Anatomical Variations in the Intratemporal Course of the Facial Nerve in Wet Temporal Bones: A Cross-sectional Study
- 1Professor and Head, Department of Otorhinolaryngology, Dr. D. Y. Patil Medical College, Hospital and Research Centre, Pune, Maharashtra, India.
Abstract
Introduction: The Facial Nerve (FN) has a complex intratemporal course within the temporal bone and maintains close anatomical relationships with middle ear and mastoid structures, rendering it particularly vulnerable to iatrogenic injury during otologic surgery. Anatomical variations in its course, including facial canal dehiscence and Oval Window (OWL) overhang, may significantly increase surgical difficulty and risk of FN injury. Aim: To study the anatomical variations in the intratemporal course of the FN in wet temporal bones and correlate them with mastoid pneumatisation patterns. Materials and Methods: The present cross-sectional study was conducted in the Department of Otorhinolaryngology in the temporal bone dissection laboratory at Dr. D.Y. Patil Medical College and Research Institute, Pune, Maharashtra, India, over 18 months from March 2024 to June 2025. Fifty wet cadaveric temporal bones were dissected under an operating microscope. Mastoid pneumatisation patterns were recorded, and the lengths of the tympanic and mastoid segments were measured. Second Genu (SG) angle, depth from mastoid cortex, degree of descent, facial canal dehiscence, OWL overhang, lateral hump, and key anatomical distances were recorded. Statistical analysis was performed using a Chi-square test. Results: The majority of specimens showed a pneumatised mastoid pattern 39 (78%), followed by diploeic 6 (12%) and sclerotic 5 (10%) mastoids. Facial canal dehiscence was identified in 6 (12%) specimens, OWL window overhang in 8 (16%), and lateral hump at the SG in 6 (12%). The mean tympanic and mastoid segment lengths were 9.18±1.044 mm and 13.89±1.297 mm, respectively. A statistically significant association was found between mastoid pneumatisation and oval window overhang (p=0.005). Conclusion: Clinically, significant variations such as facial canal dehiscence, oval window overhang and lateral hump occur in a considerable proportion of cases.
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BibTeX
@article{ingale2026anatomical,
title = {{Anatomical Variations in the Intratemporal Course of the Facial Nerve in Wet Temporal Bones: A Cross-sectional Study}},
author = {Mayur Ingale and Sarthak Gupta},
journal = {Journal of Clinical and Diagnostic Research},
year = {2026},
month = oct,
doi = {10.7860/jcdr/2026/89351.24666},
url = {https://doi.org/10.7860/jcdr/2026/89351.24666},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Anatomical Variations in the Intratemporal Course of the Facial Nerve in Wet Temporal Bones: A Cross-sectional Study
AU - Mayur Ingale
AU - Sarthak Gupta
PY - 2026
DA - 2026/10/30
JO - Journal of Clinical and Diagnostic Research
DO - 10.7860/jcdr/2026/89351.24666
UR - https://doi.org/10.7860/jcdr/2026/89351.24666
AB - Introduction: The Facial Nerve (FN) has a complex intratemporal course within the temporal bone and maintains close anatomical relationships with middle ear and mastoid structures, rendering it particularly vulnerable to iatrogenic injury during otologic surgery. Anatomical variations in its course, including facial canal dehiscence and Oval Window (OWL) overhang, may significantly increase surgical difficulty and risk of FN injury. Aim: To study the anatomical variations in the intratemporal course of the FN in wet temporal bones and correlate them with mastoid pneumatisation patterns. Materials and Methods: The present cross-sectional study was conducted in the Department of Otorhinolaryngology in the temporal bone dissection laboratory at Dr. D.Y. Patil Medical College and Research Institute, Pune, Maharashtra, India, over 18 months from March 2024 to June 2025. Fifty wet cadaveric temporal bones were dissected under an operating microscope. Mastoid pneumatisation patterns were recorded, and the lengths of the tympanic and mastoid segments were measured. Second Genu (SG) angle, depth from mastoid cortex, degree of descent, facial canal dehiscence, OWL overhang, lateral hump, and key anatomical distances were recorded. Statistical analysis was performed using a Chi-square test. Results: The majority of specimens showed a pneumatised mastoid pattern 39 (78%), followed by diploeic 6 (12%) and sclerotic 5 (10%) mastoids. Facial canal dehiscence was identified in 6 (12%) specimens, OWL window overhang in 8 (16%), and lateral hump at the SG in 6 (12%). The mean tympanic and mastoid segment lengths were 9.18±1.044 mm and 13.89±1.297 mm, respectively. A statistically significant association was found between mastoid pneumatisation and oval window overhang (p=0.005). Conclusion: Clinically, significant variations such as facial canal dehiscence, oval window overhang and lateral hump occur in a considerable proportion of cases.
SN - 2249-782X
SN - 0973-709X
ER -