Anatomical variations of the brachial plexus in adult cadavers: A descriptive study and clinical significance.

BACKGROUND: Brachial plexus injury is recognized as one of the most severe clinical challenges due to the complex anatomical configuration of the brachial plexus and its propensity for variation, which complicates safe clinical interventions. This study aimed to ascertain the prevalence and characterize the types of brachial plexus variations, and to elucidate their clinical implications. MATERIALS AND METHODS: We conducted meticulous dissections of 60 formalin-fixed cadavers' upper arm, axilla and lower neck to reveal and assess the roots, trunks, divisions, cords, and branches of the brachial plexus. The pattern of branching was noted by groups of dissecting medical students and confirmed by the senior anatomists. The variations discovered were record and photographed using a digital camera for further analysis. RESULTS: Variations in the brachial plexus were identified in 40 of the 60 cadavers, yielding a prevalence rate of 66.7%. These variations were classified into root anomalies (2.1%), trunk anomalies (8.5%), division anomalies (2.1%), and cord anomalies (4.3%). Notably, anomalies in communicating branches were observed in 39 cadavers (83.0%): 14 with bilateral anomalies, 14 with anomalies on the left side, and 11 on the right side. These communicating branches formed connections between the roots and other segments, including trunks, cords, and terminal nerves, and involved the median, musculocutaneous, and ulnar nerves. CONCLUSION: The frequency and diversity of brachial plexus variations, particularly in communicating branches, are significant in cadavers. It is imperative that these variations are carefully considered during the diagnostic process, treatment planning, and prior to procedures such as supraclavicular brachial plexus blocks and nerve transfers, to mitigate the risk of iatrogenic complications.

Rare case of divided phrenic nerve variation: a cadaveric case report.

The phrenic nerve innervates the respiratory diaphragm, the primary muscle active during ventilation. The canonical path of the phrenic nerve originates from the cervical spine at C3-C5 spinal nerves and travels inferiorly through the neck and thoracic cavity to reach the diaphragm. During a cadaver dissection, a variation of the phrenic nerve was discovered in a 93-year-old male specimen. A traditional origin of the phrenic nerve was noted; however, the nerve branched into medial and lateral components at the level of the superior trunk of the brachial plexus. The branches reconnected at the apex of the aortic arch and continued inferiorly to innervate the ipsilateral diaphragm. This case study describes a rare type of branching of the phrenic nerve and explores its potential impact on clinical procedures.

Anatomic Variation of the Phrenic Nerve and Brachial Plexus Encountered during 100 Supraclavicular Decompressions for Neurogenic Thoracic Outlet Syndrome with Associated Postoperative Neurologic Complications.

BACKGROUND: The objective of this study was to characterize phrenic nerve and brachial plexus variation encountered during supraclavicular decompression for neurogenic thoracic outlet syndrome and to identify associated postoperative neurologic complications. METHODS: A multicenter retrospective review was performed to evaluate anatomic variation of the phrenic nerve and brachial plexus from November 2010 to July 2018. After initial characterization, the following two groups were identified: variant anatomy (VA) group and standard anatomy (SA) group. Complications were analyzed and compared between the two groups. RESULTS: In total, 105 patients were identified, and 100 patients met inclusion criteria. Any anatomic variation of the standard course or configuration of the phrenic nerve and/or brachial plexus was encountered in 47 (47%) patients. Phrenic nerve anatomic variations were identified in 28 (28%) patients. These included 9 duplicated nerves, 6 lateral accessory nerves, 8 medial displacement, and 5 lateral displacement. Brachial plexus anatomic variation was found in 34 (34%) patients. The most common variant configuration of a fused middle and inferior trunk was identified in 25 (25%) patients. Combined phrenic nerve and brachial plexus anatomic variation was demonstrated in 15 (15%) patients. The VA and SA groups consisted of 47 and 53 patients, respectively. Transient phrenic nerve injury with postoperative elevation of the ipsilateral hemidiaphragm was documented in 3 (6.4%) patients in the VA group and 6 (11.3%) patients in the SA group (P = 0.49). Permanent phrenic nerve injury was identified in 1 (2.1%) patient in the VA group (P = 0.47) and none in the SA group. Transient brachial plexopathy was encountered in 1 (1.9%) patient in the SA group (P = 1.0) with full recovery to normal function. CONCLUSIONS: Anatomic variability of the phrenic nerve and brachial plexus are encountered more frequently than previously reported. While the incidence of nerve injury is low, surgeons operating within the thoracic aperture should be familiar with variant anatomy to reduce postoperative complications.

Five Roots Pattern of Median Nerve Formation.

