An uncommon form of the rare extensor carpi radialis accessorius.

Two accessory muscles were found in the lateral compartment of the forearm while dissecting a 92-year-old female cadaver. One of these originated from the extensor carpi radialis brevis, became tendinous and travelled between the two radial extensor tendons. It inserted independently into the second metacarpal bone, and may be regarded as an extensor carpi radialis intermedius. The other accessory muscle originated from the extensor carpi radialis longus, passed superficially over the parent tendon and inserted into the abductor pollicis brevis. This variation appeared to be a rare extensor carpi radialis accessorius, an additional muscle, which usually arises from below the extensor carpi radialis longus and inserts into the first metacarpal bone. Various forms of the accessorius have been described previously, including one that inserts into the abductor pollicis brevis. The tendon of the accessory muscle described in this study passed through its own dorsal tunnel under the extensor retinaculum, making it an uncommon form of the rare accessorius.     

Multiple variations in the region of Mm. extensores carpi radialis longus and brevis.

While dissecting the body of an 80-year-old female we observed multiple variations in the right region of Mm. extensores carpi radialis longus and brevis. The M. extensor carpi radialis longus gave origin to an accessory head. The tendon of this accessory head passed through a separate tunnel in the extensor retinaculum and inserted in the middle of the first metacarpal bone. Concerning its function, this accessory head of the M. extensor carpi radialis longus could be regarded as an additional abductor pollicis. The M. extensor carpi radialis brevis had an accessory tendon lying underneath the main tendon of this muscle. The accessory tendon joined with the main tendon just when undercrossing Mm. abductor pollicis longus and extensor pollicis brevis. Afterwards the tendon lay in the second tunnel of the extensor retinaculum and inserted in the base of the third metacarpal. In her lifetime the individual's tabatière probably must have been conspicuously pronounced at its radial margin.     

An additional radial wrist extensor and its clinical significance

The knowledge of anatomical variations in the antebrachial and dorsal regions of the arm and hand are useful in hand surgery. The extensor carpi radialis intermedius and extensor carpi radialis accessorius are two classic variants described for the radial wrist extensors, in the antebrachial region. We report an additional extensor carpi radialis muscle taking origin from the common extensor origin, between the extensor carpi radialis longus and extensor digitorum communis. The tendon of the variant muscle divides below the abductor pollicis longus and becomes attached to the base of the second and third metacarpal bone. Due to its considerable size and independent origin from the lateral epicondyle, we suggest the present variation should be named extensor carpi radialis tertius. The clinical significance of the present variation is discussed.     

Bilateral abductor pollicis longus muscle variation. Case report and review of the literature

An abnormal abductor pollicis longus muscle was encountered bilaterally during the dissection of the upper limb of a 26-year-old male cadaver. In the left side, the abductor pollicis longus had seven tendon slips. The medial two inserted into the abductor pollicis brevis, the other five inserted into the base of the first metacarpal bone. In the right side of the case, the abductor pollicis longus was consisted of three bellies. The lateral belly's tendon was the main abductor pollicis longus tendon and inserted into the base of the first metacarpal bone. The medial belly inserted into the abductor pollicis brevis. Between these muscle bellies, there was an intermediate belly. Its tendon was split into two thin slips and inserted into both the abductor pollicis brevis and the opponens pollicis muscles. The number of such accessory tendons has a functional significance in the development of de Quervain's stenosing tendovaginitis and possibly also has a practical significance. This paper is the first to describe seven tendons of the abductor pollicis longus and extensor pollicis brevis in the same compartment.     

用于显露前臂骨间膜的桡骨背侧入路应用解剖

目的 找出显露前臂骨间膜的最佳入路.方法 用卡尺测量了30例成人上肢,测量项目如下:桡骨头至旋后肌腱弓处骨间背神经的长度(LHA);桡骨头到旋后肌管下口之间骨间背神经的长度(LHS);骨间背神经从旋后肌管下口至桡骨外缘的距离(DSR);骨间背神经从旋后肌管下口至尺骨内缘的距离(DSU);骨间背神经最外侧分支穿拇长展肌处至桡骨外缘的距离(DSP).结果 LHA、LHS、DSR、DSU和DSP的测量结果分别为19.3±4.4mm(11mm～29mm)、53.4±5.2mm(45mm～62mm)、9.7±3.1mm(4mm～15mm)、22.8±3.5mm(20mm～28mm)和7.5±1.6mm(5mm～9mm).牵开拇长展肌、拇短伸肌和拇长伸肌,于桡侧腕短伸肌与指伸肌之间显露前臂骨间膜中1/3和远1/3段.结论 桡骨背侧入路可较少剥离肌肉和软组织,能方便、安全显露前臂骨间膜中1/3和远1/3段.     

