Are There Other Muscle Fibers on the Orbicularis Oris Muscle in the Upper Lip?

BACKGROUND: The elevator muscles of the upper lip are the levator labii superioris alaeque nasi, levator labii superioris, and zygomaticus minor muscles, which function by means of their insertions into the skin of the upper lip. However, many textbooks and journal articles state that no muscle fibers are present on the orbicularis oris muscle in the upper lip. The authors attempted to determine whether there is a superficial muscle layer in addition to the orbicularis oris muscle in the upper lip. METHODS: The authors performed gross dissections of 10 formalin-fixed cadavers and applied micro-computed tomography to six formalin-fixed cadavers. The fine dissection of the upper lip was performed in a layer-by-layer manner that elucidated its muscle layers. The entire layer of the upper lip was separated and pretreated with phosphotungstic acid for micro-computed tomography. The samples used for micro-computed tomography were repurposed for use in histologic analysis. An ultrasonography study was also performed. RESULTS: The presence of a muscle layer on the orbicularis oris muscle was confirmed in all samples. The elevator muscle fibers of the upper lip formed a layer by combining with connective tissue. Micro-computed tomography indicated lower terminal insertions of the elevator muscles throughout the upper lip. All parts of the upper lip skin were inserted into the orbicularis oris muscle. The histologic findings were similar to those of micro-computed tomography. CONCLUSION: The authors' findings could be used to improve aesthetic and surgical procedures performed on the upper lip, such as correction of gummy smile and transverse upper labial crease, or postresection reconstruction of the upper lip.

Lateral branches of the facial artery and its clinical implications.

The facial artery is the main artery supplying blood to the face and is known to have facial branches of the inferior labial, superior labial, lateral nasal and angular arteries. These known major branches of facial artery run medially, however, there are sometimes branches of the facial artery heading laterally. The purpose of the present study was to investigate the lateral branches of the facial artery in face. We dissected facial branches of the facial artery in 74 cadaveric hemifaces. We investigated the presence of the lateral branches of the facial artery. Following parameters were investigated: lateral branch presence, the location of its origin, and the lateral branch diameter. Among the lateral branches, we evaluated the prevalence and diameter of the premasseteric branch. Lateral branches were observed in 48 of the 74 hemifaces (64.9%). The total number was 81 in the 48 hemifaces. The most common origin was between the inferior border of the mandible and inferior labial artery origin (42 of 81, 51.9%). The mean diameter of all lateral branches of the facial artery was 0.7 mm. Among the lateral branches, the premasseteric branches were present in 38 of 74 specimen (51.4%) and the mean diameter was 0.8 mm. The lateral branches of the facial artery may be registered in Terminologia Anatomica based on their prevalence. Accurate knowledge of the anatomy of the lateral branches of the facial artery is helpful for clinicians to avoid complications during facial procedures or maxillofacial surgeries.

Three-dimensional linear and volumetric computed tomography analysis of the frontal sinus.

The frontal sinus is one of the four paranasal sinuses in humans, and knowledge of its anatomy is important when performing surgery involving the frontal bone or sinus. Although many studies have measured the frontal sinus using radiography and computed tomography (CT), few studies have evaluated by using three-dimensional (3D) analysis. The purpose of this study was to analyze the frontal sinus using 3D reconstruction analysis and determine the differences in linear and volumetric measurements between sexes, sides, and ages. The sample comprised 281 facial CT scans: 173 and 108 from males and females, respectively. The width, height, and length of each frontal sinus and total volume were all larger in males than in females. Almost all linear and volumetric measurements were larger in young adults than in older for both sexes, but not all of the differences were statistically significant. Linear and volumetric measurements were larger for males than females regardless of age group. There were no statistically significant differences between the right and left sides except the width in males. The size of the frontal sinus was strongly influenced by sex and age. The measurements reported here might be useful for improving surgical procedures involving the frontal sinus.

Topography of the orbital part of the lacrimal gland for treating epiphora using botulinum toxin injection.

