Sung-Yoon Won

Sihler staining study of anastomosis between the facial and trigeminal nerves in the ocular area and its clinical implications

Introduction: The trigeminal nerve (CN V) supplies mostly sensory innervation to the face, and the facial nerve (CN VII) conveys primarily motor fibers. The aim of this study was to elucidate their distributions and anastomoses. Methods: Fourteen specimens of hemisectioned faces were gathered from human cadavers and stained with Sihler staining. Results: The temporal (Tbr), zygomatic (Zbr), and buccal (Bbr) branches of CN VII formed trigeminofacial anastomoses in the ocular area. Communications were observed between the supraorbital nerve and the Tbr (85.7%), the infraorbital nerve and the Bbr (100%) and Zbr (28.6%), and the zygomaticofacial nerve and the Zbr (41.7%). Anastomoses were formed between the supratrochlear nerve and the Tbr (57.1%) and Bbr (50%), and the infratrochlear nerve and the Bbr (85.7%). Conclusions: Motor and sensory axons to the face contribute to trigeminofacial anastomoses, which may play key roles in subtle movements of muscles of facial expression. Muscle Nerve 48: 545–550, 2013

Clinical implications of the middle temporal vein with regard to temporal fossa augmentation.

BACKGROUND The middle temporal vein (MTV) traverses the temporal fossa between the superficial and deep layers of the deep temporal fascia. During filler injection into a deficient temporal fossa, filling agents may be inadvertently injected into the MTV, which results in vascular complications. OBJECTIVE To investigate the course of the MTV to enable safe filler injection in the temple area. MATERIALS AND MATERIALS The course and diameter of the MTV were measured in 18 hemifaces from 9 Korean cadavers. RESULTS The MTV was located 23.5 and 18.5 mm above the zygomatic arch at the jugale and the zygion, respectively. The diameter of the MTV at its thickest point was 5.1 mm. A splitting and reuniting pattern, such that the MTV occupied more space than a single trunk, was observed in 28% of cases. CONCLUSION We propose that the safest area for filler injection in temporal fossa augmentation is one finger width above the zygomatic arch.

Extra- and intramuscular nerves distributions of the triceps surae muscle as a basis for muscle resection and botulinum toxin injections

PurposeTo compare the distribution of extramuscular nerve branches with their intramuscular ramifications in the triceps surae muscle, thus providing anatomical substantiation for the topography of muscle resection and botulinum toxin injections.MethodsDissection and modified Sihler’s staining of 18 whole-mount human cadaveric specimens.ResultsThe distance between the areas with the highest extramuscular branch density and the area of densest intramuscular arborization in gastrocnemius and soleus muscles is approximately 10% of the calf length. This finding should be taken into consideration during nerve blocking and botulinum toxin injections for the treatment of spasticity. Intramuscular nerve arborization patterns make it possible to outline neuromuscular segments in the gastrocnemius and soleus muscles.ConclusionsSurgical or therapeutic interventions in areas of high extramuscular and intramuscular nerve density can increase the efficacy and safety of botulinum toxin injections and neurotomy. Intramuscular nerve branching patterns should be taken into consideration during triceps surae resection.

Topography and Spatial Fascicular Arrangement of the Human Inferior Alveolar Nerve

BACKGROUND Topography and fascicular arrangement of the inferior alveolar nerve (IAN) can provide critical information for the estimation of damage to IAN based on patient symptoms, or conversely to evaluate the symptoms resulting from injury to the IAN. PURPOSE The fascicular composition and organization of the IAN were determined to confirm the microarchitecture of the IAN bundles into each of the mandibular teeth, including the composition of the mental nerve. MATERIALS AND METHODS The IAN within the mandibular canal (MC) was examined in 30 hemifaces of embalmed Korean cadavers. RESULTS The most common patterns of nerve fascicle innervation to the mandibular teeth could be grossly classified into three: (1) the superior buccal portion of the IAN innervating the molars, (2) the superior portion innervating the premolars, and (3) the superior lingual or the superior lingual and inferior lingual portions in the posterior MC and the lingual portions in the anterior MC, innervating the incisors and canine. The buccal two-thirds portion of the IAN was composed of the mental nerve. CONCLUSION The IAN had distinctive fascicular organizations, which make it possible to forecast the degree, location, and extent of nerve damage according to presenting symptoms.