Anatomical study on the extensor digitorum profundus muscle in the Japanese

An anatomical study on the extensor digitorum profundus muscle was made using 832 upper limbs from 416 Japanese adults. The separate muscles derived from the extensor digitorum profundus consist of 10 kinds: namely, the extensor pollicis longus, extensor pollicis et indicis accessorius, extensor indicis radialis, extensor indicis proprius, extensor indicis ulnaris, extensor indicis et medii accessorius, extensor medii proprius, extensor annularis proprius, extensor carpi profundus and extensor digiti brevis. The configuration of the muscles (except for the extensor digiti brevis) in the upper limb was classified into 13 types according to their arrangement and insertion. The most frequent type involved coexistence of the extensor pollicis longus and the extensor indicis proprius: it was observed in 664 limbs (79.8%). The next type involved coexistence of the extensor pollicis longus, extensor indicis proprius and the extensor medii proprius: it was observed in 67 limbs (8.1%). It appears that the extensor digiti brevis of man is derived from the most ulnar part of the extensor digitorum profundus which does not migrate proximally.     

微创治疗桡骨远端骨折安全进针区域的解剖学研究

目的　测量桡骨茎突在腕关节不同角度时与周围肌腱、血管的距离,探讨手法复位经皮闭合穿针内固定术微创治疗桡骨骨折经桡骨茎突的相对安全进针区域。 方法　20侧成人前臂标本,以腕部外固定支架固定腕部,分别在腕关节掌屈0°、20°、40°、60°和尺偏0°、30°等8个位置,测量桡骨茎突最高点与桡侧腕长伸肌腱、拇短伸肌腱的最短距离,桡骨茎突最高点与桡侧腕长伸肌腱、拇长伸肌腱、拇短伸肌腱、桡动脉各交点的距离。 结果　腕关节掌屈、尺偏运动引起桡骨茎突周围肌腱相对位置规律性地变化,腕关节在尺偏30°掌屈0°~20°范围内时,桡骨茎突的相对安全进针区域最大。 结论　以桡骨茎突最高点为体表标志,当腕关节在尺偏30°掌屈0°~20°范围内,桡骨茎突最高点周围一定距离范围内,经皮克氏针固定桡骨骨折,能最大限度降低对肌腱及血管的损伤率。     

Extensor pollicis et indicis communis or extensor indicis radialis muscle

Anatomical variations of the fingers extensor tendons are not uncommon and have been described by several authors. Participation of intertendinous band of fascia in this kind of variation can change muscle functionality. However, this element is scarcely described in the literature. In this case report, we describe the finding of an accessory tendon located between the extensor digitorum communis muscle tendon, destined for the index finger, and the extensor pollicis longus tendon. In an anatomical analysis, we observed a connection between the radial portion of the accessory tendon and the ulnar portion of the extensor pollicis longus tendon by intertendinous fascia. This finding corresponds anatomically to the supernumerary muscle denominated extensor indicis radialis, but due to the fascial connections observed with the extensor pollicis longus, this muscle would behave functionally as a supernumerary muscle denominated extensor pollicis et indicis communis. This report suggests that participation of fascia in muscular variation in this anatomical segment is essential to establish the correct morpho-functional denomination of muscular variants.     

Anatomic basis of dorsoradial approach for radioulnar synostosis

The object of this study was to identify the best approach for exposing the radioulnar interosseous membrane while protecting the posterior interosseous n. (PIN). Twenty paired upper limbs were used to obtain measurements of the PIN and expose the distal two-thirds of the interosseous membrane in the forearm through a dorsoradial approach. The length of the PIN from the radial head to the arcade of Frohse (AF) was 26.5 ± 1.6 mm in males and 25.3 ± 1.1 mm in females. The length of the PIN between the radial head and the point where the PIN exits from the supinator was 66.7 ± 4.7 mm in males and 64.0 ± 2.5 mm in females. The length of the PIN covered by the supinator was 44.0 ± 0.5 mm in males and 37.0 ± 0.5 mm in females. The distance between the point where the PIN exits from the supinator and the lateral margin of the radius was 15.0 ± 0.9 mm in males and 14.5 ± 0.9 mm in females. The distance between the exit point of the PIN from the supinator and the lateral margin of the ulna was 18.2 ± 0.6 mm in males and 17.9 ± 0.7 mm in females. The distance from the point where the most lateral branch of the PIN entered the abductor pollicis longus (APL) to the lateral margin of the radius was 3.5 ± 0.5 mm. In 20 cadaveric upper limbe, the middle and distal portions of the interosseous membrane were exposed through the interval between the extensor carpi radialis brevis (ECRB) and extensor digitorum communis (EDC) m., after the origine of the extensor pollicis brevis (EPB), and extensor pollicis longus (EPL) mm. had been elevated from the lateral margin of the radius. The present study suggests that usina dorsoradial approach facilitates exposure of the middle and distal portions of the interosseous membrane.     

