Navigational guidelines and positional relationships of the human auditory ossicles from three-dimensional topography for ensuring safe and effective malleostapedotomy : Stereotactic topography of the auditory ossicles and its clinical implication.

PURPOSE: The aims of the present study were to identify detailed positional relationship between the auditory ossicles and to provide theoretic navigational guidelines for optimal prosthesis adaptation and effective malleostapedotomy. METHODS: Fifty sides of the temporal bone from donated cadavers were scanned by MicroCT and the malleus, incus, stapes and tympanic membrane were materialized three dimensionally using computer software. Dimensions between the auditory ossicles closely related to malleostapedotomy were measured twice. RESULTS: The grip site of malleus handle was mean 1.8 mm superior and mean 1.3 mm anterior, and linear distance between the grip site of malleus handle and the footplate of the stapes was mean 6.5 mm. The stapes was not parallel to the tympanic membrane and rotated mean 10.7° posteriorly relative to the tympanic membrane. CONCLUSION: Surgeons should start with at least 8.75 mm prosthesis to cover the upper limits of potential anatomy and then trim down to the individualization to the case. The ideal loop morphology has to be oval shape more than 1.4 mm in the long diameter and 1.0 mm in the short diameter. The wire of the prosthesis has to be bended at the two points: about 10° anteriorly at the most proximal point of the wire and about 50° superiorly at the stapes head point.

Anatomical study of gasless transoral thyroidectomy and clinical application.

BACKGROUND: Transoral thyroidectomy is becoming a preferred technique because it has the advantage of not leaving a scar after surgery. However, it is not yet standard because of the anatomic nerve complexity of this oral cavity and difficulty of approach. The aim of this study was to determine the safety zone of a gasless transoral thyroidectomy approach using an anatomical study and to evaluate the efficacy of this approach on clinical application. METHODS: Phase 1, twenty unilateral specimens from fresh cadavers underwent staining by the modified Sihler's method to identify nerves around the oral vestibules. Then, the safety zone of the transoral thyroidectomy approach was proposed. Phase 2, a comparative analysis of the clinical outcomes of gasless transoral thyroidectomy through the safety zone versus transcutaneous thyroidectomy approach. RESULTS: In phase 1, numerous inferior labial branches diverged from the mental nerve and were distributed across the lower lip. In most cases, the most lateral branch reached almost to the corner of the mouth, whereas a nerve-free area was present at the medial region of the lower lip. The suggested safety zone was presented as a trapezoid shape. In phase 2, there were no significant differences in age, mass size, or complications between the two groups. However, the operation time in the transoral thyroidectomy group was longer than in the transcutaneous group (p = 0.001). CONCLUSIONS: Based on the anatomical study, we suggested a safety zone for the gasless transoral thyroidectomy. On application of this safety zone, gasless transoral thyroidectomy is a safe and feasible procedure.

Location of the infraorbital foramen with reference to soft tissue landmarks for regional nerve blocks during midface surgery.

PURPOSE: An infraorbital nerve (ION) block is widely used to accomplish regional anesthesia during surgical procedures involving the midface region. This study aimed to elucidate the exact location of the infraorbital foramen (IOF) in relation to clinically useful soft-tissue landmarks for achieving an effective ION block. METHODS: Forty-three hemifaces from 23 embalmed Korean cadavers were dissected. The lateral canthus, peak of Cupid's bow, medial limbus, and midline were used as reference points. The distances from the IOF to the midline and the lateral canthus were measured. RESULTS: The IOF was located approximately 25 mm below the lateral canthus and 27 mm lateral to the midline. In all cases, the IOF was situated within 9.0 mm of the crossing point of the oblique line connecting the lateral canthus to the peak of Cupid's bow and the vertical line through the medial limbus. CONCLUSION: Considering the spread of an anesthetic agent, injecting it into the crossing point of the oblique line through the lateral canthus to the peak of Cupid's bow and the vertical line through the medial limbus would successfully block the ION in most patients.

Anatomical consideration of the occipital cutaneous nerves and artery for the safe treatment of occipital neuralgia.

