Sihler's Staining Research Articles

Intramuscular innervation of the lateral rectus muscle evaluated using sihler's staining technique: Potential application to strabismus surgery.

The latest research suggests that the abducens nerve may be divided into subbranches that reach functionally distinct zones of the lateral rectus muscle. The goal of the study was to examine this muscle's innervation, including the detailed distribution of the intramuscular subbranches of the abducens nerve. Twenty-five lateral rectus muscle specimens were harvested (with the orbital segment of the abducens nerve), fixed in 10% formalin solution, and stained with Sihler's whole mount nerve staining technique. Subbranches running to the lateral rectus divided into two main groups: superior and inferior. Both groups of subbranches are distributed in a fan-shaped manner, show a characteristic "tree-like" branching pattern and form terminal plexus near the proximal half of the lateral rectus muscle. However, some smaller subbranches run as far as the muscle's insertion, and recurrent subbranches also reach its origin. With respect to their course to the muscle's origin or insertion, the smallest subbranches running within the muscle may be associated with innervation of the tendon. In the majority of cases (88%), superior and inferior subbranches of the abducens nerve overlapped in the central one-third of the lateral rectus muscle's width so that any clearly distinct anatomical segments of the muscle could be observed based on Sihler's technique. In the remaining 12% of specimens, superior and inferior groups of subbranches innervated two distinct compartments of the lateral rectus muscle with no overlapping. Dense, fan-shaped distribution of abducens nerve intramuscular subbranches can be observed within the lateral rectus muscle. Clin. Anat. 33:585-591, 2020. © 2019 Wiley Periodicals, Inc.

Detailed anatomy of the trochlear nerve in the superior oblique muscle.

The purpose of this study was to elucidate the detailed anatomy of the trochlear nerve in the superior oblique muscle (SOM) and the intramuscular innervation pattern using Sihler staining. SOMs were dissected from their origin to the insertion in 28 eyes of 14 cadavers. The following distances were determined: from the SOM insertion to the trochlear, from the trochlear to the entry site of the anterior branch or posterior branch, and the widths of the main trunk and anterior and posterior branches. Sihler staining was then performed. The trochlear nerve traveled straight ahead medially and divided. Eighteen of 28 (64.3%) orbits showed two anterior and posterior branches, six (21.4%) showed three branches, and four (14.3%) showed no branching. The most distally located intramuscular nerve ending was observed at 62.4 ± 2.4% of the length of each muscle (35.8mm from insertion when considering that the length of the SOM was 57.4mm) and at 29.9 ± 3.2% of the length of each muscle (17.2mm from the trochlear). Additionally, the length of the intramuscular arborization part was 9.4 ± 1.1% of the length of the SOM (5.4mm when considering that the length of the SOM was 57.4mm). Nonoverlap between two intramuscular arborizations of the nerve was detected in 20 of 28 cases (71.4%). Eight cases (28.6%) showed a definite overlap of two zones. This study provided a good understanding of the anatomy of the trochlear nerve in the SOM.

Effective botulinum toxin injection guide for treatment of cervical dystonia.

The aim of this study was to elucidate the distribution of the accessory nerve within the sternocleidomastoid muscle (SCM) to aid identifying the optimum sites for botulinum neurotoxin (BoNT) injections and applying chemical neurolysis. Thirty SCM specimens from 15 Korean cadavers were used in this study. Sihler's staining was applied to 10 of the SCM specimens. Transverse lines were drawn in 20 sections to divide the SCM into 10 divisions vertically, and a vertical line was drawn into the medial and lateral halves from the mastoid process to the sternoclavicular joint. The most densely innervated areas were 5/10-6/10 and 6/10-7/10 along the lateral and medial parts of the muscle, respectively. We suggest injecting BoNT in the medial region 6/10-7/10 along the SCM prior to injecting in the lateral region 5/10-6/10 along the muscle to ensure safe and effective treatment. Clin. Anat. 33:192-198, 2020. © 2019 Wiley Periodicals, Inc.

