Neurovasculature of the Upper Extremity in the Aye‐aye, Daubentonia madagascariensis

Abstract

The aye‐aye, Daubentonia madagascariensis, is an arboreal lemuroid primate and is the sole representative of its genus. The aye‐aye has unique anatomical characteristics including a thin, long, flexible third digit, unique dental anatomy, a single pair of inguinal mammary glands, greater brain size than those of other strepsirrhines, and large mobile ears that separate it from other lemuroids and make it an interesting organism to study from an anatomical, developmental, and evolutionary standpoint. The aye‐aye also has a distinctive method of obtaining its food from trees known as percussive foraging, which entails tapping on wood with its long middle finger, listening to the resulting sounds to determine the locations of cavities that may contain larvae, and then scooping out the larvae with its specialized third digit. The bony and muscular anatomy of the brachium, antebrachium, and manus of the aye‐aye has been previously studied and described in detail. However, there have been no studies that have described and depicted the complete neurovasculature of the forelimb of the aye‐aye, including the important brachial plexus. Given the unique anatomy and behavioral forelimb adaptations of this species, understanding the various nerves and blood vessels in relation to the musculature will provide a more complete picture of aye‐aye functional morphology and comparative anatomy.This study identifies and describes the neurovasculature of the forelimb of the aye‐aye with emphasis placed on the musculature and neurovasculature on the hand. The forelimbs from one female Daubentonia madagascariensis were dissected, photographed, and described in detail. In this specimen, we confirmed that the anatomy of the forelimb muscles was generally consistent with previous descriptions, although we observed a few minor variations. The brachial plexus was found to originate from the C5‐T2 roots, a feature that has also been observed in other lemurs and rhesus monkeys. The large deltoid and brachioradialis muscles observed in this specimen may serve to support the frequent use of head‐first descent, which requires a robust shoulder girdle and specific alterations in hand and body position that allow the forelimbs to undergo increased compressive forces. Future studies will analyze the development of the muscles of the arm and hand, along with the vasculature that migrated with them, and also compare them to the developmental patterns of related primates which can give insight into the aye‐aye's specialized adaptations.Support or Funding InformationThis research was supported by a Midwestern University Kenneth A. Suarez summer research fellowship to MA.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.