The purpose of this study is to identify the location of the orbital part of the lacrimal gland using external landmarks to facilitate effective botulinum toxin A (BTX-A) injections for epiphora treatment. Dissections were performed on 45 hemifaces from 27 cadavers. The length, anterior protrusion, and thickness of the orbital part of the lacrimal gland were measured directly. The midpoint of the line running horizontal through the medial and lateral canthus was used as the horizontal reference point. Vertical lines perpendicular to the midpoint of the horizontal reference line were the vertical reference lines. The angles from the horizontal reference line to the lacrimal gland center and to the frontal tubercle were also measured. The length and thickness of the lacrimal gland were 12.8 and 2.4 mm, respectively. The lacrimal gland had an anterior protrusion of 4.1 mm from the superolateral orbital margin. The superior and inferior margins of the lacrimal gland were located 35.7° and 15.8° from the two reference lines, respectively. The angle from the horizontal reference line to the lacrimal gland center was 35.1°, which was similar to that to the frontal tubercle (34.4°). The orbital part of the lacrimal gland was more inferior in elderly subjects and the angle between the horizontal reference line and its center was 35.1°, which was similar to the location of the frontal tubercle. The location of this tubercle can help clinicians to perform BTX-A injections into the lacrimal gland, thereby enhancing the effectiveness of epiphora treatment.

Topographic Anatomy of the Zygomatico-Orbital Artery.

ABSTRACT: The zygomatico-orbital artery (ZOA) originating from the superficial temporal artery and supplying the lower temporal region superficially has been reported. Previous studies of this artery have used definitions that are too ambiguous for the results to be directly adapted to clinical practice, including since they have resulted in marked variations in the reported incidence ofthe artery. This study dissected 193 hemifaces of 123 fixed human cadavers aged 36 to 102 years (119 males and 74 females). The authors investigated the ZOA based on the following definition: (1) it originates from the superficial temporal artery, (2) it runs mostly above the zygomatic arch, and (3) it terminates below the superior border of the orbicularis oculi muscle. The incidence of the ZOA was 22.8% (44 cases of 193 sides), and its mean diameter was 1.1 mm. The meanvertical distances from the superior borderofthe zygomatic arch to the artery were 29.6, 17.8, and 2.9 mm at the jugale, zygion, and the origin of the ZOA, respectively. An accurate definition of the ZOA and accurate knowledge of its incidence and course could be important for clinicians to avoid unintentional complications in clinical practice.

Anthropometric Analysis of the Growth Proportions of the Head and Face in Koreans.

ABSTRACT: The present study is to identify primarily the morphological characteristics in the growth proportion of the head and face for young Korean (8-24 years) and compare the magnitude of growth changes to the sex-related differences. Total 1255 were divided into 3 age groups: childhood (8-10 years), adolescence (14-16 years), and young adult (20-24 years). The anthropometric assessments were performed with 11 landmarks on the head and facial dimensions. The standardized frontal and lateral head and face photographs were analyzed the craniofacial growth proportions and morphological features for the comparison of both sexes. The noteworthy differences of anthropometric measurements between sexes with growing were noted on the lower head height (22.6%, 17.8%), midface height (22.0%, 19.6%), lower face height (23.5%, 14.7%), and face length (21.1%, 14.9%), face breadth (14.8%, 11.3%) of males and females, respectively. Whereas the upper head height (7.9%, 6.0%) and upper face height (4.2%, 0%, respectively) were less growing features. The most remarkable changes are the dimension of midface height and lower face height in both sexes. The present study could demonstrate a fundamental example to elucidate the sex-related dimensional differences for the analysis of the growth proportion of both sexes in Koreans.

Investigation of the Orbital Arterial Distribution Using Image Superimposition to Determine Safe Zones for Retrobulbar Injection and to Prevent Filler Complications.

