Musculocutaneous and median nerve branching: anatomical variations. Case Series from UR clinical anatomy and literature review

Kubwimana, Olivier; Ndata, Albert; Ivang, Andrew; Ndahimana, Paul; Nzayisenga, Albert; Byiringiro, Jean Claude; Gashegu, Julien

doi:10.4314/ahs.v22i1.33

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…The brachial plexus is prone to anatomical variations, which make up 50% of all nervous system anatomical variants [1,14]. Based on the variation, the brachial plexus may be pre-fixed due to contributions from C4 or post-fixed due to contributions from T2 [15]. Additional variants have been observed in peripheral branches, where the median nerve has received branches from the lateral, medial, or posterior cord, and the musculocutaneous nerve has given a branch to the median nerve [1].…”

Section: Discussionmentioning

confidence: 99%

Ansa brachii from a median-musculocutaneous trunk: an anatomical variation - a case report

Rugambwa,

Kubwimana,

Hirwa

et al. 2024

rmj

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Anatomical variations in humans are widespread but highly complex. A thorough understanding of anatomy is essential for successful surgical and anesthetic procedures. Brachial plexus anatomical variations are prevalent and account for more than 50% of anatomical variations in cadaveric analyses of the human nervous system. Clinical outcomes may be unsatisfactory if specific brachial plexus anatomical variations are overlooked. In 22% of axillary blocks, the musculocutaneous nerve location was found to be irregular. It may be joined to the median nerve and extended distally before disconnecting from it or may be located close to the axillary artery more frequently. Hence, understanding the anatomy of the brachial plexus is necessary for excellent clinical outcomes in upper extremity surgical procedures. We identified a complex left brachial plexus anatomical variation during the upper limbs dissection course. From the lateral cord, two parallel nervous brands emerge as the musculocutaneous nerve and median nerve fusing into the median-musculocutaneous common trunk. Distally, this trunk forms the ansa brachii that gives the nerve to the biceps brachii muscle, the nerve to the brachialis muscle, and the lateral cutaneous nerve of the forearm. Four branches from the lateral cord, the musculocutaneous nerve, and the median-musculocutaneous trunk sequentially innervated the coracobrachialis muscle. Successful upper extremity surgery and anesthesia need a thorough understanding of the human brachial plexus anatomy and its variations. Additional research and dissections are encouraged to understand human anatomy and its variations.

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Section: Discussionmentioning

confidence: 99%

Ansa brachii from a median-musculocutaneous trunk: an anatomical variation - a case report

Rugambwa,

Kubwimana,

Hirwa

et al. 2024

rmj

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“…Undeniably a detailed knowledge of anatomical variations is primordial in clinical practice (Kubwimana et al, 2022). Cadaver dissection is a valuable tool to understand the range of normal anatomy including variations (Alraddadi, 2021;Willan & Humpherson, 1999).…”

Section: Differential Diagnosismentioning

confidence: 99%

Upper Limb Nerve Variations May Alter Clinical Diagnosis: A Scoping Review

Scafoglieri,

Wynant,

Héréus

et al. 2023

Int. J. Morphol.

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Upper limb nerve variations may be related to the absence of a nerve, an interconnection between two nerves or a variant course. The purpose of this review is to screen the existing literature on upper limb nerve variations that may alter the neurologic diagnostic process. A scoping review was performed following PRISMA for Scoping Reviews guidelines. Initially, 1331 articles were identified by searching Pubmed and Web of Science until the 22nd of October 2022. After screening, reading, and additional searching 50 articles were included in this review. Variations were divided into two categories: 1) variations causing a different innervation pattern involving sensory, motor, or both types of fibers, and 2) variations causing or related to compression syndromes. Two-thirds of the included articles were cadaver studies. Nine articles were diagnostic studies on symptomatic or healthy individuals involving medical imaging and/or surgery. Nerve variations that may cause a different innervation pattern concern most frequently their interconnection. The connection between the median and musculocutaneous nerve in the upper limb and the connection between the median and ulnar nerve in the forearm (Martin-Gruber) or hand (Riche-Cannieu) may be present in half of the population. Injury to these connections may cause compound peripheral neuropathies a result of variant sensory and motor branching patterns. Muscular, vascular, or combined anomalies in the forearm were reported as causes of entrapment neuropathies. These nerve variations may mimic classical entrapment syndromes such as carpal tunnel syndrome or compression at ulnar canal (Guyon's canal). Knowledge of frequent nerve variations in the arm may be important during the diagnostic process and examination. Variant innervation patterns may explain non-classical clinical signs and/or symptoms during provocative tests. Classical nerve compression syndromes in the arm may warrant for differential diagnosis, especially in the case of persistent or recurrent symptoms.