Hip Adductor Intramuscular Nerve Distribution Pattern of Children: A Guide for BTX-A Treatment to Muscle Spasticity in Cerebral Palsy.

To investigate the intramuscular nerve distribution pattern in the hip adductors of children and to precisely locate the injection site for botulinum toxin type A (BTX-A) as a treatment for hip adductor spasticity in children with cerebral palsy. Modified Sihler's whole mount nerve staining technique was employed to observe the distribution of intramuscular nerves in hip adductors of children and to further locate zones where terminal nerves are concentrated. The terminal nerves of the adductor longus appeared in a longitudinal distribution band parallel to the line between the upper 1/3 point of the lateral boundary and the center of the medial boundary. In adductor brevis, the terminal nerves showed a sheet-like distribution with a nerve dense area located in the middle of the muscle belly that extends from the upper-inner region to the lower-outer region. Gracilis showed a dense area of terminal nerves in the middle of the muscle belly, closer to the posterior boundary. In adductor magnus, the dense area of terminal nerves showed a sheet-like distribution in the middle and lower region of the muscle belly. The dense area of terminal nerves in the pectineus was located in the middle of the muscle belly. This study is the first to systematically investigate the intramuscular nerve distribution pattern in the hip adductors. The results indicated that the best targets for BTX-A injection, when treating spasticity, are the dense regions of terminal nerves described above.

Anatomical Variations of the Pectoralis Major Muscle: Notes on Their Impact on Pectoral Nerve Innervation Patterns and Discussion on Their Clinical Relevance.

Background The presented study attempts to classify individual anatomical variants of the pectoralis major muscle (PM), including rare and unusual findings. Rare cases of muscular anomalies involving the PM or its tendon have been presented. An attempt has also been made to determine whether anatomical variations of the PM may affect the innervation pattern of the lateral and medial pectoral nerves. Material and Methods The research was carried out on 40 cadavers of both sexes (22 males, 18 females), owing to which 80 PM specimens were examined. Results Typical PM structure was observed in 63.75% of specimens. The most frequently observed variation was a separate clavicular portion of the PM. In one female cadaver (2.5% of specimens) the hypotrophy of the clavicular portion of the PM was noticed. In two male cadavers (5% of specimens) the fusion between the clavicular portion of the PM and the deltoid muscle was observed. In one of those cadavers, small sub-branches of the lateral pectoral nerve bilaterally joined the clavicular portion of the deltoid muscle. The detailed intramuscular distribution of certain nerve sub-branches was visualized by Sihler's stain. PM is mainly innervated by the lateral pectoral nerve. In all specimens stained by Sihler's technique, the contribution of the intercostal nerves in PM innervation was confirmed. Conclusions Surgeons should be aware of anatomic variations of the PM both in planning and in conducting surgeries of the pectoral region.

Intramuscular innervation of the subscapularis muscle and its clinical implication for the BoNT injection: An anatomical study using the modified Sihler's staining.

Shoulder pain is commonly associated with spasticity of the rotator cuff muscles including the subscapularis (SSC). The aim of this study was to elucidate the intramuscular innervation pattern of the SSC using the modified Sihler's staining technique to facilitate the targeting of botulinum neurotoxin (BoNT) injections to alleviate shoulder spasticity. Ten SSC specimens (mean age, 81.5 years) were used in this study. Modified Sihler's staining was used to clarify the muscle and to stain the intramuscular nerves. Their extramuscular and intramuscular innervation patterns were examined. The upper subscapular, lower subscapular, thoracodorsal, and axillary nerves (USN, LSN, TDN, and AXN) innervated the SSC in 100%, 80%, 20%, and 40% of specimens, respectively. There was an anastomosis between the USN and LSN in the central portion of the SSC in more than half of the cases. The USN innervated the overall portion of the muscle. In contrast, the additional branches from the TDN and AXN innervated the inferior SSC portion. The superficial branches of the USN were mostly distributed in the superior SSC portion while the deep branches were distributed in the inferior portion. As a major intramuscular nerve within the SSC, the USN should be targeted by a BoNT injection. Regarding the USN distribution, the aim should be to spread the BoNT injectate within the central SSC portion. For supplementary injection to the AXN, the lateral approach would be more appropriate than alternatives. A physician performing a BoNT injection should consider the intramuscular innervation of the SSC portion. Clin. Anat. 32:110-116, 2019. © 2018 Wiley Periodicals, Inc.

