CT examination of the manipulation system in the giant panda (Ailuropoda melanoleuca)

The manipulation mechanism of the giant panda ( Ailuropida melanoleuca ) was examined by means of CT (computed tomography) and 3-dimensional (3-D) Volume Rendering techniques. In the 3-D images of the giant panda hand, not only the bones but also the muscular system was visualised. Sections of the articulated skeleton were obtained. It was demonstrated that the hand of the panda is equipped with separately moulded manipulation units as follows: (1) the radial sesamoid (RS), the radial carpal, and the first metacarpal (R–R–M) complex; and (2) the accessory carpal (AC) and the ulnar (A–U) complex. When the giant panda grasps anything, the R–R–M complex strongly flexes at the wrist joint, the RS becomes parallel with the AC, and the phalanges bend and hold the object. It is shown that the well-developed opponens pollicis and abductor pollicis brevis muscles envelop and fix the objects between the R–R–M complex and the phalanges during grasping.     

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.     

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 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.     

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.     

拇指掌指关节绞锁18例临床分析及发病机制的探讨

目的 探讨拇指掌指关节绞锁的发病机制,对现有治疗方法做出改良。方法 回顾性分析北京积水潭医院2007年3月-2014年10月收治的18例拇指掌指关节绞锁患者的临床资料,其中男17例、女1例,年龄19~41岁,右侧15例、左侧3例。手术治疗4例,根据手术中发现的解剖特征,推断发病机制;保守治疗14例,其中改良复位手法治疗3例,传统复位手法治疗11例。观察患者治疗后拇指掌指关节的主、被动活动度、疼痛、稳定性以及和关节绞锁是否复发等。结果 (1)4例手术治疗患者术中观察到桡侧籽骨近侧缘撞击掌骨头关节面导致出现软骨缺损,籽骨嵌于软骨缺损内致使拇指掌指关节绞锁。在近节指骨基底处部分松解拇短展肌和拇短屈肌腱止点,可以很容易地解除关节绞锁。术后随访3~6个月,所有患者拇指掌指关节未见不稳定和疼痛,未见绞锁复发。患者术前拇指掌指关节主动活动度平均为-31.8°~-19.3°,被动活动度平均为-32.5°~30°;术后关节主、被动活动度一致,平均为-3.8°~52.5°;患者对手术疗效的主观评价均满意。(2)14例保守治疗患者均复位成功,其中改良复位手法3例,传统复位手法11例。复位前拇指掌指关节活动度平均为-28.6°~-15.2°,被动活动度为-30.4°~26.5°;复位后关节主、被动活动度一致,平均活动度为-15.8°~47.5°。随访6~8周,末次随访双侧拇指掌指关节活动度一致,未见关节不稳定和疼痛,未见绞锁复发。结论 拇指掌指关节绞锁的发病机制为拇指过伸时桡侧籽骨向远端和桡侧移位,其近侧缘在掌骨头关节面上刻划出一沟槽状软骨缺损,在拇短展肌和拇短屈肌腱的张力作用下,籽骨嵌于软骨缺损中而导致关节发生绞锁。根据这一损伤机制,改良复位手法可被用于治疗拇指掌指关节绞锁。     

Neurovascular relationships of the approaches for arthroscopic total trapeziectomy with ligamentous stabilization

The aim of this study was to define the neurovascular relationships of the approaches used during arthroscopic total trapeziectomy with the Thompson "suspension-plasty." Fifteen fresh cadavers in which trapezio-metacarpal arthritis had been confirmed by preoperative radiographs were chosen. There were 12 women and 3 men (average age: 87 years), and small joint arthroscopy equipment was used. Two approaches for the trapezio-metacarpal joint were used: an ulnar approach situated at the ulnar border of the extensor pollicis brevis tendon and a radial approach placed at the middle of a line joining the tendons of the flexor carpi radialis and the abductor pollicis longus. A new transosseous approach at the base of the first metacarpal ("trans-M1" approach) is suggested and was used to do the ligamento-plasty. After the operation, a large skin flap was elevated in order to measure the distance between each surgical approach and the different neurovascular structures (radial artery, dividing branches of the superficial branch of the radial nerve and the end of the lateral cutaneous nerve of the forearm) and to verify the absence of neurovascular lesions. The different neurovascular structures at risk during this arthroscopic maneuver were the radial artery for the ulnar approach, the branches of the superficial branch of the radial nerve for all of the approaches and the ending of the lateral cutaneous nerve of the forearm for the radial and "trans-M1" approaches. The use of the approaches described allows arthroscopic trapeziectomy with the Thompson suspension-plasty without us having noted neurovascular lesion.     

Carpal bone movements in gripping action of the giant panda (Ailuropoda melanoleuca)

The movement of the carpal bones in gripping was clarified in the giant panda ( Ailuropoda melanoleuca ) by means of macroscopic anatomy, computed tomography (CT) and related 3-dimensional (3-D) volume rendering techniques. In the gripping action, 3-D CT images demonstrated that the radial and 4th carpal bones largely rotate or flex to the radial and ulnar sides respectively. This indicates that these carpal bones on both sides enable the panda to flex the palm from the forearm and to grasp objects by the manipulation mechanism that includes the radial sesamoid. In the macroscopic observations, we found that the smooth articulation surfaces are enlarged between the radial carpal and the radius on the radial side, and between the 4th and ulnar carpals on the ulnar side. The panda skilfully grasps using a double pincer-like apparatus with the huge radial sesamoid and accessory carpal.     

