Undescribed variant muscle – “Deep abductor-flexor” of the little finger, in relation to ulnar nerve compression at the wrist

During routine anatomical dissection in the hypothenar region of the left hand of a 64-year-old female cadaver, a number of variant structures were observed. The most prominent finding in our case was a supernumerary muscle hitherto unknown in the anatomical literature. This variant muscle had a muscular body formed by the connection of two deeply situated muscular bellies--medial and lateral. The lateral belly originated from the flexor retinaculum, the medial one--from the hamate bone. The common muscular body inserted to the antero-lateral surface of the base of the fifth proximal phalanx. Due to its location and possible function, we named the variant muscle "deep abductor-flexor" of the little finger. The flexor digiti minimi brevis muscle showed two proximal tendons--the medial tendon was attached to the hamulus of the hamate bone while the aberrant lateral tendon originated from the lateral part of the flexor retinaculum. Both, the aberrant lateral tendon of the flexor digiti minimi brevis and the lateral belly of the "deep abductor-flexor", passed over the palmar branch of the ulnar nerve, which define their possible clinical significance in ulnar nerve compression. Therefore, the variations of the hypothenar muscles are reviewed and their relation to the compression of the ulnar nerve is discussed.     

The abductor pollicis longus: relation between innervation, muscle bellies and number of tendinous slips

The aim of this study was to assess the relation between the insertions of the distal tendinous slips, the muscle bellies and the innervation pattern of the abductor pollicis longus (APL) muscle and of the extensor pollicis brevis (EPB). The upper extremities of 31 frozen cadavers were dissected under magnifying lenses to describe the distribution of the posterior interosseous nerve (PION). The number and the distribution of distal tendinous slip insertions of the APL muscle were variable. Two superficial and deep distal tendon groups were noted. The separation into superficial and deep muscular parts of the APL was frequent (87%). The EPB muscle was generally constituted by one muscle belly and one tendinous slip (93.5%). The innervation by the PION to the APL and EPB muscles was classified into five types. The specific innervation between superficial and deep muscular parts of the APL muscle, the specific innervation of the deep muscle bellies and the independence of the superficial and deep distal tendon groups of the APL muscle are arguments in favor of a complex functional role of the APL motor unit in thumb mechanics. However, no independence of the tendinous slips in the two distal tendon groups and no correlation between the number of tendinous slips and muscle bellies or innervation were observed. These limit the functional role of the two independent superficial and deep musculotendinous APL motor units. The use of the APL tendon for interposition arthroplasty, for tendon transfer or tendon translocation seems logical, particularly if using one of the two distal tendon groups.     

A rare muscular anomaly in the upper arm--the chondroepitrochlearis muscle with an aberrant type of the muscular arch of axilla.

A rare muscular anomaly was found in the right arm of a 92-year-old man at Nagoya University in 1995. The anomalous muscle had two heads, one ventral and one dorsal. The ventral head was a continuation of the abdominal part of the pectoralis major muscle, and the dorsal head arose from the lateral surface of the latissimus dorsi muscle. The two heads united at the medical surface of the upper third of the arm to form a common tendon, which descended on the medial surface of the upper arm parallel with a long tendon of the coracobrachialis muscle and attached to the medial epicondyle of the humerus. This anomalous muscle was supplied by the most caudal branch of the pectoral ansa (caudal pectoral nerve) and the intercostobrachial nerve (Th2). This pectoral nerve first innervated the ventral head, and next the greater part of the dorsal head. The intercostobrachial nerve (Th2) innervated a small part of the dorsal head. The present anomaly looked quite similar to the case reported by Yokoh as the coexistence of the chondroepitrochlearis and the dorsoepitrochlearis muscles. However, judging from the muscular origin, insertion and innervation, the ventral head was considered to be the chondroepitrochlearis muscle, whereas the dorsal head was not dorsoepitrochlearis muscle but an aberrant type of the muscular arch of axilla.     