Anatomical analysis of the distribution patterns of occipital cutaneous nerves and the clinical implications for pain management.

PurposeEstablishing the distribution patterns of occipital cutaneous nerves may help us understand their contribution to various occipital pain patterns and ensure that a proper local injection method for treatment is employed. The aim of this study was to demonstrate the detailed distribution patterns of the greater occipital nerve (GON), lesser occipital nerve (LON), and third occipital nerve (TON) using the modified Sihler’s staining technique.MethodsTen human cadavers were manually dissected to determine the nerve distributions. Specimens from eight human cadavers were treated using the modified Sihler’s staining.ResultsIn all cases, distinct GON branches proceeded laterally and were intensively distributed in the superolateral area from their emerging point. Very thin twigs were observed at the middle-trisected area, which had a fan-like shape, in the middle-upper occipital region.ConclusionThe LON and TON distribution areas were biased to the lateral side below the superior nuchal line, although these nerves exhibited multiple interconnections or overlapping areas with the GON. Furthermore, a nerve rarified zone in the shape of an inverted triangle was identified in the middle occipital area. Our findings improve our understanding of the occipital nerve anatomy and will aid in the management of occipital pain in clinical practice.

Sensory Innervation of the Human Soft Palate.

The human soft palate plays an important role in respiration, swallowing, and speech. These motor activities depend on reflexes mediated by sensory nerve endings. To date, the details of human sensory innervation to the soft palate have not been demonstrated. In this study, eight adult human whole-mount (soft palate-tongue-pharynx-larynx-upper esophagus) specimens were obtained from autopsy. Each specimen was bisected in the midline, forming two equal and symmetrical halves. Eight hemi-specimens were processed with Sihler's stain, a whole-mount nerve staining technique. The remaining eight hemi-soft palates were used for immunohistochemical study. The soft palatal mucosa was dissected from the oral and nasal sides and prepared for neurofilament staining. Our results showed that the sensory nerve fibers formed a dense nerve plexus in the lamina propria of the soft palatal mucosa. There was a significant difference in the innervation density between both sides. Specifically, the oral side had higher density of sensory nerve fibers than the nasal side of the soft palate. The mean number and percent area of the sensory nerve fibers in the mucosa of the nasal side was 78% and 72% of those in the mucosa of the oral side, respectively (P < 0.0001). The data presented here could be helpful for further investigating the morphological and quantitative alterations in the sensory nerves in certain upper airway disorders involving the soft palate such as obstructive sleep apnea (OSA) and for designing effective therapeutic strategies to treat OSA. Anat Rec, 301:1861-1870, 2018. © 2018 Wiley Periodicals, Inc.

Clinical Implication of the Arterial Supplies and Their Anastomotic Territories of the Nasolabial Region for Avoiding Arterial Devastation and Complications during Soft Tissue Filler injection

