Otologic complaints, including otalgia, tinnitus, vertigo, and hearing loss, are known to be related to temporomandibular disorders (TMDs). There have been several hypotheses regarding the clinical correlation between otologic complaints and TMDs, based on clinical phenomena with corresponding symptoms, the close neurological relationship between otic and masticatory structures, and anatomical features of the tympanic cavity and jaw joint. Function of the tensor tympani muscle seems to be crucial to understanding TMD-related otologic symptoms. The tensor tympani inserts into the handle of the malleus and it modulates sound transduction in situations of excessive noise. This muscle is innervated by the trigeminal nerve, like the masticatory muscles. Voluntary eardrum movement by pathological tensor tympani contraction results in various otologic symptoms. Thus, co-contraction of the tensor tympani with the masticatory muscle could be a possible cause of TMD-related otologic symptoms. The tensor tympani is rather unrelated to the acoustic reflex, in which the stapedius is strongly involved. The tensor tympani seem to be controlled by proprioceptive information from the trigeminal sensory nucleus. The peripheral innervation pattern of the tensor tympani and masticatory muscles is also supposed to be interconnected. The middle ear structure, including the malleus, incus, and tensor tympani, of mammals had been adapted for acoustic function and lacks the masticatory role seen in non-mammalian jawed vertebrates. The tensor tympani in non-mammals is one of the masticatory muscles and plays a role in the modulation of sound transduction and mastication. After the functional differentiation of the mammalian middle ear, the nervous connection of the tensor tympani with other masticatory apparatus still remains. Through this oto-stomatognathic vestige, the tensor tympani seems to contract unnecessarily in some pathological conditions of the TMD in which the masticatory muscles contract excessively. We hypothesized that the phylogenic relationship between the tensor tympani and masticatory apparatus is a significant and logical reason for TMD-related otologic complaints.
Acoustics ; Ear, Middle ; Earache ; Hearing Loss ; Incus ; Jaw* ; Joints ; Logic ; Malleus ; Mammals ; Mastication ; Masticatory Muscles ; Noise ; Reflex, Acoustic ; Stapedius ; Temporomandibular Joint Disorders ; Tensor Tympani* ; Tinnitus ; Trigeminal Nerve ; Tympanic Membrane ; Vertebrates ; Vertigo

PURPOSE: Stress distribution and mandible distortion during lateral movements are known to be closely linked to bruxism, dental implant placement, and temporomandibular joint disorder. The present study was performed to determine stress distribution and distortion patterns of the mandible during lateral movements in Class I, II, and III relationships. METHODS: Five Korean volunteers (one normal, two Class II, and two Class III occlusion cases) were selected. Finite element (FE) modeling was performed using information from cone-beam computed tomographic (CBCT) scans of the subjects' skulls, scanned images of dental casts, and incisor movement captured by an optical motion-capture system. RESULTS: In the Class I and II cases, maximum stress load occurred at the condyle of the balancing side, but, in the Class III cases, the maximum stress was loaded on the condyle of the working side. Maximum distortion was observed on the menton at the midline in every case, regardless of loading force. The distortion was greatest in Class III cases and smallest in Class II cases. CONCLUSIONS: The stress distribution along and accompanying distortion of a mandible seems to be affected by the anteroposterior position of the mandible. Additionally, 3-D modeling of the craniofacial skeleton using CBCT and an optical laser scanner and reproduction of mandibular movement by way of the optical motion-capture technique used in this study are reliable techniques for investigating the masticatory system.
Bruxism ; Cone-Beam Computed Tomography* ; Dental Implants ; Finite Element Analysis* ; Incisor ; Malocclusion* ; Mandible ; Mastication* ; Masticatory Muscles ; Reproduction ; Skeleton ; Skull ; Stomatognathic System ; Temporomandibular Joint Disorders ; Volunteers

PURPOSE: To investigate the changes of epiblepharon by evaluating the severity of epiblepharon before and after induction of general anesthesia (GA) with a muscle relaxant and total intravenous anesthesia (TIVA) without a muscle relaxant. METHODS: Thirteen pediatric patients (26 eyes) underwent surgery for epiblepharon under GA using a muscle relaxant and 19 pediatric patients (38 eyes) underwent surgery for epiblepharon under TIVA without a muscle relaxant. The severity of epiblepharon in each eye was scored according to skin-fold height (scored 1-4) and area of ciliocorneal touch (scored 1-3) while the patient was in the supine position before induction and after induction of GA. RESULTS: Skin-fold height scores and ciliocorneal touch area scores decreased after induction of GA with a muscle relaxant (skin-fold height score before GA: 2.42 ± 0.86, after GA: 1.87 ± 0.88 p-value < 0.001; ciliocorneal touch area score before GA: 2.05 ± 0.70, after GA: 1.61 ± 0.68, p-value < 0.001). In the TIVA group, skin-fold height scores and ciliocorenal touch area scores were not statistically different before and after GA (skin-fold height score before GA: 2.23 ± 1.18, after GA: 2.38 ± 1.10, p-value = 0.212; ciliocorneal touch area score before GA: 2.06 ± 0.74, after GA: 1.94 ± 0.80, p-value = 0.161). CONCLUSIONS: The change of epiblepharon severity was significantly reduced by induction of TIVA without a muscle relaxant and there was no recurrence of epiblepharon 3 months after surgery. When using TIVA without a muscle relaxant, the change of epiblepharon severity was reduced and thus, this method can help prevent its undercorrection.
Anesthesia, General ; Anesthesia, Intravenous* ; Humans ; Recurrence ; Supine Position