肘肌游离肌瓣重建拇指对掌功能的解剖

目的 通过对肘肌和拇短展肌（APB）的解剖学研究,为肘肌作为游离肌瓣重建拇指对掌功能提供解剖学依据。 方法 选取8具肘部、前臂部与手部保存完好的尸体标本,使用游标卡尺（精度0.1 mm）和Image J 1.45 d软件测量肘肌与拇短展肌肌肉面积与肌纤维角度,以及支配两者的神经血管长度与直径,以定量描述肌肉结构以及涉及肘肌游离肌瓣重建拇指对掌功能手术规划的神经脉管系统。 结果 肘肌肌肉纤维长度为(82.0±12.0) mm,拇短展肌肌肉纤维长度为(51.6±8.3) mm;肘肌面积为(937±221) mm²,拇短展肌面积为(704±244) mm²;说明肘肌面积和长度均大于拇短展肌。肘肌和拇短展肌纤维平均角度分别为61°±10°和71°±12°,差异无显著性（P>0.05）。肘肌和拇短展肌神经血管直径分别为： 动脉直径（1.16±0.28）/（1.4±0.4）mm, 神经直径（1.7±0.3）/（1.9±0.3）mm,差异无显著性（P>0.05)。肘肌血管蒂（骨间后动脉）的长度（32.0±3.1）mm、直径（1.16±0.28）mm和并行静脉直径0.8 mm足够进行显微吻合术。 结论 与其他游离肌瓣相比,肘肌在解剖结构、供体并发症等方面优势明显,因此肘肌游离肌瓣进行拇指对掌功能重建十分适宜。     

Modulation of intracortical excitability in human hand motor areas. The effect of cutaneous stimulation and its topographical arrangement

Changes in afferent input can alter the excitability of intracortical inhibitory systems. For example, using paired transcranial magnetic stimulation (TMS), both electrical digital stimulation and muscle vibration have been shown to reduce short-interval intracortical inhibition (SICI). The effects following muscle vibration are confined to the corticospinal projection to the vibrated muscles. The results following digital stimulation are less clear and the relative timing of the cutaneous stimulation and TMS is critical. Here we investigated further whether changes in SICI following digit stimulation exhibit topographic specificity. Eleven normal subjects were investigated (age 28.2±7.5 years, mean±SD). Electromyographic recordings were made from the right first dorsal interosseous (FDI), abductor digiti minimi (ADM) and abductor pollicis brevis (APB) muscles. SICI was measured, with and without preceding electrical digit II or digit V cutaneous stimulation. The interval between the digital nerve stimulus and test magnetic stimulus was independently set for each subject and established by subtracting the onset latency of the motor evoked potential (MEP) from the latency of the E2 component of the cutaneomuscular reflex. Therefore, measures of intracortical excitability were made at a time at which it is known that cutaneous input is capable of modulating cortical excitability. Single digital nerve stimuli applied to digit II significantly reduced SICI in FDI but not in ADM. Single digital nerve stimuli applied to digit V significantly reduced SICI in ADM but not in FDI or APB. There was a more generalised effect on intracortical facilitation (ICF) with both digit II and digit V stimulation significantly increasing ICF in FDI and ADM. Digital stimulation (either DII or DV) did not significantly affect SICI/ICF in APB. These findings show that appropriately timed cutaneous stimuli are capable of modulating SICI in a topographically specific manner. We suggest that the selective decrease in SICI seen with cutaneous stimulation may be important for focusing of muscle activation during motor tasks.     

An accessory belly of the abductor digiti minimi muscle: a case report and embryologic aspects

Accessory fasciculi of the hypothenar muscles have been involved in vascular and nerve compressions. During a routine dissection an accessory belly of the abductor digiti minimi muscle arising from the tendon of the palmaris longus muscle was found in the lower third of the forearm. The accessory fasciculus ran through Guyon’s canal enclosing the ulnar nerve and vessels. It was attached by means of two tendons where the fibres of the abductor digiti minimi muscle ended in a single pennate form. This anatomic variation was associated with a marked reduction of the caliber of the fourth tendon of the flexor digitorum superficialis muscle and a split of the median nerve. The nerve supply arose from the ulnar nerve. A fibrous band originating from this accessory muscular belly was found covering the median nerve. Based on the development of muscles and fibrous structures within the hand and forearm, as well as on our results, we consider the present anomalies as an unusual persistence of an undifferentiated group of mesenchymal cells. These belong to the superficial muscular anlagen layer of the hand, just between the flexor digitorum superficialis muscle blastema (which has the capacity of migration) and that for the abductor digiti minimi muscle.     