An unusual combination of median nerve's variations has been encountered in a male cadaver during routine educational dissection. In particular, the median nerve was formed by five roots; three roots originated from the lateral cord of the brachial plexus joined individually the median nerve's medial root. The latter (fourth) root was united with the lateral (fifth) root of the median nerve forming the median nerve distally in the upper arm and not the axilla as usually. In addition, the median nerve was situated medial to the brachial artery. We review comprehensively the relevant variants, their embryologic development and their potential clinical applications.

A Prefixed Four-Trunk Brachial Plexus with Anomalous Anatomy of All Subsequent Divisions, Cords, and Terminal Branches: A Cadaveric Case Report.

BACKGROUND The brachial plexus is a complex neural structure providing motor and sensory innervation to structures of the arm, shoulder, and upper chest. The anatomical structure is typically divided into roots, trunks, divisions, and cords. Due to the presence of multiple nerve roots and branches, anatomical variations are common. Awareness of variations from normal anatomy is important in imaging, administration of nerve blocks, and surgical procedures of the neck and shoulder region. CASE REPORT We present a case of multiple anatomic variations of the right brachial plexus identified in a cadaver during routine dissection. To summarize, we identified a prefixed plexus with anomalous contributions from the C4 nerve root. Nerve roots C4 and C5 emerged anterior to the anterior scalene muscle. Furthermore, 4 trunks, rather than the typical 3, gave rise to multiple anomalies in the branching pattern of the distal divisions and cords. To the best of our knowledge, this is the first such case reported in the published literature. CONCLUSIONS The current case report presents a combination of brachial plexus anomalies not previously described in the medical literature - specifically, a prefixed (C4-T1) brachial plexus positioned anterior to the anterior scalene muscle with anomalies of the trunks, divisions, cords, and terminal branches. The variations presented have implications in neurogenic compression, interscalene blocks, and trauma to the upper limb. Knowledge of these anomalies may better equip anatomists and clinicians to understand pathology and intervention of the upper limb.

Neglected Sprengel's deformity in an 80-year-old female cadaver: a case report.

BACKGROUND: Sprengel's deformity is a congenital abnormality of the shoulder girdle. Because scapular retraction, such as the Green procedure, is usually performed during childhood to improve esthetics and shoulder function, Sprengel's deformity is rarely found in older patients. CASE PRESENTATION: We presented a unique case of a Japanese female cadaver with Sprengel's deformity at the age of 80 years. Anatomical dissection and radiological imaging revealed musculoskeletal anomalies associated with Sprengel's deformity, including Klippel-Feil syndrome, presence of an omovertebral bone, and absence of the trapezius muscle. In addition, bilateral cervical ribs were in contact with the brachial plexus. These anomalies may lead to numbness, pain, and limited range of motion of the neck and upper girdle with aging. CONCLUSIONS: Because most adult patients with Sprengel's deformity experience neck pain and limited movement of the shoulder, the presented case is a rare case of neglected Sprengel's deformity in an 80-year-old cadaver.

A rare anatomical variation of the brachial plexus: single cord anomaly.

Anatomical variations of the brachial plexus may be important in regional anesthesia and upper limb procedures. A fused single cord of the brachial plexus, although considered rare, was discovered in 4 Indian male cadavers during the dissection of 90 brachial plexuses. All 4 cases demonstrated deviation from the usual pattern starting at the division of trunks continuing to the formation of cords. The location of these single cords was lateral to the axillary artery instead of the typical perivascular relationship. A fused single cord of brachial plexus might be more common than previously thought. The impact on the performance or success of blockade remains unknown.

A four trunked brachial plexus and a post fixed brachial plexus: a conjunction or a co-incidence? Report of three cases.

The anatomical variations of the brachial plexus in humans have clinical significance for surgeons, radiologists, and anatomists. In a study of 60 brachial plexuses, four trunked brachial plexuses were encountered in three limbs (two female and one male), all of them being post fixed and on left side of cadavers. The third trunk in all these limbs gave rise to two anterior divisions (upper and lower) and one posterior division. In two limbs belonging to the female sex, the upper anterior division joined with the anterior division of the second trunk to form the lateral cord while its lower anterior division joined with the anterior division of the fourth trunk to form the medial cord. In the sole male limb, along with the third trunk, the fourth trunk also divided into upper and lower anterior divisions. Upper anterior divisions of the third and fourth trunks joined to form the medial root of the median nerve while lower anterior divisions joined to form the ulnar nerve. No medial cord was formed as such. Further, it is inferred that in postfixed brachial plexus, there is a tendency to failure on part of T1 and T2 to join C8 which continues as the third trunk while T1 and T2 continue as the fourth trunk. Since it was seen in all postfixed brachial plexuses of the present study, it is emphasized to be given a place in the textbooks of anatomy or to conduct a study on a larger database.

