulnar, radial, common interos-seus or median artery (22), ulnar, radial and radial recurrent arteries

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Legends

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Click to view figure 1

of the radial neck into ulnar (black arrow) and radial arteries (red star). B: Proximal third arm bifurcation of the BrA (single red circle), HH is the head of the humerus while Biceps LH is the long head of biceps. Ra is the radial artery, Ua is the ulnar artery. The red star is on the radial nerve. C: Mid arm bifurcation of the brachial artery (Red arrow), into the ulnar (Ua) and radial (Ra) arteries. Note that the radial artery courses superficial to the radial nerve (red star). The biceps muscle is transected at its mid-point. D: Low trifurcation of the BrA, at the level of the radial tuberosity where the biceps tendon inserts as shown by the red arrow. Note that it trifurcates into the ulnar, radial and common interosseous arteries as shown by the black arrows. E: Trifurcation of the brachial artery (BrA), into the common interosseous (CIa), radial (Ra) and ulnar arteries (Ua). F: Trifurcation of the brachial artery in the proximal arm into the profunda brachii artery (two red arrows), ulnar artery (three black stars), and radial artery (single black arrow). Note that the radial artery courses superficial to the radial nerve (red stars).

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and ulnar, radial and common interosseous arteries Other unique forms of trifurcations include divi-sions into the radial, ulnar and superior ulnar collateral arteries (24) and radial, ulnar and radial recurrent arter-ies (6). We report an inimitable trifurcation of the bra-chial artery into the profunda brachii, ulnar and radial arteries and a low termination of the brachial artery. Our consult of literature reveals only a single case report of this variant (25). Low termination of the brachial artery may lead to inadvertent vascular complications in fore-arm surgeries.

 

Variations of the brachial artery in its relationship with the median nerve, level and pattern of termination are not uncommon. These may complicate arm surgical exposures, interventional radiology, flap and vascular surgery. Pre-operative angiographic evaluation is recom-mended.

 

Acknowledgement

We are thankful to the staff of Gross Anatomy Laborato-ry namely Mr. Jacob Gimongo, Charles Githinji and Pe-ter Nziu for their technical support. We thank Dr. Beda Otieno and Dr. Duncan Anangwe for their assistance in data collection. We are grateful to Dr. Pamela Mandela for her assistance in photograph management.

 

Conflict of interest: None

 

Source of funding: None

 

References

 

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