丹参、生脉注射液对中枢和神经肌接头兴奋传递及肌肉收缩疲劳的影响

目的 :研究复方丹参、生脉注射液对中枢、神经肌接头和肌肉疲劳的影响。方法 :记录蟾蜍坐骨神经干动作电位和腓肠肌收缩曲线 ,测定中枢、神经—肌接头、肌肉出现疲劳的时间。结果 :同对照组比较 ,丹参组和生脉组中枢、神经—肌接头、肌肉出现疲劳的时间都明显延长。差异具有显著性 (P <0 .0 1 )。结论 :复方丹参、生脉注射液具有抗中枢、神经—肌接头和肌疲劳的作用。     

Studies on the morphology Of Cotugnia digonopora Pasquale 1890 (Cestoda: Davaineidae)

Summary The present paper, Part V of the series deals with the detailed study of the nervous system of C. digonopora. The nervous system in this cestode is divisible into a central nervous system and a peripheral nervous system. The former includes the anterior rostellary nerve ring, cephalic ganglionic mass, the nerves to the four suckers and the lateral longitudinal nerve cords. The peripheral nervous system includes the branches of the lateral longitudinal nerve cords and the neuromuscular cells which connect the muscle fibres with the lateral nerve cords.With 17 Figures in the Text     

骨间后神经及其拇示指肌支的解剖学特征

目的　观察前臂骨间后神经及其拇示指肌支的解剖学特征。 方法　解剖43具尸体的86侧上肢部桡神经深支及其分支到腕背部,观测骨间后神经的行程与投影及其拇示指肌支起始部位横径、长度和骨性标志线与神经干间夹角关系等参数。 结果　骨间后神经及其各分支均呈扁薄的窄带状神经束,其主干和多数肌支都走行在前臂后面中2/4段浅、深层肌之间,终末支止于腕背侧的梭形膨大部;主干起始处横径为（3.79±0.64）mm,各分支在起始部的平均横径（除指伸肌支约2.0 mm外）均小于1.0 mm;在旋后位,它呈向桡侧开放的弓形线段投影在肱骨外上髁至尺骨茎突连线的尺侧,半旋前位时则投影于该连线上或其桡侧。 结论　前臂后面中2/4段是骨间后神经主干及其大多数拇示指肌支在临床上易被损伤、误伤发生的高风险区域。     

Nerve fiber analysis on the so-called accessory subscapularis muscle and its morphological significance

A rare muscular anomaly, so-called accessory subscapularis muscle, was found in the left axillary fossa of a 95-year-old male cadaver during a student dissection practise. The muscle arose near the lateral margin of the scapula from the surface of the subscapularis muscle and ran upward to fuse with the capsule of the shoulder joint via a tendon. It measured 1.0 cm in width, 7.0 cm in length and 1.5 mm in thickness, and was separated from the underlying subscapularis muscle by the axillary and inferior subscapular nerves. Macroscopically, the anomalous muscle received its nerve supply from a branch arising from the lower root of the radial nerve near the origin of the thoracodorsal nerve and entered the muscle from its ventral surface. Nerve fiber analysis showed that the supplying nerve originated from fibers of the dorsal element of C7 immediately cranial to the thoracodorsal nerve. These findings indicate that the present anomalous muscle might be close to the formation of the latissimus dorsi muscle in its derivation rather than the subscapularis muscle.     

Variant abductor pollicis longus muscle: a case report

Abductor pollicis longus (APL) muscle is known to exhibit different variations with respect to its attachments. Various studies have reported the splitting of the APL muscle. Comparative anatomical findings of split insertion of APL is commonly found in chimpanzees, gorillas and gibbons. In the present study, we describe an anomalous APL muscle, which originated from the posterior surface of the shaft of the radius and ulna and traversed a course deep to the extensor retinaculum. Interestingly, immediately after emerging form the deeper aspect of extensor retinaculum, the thin tendon of the APL muscle continued again as a muscular belly in relation to the dorsolateral part of the 1st metacarpal bone, to end as a tendon with its attachment to the base of the proximal phalanx. Such an unusual variation of APL with its attachment into proximal phalanx is a rare finding and may be of importance in altering the mechanics of the thumb during abduction. The clinical significance of such an anatomical variation of APL may be important during reconstructive surgeries involving thumb and also of academic interest.     

Effect of muscle electrostimulation on afferent activities from tibialis anterior muscle after nerve repair by self-anastomosis