There is no standardized approach to the greater occipital nerve (GON) block technique for treating occipital neuralgia. The aim of the present study was to validate the previously-suggested guidelines for conventional injection techniques and to provide navigational guidelines for safe GON block. The GON, lesser occipital nerve (LON) and occipital artery (OA) were carefully dissected in the occipital region of embalmed cadavers. Using a 3 D digitizer, the GON, LON, and OA were observed on the two reference lines. The distances between the landmarks were recorded and statistically analyzed. On the superior nuchal line, the mean distances between the external occipital protuberance (EOP) and the most medial branch of the GON was 33.5 mm. The mean distance between the EOP and the most medial branch of the OA was 37.4 mm. On the EOP-mastoid process (MP) line, the GON was on the medial third and the LON the lateral third of the EOP-MP line. The safe injection points on the EOP-MP line are about 3 cm from the EOP, 1 cm inferior parallel to the EOP-MP line, and about 3 cm away from the MP. Clin. Anat. 31:1058-1064, 2018. © 2018 Wiley Periodicals, Inc.

Surgical anatomy of the superficial temporal artery to prevent facial nerve injury during arterial biopsy.

To investigate the topographical relationship between the frontal branch of the superficial temporal artery (FSTA) and the temporal branch of the facial nerve (TFN) with the aim of preventing nerve injury during FSTA biopsy. Fifty-seven hemifaces of 33 cadavers were dissected. Vertical lines drawn to the lateral orbital margin (LOM) and the superior root of the helix were used as the anterior and posterior reference positions, respectively. Horizontal lines drawn through the supraorbital margin and lateral canthus were used as the superior and inferior reference points, respectively. The depth and course relationships of the FSTA and TFN were examined. Midpoints between the FSTA and TFN are situated approximately 6.0 and 4.5 cm posterior to the lateral orbital margin at the levels of the lateral canthus and supraorbital margin, respectively. The TFN is generally situated 1-2 cm anteriorly and inferiorly to the FSTA in the temporal region. However, in two cases (3.6%), the TFN ran just underneath the FSTA with only a very small safe distance, making it highly vulnerable to iatrogenic injury. In conclusion, when performing an FSTA biopsy, the surgeon should not dissect below the superficial temporal fascia because there is an overlap between the course of the FSTA and the TFN in a minority of cases. Also, surgical incisions should be made outside the area delineated by an oblique line passing through the points 6.0 and 4.5 cm posterior to the lateral orbital margin at the levels of the lateral canthus and the supraorbital margin, respectively. Clin. Anat. 31:608-613, 2018. © 2017 Wiley Periodicals, Inc.

Visualization of the tentorial innervation of human dura mater.

Posterior projections of the ophthalmic division of the trigeminal nerve (the ophthalmic nerve) are distributed in the tentorium cerebelli as recurrent meningeal branches. We investigated the morphological tentorial distribution of the ophthalmic nerve. Fifty-two sides of the tentorium cerebelli and adjacent dura mater obtained from 29 human specimens were stained using Sihler's method to examine the nerve fibres in the dural sheets. The innervation patterns of the tentorium cerebelli were classified into the following four types according to their distributions: Type 1, where nerve fibres projected to both the straight and transverse sinuses; Type 2, where nerve fibres projected only to the transverse sinus and lateral convexity; Type 3, where nerve fibres projected medially only to the straight sinus and the posterior part of the falx cerebri; and Type 4, where the nerve fibres terminated within the tentorium cerebelli. Images of the tentorium cerebelli were superimposed to identify areas of dense innervation. The incidence rates of Types 1-4 were 71.2% (n = 37), 21.2% (n = 11), 3.8% (n = 2) and 3.8% (n = 2), respectively. More branches of nerve fibres traversed towards the transverse sinus posterolaterally than towards the straight sinus medially. The space between the anterior half of the straight sinus and the medial tentorial notch can be considered a safe surgical area where innervation is scarce. The posterior part of the falx cerebri was innervated by the ophthalmic nerve that traversed to the straight sinus. The parietal branches of the middle meningeal artery in the lateral convexity that were projected orthogonally by the ophthalmic nerve traversed the transverse sinus, implicating their vulnerability and possible sensitivity under physiological or neurosurgical conditions. This study has revealed the macroscopic tentorial innervation of the dura mater in humans, which could be useful information for both neurosurgeons and neurologists.

Anatomy of the lateral femoral cutaneous nerve relevant to clinical findings in meralgia paresthetica.