Intramuscular innervation patterns of the brachialis muscle.

The aim of this study was to provide accurate anatomical descriptions of the patterns of innervation of the brachialis muscle by the musculocutaneous, radial, and median nerves. Sihlers staining method was applied to 20 brachialis muscles from 10 cadavers to reveal the intramuscular distribution patterns of the musculocutaneous, radial, and median nerves. Three patterns of innervation of the brachialis muscle by the three studied nerves were found: single, double, and triple. These innervation patterns were categorized into four types: Type I—only the musculocutaneous nerve; Type II—double innervation by the musculocutaneous and radial nerves; Type III—double innervation by the musculocutaneous and median nerves; and Type IV—triple innervation by all three nerves. Single, double, and triple innervation patterns occurred 25%, 70% (Type II, 55%; Type III, 15%), and 5% of the samples, respectively. The brachialis muscle is not solely innervated by the musculocutaneous nerve but also by the radial and median nerves, thus making it a potentially triply innervated muscle. Double innervation of this muscle with either the musculocutaneous and median nerve or the musculocutaneous and radial nerves was also observed. Clin. Anat. 28:123–127, 2015.

Realization of Masticatory Movement by 3-dimensional Simulation of the Temporomandibular Joint and the Masticatory Muscles

AbstractMasticatory muscles are closely involved in mastication, pronunciation, and swallowing, and it is therefore important to study the specific functions and dynamics of the mandibular and masticatory muscles. However, the shortness of muscle fibers and the diversity of movement directions make it difficult to study and simplify the dynamics of mastication. The purpose of this study was to use 3-dimensional (3D) simulation to observe the functions and movements of each of the masticatory muscles and the mandible while chewing. To simulate the masticatory movement, computed tomographic images were taken from a single Korean volunteer (30-year-old man), and skull image data were reconstructed in 3D (Mimics; Materialise, Leuven, Belgium). The 3D-reconstructed masticatory muscles were then attached to the 3D skull model. The masticatory movements were animated using Maya (Autodesk, San Rafael, CA) based on the mandibular motion path. During unilateral chewing, the mandible was found to move laterally toward the functional side by contracting the contralateral lateral pterygoid and ipsilateral temporalis muscles. During the initial mouth opening, only hinge movement was observed at the temporomandibular joint. During this period, the entire mandible rotated approximately 13 degrees toward the bicondylar horizontal plane. Continued movement of the mandible to full mouth opening occurred simultaneously with sliding and hinge movements, and the mandible rotated approximately 17 degrees toward the center of the mandibular ramus. The described approach can yield data for use in face animation and other simulation systems and for elucidating the functional components related to contraction and relaxation of muscles during mastication.

Intramuscular nerve distribution pattern of the adductor longus and gracilis muscles demonstrated with sihler staining: Guidance for botulinum toxin injection

Introduction: The aims of this study were to clarify the intramuscular branching patterns and arborizing area of hip adductor muscles with reference to surface landmarks on the thigh and to thus suggest effective and safe injection points for botulinum neurotoxin (BoNT). Methods: Ten gracilis and 10 adductor longus specimens were subjected to Sihler staining to reveal intramuscular nerve arborization patterns, and findings were matched with and referred to surface landmarks. Using these results, we determined the optimal location for BoNT injection in hip adductors in relation to the long axis of the femur. Results: The corrected, most dense areas of innervation in adductor longus and gracilis were typically 30–50% and 40–50% from the anterior superior iliac spine (ASIS) along the vertical line of the femur, respectively. Conclusions: The most effective and safest point for BoNT injection into adductor muscles appears to be between 35% and 50% from ASIS, where neuromuscular junctions are most densely distributed. Muscle Nerve 46: 80–85, 2012

Extra- and intramuscular nerve distribution patterns of the muscles of the ventral compartment of the forearm.

