Yong Seok Nam

The intramuscular course of the inferior gluteal nerve in the gluteus maximus muscle and augmentation gluteoplasty.

The aim of this study was to elucidate the intramuscular course of the inferior gluteal nerve in the gluteus maximus muscle and its association with augmentation gluteoplasty.Twenty buttocks of 10 Korean adult cadavers (age range: 47–87, 7 men and 5 women) were used for the study. The inferior gluteal nerve (IGN) was traced from the infrapiriform foramen at the deep surface of gluteus maximus (GM) until the nerve thickness became 0.3 mm. The depth of the IGN was measured and the relative depth of the nerve was calculated according to the thickness of the GM at 15 points.The muscle thickness varied according to its location. The medial part (17.1–18.1 mm) was thicker than the lateral (14.5–15.7 mm) or inferior parts (14.5–14.7 mm). The IGN runs deep through the GM (59%–82% of muscle thickness). Except for below the Coccyx-Greater trochanter line, where the IGN was located (59%–62% depth), the IGN was traced to 63–82% of the depth in the GM. The IGN ran relatively superficial (below 70%) in the medial part of the GM, and was a little deeper (above 70%) in the lateral part.There results of this study showed that intramuscular augmentation gluteoplasty could be performed safely unless intramuscular dissection is performed too deeply.

Surgical Anatomy of Retaining Ligaments in the Periorbital Area

The aim of this study was to elucidate an anatomic detail of ligamentous attachments in the periorbital areas of Korean cadavers. Sixty-one hemifaces of 35 Korean adult cadavers (age range, 43-101 years; 23 men and 9 women) were used. Fifty-five specimens were dissected, 12 used for tension measurement, and 6 for histologic study. Definite retaining ligaments were found in 42 (76.4%) of 55 dissected hemifaces. We named the retaining ligaments attached to the bony orbit periorbital ligament (PL). Periorbital ligament was in the medial and lateral orbital area. Medial PL (MPL) was curvilinear shaped and between an angle of +23.4 and −23.1 degrees on the horizontal at a midpupillary line. Lateral PL (LPL) was crescent shape and between an angle of +39.1 and −42.1 degrees. The MPL was vertical along the medical orbital rim just outer to the orbital septum. The width of MPL was 0.8 mm, and vertical length was 22.1 mm. The crescent-shaped LPL was located a few millimeters (up to 4 mm) lateral to the lateral orbital rim. The maximum width of LPL was 6.9 mm, and vertical length was 28.2 mm. The breaking strength of the LPL (14.2 ± 11.1 N) was significantly higher (P = 0.016) than that of the central lower eyelid (5.1 ± 2.5 N). The breaking strength of the MPL (8.4 ± 3.0 N) was also significantly higher (P = 0.013) than that of the central lower eyelid. However, there was no significant difference between LPL and MPL (P = 0.055). Knowledge of the retaining ligaments is conducive to performing the midfacial rejuvenating surgery.

Anatomic study of the lateral palpebral raphe and lateral palpebral ligament.

The aim of this study is to elucidate anatomic detail of the lateral canthal area relating to lateral canthoplasty. Thirty-three hemifaces of 22 Korean adult fresh cadavers were used. Thirty-one specimens were used for tension measurement and 2 for histologic study. There were 3 components of the lateral canthal area under the skin; lateral palpebral raphe (LPR), superficial lateral palpebral ligament (SLPL), and deep lateral palpebral ligament (DLPL). Lateral ends of superior and inferior orbicularis oculi muscles interlaced at the lateral commissure and formed LPR. SLPL extended from the lateral ends of tarsal plate to the periosteum of lateral orbital rim. Its transverse length was 9.4 ± 2.6 mm and vertical width was 3.6 ± 1.3 mm. DLPL extended from the lateral ends of tarsal plate deep to the origin of SLPL to Whitnalls tubercle on zygomatic bone inside the orbital margin. It is located deeper than SLPL. Its transverse length was 7.3 ± 1.6 mm and its vertical width was 9.0 ± 1.6 mm. Tensile strength of DLPL was 73.2 ± 26.8 N and stronger significantly than SLPL (30.0 ± 17.3 N). Tensile strength of LPR was 12.2 ± 8.0 N and weaker significantly than SLPL and DLPL. A detailed understanding of 3 layered structures (LPR, SLPL, and DLPL) at lateral canthal area is conducive to performing lateral canthoplasty.

Vulnerable structures during intraoral sagittal split ramus osteotomy.

