Variations of lumbrical muscle and its nerve innervation in hands of Koreans

의과학과/석사[한글]벌레근육의 신경분포는 둘째와 셋째 손가락 벌레근에 정중신경이, 넷째와 다섯째 손가락 벌레근에는 자신경이 분포하는 것으로 알려져 있다. 손에서 자신경 얕은가지에서 정중신경으로의 교통가지 이후에 정중신경에서 나온 가지가 넷째 손가락 벌레근에 흔하게 분포한다. 넷째 손가락 벌레근에 분포하는 신경가지의 기원은 신경다발의 분리로 확인할 수 있다. 이 연구의 목적은 벌레근육의 다양한 형태변이를 관찰하고 벌레근육에 분포하는 신경다발을 분리하여 벌레근육의 정확한 신경분포를 밝히기 위함이다.한국 성인 시신 45구의 손 70쪽을 사용하였다. 신경다발의 분리가 필요한 경우는 벌레근육과 분포신경을 함께 떼어내 0.1M Guanidine hydrochloride 용액에 일주일 담근 후 초음파세척기로 한 시간 동안 처리하여 결합조직을 부드럽게 하였다. 신경다발 분리는 수술현미경 하에서 하였다.벌레근육은 근육 모양에 따라 크게 3가지로 구분하고 벌레근육이 닿는 부위에 따라 10가지 유형으로 분류하였다. 벌레근육의 근육 모양은 크게 둘째와 셋째 손가락 벌레근이 반깃근육이고 넷째와 다섯째 손가락 벌레근이 깃근육인 경우, 둘째 손가락 벌레근은 반깃근육이고 셋째, 넷째, 다섯째 손가락 벌레근은 깃근육인 경우, 벌레근 4개 중 벌레근이 하나라도 없는 경우로 구분하였다. 둘째와 셋째 손가락 벌레근이 반깃근육이고 넷째와 다섯째 손가락 벌레근이 깃근육인 경우, 벌레근 4개가 모두 해당 손가락의 노쪽에 닿는 유형은 40.0%, 넷째 손가락 벌레근, 다섯째 손가락 벌레근이 두 가닥으로 나뉘어져 닿는 유형은 각각 12.9%, 14.3%였다. 넷째와 다섯째 손가락 벌레근이 모두 두 가닥으로 나뉘어져 닿는 유형은 2.9%였다. 둘째 손가락 벌레근은 반깃근육이고 셋째, 넷째, 다섯째 손가락 벌레근은 깃근육인 경우, 벌레근 4개가 모두 해당 손가락의 노쪽에 닿는 유형은 14.3%, 넷째 손가락 벌레근, 다섯째 손가락 벌레근이 두 가닥으로 나뉘어져 닿는 유형은 각각 5.7%, 4.3%였다. 벌레근 4개 중 벌레근이 하나라도 없는 경우는 2.9%였다. 굽힘근지지띠 아래모서리에서 벌레근 이는곳까지의 평균거리는 둘째, 셋째, 넷째, 다섯째 손가락 벌레근의 경우 각각 +1.8 mm, -1.4 mm, +5.1 mm, +11.2 mm였다. 벌레근육의 신경분포는 정중신경과 자신경의 분포 또는 이중신경분포에 따라 7가지 유형으로 분류하였다. 둘째와 셋째 손가락 벌레근에 정중신경이, 넷째와 다섯째 손가락 벌레근에 자신경이 분포하는 유형은 26.0%에서만 나타났다. 일반적인 유형은 둘째와 셋째 손가락 벌레근에 정중신경이 분포하고, 넷째 손가락 벌레근에 정중신경과 자신경의 이중신경분포를, 다섯째 손가락 벌레근에 자신경이 분포하는 경우로 60.0%였다. 벌레근육의 이중신경분포는 둘째, 셋째, 넷째 손가락 벌레근에서 나타났다. 벌레근육의 이중신경분포 빈도는 68.0%였으며, 넷째 손가락 벌레근의 이중신경분포 빈도는 64.0%였다. 손에서 자신경 얕은가지에서 정중신경으로의 교통가지 이후에 정중신경에서 나온 가지가 넷째 손가락 벌레근 앞면에 분포하는 경우는 19쪽(38.0%)이었다. 이 교통가지의 신경다발을 분리한 결과, 교통가지에서 유래한 자신경 다발이 정중신경과 함께 넷째 손가락 벌레근 앞면에 분포하는 경우는 9쪽(18.0%)이었고, 자신경 다발이 모두 고유바닥쪽손가락신경이 되고 정중신경이 넷째 손가락 벌레근 앞면에 분포하는 경우는 10쪽(20.0%)이었다. 자신경 얕은가지가 넷째 손가락 벌레근에 분포하는 경우는 모두 자신경 깊은가지가 분포하였다. 벌레근육에 분포하는 자신경은 주로 깊은가지에서 일어났다. 자신경 얕은가지와 자신경 깊은가지가 동시에 벌레근육에 분포하는 경우는 다섯째 손가락 벌레근에 5쪽(10.0%), 넷째 손가락 벌레근에 10쪽(20.0%)이었다. 전기진단에서 셋째 손가락 벌레근은 손목굴증후군의 예후를 판단하는 데 중요하게 사용되며 둘째와 셋째 손가락 벌레근은 근육피판수술에 사용될 수 있다. 이때 벌레근육의 신경분포 변이에 대한 자료는 전기진단과 근육피판수술에 도움이 될 수 있을 것으로 생각된다. [영문]The first and second lumbricals have been described to be innervated by the median nerve, and the third and fourth lumbricals by the ulnar nerve in the anatomy literatures. However, the 3rd lumbrical muscle was frequently observed to be innervated by a branch arising from the median nerve distal to the joining site of the ulnar nerve branch to median nerve. Thus this study was conducted to clarify the nerve innervations of the lumbrical muscle by identifying the origin of the nerve fascicles innervating the muscles. Seventy hands