The rabbit brachial plexus as a model for nerve injury and repair Part 1: Anatomic study of the biceps and triceps innervation

Abstract

Purpose Animal models can be helpful in evaluating new surgical strategies for brachial plexus reconstruction. While several groups have already used the rabbit brachial plexus to model injury, reports conflict in anatomic detail and do not identify a nerve‐muscle pair to measure motor function recovery after reconstruction. The purpose of the current study is to describe the innervations of the biceps and triceps muscles in rabbits, which are both amenable to study in brachial plexus injury models. Materials and Methods Thirteen rabbits weighing 2–2.5 kg were anesthetized. Six rabbits were sacrificed and dissected using loupe and microscope magnification to understand the overall morphology of the brachial plexus. Seven rabbits underwent electrophysiologic investigation. A bipolar nerve stimulator was used to systematically stimulate the roots, trunks and divisions, and nerve branches of the rabbit brachial plexus and compound muscle action potential was used to record muscle response. Nerve length and width measurements were not recorded. Results Roots contributing to the brachial plexus were C5, C6, C7, C8, and T1. In contrast to other anatomical studies, T2 did not contribute to the brachial plexus. The triceps was innervated by the radial nerve, which received contributions from C6 (1.6 mA), C7 (1.9 mA), C8, and T1 (12.2 mA).The biceps had dual innervation (proximally and distally). The proximal branch received contributions from C6 (3.5 mA) and C7 (5mA). The distal portion was innervated by a branch from the median nerve, which received innervation from C6, C7, C8, and T1. Conclusions The overall structure of rabbit brachial plexus is described and innervation of the biceps and triceps is described in detail. This anatomic investigation will form the basis of a future brachial plexus model of injury and repair.

Brachial plexus anatomy in the miniature swine as compared to human

“…While the human brachial plexus is organized into key trunks, divisions, and cords, most animal models (pigs, cats, dogs, oxen, sheep, and goats) do not have this notable organization of the nerves (Septimus Sisson and Getty, 1986). While rabbits also do not have notable divisions and cords, they do have upper, middle, and lower trunks (Kollitz et al, 2020). Primates, most similar to humans, have three trunks, varying divisions, and three cords (Figueredo‐da‐Silva et al, 2021).…”

Brachial plexus nerve injury and repair in a rabbit model part II: Does middle trunk injury result in loss of biceps function while repair results in recovery of biceps function

“…In this study, we sought to create an animal model of brachial plexus injury and motor functional recovery rather than simulate the injury in the lower extremity. To appropriately validate a model, we undertook (a) to accurately describe the anatomy (Kollitz et al, ) (b) to identify a nerve to injure and the muscle that will respond to injury and repair; (c) to validate a measure of motor functional outcome, and (d) to demonstrate though a proof‐of‐concept experiment that nerve damage will lead to a loss of motor function, with no alternative innervations for recovery. In addition, our study uses ultrasound measurement of muscle cross‐sectional area, a noninvasive measure that can be repeated over time.…”

“…Previous rabbit brachial plexus anatomy and biceps innervation studies demonstrated that it has a dual innervation primarily by C7 via the cranial portion of the caudal trunk (“middle trunk” homolog) and a distal innervation by a median nerve branch (C7, C8, T1) (Kollitz, Giusti, Friedrich, Bishop, & Shin, ). Division of the distal innervation, resulted in a biceps innervated only via the “middle trunk” homolog.…”

A Rabbit Model for Peripheral Nerve Reconstruction Studies Avoiding Automutilation Behavior

“… 19 In an effort to better analyze nerve regeneration and provide another model of nerve injury, recent studies have been performed in an attempt to better characterize the rabbit brachial plexus and its motor innervation. 47 However, nerve selection beyond the sciatic nerve or its divisions has been limited, with the peroneal nerve being the second most well-studied nerve in just 18% of studies. An isolated injury to the tibial nerve has been selected in only 8% of studies.…”