The aim of this study was to elucidate the anatomical structures that are vulnerable to injury during sagittal split ramus osteotomy (SSRO). Twenty-nine hemifaces of 19 Korean adult cadavers (11 men and 8 women; age range, 50-91 years) were dissected, and the locations of the facial nerve, retromandibular vein (RMV), and external carotid artery (ECA) were measured on the base of the mandibular posterior border and occlusal plane. Sagittal split ramus osteotomy was performed on the cadaver heads at intervals of 10 mm, and the proximity of the facial nerve was observed. The buccal branch and mandibular branch crossed the posterior border of the mandible (PBM). Most buccal branches (86%) crossed between 7/10 and 10/10 of the distance from gonion to mandibular notch (MN). Most mandibular branches (86%) were between 6/10 and 1/10 of the distance from gonion to MN. Most facial nerve trunks (FNTs) (82%) were within a circle of 9 mm in radius. Its center was located 34 mm posterior and 7 mm inferior to the MN. The FNT was located in the range of 11 to 14 mm medial to the PBM. The FNT emerged out of the stylomastoid foramen and ran anteroinferiorly in a direction of 45 degrees. In 10-mm ramus setback osteotomy, FNT was very close to the PBM, running almost vertically. Retromandibular vein was 5.5 to 8.6 mm posterior and 4.2 to 9.1 mm medial to the PBM. The ECA was located at 5.7 to 6.5 mm posterior and 10.5 to 12.9 mm medial to PBM. Facial nerve could be averted from injury by doing less setback. Bleeding after SSRO is likely to be due to the injury of RMV which is closer to the PBM (4-9 mm) than ECA (12-13 mm).

Anatomy of tympanoparotid fascia relating to neck lift.

The aim of this study is to elucidate anatomical detail of the tympanoparotid fascia (TPF), deployed anteroinferiorly to the tragus, in relation to neck lift and platysmaplasty. Forty-one hemifaces of 25 Korean adult cadavers (age range: 43-101 years, 19 males and 6 females) were used for the study. Thirty-seven were dissected. Twenty-one were used for tension measurement and 4 for the histologic study. Tympanoparotid fascia was found in almost 36 hemifaces (100%). It was white-colored dense connective layer anteroinferior to tragus. The whitish fascia was a dense connective tissue layer deployed anteroinferiorly to the tragus. Two thirds of TRF originated from the tympanomastoid fissure and one third from the auricular cartilage and interfused with the parotid fascia, covering the parotid gland in front of the tragus. Tympanoparotid fascia was tetragonal in shape. The anterior side (15.1 ± 5.4 mm) was longer than the posterior side (10.4 ± 4.4 mm). It was 11.3 ± 3.9 cm in upper width and 9.5 ± 3.8 cm in lower, respectively. It was located 43.0 ± 7.7 mm inferior to the otobasion superioris (obs) and 6.0 ± 5.5 mm superior to the otobasion inferioris (obi). The anterior side was at 9.5 to 11.3 mm anterior to the auricle (obs-obi) and the posterior side at obs-obi line of the auricle. The tensile strength of the 5 mm width of TPF was 38.4 ± 18.2 N. It is significantly stronger (P = 0.00) than the central portion of the parotid fascia (22.7 ± 12.2 N). Tympanoparotid fascia strength (38.4 N) is enough to pull and hold the platysma as much as sternocleidomastoid muscle fascia (44.5 N) does. Such an anatomical component of TPF is useful in performing platysmaplasty or platysma suspension.

Cutaneous innervation of lower eyelid.

The loss of skin sensation or numbness after lower blepharoplasty is not uncommon. The aim of this study is to elucidate the infraorbital nerve (ION) and zygomaticofacial nerve (ZFN) in detail. Twenty-one hemifaces of 14 fresh Korean adult cadavers were dissected. Infraorbital nerve and ZFN came out of infraorbital foramen and zygomaticofacial foramen. They ran along superficial to the periosteum within and beneath the epimysium of the orbicularis oculi muscle and then through orbicularis oculi muscle perpendicularly and distributed to the skin. The distal branch approached to the lower border of the tarsal plate. Most terminal branches (93.8%) of ION were distributed medial to the lateral canthus. Only a few branches (6.2%) were lateral to the lateral canthus. Most (99.4%) terminal branches of ZFN were distributed lateral to the lateral canthus. Very few (0.6%) branches were medial to the lateral canthus. We conclude that the skin-muscle flap infringes less than the skin flap on the terminal branches of ION and ZFN in exposure of the orbital floor as well as in lower blepharoplasty.

Location of the mandibular branch of the facial nerve according to the neck position.

Abstract The aim of this study was to elucidate the exact location of the mandibular branch of the facial nerve according to different neck positions. Twenty-two hemifaces of 11 fresh human cadavers were used (age range, 53–89 y; mean age, 72.3 ± 10.5 y; 8 men and 3 women). Working through skin windows, the distance from the mandibular border to the mandibular branch of the facial nerve (border–nerve distance or BND) was measured at 3 points: (1) the mandible angle (gonion or Go point), (2) the point where the mandibular branch of the facial nerve crosses the facial artery (FA point), and (3) the one-fourth point from the gonion to the menton (1/4 point). Threads were hung on the skin windows along the mandibular border. With the neck in the neutral position and then full flexion (15 degrees), extension (15 degrees), and left and right rotations (30 degrees), the distance of the mandibular branch from the thread of the mandibular border was measured using calipers. In the neutral position, the mandibular branch was 3.50 ± 2.82 mm above the mandibular border at the Go point, 5.34 ± 2.98 mm above the mandibular border at the FA point, and 5.28 ± 1.86 mm above the mandibular border at the 1/4 point. At all 3 points, flexion or extension of the neck did not significantly move the mandibular branch. At the Go point and FA point, there was no significant difference between the ipsilateral rotation position and the contralateral rotation. Yet at the1/4 point, the BND decreased (4.32 ± 2.60 mm) with the neck in ipsilateral rotation and the BND increased (5.97 ± 2.62 mm) with the neck in contralateral rotation. There was a significant difference between the ipsilateral rotation position and the contralateral rotation position (P = 0.020, t-test). Surgeons should keep in mind that at the 1/4 point, the mandibular branch of the facial nerve moves downward 1.10 ± 1.42 mm with the neck in ipsilateral rotation and moves upward 0.49 ± 1.84 mm with the neck in contralateral rotation.