of Korean adult cadavers were used. In the cases that the ulnar nerve was anastomosed with the median nerve before entering the 3rd lumbricals, the muscles and nerves were removed and immersed in guanidine hydrochloride solution (0.1mol/L) for 1 week. Then the nerve fascicles were separated and traced up under a surgical microscope. The lumbrical muscles were classified into 3 types based on their shapes, and also into 10 types based on their insertion sites. In the cases that the first and second lumbricals were unipenniform, and the third and fourth were bipenniform, all lumbricals inserted on the radial side of the corresponding fingers in 40.0%, the third inserted in split on 3rd and 4th digits in 12.9%, and the fourth inserted in split on 4th and 5th digits in 14.3%. In the cases that the first lumbrical was unipenniform, and the second, third, fourth were bipenniform, all lumbricals inserted on the radial side of the corresponding fingers in 14.3%, the third inserted in split on 3rd and 4th digits in 5.7%, the fourth inserted in split on 4th and 5th digits in 4.3%. The lumbricals were not found in 2.9%. The average distances from the distal border of the flexor retinaculum to the origins of the first, second, third, and fourth lumbricals were +1.8 mm, -1.4 mm, +5.1 mm, and +11.2 mm, respectively. The nerve innervation of the lumbrical muscle was classified into seven types. The most common type (60.0%) was that the first and second lumbricals were innervated by the median nerve, and the third by both the median and ulnar nerves, and the fourth by the ulnar nerve. The second most common type (26.0%) was that the first and second lumbricals were innervated by the median nerve, and the third and fourth by the ulnar nerve. The dual innervation of at least one lumbrical muscle was observed in 34 out of 50 specimens (68.0%), and the dual innervation of the 3rd lumbrical was most frequently observed (64.0%). In 19 specimens (38.0%), the 3rd lumbrical muscle was innervated by a branch arising from the median nerve distal to the joining site of the ulnar nerve branch to the median nerve. When separating and tracing up the nerve fascicles from the median nerve, the fascicles contained the components from the median and ulnar nerves in 9 cases, and the median nerve component in 10 cases. In these cases, the 3rd lumbricals were all innervated by the deep branch of the ulnar nerve. The ulnar nerve innervated the lumbricals generally through its deep branch. However, both the superficial and deep branches of the ulnar nerve innervated the fourth lumbrical in 5 cases and the third in 10 cases.ope

