Levator ani muscle innervation: Anatomical study in human fetus.
OBJECTIVE
To characterize the nature and function of the levator ani muscle innervation pathways and to perform a comprehensive three-dimensional reconstruction of female pelvic innervation.


METHODS
A computer-assisted anatomical dissection protocol was applied to seven female human fetuses, after approval from the national biomedicine agency. Specimens were serially sectioned and immunostained for overall (antibody against protein S100), somatic (antibody against peripheral myelin protein 22), adrenergic (antibody against tyrosine hydroxylase), cholinergic (antibody against vesicular acetylcholine transferase), and nitrergic (antibody against the neural isoform of nitric oxide synthase) nerve fibers. Slides were digitized for three-dimensional reconstructions using WinSurf®.


RESULTS
Three main nerve pathways to the levator ani muscle were observed: the levator ani nerve, the pudendal nerve, and the inferior hypogastric plexus. The pudendal nerve was both somatic and autonomic, located below the levator ani muscle (infralevator pathway), supplying innervation to the inferior aspect of the levator ani muscle. The levator ani nerve was solely somatic, located above the levator ani muscle (supralevator pathway), supplying innervation to the superior aspect of the levator ani muscle. The inferior hypogastric plexus nerve fibers were solely autonomic, located in between the levator ani muscle and pelvic organs (endolevator pathway), supplying innervation to the medial portion of the levator ani muscle.


CONCLUSIONS
Our study provides a new representation of levator ani muscle innervation with three nerve pathways, and the levator ani muscle itself as an anatomical landmark.
UMR 1195, Université Paris-Sud, INSERM, Université Paris-Saclay, Le Kremlin-Bicetre, France.|EA4465 URDIA, University Paris Descartes, Paris, France.
Krystel
K
Nyangoh Timoh
UMR 1195, Université Paris-Sud, INSERM, Université Paris-Saclay, Le Kremlin-Bicetre, France.|Department of Urology, Hopitaux Universitaires Paris-Sud, Le Kremlin-Bicetre, France.
Thomas
T
Bessede
UMR 1195, Université Paris-Sud, INSERM, Université Paris-Saclay, Le Kremlin-Bicetre, France.
Cedric
C
Lebacle
UMR 1195, Université Paris-Sud, INSERM, Université Paris-Saclay, Le Kremlin-Bicetre, France.
Mazen
M
Zaitouna
Department of Fetal Pathology, Hopitaux Universitaires Paris-Sud, Clamart, France.
Jelena
J
Martinovic
UMR 1195, Université Paris-Sud, INSERM, Université Paris-Saclay, Le Kremlin-Bicetre, France.
Djibril
D
Diallo
UMR 1195, Université Paris-Sud, INSERM, Université Paris-Saclay, Le Kremlin-Bicetre, France.
Maud
M
Creze
EA4465 URDIA, University Paris Descartes, Paris, France.
Jean-Marc
JM
Chevallier
Department of Obstetrics and Gynecology, Tenon University Hospital, France Research Unit S938, Pierre and Marie Curie University, Paris, France.
Emile
E
Darai
UMR 1195, Université Paris-Sud, INSERM, Université Paris-Saclay, Le Kremlin-Bicetre, France.
Gérard
G
Benoît
UMR 1195, Université Paris-Sud, INSERM, Université Paris-Saclay, Le Kremlin-Bicetre, France.|EA4465 URDIA, University Paris Descartes, Paris, France.
David
D
Moszkowicz
D004210:Dissection; D005260:Female; D006801:Humans; D007001:Hypogastric Plexus / Q000033:anatomy & histology*; D018482:Muscle, Skeletal / Q000294:innervation*; D009434:Neural Pathways / Q000033:anatomy & histology; D017773:Pelvic Floor / Q000294:innervation*; D060525:Pudendal Nerve / Q000033:anatomy & histology*
anatomy; fetus; innervation; levator ani muscle; pelvic floor dysfunction