BackgroundThe nasolabial fold is one of the most concerning aging property in the middle face region. This fold initially appears when people are coming age‐wise to their 20s. To correct this fold, the aesthetic nonsurgical procedure, known as filler injection, has been popularly and increasingly performed. However, the arterial complications occurring as a consequence of nasolabial fold filler injection have been continually reported in a recent year. Therefore, the objective of this study was to investigate the arterial location related to nasolabial fold filler injection sites and their anastomotic pathways.MethodsThirty hemi‐faces of 15 Thai embalmed cadavers were performed by dissection method. The nasolabial folds (NLF) were used as the anatomical landmarks: at the inferior margin of NLF (NLF1), at the level of the mid philtral horizontal line of NLF (NLF2), and at the inferior alar level of NLF (NLF3). Additionally, the 5 cadavers were underwent the modified Sihler's staining procedure to investigate the arterial anastomoses.ResultsThe main artery nearby of NLF1 and NLF2 was the facial artery. The facial artery located inferior and medial to NLF1 (Type I, 7 of 25 cases); moreover, the mean distance was 3.53 ± 2.11 mm along the X‐axis and 3.53 ± 1.75 mm along the Y‐axis. The facial artery located medial (Type V, 12 of 22 cases) to NLF2 and the distance was 4.93 ± 1.53 mm along the X‐axis. For the NLF3, there were several accurate arteries including the facial artery (10 of 30 cases), the infraorbital artery (9 of 30 cases) and the lateral nasal artery (10 of 30 cases). The anastomosis of the nasolabial arteries was served both as the connection of external‐external carotid system and the connection of internal‐external carotid system. The communication between the facial artery and the transverse facial artery was found in all specimen. Similarly, the communication between the facial artery and the infraorbital artery was seen in all cases. Finally, the anastomosis between the dorsal nasal artery and the lateral nasal artery was found in 5 of 10 (50%) cases.ConclusionAt the lower part of NLF, the facial artery must be concerned. The filler injection should not over approximately 1.5 mm medial to NLF1 and 1 mm inferior to NLF1. For the NLF2, the safe injection point should less than 2.5 mm in the medial direction. In order to prevent injury of the facial artery and the infraorbital artery, the injection tools must not be exceeded 2 mm lateral to NLF3, while the injection less than 2 mm medial to NLF3 is the harmless point for the lateral nasal artery. The possibility of blindness might be caused by the anastomosis between the lateral nasal artery and the dorsal nasal artery.Support or Funding Information The 100th Anniversary Chulalongkorn University Fund for Doctoral Scholarship from the Graduate School, Chulalongkorn University Overseas Academic Presentation Scholarship for Graduate Students from the Graduate School, Chulalongkorn University This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Detailed anatomy of the abducens nerve in the lateral rectus muscle.

The aims of this study were to elucidate the detailed anatomy of the abducens nerve in the lateral rectus muscle (LRM) and the intramuscular innervation pattern using Sihler staining. In this cohort study, 32 eyes of 16 cadavers were assessed. Dissection was performed from the LRM origin to its insertion. The following distances were measured: from LRM insertion to the bifurcation point of the abducens nerve, from LRM insertion to the entry site of the superior branch or inferior branch, from the upper border of the LRM to the entry site of the superior branch, from the lower border of LRM to the entry site of inferior branch, and the widths of the main trunk and superior and inferior branches. The single trunk of the abducens nerve divided into two branches 37 mm from insertion of the LRM, and 22 of 32 (68.8%) orbits showed only two superior and inferior branches with no subdivision. The superior branch entered the LRM more anteriorly (P = 0.037) and the superior branch was thinner than the inferior branch (P = 0.040). The most distally located intramuscular nerve ending was observed at 52.9 ± 3.5% of the length of each muscle. Non-overlap between the superior and inferior intramuscular arborization of the nerve was detected in 27 of 32 cases (84.4%). Five cases (15.6%) showed definite overlap of the superior and inferior zones. This study revealed the detailed anatomy of the abducens nerve in the LRM and provides helpful information to understand abducens nerve palsy. Clin. Anat. 30:873-877, 2017. © 2017 Wiley Periodicals, Inc.