BACKGROUND: Retrobulbar filler injection has recently been considered an ideal method for orbital volume enhancement due to its nontoxic, easily reversible, and noninvasive characteristics. This study determined the arterial distribution in the orbit with the aim of defining a safety zone for retrobulbar filler injections used to enhance the orbital volume. METHODS: Twenty-seven orbits of 24 formalin-embalmed cadavers were dissected. The orbital arteries were identified after removal of the eyeball, extraocular muscles, and connective tissues. The course of each orbital artery was then recorded in each specimen, and all of the courses were then superimposed to determine the arterial distribution in the orbit. RESULTS: The superimposition of lined images based on the orbital vasculature of each specimen revealed that the arterial density was highest in the superonasal region and lowest in the inferotemporal region. In particular, orbital arteries were scarce at 8 o'clock and 4 o'clock in the right and left orbits, respectively, and an artery-free zone was demonstrated in the outer part of those directions. CONCLUSIONS: When performing a transcutaneous retrobulbar injection of filler for orbital volume enhancement, the relative safety zone could be considered to be located at 8 o'clock and 4 o'clock in the right and left orbits, respectively. The detailed topographic information about the arterial distribution in the orbit, provided by the present study, may help oculofacial surgeons to avoid injury to major vessels and decrease the risk of retrobulbar hemorrhage and vision-threatening complications.

Anatomic, histologic, and ultrasound analyses of the dorsum of the hand for volumetric rejuvenation.

BACKGROUND: Volumetric rejuvenation of the dorsum of the hand with fat grafting or injectable fillers has increased in popularity in recent years. It has become widely accepted that the dorsum of the hand contains three fatty laminae: superficial, intermediate, and deep laminae. The dorsal venous plexus and dorsal cutaneous nerves are known to reside in the dorsal intermediate lamina. However, the superficial vein and cutaneous nerve might not be located in the same layer of subcutaneous tissue, as is the case in other body regions. MATERIALS AND METHODS: Eight hands were dissected in a layer-by-layer fashion from the skin to the extensor tendons. In another 13 hands from among 21 investigated cadavers, samples from the dorsum of the hand were harvested and stained using trichrome stains for histologic analysis. B-mode ultrasound was also performed for identifying structures of the dorsum of the hand. RESULTS: Anatomic dissection and histologic analysis of the dorsum of the hand revealed the presence of an unknown fascia in addition to the three known fascial layers. The additional fascia was located in the dorsal intermediate lamina and separated it into two compartments: one containing the dorsal venous plexus superficially and the other containing the dorsal cutaneous nerves deeply. Ultrasound showed corresponding structures including three hyperechoic fascial layers, three hypoechoic laminae, and additional hyperechoic fascia in dorsal intermediate lamina. CONCLUSIONS: Accurate anatomic knowledge of the dorsum of the hand will help practitioners determine the optimal and safe locations for performing fat grafting and injecting dermal fillers.

Three-dimensional reconstruction of the luminal structure of human seminal vesicle.

The seminal vesicles are the glands of male reproductive organs that produce the fluid and nutrient constituents of semen. It has been believed for a long time that the lumen of a seminal vesicle was a single-coiled tubular structure with irregular diverticula. There are several previous reports on the symmetry, differences in morphological sizes and classification of the seminal vesicles. However, a three-dimensional-coiled tubular structure is difficult to understand using a classical anatomical methodology, and hence, three-dimensional reconstruction is needed to understand the structure of the lumen. Thirty-one seminal vesicles harvested from 21 formalin-embalmed cadavers were investigated. The seminal vesicle along with the ampulla of the ductus deferens was separated, and the length and width of each seminal vesicle were measured. The vesicles were then embedded in coloured paraffin, and the resulting paraffin block was sectioned transversely and photographed at an interval of 500 µm, with the sectioned surfaces then utilized in three-dimensional reconstruction performed by 'Reconstruct' software. The mean length and width of the seminal vesicles were 39.4 mm and 13.4 mm, respectively, and the right seminal vesicle was a little larger than the one on the left. The size differed from previous reports, while the luminal structure was similar to the classification of Aboul-azm (Archives of Andrology, 3, 1979, 287-292) but differed from that of Pereira (AJR. American Journal of Roentgenology, 69, 1953, 361-379). The seminal vesicles typically comprised about 9 curls and had about 12 diverticula. The seminal vesicles resembled a skein of coral rather than comprising a single strand. These findings will help in improving the understanding of pathophysiologies of the seminal vesicles, such as recurrent inflammation of the gland.

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.

Macro/microscopic distribution of the dorsal nerve of penis in human glans penis.