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)     

手骨间掌侧肌数目的观察

解剖、观察25例成人手的第1掌骨间隙,发现具有额外肌束者18例(72%),分析认为位于此间隙内、止于拇指近侧节指骨的额外肌束属于拇收肌的扩展部分,不宜命名新的“骨间掌侧肌”。     

Insertion of the abductor hallucis muscle in feet with and without hallux valgus

Textbooks of human anatomy present different opinions on the insertion of the abductor hallucis muscle which is concerned in etiology as well as in therapy of hallux valgus. In plastic and reconstructive surgery the muscle is taken as a graft for flap-surgery. In this study 109 feet (58 right, 51 left) were examined, 18 of these with clinical hallux valgus. The tendon of the muscle may attach to the tendon of the medial head of the short flexor hallucis muscle where a subtendineous bursa can be found. At the head of the first metatarsal bone the joint capsule is reinforced by fibres arising from the medial sesamoid bone which may be called "medial sesamoidal ligament." The tendon passes the first metatarsophalangeal joint plantarily to its transverse axis. Three types of insertion could be distinguished: type A, insertion at the proximal phalanx (N = 42); type B, insertion at the medial sesamoid ligament and at the medial sesamoid bone (N = 65); type C, insertion at the medial sesamoid bone (N = 2). In all types superficial fibres of the tendon extended to the medial and plantar sides of the base of the proximal phalanx, running in a plantar to dorsal direction. Statistical analysis exposed neither significant differences between both sides nor significant difference between normal feet and feet with hallux valgus. Therefore, a specific pattern of insertion of the abductor hallucis muscle in hallux valgus cannot be stated.     

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.     

The tabatière anatomique

There is scant detailed information regarding the tabatière anatomique (anatomical snuff box) in the literature. The authors dissected this area in 15 adult cadavers (30 sides) and made measurements and observations of this region. We found that the average mean width and length of this geometric area was 4 cm and 6 cm, respectively. Although the dimensions of the tabatière anatomique tended to be larger among male specimens this trend did not reach statistical significance (P > 0.05). There was no statistical difference between left and right sides. The majority (70%) of specimens was noted to have connections between the cephalic vein and the vena comitantes of the radial artery within the tabatière anatomique. Five specimens were noted to have a muscular branch to the abductor pollicis brevis muscle arising from the dorsalis pollicis artery in the tabatière anatomique. The dorsalis pollicis artery was found to originate in the tabatière anatomique in all specimens. One right-sided specimen was noted to have an intraosseous branch of the radial artery that entered the styloid process of the radius. A well-formed collection of fat was noted between the styloid process and base of the first metacarpal in all specimens. This fat pad completely covered the radial artery in the majority of specimens and had loose connections to both the first and second dorsal compartments. The branches of the superficial branch of the radial nerve always originated distal to the tendon of the EPB muscle. These data may prove useful to the surgeon or clinician who operates or examines this interesting anatomical area.     

Palmar interosseous muscle of the human thumb

The adductor pollicis muscle was studied in fifty hands of Japanese adult cadavers of both sexes. The radial portion of the oblique head of the adductor pollicis muscle has carpal and metacarpal origins and an insertion into the wing tendon of the extensor apparatus. This portion was located dorsal to the palmar metacarpophalangeal articular nerve and superficial palmar metacarpal artery. Thus, the radial portion of the oblique head of the adductor pollicis muscle (more strictly, the slips dorsal to the palmar-penetrating twig of the ulnar nerve) is similar to the palmar interosseous muscles, except that its slips cannot be clearly distinguished from each other.     

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.     

Superficial palmar arch completion at the first interdigital cleft: a case report

Knowledge of variations in the formation of superficial palmar arch is beneficial for successful vascular surgery in the hand as well as for plastic surgeons. The authors describe an unusual completion of superficial palmar arch by first dorsal metacarpal branch of radial artery at the first interdigital cleft which was encountered during routine upper limb dissection for undergraduates. The arteria princeps pollicis and arteria radialis indicis also were the branches of first dorsal metacarpal artery at the first interdigital cleft.     

以拇指桡侧筋膜血管为蒂第1掌骨背侧皮瓣的应用解剖

目的：为以拇指桡掌侧动脉掌指关节周围分支为蒂的第１掌骨背侧皮瓣提供解剖学基础。方法：新鲜尸体手标本３２个,分别进行血管染料灌注、血管造影、透明标本、显微解剖观察。结果：①拇指桡掌侧动脉掌指关节周围分支在第１掌指关节桡背侧与拇指桡侧指背动脉吻合,并在第１掌骨背侧区域形成筋膜、皮下血管网;②第１掌骨背侧有２条同行浅静脉干,其位于拇短伸指肌腱两侧,并存在静脉瓣膜。结论：以拇指桡掌侧动脉第１掌指关节周围支为主要血供来源,经拇指背静脉交通至头静脉为主要回流途径的血管筋膜蒂皮瓣,血供可靠、切取方便、供区创伤较小,临床上可用于修复拇、示、中、环指皮肤软组织缺损。