Topography and location of the depressor anguli oris muscle with a reference to the mental foramen

The labiomandibular fold (LMF) is the area of the face that extends from the mouth corner to the mandibular border, and its prominence tends to increase with age. The LMF can be formed by the medial or lateral border of the depressor anguli oris (DAO). The aim of this study was to demonstrate the topographical anatomy between the DAO and mental foramen, thereby providing critical information for the safest and most effective site at which to inject botulinum toxin type A (BTX-A). Thirty-four hemifaces from Korean adult cadavers were dissected. The maximum width between the medial borders of the bilateral DAO, parallel to the intercheilion horizontal line, was 59.9 +/- 4.6 (mean +/- SD) mm below the lower lip. The minimum width between the medial borders of the attachment of bilateral DAO was 29.7 +/- 4.8 mm at the mandibular border. The mental foramen was located in the middle third from the cheilion to the mandibular border in 28 cases (90.3%), and it was mostly confined within the DAO muscle coverage in 21 cases (67.7%). The buccal branch of the facial nerve entered through the middle third of the lateral border of DAO and then distributed. Concomitantly, the marginal mandibular branch of the facial nerve entered through the lower third of the lateral border of DAO in 17 cases (60.7%). These results represent additional reference data for identifying the position of the mental foramen on the facial skin, and will be useful for providing criteria for the most effective site for injecting BTX-A when treating the LMFope

Branching Patterns and Intraosseous Course of the Mental Nerve

PURPOSE: The purpose of this study was to clarify the branching patterns of the mental nerve (MN) and intraosseous courses of the MN branches, and to determine the clinical relevance of the various courses of the MN branches. MATERIALS AND METHODS: We investigated the topography of the MN by dissecting 31 hemifaces of Korean cadavers. Based on the distribution area of the MN, it was divided into angular (A), medial inferior labial (ILm), lateral inferior labial (ILl), and mental (M) branches. We classified the branching patterns of the 4 branches of the MN into 5 types. RESULTS: Type II, in which the MN divided into 3 branches (A, ILm, and M), with the ILl branch separating from the A branch, was the most common (35.4%). The MN was classified based on the shape of the anterior loop into loop, straight, and vertical patterns, which constituted 61.5%, 23.1%, and 15.4%, respectively. In the mandibular canal, the inferior alveolar nerve completely divided into the MN and the dental nerve, which supplies the teeth. In 17 cases (81%), the nerve bundles constituting the A branch were located at the superior aspect, whereas the nerve bundles of the inferior labial and mental branches were in the middle and inferior aspects within the mandibular canal, respectively, at the mental foramen region. CONCLUSION: These observations can help clinicians to predict the location or extent of paresthesia in the facial region according to the location and extent of nerve damage during dental implant surgery or genioplasty.ope

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

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Clinical implications of the topography of the arteries supplying the medial pterygoid muscle

The literature contains numerous accounts of the muscular anatomy of the medial pterygoid muscle, but little is known about the detailed vascular supply of the muscle. Numerous surgical procedures, such as mandibular ramus osteotomy, angle reduction, and/or parotidectomy, are performed around the muscle in the absence of this information. This study aimed to clarify the arterial supplies to the medial pterygoid muscle to provide critical information for use during various surgical procedures. Detailed dissections were performed on 20 sides of adult cadaveric head and neck specimens after injecting the carotid artery with red liquid neoprene latex. The medial pterygoid muscle was supplied by the following 5 branches of the external carotid artery: (1) the pterygoid artery of the maxillary artery, (2) a direct muscular branch of the facial artery, (3) the ascending palatine artery, (4) an anterior muscular branch of the facial artery, and (5) a previously undescribed muscular branch of the external carotid artery. This analysis of vascular anatomy has revealed new anatomic information on the blood supplies to the medial pterygoid muscle and will be useful to the development of guidelines for preventing hemorrhage during surgical proceduresope

Clinical implications of the topography and distribution of the posterior superior alveolar artery