前臂后外侧中段穿支蒂皮神经营养血管皮瓣的应用解剖

目的为前臂后外侧中段穿支蒂皮神经营养血管皮瓣提供解剖学基础。方法在30侧动脉内灌注红色乳胶的成人上肢标本上解剖观测:①前臂后皮神经走行与分布;②前臂后外侧中段穿支与前臂后皮神经营养血管间的吻合关系。另在1侧新鲜标本上进行摹拟手术设计。结果①前臂后皮神经主干行于前臂背侧,约在指伸肌与尺侧腕伸肌之间下行达腕背部,分布于前臂后外侧1/3区域;②营养血管为多节段、多源性,其中前臂后外侧中段穿支的位置相对恒定,在指伸肌与桡侧腕短伸肌的肌间隙、旋后肌与拇长展肌之间(肱骨外上髁下12.5～15.8cm范围内)穿过深筋膜至皮下,并分出众多的细小血管与前臂后皮神经的神经旁和神经干血管链的分支密切吻合,在指伸肌与桡侧腕短伸肌之间形成顺沿肌间隙和前臂后皮神经纵轴的血管丛。结论可以前臂后外侧中段穿支为蒂形成皮神经营养血管皮瓣转位修复前臂、腕部软组织缺损。     

足部相关肌肉、肌腱组织材料弹性模量的测定

背景：目前,几乎所有足部三维有限元模型的材料参数均来自国外研究,尚未见有关国人组织材料参数的测量与报道。 目的：对国人足部的相关肌肉、肌腱材料做测量,获得初步的参数数据。 方法：解剖成年女性左小腿足新鲜标本拇长屈肌及其肌腱、拇短屈肌内外侧头、拇长伸肌及其肌腱、拇收肌横头及斜头、拇展肌,分别测量和计算各试样的截面积和位于夹具之间的长度并记录数值,将标本加载载荷,1个测样反复测量4次,采集强度极限、最大载荷等数据,以及载荷-位移曲线。根据胡克定律,计算各标本的弹性模量。 结果与结论：共得到了包括拇长伸肌、拇长屈肌、拇收肌、拇展肌横头和斜头、拇短屈肌内外侧头、拇长屈肌腱、拇长伸肌腱9个样本的相关测量数据,主要包括长度、宽度、厚度、横截面积、最大载荷、强度极限和弹性模量。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

The innervation of deep muscles of the human forearm extensors]

The innervation of four deep muscles of the human forearm extensors (the abductor pollicis longus, the extensor pollicis brevis, the extensor pollicis longus, and the extensor indicis muscles) were investigated in 24 bodies (48 sides) from those used in the 1989 and 1990 student courses in gross anatomy dissection at the Iwate Medical University School of Medicine. The forearm extensor muscles and the deep branch of the radial nerve were dissected intensively in the student courses in gross anatomy and were removed afterwards. The four deep muscles of the human forearm extensors and the nerves innervating the muscles were observed while they were immersed in the water and with use of a stereomicroscope--with the assistance of which they were drawn. In six sides the intramuscular nerve supply was also examined carefully and drawn. The results were as follows. 1. The nerves to the four deep muscles of the forearm extensors arose usually from the deep branch of the radial nerve after emerging the supinator muscle and sending branches to superficial forearm extensors. In some cases a nerve or nerves to the superficial forearm extensors were observed arising from the deep branch of the radial nerve after sending one or more branches to the deep forearm extensor muscles, or from the branches to the deep muscles themselves. However they were split easily from the deep branch of the radial nerve and from the branches to the four deep forearm extensors proximally near to the emerging of the deep branch from the supinator muscle. Therefore, it was considered to be constant that the nerves to the four deep forearm extensors arose from the deep branch of the radial nerve after branching to the superficial forearm extensors. 2. The radial group of the deep forearm extensors (the abductor pollicis longus and the extensor pollicis brevis muscles) was innervated usually by one branch that arose from the deep branch of the radial nerve just after emerging from the supinator and giving off branches to the superficial forearm extensors. This branch ran on the dorsal (extensor) surface of the abductor pollicis longus muscle distally, sending many twigs to this muscle, and entered into the muscle at various distances from the origin (Figs. 1-6). The abductor pollicis brevis muscle was innervated by some twigs that ran usually inside but occasionally outside of the abductor pollicis longus muscle (Figs. 7-10).(ABSTRACT TRUNCATED AT 400 WORDS)     