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“…Er verläuft anschließend durch den Sulcus bicipitalis lateralis und durchbricht die Fascia brachii in der Ellenbeuge 3 um als Nervus cutaneus antebrachii lateralis, sensibel den Unterarm zu versorgen. Variable Verläufe des Plexus brachialis in Zusammenschau mit dem N. musculocutaneus sind beschrieben und können auf vielseitige Art und Weisen imponieren 4 5 . So kann der N. musculocutaneus direkte Verbindungen zum N.medianus aufweisen, oder diesen als direkter dritter Zuschuss anteilweise bilden.…”

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Anatomische Varianten des N. medianus und N. musculocutaneus – ein Fallbericht

Wachenfeld-Teschner,

Schäfer,

Beier

et al. 2024

Handchir Mikrochir Plast Chir

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EinleitungTraumatische Schädigungen des Plexus brachialis resultieren häufig in einer eingeschränkten oder aufgehobenen Flexionsbewegung des Ellenbogens. Die Wiederherstellung dieser Bewegung ist ein wichtiges Ziel der chirurgischen Therapie 1 2. Maßgeblich für die Flexionsbewegung und Innervation der Zielmuskeln ist der N. musculocutaneus (MSC). Dieser bildet einen der beiden Endäste des Fasciculus lateralis des Plexus brachialis (C5-C7). In den meisten Fällen verläuft er an der ventralen Oberarmseite, in der Flexorenloge, zwischen dem M. brachialis und M. biceps brachii nach distal und gibt Äste zur motorischen Innervation der beiden Muskeln ab. Er verläuft anschließend durch den Sulcus bicipitalis lateralis und durchbricht die Fascia brachii in der Ellenbeuge 3 um als Nervus cutaneus antebrachii lateralis, sensibel den Unterarm zu versorgen. Variable Verläufe des Plexus brachialis in Zusammenschau mit dem N. musculocutaneus sind beschrieben und können auf vielseitige Art und Weisen imponieren 4 5. So kann der N. musculocutaneus direkte Verbindungen zum N.medianus aufweisen, oder diesen als direkter dritter Zuschuss anteilweise bilden. Der N. medianus kann also sowohl Äste an den N. musculocutaneus abgeben als auch solche von diesem erhalten. Vorliegende Kadaverstudien zeigen in über 50+% der Fälle Verbindungen zwischen dem N. musculocutaneus und dem N. medianus, wobei ein Großteil solcher Verbindungen proximal des Eintrittes des N. musculocutaneus in den M. coracobrachialis liegt 6. Trotzdem sind diese Variationen im klinischen Alltag meist Zufallsbefunde bei chirurgischen Interventionen 7.

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Musculocutaneous and median nerve branching: anatomical variations. Case Series from UR clinical anatomy and literature review

Cited by 5 publications

References 10 publications

Ansa brachii from a median-musculocutaneous trunk: an anatomical variation - a case report

Ansa brachii from a median-musculocutaneous trunk: an anatomical variation - a case report

Upper Limb Nerve Variations May Alter Clinical Diagnosis: A Scoping Review

Anatomische Varianten des N. medianus und N. musculocutaneus – ein Fallbericht

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