Won S-Y, Hur M-S, Rha D-W, Park H-D, Hu K-S, Fontaine C, Kim H-J: Extra- and intramuscular nerve distribution patterns of the muscles of the ventral compartment of the forearm. Objective:This study describes the extra- and intramuscular nerve branching of muscles of the ventral compartment of forearm, thereby providing critical information on determining the points for botulinum toxin injections that would be effective at reducing muscular spasticity. Design:Twenty-three Korean and French cadavers were dissected and subjected to Modified Sihlers staining to investigate nerve entry points and intramuscular nerve arborization patterns. Nerve entry point and abundant arborizing area of each muscle were analyzed on 20 segments with reference to transverse lines obtained by dividing the forearm into ten equal divisions and a vertical line bisecting the medial and lateral halves of the forearm. Results:The nerve entry points of the first and second layers of forearm muscles were located at medial levels 3 and 2, respectively. The entry points of the median and ulnar nerves innervating the flexor digitorum profundus (third layer) were located at medial levels 4 and 3, respectively. The intramuscular regions of abundant arborization in each muscle were located one level distal to the nerve entry point. Conclusions:This study has yielded a map of nerve entry and abundant arborization of motor nerves innervating each muscle of the ventral compartment of the forearm.

The Sihler staining study of the infraorbital nerve and its clinical complication.

Abstract The infraorbital nerve (ION) is a cardinal cutaneous nerve that provides general sensation to the mid face. Its twigs are vulnerable to iatrogenic damage during medical and dental manipulations. The aims of this study were to elucidate the distribution pattern of the ION and thus help to prevent nerve damage during medical procedures and to enable accurate prognostic evaluation where complications do occur. This was achieved by treating 7 human hemifaces with the Sihler modified staining protocol, which enables clear visualization of the course and distribution of nerves without the accidental displacement of these structures that can occur during classic dissection. The twigs of the ION can be classified into the usual 5 groups: inferior palpebral, innervating the lower eyelid in a fan-shaped area; external and internal nasal, reaching the nosewing and philtrum including the septal area between the nostrils, respectively; as well as medial and lateral superior labial, supplying the superior labial area from the midline to the mouth corner. Of particular note, the superior labial twigs fully innervated the infraorbital triangle formed by the infraorbital foramen, the most lateral point of the nosewing, and the mouth corner. In the superior 3-quarter area, the ION twigs made anastomoses with the buccal branches of the facial nerve, forming an infraorbital nervous plexus. The infraorbital triangle may be considered a dangerous zone with respect to the risk for iatrogenic complications associated with the various medical interventions such as implant placement.

Neuroanastomosis and the innervation territory of the mental nerve

The aim of this study was to clarify the distribution pattern and innervation territory of the mental nerve (MN) in the skin and mucosa by topographic examination by Sihlers staining, thereby providing reference anatomical information for surgical procedures and to enable prediction of regions of sensory disturbance following nerve damage. Ten human specimens were subjected to Sihlers staining, which is a highly accurate method for visualizing the distribution of nerve fibers without altering their topography. Each branch of the MN overlapped adjacent branches (five cases), or else they were distributed individually at the lower lip (five cases). The MN anastomosed with some branches of the facial nerve near the mental foramen. Moreover, some branches of the MN anastomosed with the buccal nerve of the trigeminal nerve, which supplies sensation to the skin and mucosa over the lateral region of the lower lip (six cases). The details of the distribution pattern and innervations territory of the MN presented herein may enable the prediction of a region of sensory disturbance following MN damage. Moreover, knowledge of the pattern of synapses with adjacent branches of other nerves, such as the facial (marginal mandibular and cervical branches) and the buccal nerves, might help to improve our understanding around incomplete anesthesia during the surgical procedures in oral & maxillofacial region. Clin. Anat. 598–602, 2014.