Ki-Seok Koh

Microanatomy of the incisive canal using three-dimensional reconstruction of microCT images: An ex vivo study

OBJECTIVES The purpose of this study was to investigate the general structure of the incisive canal (IC) using 3-dimensional reconstruction and to classify into various types according to several criteria. STUDY DESIGN The materials used in the study were 56 anterior maxillae harvested from human cadavers. The specimens were scanned with microscopic computerized tomography (microCT), and the resulting microCT images were reconstructed in 3 dimensions. RESULTS Many ICs had 1 foramen inferiorly and 2 foramina superiorly, and the separating level was just beneath the nasal floor. The middle part of the IC was not always a single hollow canal. Single-channel, 2-channel, 3-channel, and even 4-channel ICs were observed. The ICs were classified into 4 types according to the lateral shape of the canal: vertical-straight, vertical-curved, slanted-straight, and slanted-curved. CONCLUSIONS This study disclosed the detailed morphologic features of the IC, which will be helpful in the placement of local anesthesia or implants.

Sex Determination Using Nonmetric Characteristics of the Mandible in Koreans

ABSTRACT: The mandible is the largest and hardest facial bone and retains its shape better than other bones in the forensic and physical anthropologic field. The mandible can be used to distinguish among ethnic groups and between sexes. We examined the morphological characteristics of the mandibles of 102 Koreans of either sex. Of 13 nonmetric items of the mandible, the characteristic that best allowed the sexes to be distinguished was the contour of the lower border of the mandible: rocker‐shaped mandibles predominated in males (68.1%), whereas most females (84.6%) exhibited a straight mandible. In addition, the mental region was shaped differently between the sexes: the shape of the chin in most males was generally bilobate or square (91.7%), whereas the chin in females was either square (45.5%) or pointed (54.5%). In this study, the positive predict values of male and female were 92.5% and 73.7%, respectively. Therefore, the nonmetric method used to analyze the mandible in this study can be used for sex discrimination.

Location of the infraorbital and mental foramen with reference to the soft-tissue landmarks

Background: The purpose of the present study was to determine the locations of the infraorbital foramen and mental foramen based on soft-tissue landmarks to facilitate prediction of the locations of these structures during facial surgery. Methods: Fifty embalmed cadavers (100 sides) of Koreans were dissected to expose the infraorbital foramen and mental foramen. The distances between the bilateral infraorbital foramina and between the mental foramina and the distances between the alae of the nose and between the corners of the mouth (cheilions) were measured directly on the cadavers, and the vertical and horizontal distances between the infraorbital foramen and mental foramen and the ala of the nose and cheilions, respectively, were measured indirectly on photographs. Results: The distance between the bilateral infraorbital foramina (54.9 ± 3.4 mm) was greater than that between the bilateral mental foramina (47.2 ± 5.5 mm). The infraorbital foramen was located 1.6 ± 2.7 mm lateral and 14.1 ± 2.8 mm superior to the ala of the nose. The distance between the ala of the nose and the infraorbital foramen was 15.9 ± 2.8 mm, and the horizontal angle between these structures was 64.1 ± 9.9 degrees laterosuperiorly. The mental foramen was located 20.4 ± 3.9 mm inferior and 3.3 ± 2.9 mm medial to the cheilions. The distance between the cheilions and mental foramen was 20.9 ± 3.8 mm, and the vertical angle between these structures was 9.2 ± 8.1 degrees inferomedially. Conclusions: This study provides data that will be useful in predicting the locations of the infraorbital foramen and mental foramen when used together with hard-tissue landmarks. These data may be particularly helpful for facial surgery in patients with missing teeth.

Topographic distribution area of the infraorbital nerve

The infraorbital nerve (ION) supplies the skin and mucous membranes of the middle portion of the face. This nerve is vulnerable to injury during surgical procedures of mid-face. Severe pain and loss of sense are noted in patients whose infraorbital nerve is either entirely or partially lost after these surgeries. We investigated the distribution area and topography of the ION, about which little is currently known, by dissecting 43 hemifaces of Korean cadavers. The ION produced four main branches, the inferior palpebral, internal nasal, external nasal, and superior labial branches. The inferior palpebral branch was generally bifurcated, giving off a medial and a lateral branch (58.1%). The internal nasal branch ran superior to the depressor septi muscle, along the ala of the nose. It supplied the skin of the philtrum and gave off a terminal branch that supplied the nasal septum and the vestibule of the nose. The external nasal branch was distributed diversely supplying areas between the root and the ala of the nose. The superior labial branch was the largest branch of the ION produced the most subbranches. These subbranches were divided into the medial and lateral branches depending upon the area that they supplied.

Topography of the masseter muscle in relation to treatment with botulinum toxin type A.