Visualization of Differential Myelinated Cardiac Plexus Fiber Innervation in Heart Failure Using the Sihler's Stain Technique

A whole organ staining of myelinated cardiac plexus nerve fibers was conducted to visualize the cardiac innervation pathways in relation to heart failure. This visualization could better inform treatment for heart failure and contributory conditions, including arrhythmia, valve disease, and coronary artery disease. Two pathology‐free human cadaveric heart specimens and one acute heart failure human cadaveric heart specimen were acquired as opportunity samples from the West Virginia University School of Medicine (WVUSOM) Human Gift Registry. One pathology‐free specimen was sectioned into three transverse slabs prior to staining, while the remaining pathology free specimen and the acute heart failure specimen were stained whole. Sihler's stain rendered the myocardium semi‐translucent red‐pink to purple, while the myelinated cardiac plexus fibers were stained a deep violet. Definitive nerve density was found in three major locations: along the coronary vessels, at the mitral valve, and in the ascending aorta, including the aortic valve. Due to the Sihler's nonspecific staining of myelin, the fibers exact identity is unknown. The most probable identity is pararsympathetic afferents or efferents, though sympathetic afferents are also possible. The pathology‐free and diseased specimens were compared to determine what affect heart failure had on innervation patterns. Notable differences were found in the left descending coronary artery, the AV node, the left ventricle, the mitral valve, and the pulmonary trunk. The diseased heart showed attenuated nerve staining in both the AV node and mitral valve, supporting the relationship between parasympathetic withdrawal and heart failure.

Communicating branches between lingual and hypoglossal nerve: observation using Sihler's staining technique.

Many dental procedures are at risk of injuring the lingual nerve. We performed this study to better elucidate the microanatomy that exists between the ipsilateral lingual and hypoglossal nerves so that iatrogenic injury can be avoided. Adult human cadaveric tongues (ten sides) underwent Sihler's staining to identify the microanatomy between the lingual and hypoglossal nerves. The lingual nerve entered the middle part of the anterior two-thirds of the tongue from its lateral side and divided into two to four thick branches. These branches were then disseminated to the anterior, middle, and posterior parts of the anterior two-thirds of the tongue via 7-14 thin nerve bundles as terminal branches. The hypoglossal nerve entered the tongue at the posterior border of its anterior two-thirds and traveled forward to the apex of the tongue on all sides. All specimens were found to have communicating branches between the lingual and hypoglossal nerves at its anterior, middle, and posterior thirds. Our results indicate that the ipsilateral lingual and hypoglossal nerves constantly have three connections on each side between them. This knowledge might aid the dentist in minimizing iatrogenic nerve injury.

Method to test the long-term stability of functional electrical stimulation via multichannel electrodes (e.g., applicable for laryngeal pacing) and to define best points for stimulation: in vivo animal analysis.

The study aim was to identify and analyze intramuscular electrically sensitive points. Electrically sensitive points are herein defined as positions, which allow muscles stimulation with a minimum possible fatigue for a maximum amount of time. A multichannel array electrode was used which could be interesting to retain the function of larynx muscle after paralysis. Eight array electrodes were implanted in the triceps brachii muscle of four rats. While being under anesthesia, the animals were intramuscularly stimulated at 16 different positions. Sihler's staining technique was used to make visible the nerves routes and the intramuscular position of the individual electrode plate. The positions of the motor end plates were determined by means of multichannel-electromyography. The positions that allow longest stimulation periods are located close to the points where the nerves enter the muscle. Stimulation at the position of the motor end plates does not result in stimulation periods above average. Locations initially causing strong muscle contractions are not necessarily identical to the ones allowing long stimulation periods. The animal model identified the stimulation points for minimal possible muscle fatigue stimulation as being located close to the points of entrance of the nerve into the muscle. Stimulation causing an initially strong contraction response is no indication of optimal location of the stimulation electrode in terms of chronic stimulation. The array electrode of this study could be interesting as a stimulation electrode for a larynx pacemaker.

Neuromuscular structure of the tibialis anterior muscle for functional electrical stimulation.