Unusual formation of the median nerve associated with the third head of biceps brachii.

Unilateral variations in the formation of the median nerve, with the presence of the third head of the biceps brachii entrapping the nerve are very rare. These variations were observed on the right side, of a 30-year-old male cadaver during routine dissection at the Department of Human Anatomy, University of Nairobi. The median nerve was formed by the union of three contributions; two from the lateral cord and one from the medial cord. An additional head of the biceps brachii looped over the formed median nerve. On the left side, the median nerve was formed classically by single contributions from the medial and the lateral cords. These variations are clinically important because symptoms of high median nerve compression arising from similar formations are often confused with more common causes such as radiculopathy and carpal tunnel syndrome.

Variations in the formation of the median nerve and its clinical correlation.

Variations in the formation of the median nerve are of interest to anatomists, radiologists, and surgeons. These variations may be vulnerable to damage in surgical operations, but their knowledge also helps in the interpretation of a nervous compression having unexplained clinical symptoms. We studied the variation in the formation of the median nerve in 87 cadavers, i.e. 174 upper limbs of formalin preserved cadavers at the department of Anatomy, Subharti medical college. We observed an additional root taking part in the formation of the median nerve in 26.4% of upper limbs, unusual low formation of the median nerve in the arm in front of the brachial artery in 18.4% of upper limbs, and median nerve formation medial to the axillary artery in 10.3% of upper limbs. Knowledge of such anatomical variations is of interest to the anatomist and clinician alike. Surgeons who perform procedures involving neoplasm or trauma repair need to be aware of these variations.

Bilateral superficial ulnar artery with high origin from the axillary artery: its anatomy and clinical significance.

The superficial ulnar artery (SUA) is a rare anatomical variant that usually arises either in the axilla or the arm and runs a superficial course in the forearm, enters the hand, and participates in the formation of superficial palmar arch. During the routine dissection of cadavers in the department of anatomy, whilst preparing the specimen for medical students, an unusual bilateral branch of the axillary artery was found in one of the cadavers: a rare variant of the artery known as SUA, which originates from the 2nd part of the axillary arteries of both sides. The SUA is a known anatomical variant, but the bilateral high origin from the 2nd part of the axillary artery is extremely unusual. Its occurrence is of great clinical importance to the surgical and radiological departments.

Variations of Ulnar Nerve in the Forearm and Hand: A Review of the Literature and Clinical Significance.

The ulnar nerve originates from the anterior division of the lower trunk of the brachial plexus which continues as the medial cord and gives off branches to the forearm and the hand with motor and sensory fibers. The objective of the current study is to assemble the recognized anatomical variations of the ulnar nerve (UN) and underline their clinical impact. A literature search was undertaken via PubMed database, using the term: "ulnar nerve AND variations." Classical anatomical textbooks were also used for the normal anatomy of the UN. A total of 23 articles met the inclusion criteria, 16 of which are included in this review. Fifty-four additional articles provided useful information according to the aim of this review. Of great interest is the communication between the UN and the radial nerve (RN) in the forearm, as well as the communication between the UN and the median nerve (MN) in both forearm and hand. Furthermore, variations of the UN were observed in the hand and the classification of the UN compression was also described according to the point of the neuropathy. These collecting data are categorized into five tables. Additional aberrations were also included in this review. According to literature, the UN is characterized by numerous variations of its course and branches. Therefore, good knowledge of the normal anatomy is essential. Moreover, the anomalies are of particular importance due to their significant clinical implications and should be taken into consideration by the surgeons during surgical procedures in this region.

Anomalies of thoracic outlet in human fetuses: anatomical study.

BACKGROUND: Thoracic outlet syndrome (TOS) identifies the clinical condition determined by the mechanical compression and entrapment of the subclavian vessels and the brachial plexus cords within the space delineated by the scalene muscles, the clavicle, and the first rib. To date, there are no concluding explanations concerning the real causes of the appearance of TOS in children. This is the first study to investigate the existence, frequency, and type of thoracic outlet anomalies in the prenatal stage (human fetuses). METHODS: Eighty cervical dissections (40 consecutive spontaneously aborted human fetuses) were performed, and the musculoskeletal, vascular, and nervous elements that pass through the thoraco-cervico-axillary region were investigated. RESULTS: Overall, anatomical anomalies of the thoraco-cervico-axillary region were found in 60% of the 80 cervical dissections. Nine (22.5%) of the 40 fetuses had normal bilateral anatomy. In 6.3%, the scalene hiatus had an oval shape due to the common costal insertion of the anterior and middle scalene muscles. Fibromuscular bands were found in 15% of the fetuses. Hypertrophy of the anterior scalene muscle was seen in 12.5% of the dissections. In 28.7% of the cervical dissections, hypertrophy of the C7 transversal process was noted, bilateral in seven cases. There was one case of a "C-shaped" clavicle anomaly. The absence of the internal mammary artery was noted in one case. CONCLUSION: This study shows that the presence of TOS anomalies in fetuses is not a rare occurrence, emphasizing a pathological cervical background which can be harmful in situations of cervical trauma or inflammatory processes. Having knowledge of the types of anomalies which can lead to TOS is important for performing a complete surgical correction and avoiding the high failure rate of recurrent TOS.