OBJECTIVE The objective of this study was to provide the safest and most efficient site for injection of botulinum toxin type A into the masseter muscle. STUDY DESIGN This study was performed on 40 hemifaces from cadavers. The surface of the masseter was compartmentalized into areas I to VIII. Areas I, III, V, and VII were assigned to represent the upper 4 compartments from the posterior aspect of each muscle, and areas II, IV, VI, and VIII were assigned to represent the lower 4 compartments. RESULTS The parotid gland usually covered compartments I and II, and the marginal mandibular branch of the facial nerve was located a mean of 7.4 mm above the inferior mandibular margin. The parotid duct was usually located above the reference line connecting the tragus and the cheilion. CONCLUSION The center of compartment VI is the safest and most efficient injection site for botulinum toxin type A into the masseter muscle.

A new model for the morphology of the arrector pili muscle in the follicular unit based on three‐dimensional reconstruction

In the classic model of the arrector pili (AP) muscle, each hair follicle is independently associated with a single AP muscle. Recently, new models have been proposed based on interpretations of serial histological cross‐sectional images. The purpose of this study was to confirm the morphology of the AP muscle in relation to the follicular unit (FU) using quantitative three‐dimensional (3D) reconstruction of serially sectioned images. Skin samples were obtained from the parietal region of the scalp, and processed using routine histological procedures. The serially sectioned slides were stained with Massons trichrome. All the hairs and hair follicles of the FU exhibited some degree of slanting, with the single AP muscle slanted in the same direction. The distal portion of the AP muscle was divided into branches, as in a bronchial tree. There was branching in the single AP muscle present in the FU, and it was inserted into all the hair follicles of the FU either tightly or loosely. We suggest that the classic anatomy of the AP muscle must be modified with this new model, now confirmed by computer‐based 3D reconstruction.

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.

The Morphology of the Rat Vibrissal Follicle-Sinus Complex Revealed by Three-Dimensional Computer-Aided Reconstruction

The vibrissal follicle-sinus complex (FSC) is a sensory receptor of the mammalian integumentary system that is located around the mouth. The purpose of the present study was to identify the actual 3-dimensional structure of the rat vibrissal FSC. Rat skin tissue was serially sectioned at a thickness of 10 µm and then stained with Masson’s trichrome. The serial sections were reconstructed 3-dimensionally using Reconstruct software. The rat vibrissal follicle is a spindle-shaped structure that is embedded within a blood sinus and enveloped within a thick collagenous capsule. The vibrissal FSC is innervated by the deep vibrissal and superficial vibrissal nerves. The deep vibrissal nerve, travelling in the basal-to-apical direction, penetrates the thick collagenous capsule of the vibrissal FSC. The sinus system can be divided into a superior portion, known as the ring sinus, and an inferior portion, known as the cavernous sinus. The ring sinus contains a C-shaped structure, the ringwulst, which is suspended from the mesenchymal sheath of the follicle. Collagenous trabeculae can be seen in the cavernous sinus but not in the ring sinus. The ring sinus encircles the follicle obliquely and asymmetrically. The ringwulst encircles the follicle incompletely, in a C-shaped fashion. This study has demonstrated the previously underappreciated 3-dimensional structure of the vibrissal FSC, which differs from previously reported descriptions, and provides data that will enhance the understanding of vibrissal function.

Bifid rib: anatomical considerations in three cases.

The present study involved a detailed investigation of 3 cases of bifid rib, focusing on anatomical features, and classified them into 2 types. The bifid ribs were in the right fourth rib of all 3 male cadavers. The upper intercostal spaces of the fourth bifid rib were considerably narrowed, whereas the lower intercostal spaces were widened. Although the size and shape of the bifid space between the upper and lower divisions of the bifid rib were different, the intercostal muscles were present in the bifid space in all cases. The third anterior intercostal artery from the internal thoracic artery supplied the bifid space in all cases. In 2 cases, the fourth intercostal nerve ran along the inferior margin of the fourth bifid rib and innervated the muscles of the bifid space. In the third case, there was another branch from the third intercostal nerve supplying the muscles of the bifid space as well as the fourth intercostal nerve. The bifid ribs are associated with other diseases or develop accidentally or sporadically. Knowledge of this malformation is needed for the differential diagnosis with other diseases, such as a chest wall tumor or costal fracture.

Topographic anatomy of the zygomatic arch and temporal fossa: A cadaveric study

The zygomatic arch (ZA) is a long, slender and laterally protruding structure of the face that is vulnerable to fracture by various types of trauma. Knowledge of the topographic anatomy of the ZA and temporal fossa is important for appropriate management of ZA problems. Thirty-seven male and 33 female cadavers were investigated in this study. Skin, subcutaneous tissue, fascia and periosteum were completely removed from around the ZA. Several depths and distances were measured based on three landmarks on the ZA: the anterior, middle and posterior portions of its superior margin. The thickness of the ZA was relatively constant in the three portions. The distance from the internal surface of the ZA to the surface of the temporalis muscle was similar in the anterior and middle portions, at about 8mm, and slightly lesser in the posterior portion. The distance from the external surface of the ZA to the temporal bone was the greatest at the anterior portion, and there was a large difference between the anterior and middle portions. The temporalis muscle was the thickest in the anterior portion and the thinnest in the posterior portion. This study suggests that the maximum distance from the internal surface of the ZA to the surface of the temporalis muscle is 8mm, and this should be considered when performing reduction malarplasty on the ZA.