Anatomical variation of radial wrist extensor muscles: a study in cadavers

OBJECTIVE: The tendons of the extensor carpi radialis longus and brevis muscles are quite useful in tendon transfer, such as in correction of finger clawing and restoration of thumb opposition. Knowledge of additional radial wrist extensor muscle bellies with independent tendons is useful in the above-mentioned surgical procedures. METHODS: The skin, subcutaneous tissue, and antebrachial fascia of 48 (24 on the right side and 24 on left side) male upper limb forearms were dissected. The following aspects were then analyzed: (a) the presence of additional muscle bellies of radial wrist extensors, (b) the origin and insertion of the additional muscle, and (c) measurements of the muscle bellies and their tendons. RESULTS: Five out of 48 upper limbs (10.41%) had additional radial wrist extensors; this occurred in 3 out of 24 left upper limbs (12.5%) and 2 out of 24 right upper limbs (8.3%). In one of the right upper limbs, two additional muscles were found. The length and width of each additional muscle belly and its tendon ranged between 2 - 15 cm by 0.35 - 6.4 cm and 2.8 - 20.8 cm by 0.2 0.5 cm, respectively. The additional radial wrist extensor tendons in our study basically originated either from the extensor carpi radialis longus or brevis muscles and were inserted at the base of the 2nd or 3rd metacarpal bone. CONCLUSION: The present study will inform surgeons about the different varieties of additional radial wrist extensors and the frequency of their occurrence.     

Comparative Anatomical Study of the Forearm Extensor Muscles of Cebus libidinosus (Rylands et al., 2000; Primates,Cebidae), Modern Humans,and Other Primates,With Comments on Primate Evolution,Phylogeny, and Manipulatory Behavior

Despite its abundance in Latin America, and its remarkable ability to use tools, there are only a few myological studies on the capuchin monkey, Cebus libidinosus. In the present study, we dissected the forearm extensor muscles of six adult males and two adult females of this species. We describe these muscles and compare them with those of other primates dissected by us and by other authors. The forearm extensor muscles of Cebus monkeys are, in general, more similar to those of other platyrrhines than to distantly related taxa that use tools, such as chimpanzees and modern humans, with three main exceptions: contrary to most other platyrrhines, (1) in Cebus, chimpanzees and modern humans the extensor pollicis longus usually inserts onto Digit I, and not onto Digits I and II; (2) in Cebus the abductor pollicis longus has two separate tendons, as is the case in chimpanzees, and in modern humans (where one of these tendons is associated with a distinct belly, forming the muscle extensor pollicis brevis); (3) in Cebus, and in modern humans and chimpanzees, the extensor pollicis longus is not deeply blended with the extensor indicis. Therefore, the Cebus monkeys provide an illustrative example of how phylogenetic constrains and ecological adaptations have been combined to develop a specific myological configuration that, associated with their sophisticated neurological organization, allow them to easily navigate in their arboreal habitats and, at the same time, to finely manipulate objects in order to search for food and to prepare this food for ingestion. Anat Rec, 2010. © 2010 Wiley‐Liss, Inc.     

An unique variation of the peroneus tertius muscle

Peroneus tertius (fibularis tertius) is a muscle unique to humans. It often appears to be a part of extensor digitorum longus, and might be described as its "fifth tendon". Although its insertion variation has been reported by many authors, variations of its origin points are not common. A variation of the peroneus tertius muscle was found during routine dissection of a 75-year-old male cadaver. The muscle originated from the extensor hallucis longus. The muscle belly of the extensor hallucis longus arose from the middle two-fourths of the medial surface of the fibula, medial to the extensor digitorum longus, and anterior surface of the interosseous membrane. It lay under the extensor digitorum longus, and lateral to the tibialis anterior muscle. The muscle belly of the extensor hallucis longus divided into medial and lateral parts 17 cm below its origin point. The lateral part, named as peroneus tertius, continued downward to reach the medial part of the dorsal surface of the base of the fifth metatarsal bone. The medial part ran also downward and divided into two tendons reaching the dorsal surface of the base of the distal phalanx of the great toe. This kind of variation may be important during foot or leg surgery.     