INTRODUCTION: Compression of the lateral femoral cutaneous nerve (LFCN), known as meralgia paresthetica (MP), is common. We investigated the topographic anatomy of the LFCN focusing on the inguinal ligament and adjacent structures. METHODS: Distances from various bony and soft-tissue landmarks to the LFCN were investigated in 33 formalin-embalmed cadavers. RESULTS: The mean distance from the anterior superior iliac spine (ASIS) to the LFCN was 8.8 mm. In approximately 90% of cases, the LFCN lay <2 cm from the medial tip of the ASIS, whereas, in 76% of cases, it was <1 cm away. The mean angle between the inguinal ligament and LFCN was 83.3°. CONCLUSIONS: We determined the variability of the location of the LFCN at the boundary between the pelvic and femoral portions. The reported results will be helpful for diagnosis and treatment of MP. Muscle Nerve 55: 646-650, 2017.

Three-Dimensional Topography of the Supratrochlear Nerve With Reference to the Lacrimal Caruncle, and Its Danger Zone in Asians.

BACKGROUND: The supratrochlear nerve (STN) is relatively superficial and therefore vulnerable to iatrogenic injury. OBJECTIVE: To elucidate the course of STN with reference to the lacrimal caruncle, with the aim of preventing nerve injury during surgery in the forehead region. MATERIALS AND METHODS: Thirty-four hemifaces from 18 Korean cadavers were dissected. The vertical line through the apex of lacrimal caruncle and the horizontal line through the supraorbital margin were used as horizontal and vertical reference lines, respectively. The course of STN in the frontal view and the point at which it pierced the overlaying musculature were examined. RESULTS: After exiting the corrugator muscle cushion, the STN enters the subcutaneous plane by piercing the frontalis muscle. These piercing points occurred at mean horizontal and vertical distances relative to the medial branch of the STN of 9.2 and 9.6 mm, respectively; the corresponding distances for the lateral branch of the STN were 1.1 and 15.3 mm, respectively. CONCLUSION: When performing surgery in the medial forehead region, the surgeon must ensure that the dissection plane of forehead tissue is more superficial: superiorly within 1.5 cm from the supraorbital margin and medially within 1.0 cm from the vertical line through the apex of lacrimal caruncle.

Emerging Points of the Supraorbital and Supratrochlear Nerves in the Supraorbital Margin With Reference to the Lacrimal Caruncle: Implications for Regional Nerve Block in Upper Eyelid and Dermatologic Surgery.

BACKGROUND: Blocking the supraorbital nerve (SON) and supratrochlear nerve (STN) by injecting anesthetic distal to the surgical site has the advantage in upper eyelid surgery that avoids obscuring the surgical landmarks and compromising the levator function. OBJECTIVE: To identify the emerging points of the SON and STN in the supraorbital margin with reference to the lacrimal caruncle. METHODS: Forty-nine orbits from 27 embalmed Korean cadavers were dissected. The lacrimal caruncle and facial midline were used as landmarks. The emerging points of the SON and STN in the supraorbital margin were determined. RESULTS: The emerging points of the SON and STN were, respectively, located at 3.0 mm lateral and 3.3 mm medial to the vertical line through the apex of the lacrimal caruncle along the supraorbital margin. The horizontal distances from the facial midline to the emerging points of the SON and STN were 22.8 and 15.2 mm, respectively. CONCLUSION: The optimum sites for achieving SON and STN block are, respectively, located approximately 3 mm lateral and 3 mm medial to the vertical line through the apex of lacrimal caruncle along the supraorbital margin. This knowledge will help the surgeon achieve an easy and accurate approach for regional nerve block.

Positional Relationship of Ethmoidal Foramens With Reference to the Nasion and Its Significance in Orbital Surgery.