PURPOSE: To investigate the changes of epiblepharon by evaluating the severity of epiblepharon before and after induction of general anesthesia (GA) with a muscle relaxant and total intravenous anesthesia (TIVA) without a muscle relaxant. METHODS: Thirteen pediatric patients (26 eyes) underwent surgery for epiblepharon under GA using a muscle relaxant and 19 pediatric patients (38 eyes) underwent surgery for epiblepharon under TIVA without a muscle relaxant. The severity of epiblepharon in each eye was scored according to skin-fold height (scored 1-4) and area of ciliocorneal touch (scored 1-3) while the patient was in the supine position before induction and after induction of GA. RESULTS: Skin-fold height scores and ciliocorneal touch area scores decreased after induction of GA with a muscle relaxant (skin-fold height score before GA: 2.42 ± 0.86, after GA: 1.87 ± 0.88 p-value < 0.001; ciliocorneal touch area score before GA: 2.05 ± 0.70, after GA: 1.61 ± 0.68, p-value < 0.001). In the TIVA group, skin-fold height scores and ciliocorenal touch area scores were not statistically different before and after GA (skin-fold height score before GA: 2.23 ± 1.18, after GA: 2.38 ± 1.10, p-value = 0.212; ciliocorneal touch area score before GA: 2.06 ± 0.74, after GA: 1.94 ± 0.80, p-value = 0.161). CONCLUSIONS: The change of epiblepharon severity was significantly reduced by induction of TIVA without a muscle relaxant and there was no recurrence of epiblepharon 3 months after surgery. When using TIVA without a muscle relaxant, the change of epiblepharon severity was reduced and thus, this method can help prevent its undercorrection.
Anesthesia, General ; Anesthesia, Intravenous* ; Humans ; Recurrence ; Supine Position

The aim of the study is to examine the distribution and communications of the trigeminal nerve (TN) and facial nerve (FN) and considerate their relationship with the anatomy and function of the facial expression muscles (FEMs) by means of the literature study. The TN emerged on the face via various structures of the skull, and received sensation of the skin and muscles on the face. The FN supplied the motor components to the FEMs, as ramifying five branches after running through the stylohyoid foramen. The TN and FN constituted "nervous communication between heterogeneous cranial nerves" on the ocular (supraorbital nerve and temporal branch), zygomatic (zygomatic nerve and temporal/zygomatic branch), infraorbital (infraorbital nerve and zygomatic branch), retromandibular (auriculotemporal nerve and FN trunk), buccal (buccal nerve and buccal/zygomatic branch) and mental areas (mental nerve and buccal/marginal mandibular branch). The exquisite movement of the FEM which was controlled by the facial motor nucleus would be referred by the proprioception from the TN. The motor components from the FN could be delivered to the FEM via the TN as recruiting the heterogeneous nervous communications. The sensation from the FN also could be conveyed to the TN via the communication.
Facial Expression ; Facial Nerve ; Muscles ; Proprioception ; Running ; Sensation ; Skin ; Skull ; Trigeminal Nerve

Recent development of cyber lecture system has greatly influenced on the medical education especially on anatomy related subjects. Furthermore, the technology associated to the cyber lecture system is now widely used as the evaluation tool for the medical students. The purposes of this study are to evaluate the opinions of students according to the types of cyber lectures which were applied to a basic medical subject (neuroanatomy) and to suggest practical services and applications available for the medical students. In this study, we adopted several teaching strategies such as online lecture system and web assisted instruction to the neuroanatomy class. Medical students of Dankook universitiy were classified into three groups (online lecture group, web assisted instruction group, and cyber lecture non-experienced group) and asked to complete anonymous survey in private. The majority of students had already experienced web-based leaning at least once. The degree of student satisfaction at the cyber lecture contents were relatively high in both online lecture group and web assisted instruction group. Students in all groups slightly preferred classical lecture room lecture but also seem to be familiar to the cyber lecture. Students from all groups suggested parallel progress with lecture room lecture as the proper application of cyber lecture. Growing demands of cyber lectures based on network technology is likely to make new paradigm of medical education in the near future. Practically, application of cyber lecture system to the lab course of sectional neuroanatomy and also to the preparation for the wide scoped examination might be suggested at this time.
Anonyms and Pseudonyms ; Education, Medical ; Humans ; Lectures ; Neuroanatomy* ; Students, Medical*