This study aimed to elucidate the macroscopic and microscopic distributions of the dorsal nerve of penis (DNP) that provides the greatest sensitivity over the glans penis. The glandes of 23 penises of formalin-embalmed cadavers were investigated to confirm the macroscopic and microscopic distributions of the DNP within the glans penis by whole-mount Sihler's staining and histological sectioning. Superficial regions of the mid-glans were reconstructed in three dimensions to define the microstructure of terminal branches of the DNP that project towards the skin surface. A mean of 6.7 bundles of the DNP consisting of several nerve fibres converged linearly towards the distal end of the penis, rather than diverging laterally as they travelled. Lateral branches of the DNP extended linearly to the distal end with ramifications, while dorsomedial branches of the DNP gave off nerve fibres to the dorsum of the mid-glans and the corona. The intrastromal ramifications of the DNP were more developed in the distal half of the glans penis than the proximal glans containing the corpus cavernosum. These ramifications gave rise to radial nerve fibres that project towards the skin surface to form a plexiform network of terminal branches in the dermis. Linear projections of the main branches of the DNP throughout the glans and fine networks of terminal branches in the dermis were distinctly visualized in the human penis.

Intramuscular Nerves of the Inferior Rectus Muscle: Distribution and Characteristics.

PURPOSE: Knowledge of the distribution of intramuscular nerves of the extraocular muscles is crucial for understanding their function. The purpose of this study was to elucidate the intramuscular distribution of the oculomotor nerve within the inferior rectus muscle (IRM) using Sihler's staining. METHOD: Ninety-three IRM from 50 formalin-embalmed cadavers were investigated. The IRM including its branches of the oculomotor nerve was finely dissected from its origin to the point where it inserted into the sclera. The intramuscular nerve course was investigated after performing Sihler's whole-mount nerve staining technique that stains the nerves while rendering other soft tissues either translucent or transparent. RESULTS: The oculomotor nerve enters the IRM around the distal one-fourth of the muscle and then divides into multiple smaller branches. The intramuscular nerve course finishes around the distal three-fifth of the IRM in gross observations. The types of branching patterns of the IRM could be divided into two subcategories based on whether or not topographic segregation was present: (1) no significant compartmental segregation (55.9% of cases) and (2) a several-zone pattern with possible segregation (44.1% of cases). Possible compartmentalization was less clear for the IRM, which contained overlapping mixed branches between different trunks. CONCLUSION: Sihler's staining is a useful technique for visualizing the gross nerve distribution of the IRM. The new information about the nerve distribution and morphological features provided by this study will improve the understanding of the biomechanics of the IRM, and could be useful for strabismus surgery.

Femoral nerve split with variant iliacus muscle: a potential source of femoral nerve entrapment.

The iliacus muscle is a large, flat, triangle-shaped muscle located in the iliac fossa. This muscle forms part of the iliopsoas muscle complex. Although anatomical variations of iliacus muscles are rare, some variations are clinically important due to the possible coexistence of an unusual course of the femoral nerve. The femoral nerve is the largest branch of the lumbar plexus and supplies the muscles and skin in the anterior aspect of the thigh. We encountered a case of a single aberrant slip of the iliacus muscle piercing the femoral nerve in the left iliac fossa of a male cadaver aged 97 years. The potential clinical importance of this variant iliacus muscle accompanied by a femoral nerve split would be femoral neuropathy and possible consequent alterations of sensation in the anterior and medial aspects of the thigh or motor deficit of the quadriceps muscle.

Use of the orbito-occipital line as an alternative to the Frankfort line.

Frankfort horizontal line, the line passing through the orbitale and porion, is one of the most widely used intracranial landmarks in cephalometric analysis. This study investigated the use of the orbito-occipital line extending from the orbitale to the external occipital protuberance as a novel horizontal line of the skull for substituting the Frankfort horizontal line. We evaluated the reproducibility of the new landmark and measured the angle between the orbito-occipital line and the Frankfort line. This study was conducted on 170 facial computed tomography (CT) scans of living adults from the Department of Plastic Surgery. After three-dimensionally reconstructed images were obtained from facial CT, the porion, orbitale, and external occipital protuberance were indicated by two observers twice. The angles between the orbito-meatal line (inferior orbital rim to porion; the Frankfort line) and the orbito-occipital line (inferior orbital rim to external occipital protuberance) were measured. There was no significant intraobserver or interobserver bias. The overall angle between the Frankfort line and orbito-occipital line was -0.5°±2.2° (mean±standard deviation). There was no statistically significant difference among side and sex. This study demonstrated good reproducibility of a new landmark-the external occipital protuberance-tested to replace the porion. The orbito-occipital line is a reliable, reproducible, and easily identifiable line, and has potential as a novel standard horizontal line to replace or at least supplement the Frankfort line in anthropological studies and certain clinical applications.