PURPOSE: The aim of the study was to elucidate the positional relationship of the ethmoidal foramens (EFs) with reference to the nasion to facilitate prediction of the exact location of EFs, the optic canal (OC), and the frontoethmoidal suture (FS), and thereby avoid complications during complex surgery involving the medial wall of the orbit. MATERIALS AND METHODS: One hundred two intact orbits of 57 embalmed cadavers were dissected in this observational anatomic study. Nasion' (N') was defined as the intersection point of the medial orbit margin with the horizontal line through the nasion, and this was used as a reference point. N'-OC was defined as the straight line joining N' and OC. The locations of the anterior ethmoidal foramen (AEF), posterior ethmoidal foramen (PEF), and OC were determined with reference to N'. The vertical distances from N'-OC to EFs and to FS were also determined. RESULTS: The N'-AEF, AEF-PEF, and PEF-OC distances were 18.4, 15.3, and 8.3 mm, respectively. Vertically, AEF and PEF were situated at 0.2 mm below and 0.4 mm above N'-OC, respectively. At the same reference points, N'-OC was situated at 0.4 and 0.6 mm above FS, respectively. CONCLUSIONS: N', AEF, PEF, and OC were considered to be situated on the same straight line, and N'-OC could be regarded as coinciding with FS. This means that N' is an easily identifiable and reliable landmark for identifying EFs, OC, and FS. Our navigational parameters with reference to N' will help surgeons to enhance the safety of orbital surgery.

Topographic anatomy of the ulnar tunnel.

PURPOSE: The aim of this study was to clarify the definition of the anterior wall of the ulnar tunnel and to reveal the topographical characteristics of the various components of the ulnar tunnel. MATERIALS AND METHODS: Twenty-two forearms from 11 embalmed cadavers (7 males, 4 females; mean age, 67.8 years) were carefully dissected. RESULTS: In all cases, the anterior wall of the ulnar tunnel comprised the hypothenar fascia, which originated from the tendon of the flexor carpi ulnaris muscle. The palmar carpal ligament, the distal extent of the antebrachial fascia, was located deep to the anterior wall and formed only the anterior boundary of the proximal hiatus of the ulnar tunnel. The hypothenar fascia was attached to the flexor retinaculum at 15.2 mm lateral to the pisiform bone. However, the palmar carpal ligament was attached to the flexor retinaculum just lateral to the ulnar artery; the distance between the attachment of the palmar carpal ligament and the pisiform bone was 8.7 mm. Anatomical variations potentially associated with ulnar nerve compression were observed. The accessory abductor digiti minimi muscle and the fibrous band crossing the ulnar nerve in the ulnar tunnel were found in 27 and 23 % of forearms, respectively. CONCLUSION: A more detailed description of the anterior wall of the ulnar tunnel than was previously available is presented herein, and topographic and metric data regarding each structure of the tunnel are reported.

The number and cycle of rat vibrissae according to topographic arrangement.

This study investigated the cycle of rat vibrissae by counting their number relative to their topographic arrangement. The average duration of maintaining single or double vibrissal shafts was analyzed. The ratio of the lifetime of the single and double shafts was around 3:2 weeks. The rostral and caudal vibrissae had relatively short and long cyclic durations, respectively; this difference may be related to their length and function.

Topographic relationships between the transverse facial artery, branches of the facial nerve, and the parotid duct in the lateral midface in a Korean population.

BACKGROUND: The aims of the present study were to clarify the topographic relationships between various structures in the lateral midface and to provide important anatomical information pertinent to face lifting or treatment of damage to the midface structure. METHODS: Thirty-two fixed cadavers were dissected (23 males and 9 females; mean age, 66.8 years) and 55 sides of midface were used. The transverse facial artery (TFA), zygomatic branch (Zb) and buccal branch (Bb) of the facial nerve, and the parotid duct (PD) were identified. The structures of the lateral midface were measured relative to the zygion and tragion. The vertical average distances from the zygion to each structure increased in the following order: ZB of the facial nerve, TFA, first Bb of the facial nerve, and PD. The horizontal average distance from the tragion to the point of emergence from anterior border of the parotid gland was also measured. RESULTS: The TFA was the closest and the third Bb of the facial nerve was the farthest away. The angles between the horizontal line and ZB of the facial nerve, TFA, PD, and first Bb of the facial nerve were +10.4, -2.3, -18.5, and -27.1 degrees, respectively. CONCLUSIONS: These results may be used to establish the precise locations and the courses of the important midface structures, and represent valuable data that may help to prevent complications during surgery for face lifting and reconstruction of the facial nerve and PD.

Anatomical characteristics of the nasal cartilages for successful rhinoplasty in Koreans.