Detailed anatomy of the capsulopalpebral fascia

This study was designed to elucidate the detailed anatomy of the capsulopalpebral fascia (CPF) and capsulopalpebral head (CPH), and their relationships to the inferior rectus muscle (IRM). In this cohort study, 40 eyes from 20 cadavers were observed macroscopically. Dissection was carried out from the CPF origin to its insertion, and the CPF origin pattern was photographed in each specimen. The width, length, and tensile strength of the CPF were measured. The CPF originated 25.07 ± 1.07 mm laterally and 24.86 ± 1.10 mm medially from the origin of the IRM and extended to the lower border of the inferior oblique muscle, and it firmly adhered to the IRM surface and formed into the CPH. The CPH was 4.31 ± 0.86 mm laterally and 6.18 ± 1.94 mm medially in length and 7.47 ± 0.81 mm in width. The CPF originated from the total width or 3/4 temporal part of the IRM in 32 (80%) of 40 faces. There was asymmetry in the pattern of the CPF origin between the left and right eyes in 4 of 20 paired specimens (20%). The tensile strength of the posterior layer was 19.12 ± 11.22 N, which was significantly higher than that of the anterior layer (8.59 ± 3.88 N) (P = 0.001). This study provided a good understanding of the CPF structures conducive to performing IRM surgery. Clin. Anat. 25:709–713, 2012.

Posterior cutaneous nerve of the thigh relating to the restoration of the gluteal fold.

The aim of this study was to elucidate the anatomic relationship between the posterior cutaneous nerve of the thigh (PCNT) and the gluteal fold. A total of 20 amputated thighs from 10 fresh Korean cadavers were used in this study (10 men; age range, 52–76 years). The PCNT was located at an average distance of 13.1 ± 1.7 cm (medial range, 10.5–16.0 cm) medial to the gluteal fold. The majority of the PCNT travels along the middle 1/3 of the thigh at the level of the gluteal fold (medial 3/10 to 6/10; average, 42.1% ± 8.7%; range, 23.8%–59.2%). The majority (85%) of the sites of emergence of the perineal branches were located within a rectangular region that covered the medial 1/4 to 1/2 of the thigh on the x axis and the proximal 1/12 to 1/4 of the thigh on the y axis. Most (78%) of the sites of emergence of the inferior cluneal nerve were located within 2 semicircular regions, an upper semicircle and a lower semicircle. The upper semicircle was 3 cm in diameter, and its center was located in the medial 2/5 of the thigh on the x axis. The lower semicircle was 2.5 cm in diameter, and its center was located at the midpoint of the thigh on the x axis. The majority (90%) of the main branches of the PCNT were located within a rectangular region, the base of which extended from the medial 1/3 to 2/3 of the thigh on the x axis and the height of which was in the proximal 1/10 to 2/5 of the thigh on the y axis. Our study describes the characterization of the site and reach of the PCNT in the thigh. It is imperative to know the exact location of the PCNT to avoid causing injury to the nerve during buttock lift.

Detailed anatomy of the abducens nerve in the lateral rectus muscle

The aims of this study were to elucidate the detailed anatomy of the abducens nerve in the lateral rectus muscle (LRM) and the intramuscular innervation pattern using Sihler staining. In this cohort study, 32 eyes of 16 cadavers were assessed. Dissection was performed from the LRM origin to its insertion. The following distances were measured: from LRM insertion to the bifurcation point of the abducens nerve, from LRM insertion to the entry site of the superior branch or inferior branch, from the upper border of the LRM to the entry site of the superior branch, from the lower border of LRM to the entry site of inferior branch, and the widths of the main trunk and superior and inferior branches. The single trunk of the abducens nerve divided into two branches 37 mm from insertion of the LRM, and 22 of 32 (68.8%) orbits showed only two superior and inferior branches with no subdivision. The superior branch entered the LRM more anteriorly (P = 0.037) and the superior branch was thinner than the inferior branch (P = 0.040). The most distally located intramuscular nerve ending was observed at 52.9 ± 3.5% of the length of each muscle. Non‐overlap between the superior and inferior intramuscular arborization of the nerve was detected in 27 of 32 cases (84.4%). Five cases (15.6%) showed definite overlap of the superior and inferior zones. This study revealed the detailed anatomy of the abducens nerve in the LRM and provides helpful information to understand abducens nerve palsy. Clin. Anat. 30:873–877, 2017.