This study describes the nerve entry points and intramuscular nerve branching of the tibialis anterior, providing essential information for therapeutic functional electrical stimulation and botulinum toxin injection. One hundred and ten legs from Korean and Thai cadavers were dissected. Ten specimens were harvested and subjected to modified Sihler's staining. The average total length from the lateral malleolus to the fibular head was 32.0cm (SD 1.9). The nerve entry points were densely distributed between 86.5 and 90.6% of the reference length, where the first and second nerve entry points were observable. A densely arborizing area of the intramuscular nerve branches was observed at 70-80% of the reference length. Based on the results of this study, clinicians can increase the effectiveness of therapeutic functional electrical stimulation and identify the ideal sites for botulinum toxin injection to the tibialis anterior muscle.

Intramuscular nerve distribution pattern of ankle invertor muscles in human cadaver using sihler stain.

We sought to the ideal sites for botulinum toxin injection by examining the intramuscular nerve patterns of the ankle invertors. A modified Sihler method was performed on the flexor hallucis longus, tibialis posterior, and flexor digitorum longus muscles (10 specimens each). The muscle origins, nerve entry points, and intramuscular arborization areas were measured as a percentage of the total distance from the most prominent point of the lateral malleolus (0%) to the fibular head (100%). Intramuscular arborization patterns were observed at 20-50% for the flexor hallucis longus, 70-80% for the tibialis posterior, and 30-40% for the flexor digitorum longus. These findings suggest that treatment of muscle spasticity of the ankle invertors involves botulinum toxin injections in specific areas. These areas, corresponding to the areas of maximum arborization, are recommended as the most effective and safest points for injection.

Intramuscular innervations of lower leg skeletal muscles: applications in their clinical use in functional muscular transfer.

This study aims to investigate nerve distribution patterns of human lower leg skeletal muscles using a modified Sihler's staining method. Sixteen lower leg from eight fresh adult cadavers were used in this study and all the skeletal muscles were dissected. The muscle specimens were classified according to Lim's classification. The specimens were then stained by further modified Sihler's staining technique. Data were analyzed according to research results. After the staining, we found four patterns of nerve distribution in human lower leg muscles: (1) Type 1: single nerve pattern in which the nerve branches into two either running parallel to each other or radiating in a spray pattern (such as the extensor digitorum longus, extensor hallucis longus, fibularis brevis and flexor hallucis longus). (2) Type 2: double nerve pattern, one being proximal and the other being distal (such as the extensor digitorum longus, flexor digitorum longus, flexor hallucis longus). (3) Type 3: multiple branch pattern (such as the tibialis anterior, fibularis longus, gastrocnemius, soleus, tibialis anterior and popliteus). Our modified Sihler's staining method is useful for research of large muscles and intramuscular nerves in human. These findings might provide guidance for clinicians for muscle reconstruction surgery.

Three-layered architecture of the popliteal fascia that acts as a kinetic retinaculum for the hamstring muscles.

When patients report pain in the popliteal fossa upon knee extension, the pain is usually localized in the lower region of the popliteal fossa. However, some patients complain of pain in the upper region of the popliteal fossa as the knee is flexed, which motivated us to examine the role of the popliteal fascia as the retinaculum of the hamstring muscles. Thirty-four thighs from 19 Japanese cadavers were dissected. The popliteal fascia was defined as the single aponeurotic sheet covering the popliteal fossa. We found that the fascia acted as a three-layered retinaculum for the flexor muscles of the thigh and provided a secure route for neurovascular structures to the lower leg in any kinetic position of the knee joint. The superficial layer of the popliteal fascia covering the thigh was strongly interwoven with the epimysium of biceps femoris along its lateral aspect and with that of the semimembranosus along its medial aspect, ensuring that the flexor muscles remained in their correct positions. The intermediate layer arose from the medial side of biceps femoris and merged medially with the superficial layer. The profound layer stretched transversely between the biceps femoris and the semimembranosus. Moreover, we investigated the nerve distribution in the popliteal fascia using Sihler's staining and whole-mount immunostaining for neurofilaments. The three-layered fascia was constantly innervated by branches from the posterior femoral cutaneous or saphenous nerve. The nerves were closely related and distributed to densely packed collagen fibers in the superficial layer as free or encapsulated nerve endings, suggesting that the fascia is involved in pain in the upper region of the popliteal fossa.