Location of the split line of the deep temporal fascia when reducing a zygomatic arch fracture.

BACKGROUND: The deep temporal fascia (DTF) is known to separate into two layers that descend to attach to the zygomatic arch. When surgeons reduce an isolated fracture of the zygomatic arch through a temporal approach, the temporal incision site needs to be superior to the split line of the DTF. MATERIALS AND METHODS: Sixty-seven hemifacial cadavers were investigated after removing the skin, subcutaneous tissue, and superficial temporal fascia. The superficial layer of the DTF was exposed. We cut the superficial layer along the line along, which it adhered to the deep layer inseparably. The heights of the split line of the DTF from the superior border of the zygomatic arch and from the top of the helix were measured at three points: at the jugale, zygion, and 3 cm from the tragus. RESULTS: In all cases there were thick identifiable deep layers of the DTF. The mean heights of the split line of the DTF from the superior border of the zygomatic arch were 49.8, 46.7, and 42.6 mm at the jugale, zygion, and 3 cm from the tragus, respectively; the corresponding mean heights of the split line from the top of the helix were 19.1, 15.6, and 11.4 mm. CONCLUSIONS: Knowledge of the mean height of the split line of the DTF will be helpful for surgeons to determine the temporal incision site for ensuring the safe reduction of a zygomatic arch fracture.

Effects of Reading a Free Electronic Book on Regional Anatomy with Schematics and Mnemonics on Student Learning.

BACKGROUND: To help medical students learn anatomy effectively in limited hours, a regional anatomy book enhancing students' memorization was developed. METHODS: Only anatomical terms essential for basic cadaver dissection are included along with schematic figures which enable memorization of complicated anatomical structures. Learning comics and comic strips that depict anatomy mnemonics and jokes were appended and sentences were written to be comfortably readable. The electronic book titled "Visually Memorable Regional Anatomy" has been distributed without payment or registration. With the help of 246 volunteer students from three Korean medical schools, the book's learning effects were evaluated. RESULTS: These students' book reading led to increase in their anatomy scores, including written examination scores and tag examination scores. It was an encouraging result that almost 20% of students spontaneously read the book no matter who presented their lecture or examination. A webpage version of the book was visited by thousands of users. CONCLUSION: The book with unique features may suggest a new perspective in the field of anatomy learning. After having acquaintance with essential structures from reading the book, students are able to and willing to study more from other resources.

Intramuscular Nerve Distribution of the Inferior Oblique Muscle.

Purpose: The intramuscular nerve distribution in the extraocular muscles is important for understanding their function. This study aimed to determine the intramuscular nerve distribution of the oculomotor nerve within the inferior oblique muscle (IO) using Sihler's staining.Method: Seventy-two IOs from 50 formalin-embalmed cadavers were investigated. The IO including its branch of the oculomotor nerve was finely dissected from its origin to its insertion point into the sclera. The total length of the muscle and its width were measured. The intramuscular nerve course was investigated after performing Sihler's staining, which is a whole-mount nerve-staining technique that stains the nerves while rendering other soft tissues either translucent or transparent.Results: The total length of the muscle and muscle width were 30.0 ± 2.8 mm (mean±standard deviation), 8.8 ± 1.2 mm, respectively. The oculomotor nerve enters the IO around the middle of the muscle and then divides into multiple smaller branches without distinct subdivisions. The intramuscular nerve distribution within the IO has a root-like arborization and supplies the entire width of the muscle. The Sihler's stained intramuscular nerve course (covering a length of 7.6 ± 1.2 mm) finishes around the distal one-third of the IO in gross observations.Conclusion: Sihler's staining is a useful technique for visualizing the gross nerve distribution of the IO. This new information about the nerve distribution and morphological features will improve the understanding of the biomechanics of the IO.