The aim of this study was to clarify the arrangement of the anatomic courses and distribution of the intraosseous branch (IObr) of posterior superior alveolar artery. The anatomic variations in the topographic relationships were described to provide beneficial data to minimize injury to the IObr during surgical procedure of the buccal wall of the maxillary sinus. The IObrs in 42 hemifaces of embalmed Korean cadavers were examined. The courses of the IObr of the posterior superior alveolar artery were classified into 2 categories: the straight (type 1) and the U-shaped (type 2). The type 1 was the most common (78.1%), and the type 2 was observed in 21.9% of the specimens. The minimum mean height from the cervix to the IObr was 21.1 mm in the first molar region. The IObr ran at the lowest level from the maxillary sinus floor at the first premolar region. These anatomic findings in the current study could represent useful information for the various surgical procedures of the maxillaope

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.ope

New anatomic considerations on the levator labii superioris related with the nasal ala

The levator labii superioris (LLS) muscle is well known as one of the upper-lip elevators; however, there have been few reports about the anatomic description of the LLS. Especially, the shape of the LLS and its relationship with the nasal ala were not clearly shown in the literature. The aim of this study was to clarify and describe the morphology and topography of the LLS and the anatomic variations to understand the function of the LLS related with the nasal ala. The LLS was examined in 102 specimens of embalmed Korean and French adult cadavers. The LLS was classified into 3 categories according to its shape and attachment: rectangular (83%), fan (10%), or trapezoid (7%) type. The medial fibers of the LLS were attached to the deep surface of the alar facial crease and were mainly intermingled with the alar part of the nasalis. Some of the deeper muscle fibers of the LLS extended to the vestibular skin of the nasal lobule. These new anatomic findings in the current study could be useful information for understanding the function of the LLS and the various surgical procedures of the perinasal region.ope

Surface anatomy of the lip elevator muscles for the treatment of gummy smile using botulinum toxin

OBJECTIVE: To propose a safe and reproducible injection point for botulinum toxin-A (BTX-A) as a supplementary method for the treatment of gummy smile, as determined by assessment of the morphologic characteristics of three lip elevator muscles. MATERIALS AND METHODS: A total of 50 hemi-faces from 25 adult cadavers (male 13, female 12; ages, 47 to 88 years) were used in this study. Topographic relations and the directions of the lip elevator muscles (ie, levator labii superioris [LLS], levator labii superioris alaeque nasi [LLSAN], and zygomaticus minor [ZMi]), were investigated. Possible injection points were examined through the study of predetermined surface landmarks. RESULTS: The insertion of the LLS was covered partially or entirely by the LLSAN and the ZMi, and the three muscles converged on the area lateral to the ala. The mean angle between the facial midline and each muscle vector was 25.8 +/- 4.8 degrees for the LLS, 55.7 +/- 6.4 degrees for the ZMi, and -20.2 +/- 3.2 degrees for the LLSAN; no significant differences were noted between male and female subjects or between left and right sides. The three vectors passed near a triangular region formed by three surface landmarks. The center of this triangle, named the "Yonsei point", was suggested as an appropriate injection point for BTX-A. The clinical effectiveness of the injection point was demonstrated in selected cases with or without orthodontic treatment. CONCLUSIONS: Under careful case selection, BTX-A may be an effective treatment alternative for patients with excessive gingival display caused by hyperactive lip elevator muscles.ope

Extra- and intramuscular nerve distribution patterns of the muscles of the ventral compartment of the forearm

OBJECTIVE: This study describes the extra- and intramuscular nerve branching of muscles of the ventral compartment of forearm, thereby providing critical information on determining the points for botulinum toxin injections that would be effective at reducing muscular spasticity. DESIGN: Twenty-three Korean and French cadavers were dissected and subjected to Modified Sihler's staining to investigate nerve entry points and intramuscular nerve arborization patterns. Nerve entry point and abundant arborizing area of each muscle were analyzed on 20 segments with reference to transverse lines obtained by dividing the forearm into ten equal divisions and a vertical line bisecting the medial and lateral halves of the forearm. RESULTS: The nerve entry points of the first and second layers of forearm muscles were located at medial levels 3 and 2, respectively. The entry points of the median and ulnar nerves innervating the flexor digitorum profundus (third layer) were located at medial levels 4 and 3, respectively. The intramuscular regions of abundant arborization in each muscle were located one level distal to the nerve entry point. CONCLUSIONS: This study has yielded a map of nerve entry and abundant arborization of motor nerves innervating each muscle of the ventral compartment of the forearm.ope