Purpose: Little information is known about the mentalis nerve course from the lower lip approximation margin (free margin) to the upper lip. Likewise, no difference in nerve distribution has been observed between the cutaneous and mucosal parts of the lip. Therefore, this study reexamined mentalis nerve morphology.
Methods: For macroscopic observations, three fresh cadavers were dissected (one male and two females; aged 78-93). We also evaluated histological sections obtained from five donated elderly cadavers (two males and three females, aged 82-96 years) and 15 human fetuses (11-40 weeks or crown-rump length 80-372 mm). Immunohistochemical analysis for S100 protein and tyrosine hydroxylase was performed.
Results: In both fetuses and adult cadavers, one to three nerve branches ran upward in the submucosal tissue from the mental foramen. Near the free margin of the lip, some branches passed through the orbicularis oris muscle layer toward the lip skin, whereas others followed a reversed J-shaped course along the free margin. Nerve twigs ran in parallel beneath the mucosa, whereas wavy nerve twigs attached to the basal lamina of the lip epidermis. The difference in nerve endings abruptly occurred at the skin-mucosal junction. Tyrosine hydroxylase-positive sympathetic nerve twigs surrounded arteries and formed a branch composed of S100-negative unmyelinated fibers.
Conclusion: The lower lip skin was innervated by a perforating branch passing through the orbicularis oris muscle, that was different from the lip mucosa. A sudden change in the nerve ending configuration at the mucocutaneous junction seemed to develop postnatally.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1007/s00276-024-03365-2 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Enhancing surgical precision: a novel electromyography finding for confident identification of the root exit zone during microvascular decompression surgery.
J Neurosurg
September 2024
1Department of Neurosurgery, Konkuk University Medical Center, Seoul; and.
Objective: The lateral spread response (LSR) is an important electrophysiological sign that predicts successful decompression in patients undergoing microvascular decompression (MVD) for hemifacial spasm (HFS). However, LSRs do not consistently correlate with clinical outcomes, and there are cases in which LSRs are absent. In this study, the authors identified a unique pattern on facial nerve electromyography (EMG) when the root exit zone (REZ) is touched.
View Article and Find Full Text PDFImpact of Latency Variations on the Predictive Value of Facial Nerve Proximal-to-Distal Amplitude Ratio during Vestibular Schwannoma Surgery.
J Neurol Surg B Skull Base
August 2024
Department of Neurosurgery, Emory University, Atlanta, Georgia, United States.
Article Synopsis
- This study examines how variations in the latency of compound muscle action potential (CMAP) relate to the predictive value of the facial nerve’s proximal-to-distal amplitude ratio after vestibular schwannoma surgery.
- It involved 48 patients who underwent facial nerve stimulation, with outcomes assessed using House-Brackmann grades to classify nerve function and defining a P/D amplitude ratio of >0.6 as indicative of good function.
- Findings showed that the P/D amplitude ratio was most predictive of good facial nerve function when proximal latency was between 6-8 ms, with higher sensitivity and specificity, while latencies below or above this range showed less reliable predictive abilities.
Facial nerve electrical motor evoked potential in cerebellopontine angle tumors for its anatomical and functional preservation.
Surg Neurol Int
May 2024
Department of Neurosurgery, Neurosurgery Clinic,Birgunj,Nepal.
Background: Among the technical measures to preserve facial nerve (FN) function, intraoperative neuromonitoring has become mandatory and is constantly being scrutinized. Hence, to determine the efficacy of FN motor evoked potentials (FNMEPs) in predicting long-term motor FN function following cerebellopontine angle (CPA) tumor surgery, an analysis of cases was done.
Methods: In 37 patients who underwent CPA surgery, FNMEPs through corkscrew electrodes positioned at C5-C6 and C6-C5 (C is the central line of the brain as per 10-20 EEG electrode placement) were used to deliver short train stimuli and recorded from the orbicularis oculi, oris, and mentalis muscles.
Mentalis nerve branches supplying the lower lip revisited: a study of human fetuses and donated elderly cadavers.
Surg Radiol Anat
June 2024
Department of Anatomy, Tokyo Dental College, 2-9-18 Kanda-Misakicho, Chiyoda-ku, Tokyo, 101-0061, Japan.
Purpose: Little information is known about the mentalis nerve course from the lower lip approximation margin (free margin) to the upper lip. Likewise, no difference in nerve distribution has been observed between the cutaneous and mucosal parts of the lip. Therefore, this study reexamined mentalis nerve morphology.
View Article and Find Full Text PDFImportance of changes in abnormal muscle responses during microvascular decompression for hemifacial spasm.
Clin Neurophysiol Pract
March 2024
Department of Neurosurgery, Brain Research Institute, University of Niigata, Niigata-City, Niigata, Japan.
Objective: To determine if compression sites of the facial nerve correlate with immediate postoperative outcomes in patients with hemifacial spasm (HFS), and if changes in the waveform of abnormal muscle response (AMR) during microvascular decompression (MVD) for HFS can predict the postoperative course.
Methods: In this retrospective review, we evaluated 50 patients with HFS who underwent AMR monitoring during MVD. The ratios of amplitude and duration of AMR waveforms were computed by comparing baseline with final examinations.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!