Absence of the musculocutaneous nerve associated with a supernumerary head of biceps brachii: a case report.

Unusual neural and muscular variations in the right upper limb were noted during anatomical dissection of a 54-year-old male cadaver. The absence of the musculocutaneous nerve was correlated with a three-headed biceps brachii muscle. The distribution of muscular branches innervating the anterior compartment of the muscles of the arm was different to the cases described in literature hitherto. This report contains a comparison of various instances where the musculocutaneous nerve is absent. We discuss the embryological explanation for this anomaly and its clinical results. It is important to be aware of such possible anatomical variations during clinical practice.

Unilateral intercordal neural communication coexistent with variant branching pattern of posterior cord of brachial plexus.

Variant branching pattern of the cords of brachial plexus coupled with erroneous communications has been an area of concern for surgeons opting to explore this region. Anaesthetic blocks and surgical approaches are the highlights of these interventions, where a keen familiarization of the anatomy of this region is mandatory. The present case description reports a unilateral variant branching pattern of the posterior cord coexistent with a neural communication between lateral and medial cords in an adult male cadaver. This intercordal neural communication between lateral and medial cords was oriented obliquely and measured 2.2 cm in length. Furthermore, the posterior cord revealed a variant branching pattern. It branched into three upper subscapular nerves and a common trunk for the thoracodorsal and lower subscapular nerves. The lowest of the three upper subscapular nerves gave a communicating twig to the thoracodorsal nerve. Inspite of uncountable reports on variations ofbrachial plexus, descriptions regarding anomalous branching patterns hold enormous clinical significance for the radiologists, anesthetists and surgeons, besides being of academic interest for the anatomists.

Anatomical variation in formation of brachial plexus and its branching.

Variant brachial plexus formation with two trunks and two cords is uncommon and has clinical implications as it may result in failure of regional brachial or axillary block. During routine anatomical dissection, unilateral variation in the formation of brachial plexus accompanied by unusual positional relationship with axillary artery was discovered in the left upper extremity of a 52-year-old Indian male cadaver. Brachial plexus showed two trunks formed by ventral rami of C5, C6 and C7, C8, T1 spinal nerves, respectively, which first split and then reunited in an unusual manner to form two cords: posterior and lateral instead of three. Medial cord was absent. The branching pattern of the brachial plexus also showed important variations. Second part of axillary artery was found lying inferomedial to brachial plexus instead of passing between medial and lateral cords. Transverse cervical artery was found to be coursing between two trunks instead of passing superficial to brachial plexus. Median nerve was observed to be formed from a single root, instead of usual two roots. Embryologically, this rare variation may be due to the development of axillary artery from ninth segmental artery instead of usual seventh cervical intersegmental artery. Such rare variation is clinically important as this knowledge may help the anesthesiologists and the surgeons to avoid any inadvertent damage to nerves and axillary artery during blocks and surgical interventions.

Neuroanatomy of the brachial plexus: normal and variant anatomy of its formation.

The brachial plexus is the complex network of nerves, extending from the neck to the axilla, which supplies motor, sensory, and sympathetic fibers to the upper extremity. Typically, it is formed by the union of the ventral primary rami of the spinal nerves, C5-C8 & T1, the so-called "roots" of the brachial plexus. By examining the neural architecture of the brachial plexus, the most constant arrangement of nerve fibers can be delineated, and the most predominate variations in the neural architecture defined. A thorough understanding of the neuroanatomy of the brachial plexus, with an appreciation of the possible anatomic variations that may occur is necessary for effective clinical practice.

Crucial neurovascular structures entrapped in a brachial intramuscular tunnel.

We report a case where the median nerve accompanied by brachial vessels were found to traverse an intra-muscular tunnel within the brachialis muscle, in the floor of the cubital fossa. The muscular tunnel commenced 5 cm proximal to the neck of radius, measured 4.4 cm in length, and was present unilaterally. This unusual tunnel was distally found to blend with the brachial fascia. The present study was planned with an endeavor to elucidate in an improved way the clinical implications of compressed median nerve and brachial vessels. There are several sites where median nerve maybe compressed along its course in the arm and forearm. The relevance of the present documentation lies in the fact that these vital neurovascular structures may be compressed leading to neuropathies and vascular changes.