Topography of the Central Retinal Artery Relevant to Retrobulbar Reperfusion in Filler Complications.

BACKGROUND: Vision loss caused by retrograde occlusion of the central retinal artery is a serious complication of cosmetic filler injections. Salvage methods that involve applying hyaluronidases in the retrobulbar space to degrade filler materials have been proposed recently for rescuing the retinal circulation in an ophthalmic emergency. METHODS: Sixty-six eyeballs and orbital contents were extracted from formalin-embalmed cadavers and dissected carefully to examine the topographic relationship of the central retinal artery and optic nerve. To observe the three-dimensional course of a central retinal artery that invaginates into the optic nerve, serial sections reconstructed at 100-µm intervals using software were visualized in 11 specimens. RESULTS: The central retinal artery ramified from the ophthalmic artery and entered the optic nerve inferiorly at 8.7 ± 1.7 mm (mean ± SD) from the posterior margin of the eyeball. The intraneural course of a central retinal artery changed acutely between the periorbital environment of the fibrous optic nerve sheath, intermediate subarachnoid spaces, and center of the optic nerve stroma. CONCLUSION: When applying a retrobulbar approach for central retinal artery reperfusion with hyaluronidases, the reliable access route is suggested to be at a depth of 3.0 to 3.5 cm from the border of the inferolateral orbital rim, based on consideration of the entry point of the central retinal artery into the optic nerve.

Position and size of the sphenoid door jamb in the lateral orbital wall for the orbital decompression.

The aim of this study was to identify the three-dimensional topography of the sphenoid door jamb (SDJ) in the lateral orbital wall and to propose navigational guidelines for safe deep lateral decompression using surgical landmarks. The 120 orbits and SDJs of 60 subjects were three-dimensionally reconstructed using Mimics software. The mean volumes of the orbit and SDJ were 24.3 mm3 and 2.0 mm3, respectively. The mean distances from the lateral orbital margin (LOM) to the anterior and posterior margins of the SDJ were 13.2 and 36.3 mm, respectively. The mean distances from the superior orbital fissure to the LOM and to the posterior margin of the SDJ were 40.2 mm and 4.6 mm, respectively. The mean distances from the inferior orbital fissure (IOF) to the anterior and posterior margins of the SDJ were 3.8 mm and 20.5 mm, respectively. In the superior approach of the orbit, it can be predicted that the area up to 3 cm posterior from the LOM is safe, while 1 cm posterior from the safe zone could be a dangerous zone. In the inferior approach of the orbit, the safe area will be about 1 cm posterior from the anterior tip of the IOF, and the area up to 1 cm posterior from the safe zone should be approached with extreme care.

External and Internal Diameters of the Facial Artery Relevant to Intravascular Filler Injection.

BACKGROUND: Vision loss and skin necrosis caused by an accidental intraarterial embolism or vascular compression are rare but devastating complications when injecting filler materials into the face. METHODS: The external and internal diameters and wall thicknesses of the facial artery and its branches were measured from 41 formalin-embalmed cadavers after removing connective tissues attached to the arterial wall. RESULTS: The diameter and thickness of the facial artery exhibited significant interregional differences. The external and internal diameters of the facial artery were 1.9 ± 0.4 and 1.2 ± 0.3 mm (mean ± SD), respectively, at the inferior border of the mandible; 1.7 ± 0.3 and 1.2 ± 0.3 mm in the vicinity of the inferior labial artery; 1.5 ± 0.3 and 1.0 ± 0.3 mm at the mouth corner; 1.4 ± 0.3 and 0.9 ± 0.2 mm in the vicinity of the superior labial artery; and 1.1 ± 0.2 and 0.7 ± 0.2 mm in the vicinity of the lateral nasal artery. The external and internal diameters at the proximal parts of the inferior labial artery, superior labial artery, and lateral nasal artery were 1.0 ± 0.3 and 0.6 ± 0.2 mm, 0.9 ± 0.3 and 0.6 ± 0.2 mm, and 0.8 ± 0.2 and 0.5 ± 0.2 mm, respectively. CONCLUSION: Morphometric examinations of the facial artery under stereomicroscope observation as performed in the present study are expected to be more accurate than direct measurements obtained during cadaveric dissection or conventional histologic evaluations.