Communications Between the Trigeminal Nerve and the Facial Nerve in the Face: A Systematic Review.

The aim of the article is to elucidate the communications between the trigeminal nerve and facial nerve in the face. In a PubMed search, 328 studies were found using the terms 'trigeminal nerve, facial nerve, and communication.' The abstracts were read and 39 full-text articles were reviewed. Among them, 11 articles were analyzed. In the studies using dissection, the maxillary branch (V2) had the highest frequency (95.0% ± 8.0%) of communication with the facial nerve, followed by the mandibular branch (V3) (76.7% ± 38.5%). The ophthalmic branch (V1) had the lowest frequency of communication (33.8% ± 19.5%). In a Sihler stain, all of the maxillary branches and mandibular branches had communications with the facial nerve and 85.7% (12/14 hemifaces) of the ophthalmic branches had communications. The frequency of communications between the trigeminal nerve and facial nerve were significantly higher (P = 0.00, t-test) in the studies using a Sihler stain (94.7% ± 1.1%) than the studies using dissection (76.9 ± 35.8). The reason for the significantly higher frequency of trigeminal-facial communication in the studies using a Sihler stain is because of the limitation of the Sihler stain itself. This technique cannot differentiate the motor nerves from sensory nerves at the periphery, and a crossover can be misinterpreted as communication near to nerve terminal.

Innervation to Mandibular Gingiva

General sensory innervation of the mandibular gingiva by branches of the mandibular nerve (CN V‐3) is well documented. However, general sensory branches from the lingual nerve that traverse the submandibular gland have not been well documented. Therefore, using a combination of macroscopic dissection, MicroScribe 3DX, and Sihler's nerve stain, data was gathered as to which branches of the lingual nerve traverse the submandibular gland on route to innervating the mandibular gingiva. In 30 dissected specimens, the lingual nerve enters the oral cavity near the postero‐lateral surface of the tongue and sends posterior branches into the lingual mandibular gingiva, posterior and medial to the third molars. Other small branches innervate the sublingual gland and the tongue. Anterior nerve branches emerging from the sublingual gland innervate the lingual mandibular gingiva. Altogether, there are an average of 2.62 branches to the mandibular gingiva. The data demonstrated lingual nerve branches that are not presently documented in atlases, and journals. A continuation to collect specimens will allow for a greater amount of information regarding the number of branches from the parent lingual nerve innervating the mandibular gingiva, along with the consistency of how many nervous branches are found. This information could be helpful to dentists in performing local anesthetic blocks.

Anatomy of facial and trigeminal nerve branches associated with the corrugator supercilii muscle: microdissection and modified Sihler staining.

Deactivation of the corrugator supercilii for the treatment of unintentional glabellar lines requires high selectivity to avoid sensory complications. The aim of this study was to delineate the topographic anatomy of facial and trigeminal nerves in relation to the corrugator supercilii to improve the selectivity and safety of deactivation of the corrugator supercilii muscle. The number, courses, and attachments of the facial nerve to the corrugator supercilii muscle were investigated by dissection of 27 cadaveric hemifaces. Twelve cadaveric hemiforehead flaps were stained using a modified Sihler method to trace the supraorbital and supratrochlear branches. On average, 1.8 branches of the facial nerve at the zygomatic arch were associated with the corrugator supercilii muscle through 1 (29.3%) or 2 terminal rami (70.7%). The trigeminal nerve gave off 7.7 supraorbital and 5.1 supratrochlear branches emerging from orbit. The majority of the supraorbital branches became intramuscular branches (60.4%), whereas the majority of the supratrochlear branches became superficial branches (67.8%). Resection of the muscle may damage the intramuscular trigeminal branches, leading to sensory changes. The course of the facial nerve branches to the corrugator supercilii muscle was much more predictable at their distal part than the proximal part.