Sihler's staining allows visualization of the nerve distribution within soft tissues without extensive dissection and does not require slide preparation, unlike traditional approaches. This technique can be applied to the mucosa, muscle, and organs that contain myelinated nerve fibers. In particular, Sihler's technique may be considered the best tool for observing nerve distribution within skeletal muscles. The intramuscular distribution pattern of nerves is difficult to observe through manual manipulation due to the gradual tapering of nerves toward the terminal end of muscles, so it should be accompanied by histological studies to establish the finer branches therein. This method provides useful information not only for anatomists but also for physiologists and clinicians. Advanced knowledge of the nerve distribution patterns will be useful for developing guidelines for clinicians who perform operations such as muscle resection, tendon transplantation, and botulinum toxin injection. Furthermore, it is a useful technique to develop neurosurgical techniques and perform electrophysiological experiments. In this review, Sihler's staining technique is described in detail, covering its history, staining protocol, advantages, disadvantages, and possible applications. The application of this technique for determining the arterial distribution pattern is also described additionally in this study.
Anatomists ; Arteries ; Botulinum Toxins ; Humans ; Mucous Membrane ; Muscle, Skeletal ; Muscles ; Nerve Fibers, Myelinated ; Tendons ; Transplants

The aim of this study is to identify the species characteristics of the dog mastication compared to the human by analyzing 8 landmarks on the heads from seven beagle dogs. The masticatory unit of the dog was relatively located posterior than the human. The predominance of horizontally-oriented fibers of the temporalis of the dog was shown in spite of vertical mandibular movement. The biomechanics of the coronoid process and the temporalis of the dog revealed but not superiorly-elevating like the human backward rotating the coronoid process. The masseter was also obliquely -oriented and the temporalis was observed in distinct two-layers. In the dogs, the higher coronoid process compared to the condyle was observed; the vertical difference of them was larger than human. The temporalis performs stronger action than masseter and related with marked horizontal action of the temporalis. These morphologies indicated that the mastication of the dog needs strengthened horizontal stability and it was taken by the cervical muscles attached backwardly to the skull. Thickened temporalis is adapted in feeding. The dentition of dog was longer and farther from the condyle and the pterygoid muscles were not well-developed than human, indicated unfavourable lateral movement. These findings were consistent with evolutionary tendency, feeding without hands and narrow skull.
Animals ; Biomechanics ; Dentition ; Dogs ; Hand ; Head ; Humans ; Mastication ; Muscles ; Pterygoid Muscles ; Skull ; Stomatognathic System

The facial artery (FA) and superficial temporal artery (STA) from the external carotid artery and the supraorbital, supra- and infratrochlear arteries from the internal carotid artery are the superficial arteries distributing to the face. It was broadly known that the FA winds on the antegonial notch, ascends superomedially and finally reaches to the medial canthus area as forming the angular artery (AA). However many previous studies reported that the AA was only observed in 4~68% in their studies. The superior labial artery (SLA) from the FA issues the superficial and deep septal artery proceeding superiorly toward the nasal septum. It was reported that the nasal branches were ramified from the FA, after the bifurcation of the SLA in most Korean cadavers, and it seems that the lateral nasal and dorsal nasal arteries are crucial vasculature of the external nose. The branches of the ophthalmic artery distribute the glabellar and forehead, and they form anastomoses each other or are communicated to the AA. The topography of the superficial arteries of face is very important in the reconstructive surgery and non-invasive treatment such as the botulinum neurotoxin type A or dermal filler injection.
Arteries* ; Cadaver ; Carotid Artery, External ; Carotid Artery, Internal ; Forehead ; Nasal Septum ; Nose ; Ophthalmic Artery ; Temporal Arteries ; Wind

Background: A precise anatomical understanding of the adductor canal (AC) and its neural components is essential for discerning the action mechanism of the AC block. We therefore aimed to clarify the detailed anatomy of the AC using micro-computed tomography (micro-CT), histological evaluation, and immunofluorescence (IF) assays. Methods: Gross dissections of 39 thighs provided morphometric data relevant to injection landmarks. Serial sectional images of the AC were defined using micro-CT and ultrasonography. The fascial and neural structures of the AC proper were histologically evaluated using Masson’s trichrome and Verhoeff-Van Gieson staining, and double IF staining using choline acetyltransferase (ChAT) and neurofilament 200 antibodies. Results: The posteromedial branch insertion of the nerve to vastus medialis (NVM) into the lateral border of the AC proper was lower (14.5 ± 2.4 cm [mean ± SD] above the base of the patella) than the origin of the proximal AC. The AC consists of a thin subsartorial fascia in the proximal region and a thick aponeurosis-like vastoadductor membrane in the distal region. In the proximal AC, the posteromedial branch of the NVM (pmNVM) consistently contained both sensory and motor fibers, and more ChAT-positive fibers were observed than in the saphenous nerve (27.5 ± 11.2 / 104 vs. 4.2 ± 2.6 / 104 [counts/µm2], P < 0.001). Conclusions Anatomical differences in fascial structures between the proximal and distal AC and a mixed neural component of the neighboring pmNVM have been visualized using micro-CT images, histological evaluation, and IF assays.