27 - Incidence of Cadaveric Variations of Brachial Plexus Roots and Trunks

Poster Board Number: 27
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Odd poster #s – first hour
Even poster #s – second hour

Abstract Body : Objective

Normal anatomical structure of the brachial plexus is described by the American Association for Anatomy as cervical contributions from C5 and C6 joining to form the upper trunk, cervical nerve root C7 will distally form the middle trunk, and cervical nerve root C8 joins thoracic nerve root T1, together forming the lower trunk. This research is aimed at expanding awareness of recorded variations of the brachial plexus.

Materials and Methods

This research study involved the use of 34 brachial plexuses from 17 medical cadavers. The cadavers consisted of 11 males and 6 females. Cadavers were identified via assigned specimen numbers. Materials used for proper dissection of the cadavers include surgical shears, spacers, paper towels, scalpels, and forceps. Laboratory personal protective equipment was also used. The posterior triangles of all cadavers were dissected to expose the brachial plexus nerve roots (C5-T1) and trunks. If the contribution to the brachial plexus by an additional spinal nerve root was suspected, we continued the dissections until all surrounding structures were removed. Anatomical structures were compared to published descriptions of normal brachial plexus. All variations of anatomical structures were photographed and recorded.

Results

Anomalies discovered in the dissection of 34 brachial plexus include: 4 out of 11 male cadavers with C4-C6 joining to form the upper trunk (36%), 1 out of 6 female cadavers with C4-C6 joining to form the upper trunk (17%), 1 out of 11 male cadavers with C5-C7 joining to form the upper trunk with no middle trunk present (9%), 2 out of 6 female cadavers with C7-T1 joining to form the lower trunk with no middle trunk present (33%), and 2 out of 11 male cadavers with C7-T1 joining to form the lower trunk with no middle trunk present (18%).

Conclusion

Dissection of 17 cadavers yielded a 53% chance of encountering an anatomical brachial plexus anomaly. Of the 17 cadavers dissected, 9 cadaver dissections uncovered brachial plexus different from those described as normal anatomical structures according to the American Association for Anatomy.

Significance and Implication

The brachial plexus is an essential part of the human body, providing motor and sensory fibers to the upper limb. It is important to study these variations so medical professionals gain a better understanding of the patient’s presentation with lesions to the brachial plexus. Pathologies caused by disruption of normal brachial plexus structures and physiology create much suffering for patients. Traumatic events are the leading causes of injury to the brachial plexus. Typically, brachial plexus injuries manifest as stretch injuries to the neck or compression injuries to the shoulder. In adulthood, these injuries tend to be the result of motorcyclists' involvement in traffic accidents. In infancy, the natural birthing process may induce brachial plexus damage if the infant’s arm rotates medially with contralateral flexion of the neck as the infant travels through the vaginal canal. Reparation of trauma to the brachial plexus requires surgical intervention. Anatomical variations have proven to create complications during corrective brachial plexus surgical procedures. Awareness of the anatomical variations of brachial plexus roots and trunks is essential for a successful surgical procedure for reparation of damage to the brachial plexus.