Motor branching patterns of the ulnar nerve in the forearms of fetal cadavers

The muscular branching patterns of the ulnar nerve in fetal forearms

OBJECTIVE

We aimed to present our findings systematically by examining the muscular branching patterns of the ulnar nerve (UN) in the forearms of fetuses.

METHODS

This study was conducted on the 52 forearms of 26 formalin-fixed fetal cadavers with gestational ages varying between 19 and 37 weeks. The anatomical dissection was performed by using stereomicroscope with × 8 magnification. The numbers of muscular branches leaving UN and their order of leaving main nerve were noted down. The findings were classified according to the muscles they reached, and branching typing was done.

RESULTS

It was found that a total of 2-6 muscular branches left UN to reach flexor carpi ulnaris (FCU) and flexor digitorum profundus (FDP). UN was classified by separating into five main types according to the number of muscular branches, and these types were classified into 16 different branching patterns according to the order of branches leaving from the main trunk and going to FCU and FDP. The pattern where two branches left UN was classified as Type I (n = 6), three branches left was classified as Type II (n = 18), four branches left was classified as Type III (n = 24), five branches left was classified as Type IV (n = 3), and six branches left was classified as Type V (n = 1). Martin-Gruber connection occurred in 17 (32.7%) fetal forearms.

CONCLUSION

We believe that the information that UN can demonstrate different branching patterns on the forearm can help the surgeons to prevent complications that may develop in potential nerve injury during the selection and transfer of relevant branch.

Neuroimaging perspectives on fetal motor behavior

We are entering a new era of understanding human development with the ability to perform studies at the earliest time points possible. There is a substantial body of evidence to support the concept that early motor behaviour originates from supraspinal motor centres, reflects neurological integrity, and that altered patterns of behaviour precede clinical manifestation of disease. Cine Magnetic Resonance Imaging (cineMRI) has established its value as a novel method to visualise motor behaviour in the human fetus, building on the wealth of knowledge gleaned from ultrasound based studies. This paper presents a state of the art review incorporating findings from human and preclinical models, the insights from which, we propose, can proceed a reconceptualisation of fetal motor behaviour using advanced imaging techniques. Foremost is the need to better understand the role of the intrauterine environment, and its inherent unique set of stimuli that activate sensorimotor pathways and shape early brain development. Finally, an improved model of early motor development, combined with multimodal imaging, will provide a novel source of in utero biomarkers predictive of neurodevelopmental disorders.

Innervation of the Flexor Digitorum Profundus: A Systematic Review

Purpose

The aim of this study was to review the innervation of the flexor digitorum profundus (FDP).

Methods

In PubMed and Scopus, terms (Flexor digitorum profundus OR FDP) AND (innervation OR nerve) were used, resulting in 233 and 281 papers, respectively. After excluding 142 duplicates, 73 abstracts were reviewed. Forty-seven abstracts were excluded, 26 full papers were reviewed, and 17 papers were analyzed.

Results

In most cases (97.6%), the index FDP was innervated by the anterior interosseous nerve (AIN). Dual innervation from the AIN and ulnar nerve (UN) was observed in 2.4% of papers. In majority (76.8%), the middle FDP received dual innervation from the AIN and the UN. The rest was innervated by the AIN only (22.0%) or the UN only (1.2%). In most cases (85.4%), the ring FDP was innervated by the UN only. The rest (14.6%) received dual innervation from the AIN and the UN. In majority of cases (64.6%), the little FDP was innervated by the UN only. The rest (35.4%) received dual innervation from the AIN and the UN. The AIN entered the FDP at 107.63 (8.80) mm from the elbow, corresponding to 26.75% (2.17%) of the forearm length, measured proximally. The average number of AIN branches to the FDP was 2.27 (1.33). The average number of UN branches to the FDP was 1.37 (0.94). In 8.8% of limbs, a communicating branch supplied the FDP. Among the limbs with a communicating branch, 32.3% had branches supplying the FDP.

Conclusion

The results of this study may be useful in managing nerve injury patients.