Indian Journal for the Practising Doctor

Abstract:

Variation in the arterial system of the upper limb is well documented. The superficial ulnar artery is a well-known but very rarely encountered abnormality. Superficial positions of the ulnar and radial artery make them more vulnerable to trauma and thus to hemorrhage but, at the same time, more accessible for cannulation, if necessary. Thus, we have tried to study literature on variations in this area.

Introduction

Normally the ulnar artery begins distal to the bend of the elbow as the larger of two terminal divisions of the brachial artery. Variation in the arterial system of the upper limb are well-documented [Bergman et al 1988¹, Rochiguaz- Baega et al 1995²; Tountas et al 1993³]. The variation and anomalies of the arterial system to the upper limb can best be explained on the basis of embryologic development of the vascular plexuses of the limb buds [Jurjus et al 1986⁴]. The superficial ulnar artery is well known but very rarely encountered abnormality [Anil et al 1996⁵ and Nakatani et al⁶].Superficial positions of the ulnar and radial artery make them more vulnerable to trauma and thus to hemorrhage but, at same time, more accessible for cannulation, if necessary. If they are superficial to flexor muscles, the radial and ulnar artery may be mistaken for veins. Such misinterpretations can lead to intra-arterial injections, wrong interpretations of incomplete angiographic images or severe disturbances of hand irrigation during surgical procedures on the arm or forearm.

Demonstration of patency of ulnar artery is very important before raising a free radial forearm flap which can be established by Doppler flowmeter. After such a flap, the blood supply of hand will depend entirely on adequate patent ulnar artery. Thus, any abnormal course and division of ulnar artery is important in surgical and angiographic procedures related to that region.

Material and Methods

100 randomly selected cadavers assigned to medical students for dissection were studied. All had been embalmed soon after death with mixture of 10% formaldehyde, glycerol, methylated spirits and 10% phenol in water. The topography of the upper arm arteries of all cadavers was examined during dissection and those showing anomalies were recorded and described.

Results

In the left arm of this cadaver, just after giving origin to thoraco-acromial artery in its second part, axillary artery divided into two branches at mid of arm (fig 1 ). At the level of elbow one of the branches again divided to give origin to radial and ulnar artery. Both radial and ulnar arteries were superficial to flexor group of muscles (fig 2 ). In the distal half of forearm, superficial ulnar artery lay between tendons of flexor carpi ulnaris and flexor digitorum superficialis and finally established the superficial palmar arch. Radial artery ran its own normal course through the forearm and winded dorsally through the anatomical snuffbox. The other branch of axillary, from the elbow ran deep to flexor group of muscles, giving origin to common interosseous artery. Thus this cadaver had two ulnar arteries; one superficial and another deep.

Fig 1: This photograph is showing axillary artery (AA) dividing into two branches at the middle of arm. At the elbow one branch is dividing into radial artery (RA) and ulnar artery (UA).

Fig 2: This photograph shows radial artery (RA) and ulnar artery superficial to flexor group of muscles.

Fig 3: This photograph shows the second branch of axillary artery going deep to flexor group of muscles indicated by arrow head.

Discussion

Morphologic variations in the arteries of the upper extremity are very important from the surgical point of view in relation to procedures in this area. Thus, we have tried to study literature on variations in this area. Mc Cormack et al 1953⁷ published a study of 750 dissected upper extremities where the percentage of major arterial pattern variations was 18.53% of total. They reported high origin of radial as largest group of variations and represented an occurrence of 14.27% of all specimens. The high origin of ulnar artery from the brachial artery and from axillary artery was 1.33% and 0.93% of the total respectively.

In a dissection of 451 upper limbs Weathersby 1956⁸ found high origin of ulnar artery in 0.67% case. The ulnar artery arose from brachial artery in two cases and from superficial brachial artery in third case. In our case, we found dual ulnar artery; the superficial ulnar arose from brachial artery at level of elbow joint and the deep ulnar artery took origin from axillary artery high up in the arm. Superficial ulnar artery has been reported by Fadel 1986⁹, Anil A 1996 5 and Gölshan Görműs et al 1998¹⁰. Some authors have also reported bilateral case of superficial ulnar artery [Yazar et al 1999¹¹ and Jacquemin et al, 2001¹²]

A model of development of the arteries of upper limb in 5 stages has been proposed [Senior 1926¹³ and Singer 1933¹⁴]. This states that an axial system appears first while other branches develop later from this axial system. Thus in the adult, this axial system includes axillary artery, brachial artery and anterior interosseous artery. The median artery branches from the last one. [stage 2]. Afterwards the ulnar artery branches from the brachial artery [stage 3]. Next, a superficial brachial artery develops from the axillary and continues as the radial artery [stage 4]. Regression of the median artery and an anastomosis between the brachial artery and the superficial brachial artery with regression of the proximal segment of the latter, gives rise to definitive radial artery.

The model of development of radial artery is not unanimously accepted. Though Gruber 1867¹⁵ and Meckel 1816¹⁵ agreed with it, Adachi 1928¹⁶ and Mrazkova 1989¹⁷ considered that radial artery branches directly from the interosseous artery. Poteat 1986¹⁸ modified Singer's model and proposed a sandwich of stage 2 and 3, making ulnar artery the second artery to appear in arm. The present anomaly is thus explained by the persistence of embryological vessels which may be due to hemodynamic persistence of superficial system over deep system at the origin of ulnar artery . Genetic influences are deemed to be prevalent causes of such variation, although other factors like foetal position in utero, first limb movement or unusual muscular development can not be completely excluded.

Vascular anomalies occurring in common surgical sites tend to increase the likelihood of damage during surgery. Owing to unusual course of superficial ulnar artery, it would be particularly vulnerable to different surgical procedures. Thus, it is important for surgeons and radiologists to be aware of the possible arterial variations in order to prevent complications during surgical and diagnostic procedures.

Rerences

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*Latika Arora, MS
Senior Resident;
Deptt of Anatomy,
All India Institute of Medical Sciences, New Delhi.

**Rima Dada R, MS,
Assistant Professor
Deptt of Anatomy,
All India Institute of Medical Sciences, New Delhi.

Correspondence:
Dr. Rima Dada,
Assistant Professor,
Deptt of Anatomy, AIIMS,
Ansari Nagar, New Delhi.