The thenar muscles

Examination of the thenar muscles in 30 anatomical preparations of the hand have shown that the abductor pollicis brevis, the opponens pollicis, and the adductor pollicis muscles are made up of several muscle bellies. The number and insertions of these bellies are varied. Both heads of flexor pollicis brevis do not originate from any particular muscle belly. The superficial head of this muscle always inserted into the head of the thumb metacarpal, either completely, or, some of the fibres of the dorsal aponeurosis of the thumb were attached to the base of the proximal phalanx. Furthermore the anatomy of the abductor pollicis brevis muscle was related to the presence of a tendinous slip from abductor pollicis longus. These variations could have an influence on proprioception in the thumb ray.     

Case of an abductor pollicis longus muscle: variation or differentiation?

A variation of the abductor pollicis longus muscle in a 65 year old cadaver was encountered during routine dissection in our department. The muscle was found to split into two bellies and give off two tendons, one of which inserted to the abductor pollicis brevis, opponens pollicis and flexor pollicis brevis muscles. The other tendon inserted to the first metacarpal bone which is considered a normal insertion site for the abductor pollicis longus muscle.     

Kongenitale oder erworbene Anlage des separaten Faches für die Sehne des M. extensor pollicis brevis bei der Tendovaginitis stenosans de Quervain? Makroanatomische und fetal-plastinationshistologische Untersuchungen zum 1. Strecksehnenfach

Our macroanatomical studies with cadaver specimens and clinical findings in the operative treatment of tendovaginitis stenosans de Quervain confirm the high number of anatomical variations in the first dorsal compartment of the wrist. With the help of thick transparent transversal-sections in one of 14 fetal wrists manufactured by plastination histology we found the first compartment with two tendons of the abductor pollicis longus and dorsal of this compartment a connective tissue formation and a separate compartment for the extensor pollicis brevis tendon, proved as a primary anatomical disposition. Macroscopically the septation is always located distal and dorsal-ulnar to the first compartment and is evidentally more common as an intraoperative than an cadaver dissection finding and probably should be considered as a pathological condition. The secondary formation of an incomplete until complete separate septum may depend on the multiple abductor pollicis longus tendons and on chronical inflammatory reaction of the synovialis of the constricted extensor pollicis brevis tendon.     

Focal reduction of intracortical inhibition in the motor cortex by selective proprioceptive stimulation

The influence of proprioception on motorcortical excitability was assessed by muscle vibration (MV; 80 Hz, 0.5 mm amplitude) of the flexor carpi radialis muscle (FCR) and compared to voluntary contraction and relaxation conditions. Motor thresholds, motor-evoked potentials (MEPs) in response to single pulses of transcranial magnetic stimulation (TMS) and the intracortical inhibition (ICI) and facilitation (ICF) after paired magnetic stimuli were studied. A control experiment using TMS inducing posteriorly directed current was performed. MEPs were recorded simultaneously from the FCR, the extensor carpi radialis, the abductor pollicis brevis and the first dorsal interosseus. In the FCR, MV led to an increase of excitability shown by a decrease of motor threshold, a facilitation of MEPs in response to single-pulse TMS, a reduction of ICI and an increase of ICF. Since especially the ICI and ICF remain unchanged in other recorded muscles, this increase of excitability is specific for the vibrated muscle. With posteriorly directed current the ICI in the FCR was reduced as well, showing an involvement of later I-waves. We suggest that MV induces a focused motorcortical activation which relies on a reduced activity of intracortical inhibitory interneuronal circuits targeting selectively the motorcortical representation of the vibrated muscle. Electronic Publication     

The variable anatomy of the nerve to the extensor carpi radialis brevis

The origin and course of the nerve to the extensor carpi radialis brevis are closely related to the lateral aspect of the elbow joint and proximal portion of the radius—both of which are frequent sites of pathology and surgical treatment. The specific origin of the nerve supply to the extensor carpi radialis brevis muscle has been attributed variably by diverse anatomic and clinical texts to be the radial nerve, its deep branch or its superficial branch. This study was undertaken to determine the most common source of the nerve to the extensor carpi radialis brevis, as well as the most predictable topographic site of its origin. A total of 111 limbs were dissected, with the most common origin (56.7%) found to be the deep radial nerve, followed by the superficial branch of the radial nerve (31.5%), and least frequently from the bifurcation of the radial nerve into its superficial and deep branches (11.7%). This nerve branch was found to arise in most individuals within one centimeter of the distal edge of the humeroradial joint and to pass distally about 3.5 centimeters before entrance into the extensor carpi radialis brevis muscle. © 1993 Wiley-Liss, Inc.