BACKGROUNDS: The aims of the present study were to determine the exact level of separation of the upper lateral cartilage from the septal cartilage, and to classify the patterns of connection between the upper lateral cartilage and the lower lateral cartilage. METHODS: We dissected and photographed 60 sides of noses; 18 specimens were sectioned and stained with Masson's trichrome. RESULTS: The mean length of the connection between the upper lateral cartilage and septal cartilage was 16.1 mm. The mean level for separation of the upper lateral cartilage was 7.5 mm from the nasal bone. The pattern of connection between the upper lateral cartilage and lower lateral cartilage could be classified into five types: disconnection, end-to-end, overlap, scroll, and reverse scroll. CONCLUSIONS: The results of the present study will be helpful for surgical procedures such as nasal hump reduction and nasal cartilage work and also provide information for the anthropometric study of the nose.

Morphometric analysis of the upper lip in Koreans.

The aims of this study were to provide the various dimensions of the philtrum and upper red lip in Korean young adults and to identify morphological characteristics of these structures in Koreans. A total of 10 dimensions of the philtrum and upper red lip were measured in 251 healthy young adults. Various indices were calculated among the measured features. The philtrum could be classified into three types according to its shape and index data. The mean height of the philtrum was 15.6 mm and the mean width of the mouth was 45.5 mm. The width of the superior and inferior philtrum, the height of philtrum, the width of the mouth, and the height of the upper red lip were significantly larger in males than in females (p < 0.05). A subtle morphological difference in Cupid bow was observed between the genders. There was a negative correlation between the length of the philtral column and the height of the upper red lip (p < 0.05). Furthermore, differences were identified in the dimensions of the philtrum and the upper red lip between Koreans and Caucasians. The results of this study could be a useful morphological basis for correction and reconstruction of the upper lip.

Anatomical Relationship between the Inferior Temporal Septum and the Temporal Branch of the Facial Nerve for Clinical Applications.

BACKGROUND: The inferior temporal septum (ITS) is a fibrous adhesion between the superficial temporal fascia and the superficial layer of the deep temporal fascia. This study identified detailed the anatomical relationship between the ITS and the temporal branch of the facial nerve (TBFN) for facial nerve preservation during temple interventions. METHODS: Among 33 Korean cadavers, 43 sides of TBFNs in temporal regions were dissected after identifying the ITS between the superficial temporal fascia and superficial layer of the deep temporal fascia through blunt dissection. The topography of the ITS and TBFN were investigated with reference to several facial landmarks. Regional relationships with the ITS and TBFN within the temporal fascial layers were histologically defined from five specimens. RESULTS: At the level of the inferior orbital margin by the tragion, the mean distances from the lateral canthus to the anterior and posterior branches of the TBFN were 5 and 6.2 cm, respectively. At the lateral canthus level, the mean distance from the lateral canthus to the posterior branch of the TBFN was similar to that to the ITS, at 5.5 cm. At the superior orbital margin level, the posterior branch of the TBFN ran cranial to the ITS adjacent to the frontotemporal region. The TBFN ran through the subsuperficial temporal fascia layer and the nerve fibers located cranially, and within the ITS meshwork in the upper temporal compartment. CONCLUSION: The area of caution during superficial temporal fascia interventions related to the TBFN was clearly identified in the upper temporal compartment, which is known to lack important structures.

Centralization or decentralization of facial structures in Korean young adults.

It is well known that facial beauty is dictated by facial type, and harmony between the eyes, nose, and mouth. Furthermore, facial impression is judged according to the overall facial contour and the relationship between the facial structures. The aims of the present study were to determine the optimal criteria for the assessment of gathering or separation of the facial structures and to define standardized ratios for centralization or decentralization of the facial structures.Four different lengths were measured, and 2 indexes were calculated from standardized photographs of 551 volunteers. Centralization and decentralization were assessed using the width index (interpupillary distance / facial width) and height index (eyes-mouth distance / facial height). The mean ranges of the width index and height index were 42.0 to 45.0 and 36.0 to 39.0, respectively. The width index did not differ with sex, but males had more decentralized faces, and females had more centralized faces, vertically. The incidence rate of decentralized faces among the men was 30.3%, and that of centralized faces among the women was 25.2%.The mean ranges in width and height indexes have been determined in a Korean population. Faces with width and height index scores under and over the median ranges are determined to be "centralized" and "decentralized," respectively.

