A previously undescribed dorsal branch of the anterior interosseous nerve

Shaw, Vivien; Morris, John

Abstract

The path of the anterior interosseous nerve is commonly described as passing along the deep compartment of the volar aspect of the forearm where it innervates the muscles in that compartment including pronator quadratus. Previous electromyographical studies (Stuart 1996) (Gordon et al. 2004)have recorded electrical activity in pronator quadratus during supination when a needle electrode was inserted from the dorsal aspect of the forearm. The textbook-stated functions of pronator quadratus are to pronate the forearm and to oppose separation of the distal ends of the ulna and radius. Electrical activity during supination was unexpected. To investigate this we analysed the area dorsal to pronator quadratus. We examined 18 human forearms, nine left, nine right, from 11individuals, six male, five female, average age 85, range 66–99,bequeathed to the Oxford University Medical School under the Human Tissue Act. Skin and subcutaneous fat were removed from the dorsal forearm and extensor digitorum was retracted to enable visualisation of the terminal portion of the anterior interosseous nerve. In all forearms studied a previously undescribed dorsal branch of the anterior interosseous nerve, which passes through the interosseous foramen with the anterior interosseous artery was found. The branch was largely obscured by the artery. It re-entered into the deep head of pronator quadratus from the dorsal aspect and, in many cases, also gave small branches into the tissues of extensor pollicis longus, extensor indicis and extensor digiti minimi and adjacent connective tissues. We hypothesise that this nerve branch relates to the findings of Stuart and Gordon of electrical activity in pronator quadratus during supination; the deep head is ideally placed to prevent any separation of the distal radio-ulnar joint. Further studies are required in order to establish the exact function of these nerve branches and the role that pronator quadratus plays insupination.

Citation

Shaw, V., & Morris, J. (2014, July). A previously undescribed dorsal branch of the anterior interosseous nerve. Poster presented at Anatomical Society Summer Meeting: Skin and Bones, Bradford, UK

• Presentation Conference Type: Poster
• Conference Name: Anatomical Society Summer Meeting: Skin and Bones
• Start Date: Jul 8, 2014
• End Date: Jul 10, 2014
• Deposit Date: Oct 22, 2021
• DOI: https://doi.org/10.1111/joa.12271
• Public URL: https://hull-repository.worktribe.com/output/3858398
• Additional Information: Abstract A13 published in Journal of Anatomy Volume 226, Issue 2, February 2015, Pages 189-213