Three unique variations of the neurovascular course of the profunda brachii artery: a case report

doi:10.21203/rs.3.rs-2109842/v1

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Three unique variations of the neurovascular course of the profunda brachii artery: a case report

https://doi.org/10.21203/rs.3.rs-2109842/v1

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Purpose

To report previously undocumented variants of the neurovascular course of the profunda brachii artery.

Methods

During routine cadaveric dissection, a unique combination of variations in the neurovascular course of the profunda brachii artery was noted in the right upper extremity of a 67-year-old female cadaver.

Results

The brachial artery was observed entirely anterior to the median nerve and its roots. The median nerve received an additional contribution from a branch of the lateral cord that communicates with the medial cord. The profunda brachii artery also took abnormal origin from the subscapular artery, rather than the brachial artery, in the same limb.

Conclusion

This report presents a unique combination of three neurovascular variations in the right upper limb of a single cadaver. Understanding variability in the course and continuation of the profunda brachii artery may assist surgeons and other interventionists in safely and effectively operating within the upper extremity.

brachial plexus

profunda brachii

subscapular artery

anatomic variation

Neurovascular distribution in the upper extremity is complex and subject to a great deal of variation. In the classic anatomy, the brachial plexus is a network of nerves beginning with the anterior rami of C5, C6, C7, C8, and T1. Intermediate segments include three trunks, three divisions, and three cords. Each trunk gives rise to two divisions, while each cord gives rise to two major branches. The lateral cord provides the musculocutaneous nerve and lateral root of the median nerve. The medial cord provides the ulnar nerve and medial root of the median nerve. The posterior cord provides the axillary and radial nerves [4].

Variations in this general distribution are often reported in association with vascular anomalies. Upper limb vasculature classically involves the axillary artery, which begins at the first rib and has three parts divided by the pectoralis minor muscle. It branches off the superior thoracic, thoracoacromial, lateral thoracic, subscapular, and circumflex humeral arteries. It then continues distally into the upper limb and becomes the brachial artery at the inferior border of the teres major muscle. This muscle descends posteriorly to the branches of the brachial plexus. The brachial artery also provides the profunda brachii (deep brachial) artery of the arm. The deep brachial artery typically begins along the posterior aspect of the brachial artery just below the inferior aspect of teres major [4–5]. The brachial artery is embryologically developed during complex embryogenesis by the main trunk of the axis artery [10]. Our cadaveric findings underscore an interruption of unknown origin in the proper progression of this development, though ultimate formation of the vasculature was successful.

Studies have posited that brachial plexus anatomy differs from the classic, simplified scheme to a larger extent than anticipated [4–5]. Knowledge of the anatomic variations in upper extremity neurovasculature is vital for anatomists. Vascular surgeons and radiologists, among other clinicians, should be aware of these variations when conducting procedures or performing imaging studies. Abnormal arterial branching is especially vital to consider when conducting explorative and reconstructive operations in the upper extremity. In this case report, we present an interesting combination of arterial and nerve variations seen in the upper extremity – particularly of interest is a rare abnormal origin of the profunda brachii artery.

During routine dissection of a 67-year-old female cadaver in the Department of Anatomy at the City University of New York School of Medicine, unilateral neurovascular variations in the right upper extremity were observed (Fig. 1). The presence of an additional contribution from the lateral cord to the median nerve was appreciated. This supplementary branch communicated with the medial root of the median nerve prior to forming the median nerve. Another variation observed was the presence of a brachial artery that was entirely anterior to the median nerve and its roots. This brachial artery was seen emerging anteriorly at the junction where the communicating branch of the lateral cord joined the medial root of the median nerve. The third variation observed in this cadaver involved the subscapular artery, which branched off the very distal end of the axillary artery at the junction of its continuation to form the brachial artery. The profunda brachii artery was then seen branching from the subscapular artery instead of the conventional brachial artery.

Median nerve variations are commonly reported in the literature, and thus are not a significant finding in most cadavers. Previous reports include a proximal and distal lateral root of the median nerve [3], formation of the median nerve from a single root of the lateral cord [6], the complete absence of the lateral root of the median nerve [2], and the medial root receiving a communicating branch from either the lateral or posterior cords [5]. Other reports have documented the formation of the median nerve receiving contribution from two branches of the lateral cord and one branch of the medial cord [1].

Many variations in upper extremity vasculature have been generally reported in previous literature given the complexity of development of the arterial supply of the upper limb during embryogenesis. For example, the axillary artery has been observed anteromedial to the plexus at the point of merger between the lateral and medial cords [8]. Another dissection found the axillary artery giving rise to superficial brachial and superficial subscapular arteries in the absence of a normal brachial artery. The superficial brachial artery then descended anterior to the brachial plexus and branched off a profunda brachii artery, while the superficial subscapular artery passed posterior to the plexus [9]. In another variation, the axillary artery passed normally between the lateral and medial cords, then bifurcated into large superficial brachial and deep brachial arteries [10]. These reports highlight the frequency and variety of arterial supply related to axillary, brachial, and subscapular arteries.

The profunda brachii artery, the largest branch of the brachial artery, has been documented to have many variations in origin. For instance, in 22% of cases it may arise from the axillary artery, in another 22% as a common trunk with the superior ulnar collateral artery, and in 7% of cases as a branch of the circumflex humeral artery [7]. However, to the extent of our knowledge based on the current literature available, the origin of the profunda brachii artery from the subscapular artery has not been reported. This anomaly, along with an abnormal origin of the median nerve and an anteriorly running brachial artery, makes this set of unilateral neurovascular variations unique and infrequent.

We report a case of cadaveric dissection involving three unilateral neurovascular variations of the right upper extremity. Variations involving roots of the median nerve, a superficial brachial artery, and an abnormal origin of the profunda brachii artery from the subscapular artery were observed. In clinical practice, such variations may confuse radiographic interpretation and/or lead to complications in surgery. It is important for radiologists and surgeons to be aware of these variations, particularly when performing interventions. Knowledge of these unique variations can help clinicians appreciate the breadth of normal anatomy in patients.

Ethical Approval

This cadaver was registered with the Anatomical Gift Program at the University at Buffalo Jacobs School of Medicine

Competing interests

None

Authors' contributions

S Hajtovic: Manuscript writing and editing. Figure creation and editing. Critically revising manuscript.

AP Samsonov: Manuscript writing and editing. Critically revising manuscript.

GP Schmuter: Manuscript writing and editing. Critically revising manuscript.

K Matthews: Critically revising manuscript.

Funding

Not applicable

Availability of data and materials

Not applicable.

Statements and Declarations

None reported for all authors.

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No competing interests reported.

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Three unique variations of the neurovascular course of the profunda brachii artery: a case report

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Abstract

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Introduction

Case Report

Discussion

Conclusion

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