Topography of the frontal branch of the facial nerve and its clinical implication for temporal direct browplasty.

Due to anatomic proximity to the surgical site, iatrogenic trauma to the frontal branch of the facial nerve (FbFN) with resultant brow paralysis is a recognized major complication of temporal direct browplasty. This study was aimed to elucidate the course of the FbFN in the area superolateral to the brow in order to facilitate safer temporal direct browplasty by preventing facial nerve injury. Forty-five hemifaces from 32 embalmed Korean cadavers were dissected. A horizontal line connecting the tragion to lateral canthus was established. Then, an oblique line passing through the lateral canthus and 45° to the horizontal line was used as reference line. The mean distance from the lateral canthus to the points where the FbFN cross the reference line was measured. The angle between the FbFN and reference line at the crossing points were also recorded. After crossing the zygomatic arch, FbFN continues in an anteriorly inclining curve across the temporal region, passing near the lateral end of the brow as it heads toward frontalis muscles. During the course, the FbFN laying in the innominate fascial layer was divided into 3 branches. The anterior and posterior branch of FbFN crossed the reference line superiorly and laterally at 3 and 4 cm from the lateral canthus, respectively. In conclusion, the oculofacial surgeon must bring the dissection plane of the forehead tissue more superficially around the 3 cm superolaterally to the lateral canthus in the direction of 45° from the horizontal line in order to avoid nerve injury.

Retrodural space of Okada in the posterior ligamentous complex region: clinical and anatomical findings relevant to lumbar interlaminar epidural injection.

BACKGROUND: The retrodural space of Okada is a potential space posterior to the ligamentum flavum that allows communication with the bilateral facet joints. However, the actual anatomy of this space has not been clearly visualized to date. We sought to investigate the characteristics of patients showing contrast spreading to the facet joint space during epidural injection and to clarify the anatomical structures of the retrodural space and adjacent ligamentous tissues in cadaveric specimens. METHODS: Fluoroscopic images of patients who underwent fluoroscopy-guided lumbar interlaminar epidural injection were assessed for contrast flow to the facet joints. Patient demographics, preprocedural imaging study findings, and epidural approaches were analyzed. The anatomical study included the sectional dissection, micro-CT imaging, and histological evaluation of lumbar spine specimens from 16 embalmed cadavers. RESULTS: Fluoroscopic images of 605 epidural injections were analyzed. Among them, 36 with inadvertent spread into the facet joints (5.9%) were identified. Multivariate analysis revealed that facet joint pathologies were significantly associated with inadvertent spread into the facet joints (OR 4.382; 95% CI 1.160 to 16.558; p=0.029). Micro-CT and histological findings consistently showed a retrodural space between the ligamentum flavum and interspinous ligament. Various anatomical communication routes in the posterior ligamentous complex leading to this space were observed in specimens with degenerative and pathological changes. CONCLUSION: Degenerative and pathological facet joint changes were associated with a higher incidence of spread into the retrodural space during epidural injection. Our findings confirm anatomical evidence for a false loss of resistance before the needle enters the epidural space.

Three-dimensional microstructures of the intracortical canals in the animal model of osteoporosis.

Osteoporosis is a major disease in aged women, increasing the risk for fractures accompanied by changes in the microarchitecture. The aim of this study was to investigate the three-dimensional (3D) histomorphology of femur diaphysis in the animal model for postmenopausal osteoporosis. The cortical bone of femur diaphysis of the rat was serially sectioned at a thickness of 5 µm and evaluated age-associated changes of the intracortical (osteonal) canal networks three-dimensionally. Cortical microstructures of 10-month old rats were not affected by ovariectomy. Intracortical canal networks were radial toward endosteal aspect and frequently interconnected across the neighboring canals with short arciform and irregular canals reminiscent for resorption spaces in ovarectomized 16-month old rats, contrary to intact canals in 16-month old control rat. Increased proportion of the periosteal circumference lamella and deformed endosteal regions with rare cortical canals hampered reconstructive histomorphology in ovarectomized rats of 26 month age. We have shown that 3D reconstruction of rat femur of the aged model over 16-month old is suitable methods that evaluate and microstructural change of the intracortical canals and cortical bone porosity by estrogen depletion.