Axillary nerve course and position in the fetal period

Objectives: To examine the fetal axillary nerve to reveal and compare its morphometric features within the second and third trimester. Methods: This study was conducted at the Anatomy Department, School of Medicine, Mersin University, Mersin, Turkey. Thirty-five fetal shoulders were studied to provide anatomic data and to describe its position with regard to certain landmarks around the shoulder. Results: The shortest distance between the axillary nerve and the glenoid labrum was found 2.27 mm and 2.89 mm in the second and third trimester fetuses, respectively. The shortest distances between the anterior and posterior acromial tips and the axillary nerve were also measured and were used with arm length measurements to define the anterior and posterior indexes. Conclusion: The indexes show that the distance between the axillary nerve and the anterior/posterior acromial tips are approximately one-fourth of the arm length in both the second and third trimester fetuses. The data presented in this study will be of use to surgeons, particularly to pediatric and orthopedic surgeons who will undertake surgical procedures in the axilla and arm in the newborn or early childhood. Neurosciences 2015; Vol. 20 (4): 396-399 doi: 10.17712/nsj.2015.4.20150007 T is detailed knowledge regarding the morphological features of the axillary nerve in adults, however, it in the fetal period we encountered no information. Brachial plexus injuries have been reported with a rate of 0.38-2.6 per thousand live births. Shenaq et al1 mentioned that the diagnosis, observation, and therapy are the initial approaches to these injuries, and should be initiated immediately. They also stated that early surgical intervention is essential to maximizing the long-term improvements in selected patients by helping to prevent residual growth deformities and underdevelopment of the affected limbs. The surgical treatment options include the reconstruction and neurotization.2 For the axillary nerve injuries, for example in case of C5-C6 avulsion, in which the upper roots have been avulsed from the spinal cord, and the clinical picture is that of a classic Erb palsy, they preferred to use neurotization technique. In this type of avulsion, the upper roots are not available as donors, and the C7-T1 roots are uninvolved. So, the suprascapular nerve is neurotized by the ipsilateral spinal accessory nerve, and the axillary nerve is neurotized by redundant branches to the triceps to ideally restore shoulder and elbow function. The thoracodorsal or the subscapular branches can also be neurotized to the axillary nerve to provide better shoulder function. Thus, anatomical details of the axillary nerve in fetal period become essential for such operations. We carried out this study to evaluate these parameters regarding the axillary nerve anatomy, which may be helpful to surgeons in certain conditions, such as end-to-side neurorrhaphy in brachial plexus reconstruction, neurotization, proximal humeral fracture repair, and shoulder dislocation treatment in the early childhood. Methods. This study was performed on 35 spontaneously aborted fetuses (21 female, 14 male), aged between 20 and 37 weeks of gestation. The material came from the collection of the Anatomy Department of the School of Medicine. Fetuses without any pathology or anomaly in their extremities were included in the study. This study was approved by the Ethics Board of the School of Medicine, Mersin University. The following parameters were examined in this study: location, course, and branches of the axillary nerve; diameter of the axillary nerve where it exits from the quadrangular space; course of the axillary nerve deep to the deltoid muscle, and to determine the innervation patterns of the axillary nerve branches to the deltoid muscle, and distance of the axillary nerve from certain landmarks. Gestational ages of the fetuses were determined using biparietal diameter, head circumference, and foot length. Fetuses were divided into 2 groups according to their gestational ages: Group 1 19 second trimester fetuses; and Group 2 16 third trimester fetuses. Dissections were performed with a Disclosure. This study was supported by the Scientific Research Projects Commission (BAP-SBE TTB (TU) 2012-3 YL) of Mersin University, Mersin, Turkey.