Numerous previous studies were devoted to the regeneration of motoneurons toward a denervated muscle after nerve repair by self-anastomosis but, to date, few investigations have evaluated the regeneration of sensory muscle endings. In a previous electrophysiological study (Decherchi et al., 2001) we showed that the functional characteristics of tibialis anterior muscle afferents are affected after self-anastomosis of the peroneal nerve even when the neuromuscular preparation was not chronically stimulated. The present study examines the regeneration of groups I-II (mechanosensitive) and groups III-IV (metabosensitive) muscle afferents by evaluating the recovery of their response to different test agents after self-anastomosis combined or not with chronic muscle stimulation for a 10-weeks period. We compared five groups of rats: C, control; L, nerve lesion without suture; LS, nerve lesion with suture; LSE(m): nerve lesion plus chronic muscle stimulation with a monophasic rectangular current; and LSE(b): nerve lesion plus chronic stimulation with a biphasic current with modulations of pulse duration and frequency, eliciting a pattern of activity resembling that delivered by the nerve to the muscle. Compared to the control group, (1) muscle kept only its original weight in the LSE(b) group, (2) in the LS group the response curve to tendon vibration was shifted toward the highest mechanical frequencies and the response of groups III-IV afferents after fatiguing muscle stimulation lowered, (3) in the LSE(m) group, the pattern of activation of mechanoreceptors by tendon vibrations was altered as in the LS group, and the response of metabosensitive afferents to KCl injections was markedly reduced, (4) in the LSE(b) group, the response to tendon vibration was not modified and the activation of metabosensitive units by increased extracellular potassium chloride concentration was conserved. Both LSE(b) and LSE(m) conditions were ineffective to maintain the post muscle stimulation activation of metabosensitive units as well as their activation by injected lactic acid solutions. Our data indicate that chronic muscle electrostimulation partially favors the recovery of mechano- and metabosensitivity in a denervated muscle and that biphasic modulated currents seem to provide better results.     

Microsurgical anatomy of the ocular motor nerves

This study was designed to provide anatomic data to help surgeons avoid damage to the ocular motor nerves during intraorbital operations. The microsurgical anatomy of the ocular motor nerves was studied in 50 adult cadaveric heads (100 orbits). Dissections were performed with a microscope. The nerves were exposed and the neural and muscular relationships of each portion of the nerve were examined and measured. The superior division of the oculomotor nerve coursed between the optic nerve and the superior rectus muscle after it left the annular tendon, and its branches entered into the superior rectus muscle and levator muscle. A mean of five fibers (range 3–7) innervated the superior rectus muscle, and a mean of one fiber (range 1–2) followed a medial direction (84%) or went straight through the superior rectus muscle (16%). The inferior division of the oculomotor nerve branched into the medial rectus, inferior rectus and inferior oblique muscles. The trochlear nerve ended on the orbital side of the posterior one-third of the superior oblique muscle in 76 specimens. The abducens nerve ended on the posterior one-third of the lateral rectus muscle in 86 specimens. If the belly of the lateral rectus muscle was divided into three superior–inferior parts, the nerve commonly entered into the middle one-third in 74 specimens. Based on the observed data, microanatomical relationships of the orbital contents were revised.     

Innervation of vastus lateralis muscle

The lateral surgical approach to the proximal femur potentially damages the nerve supply to the vastus lateralis (VL) muscle. This study describes the detailed anatomy of the nerve supply to the VL muscle based on dissection of ten cadaveric lower limbs. In all specimens, a single nerve trunk arose from the femoral nerve, which is most subsequently divided into two main divisions. These divisions gave two branches each. These branches coursed from anteriorly and proximally to posteriorly and distally within the muscle. When the muscle was reflected anteriorly from its attachment to the linea aspera, there was no damage to its innervation. Splitting of the VL in the midlateral line of the femur, however, resulted in denervation of the posterior half of the muscle. Precise knowledge of the nerve supply to the VL will help avoid iatrogenic denervation of the muscle in surgical procedures at the proximal femur through the lateral approach.     

The “muscular variant” of Pompe disease: Clinical,biochemical and histologic characteristics

We report on a 2-yr-old boy with progressive muscular weakness and respiratory failure. There was no clinical evidence of heart muscle involvement. Autopsy showed marked intralysosomal glycogen deposition in skeletal muscle and liver with no histological evidence of glycogen deposition in cardiac muscle. The activity of the lysosomal enzyme α-1,4-glucosidase was deficient in skin fibroblasts, skeletal muscle, cardiac muscle, and liver; however, the enzymatic activity in peripheral blood leukocytes was in the low normal range. The child's mother had normal enzymatic activity in leukocytes but heterozygote levels in skin fibroblasts.     

Muscle–tendon arrangement and innervation pattern of the m. flexor digitorum superficialis in the common marmoset (Callithrix jacchus), squirrel monkey (Saimiri sciureus) and spider monkey (Ateles sp.)

The muscle–tendon arrangement of the m. flexor digitorum superficialis (FDS) varies among different primate groups. Recent developmental investigations revealed that the primordium of FDS emerges in the hand region first and relocates to the forearm later. The relationship between the diverse muscle–tendon arrangement and the characteristic developmental process of FDS is important for understanding the evolutionary changes of the FDS. Moreover, the innervation pattern cannot go unremarked when discussing the muscle homology and evolution. We examined the muscle–tendon arrangement and intramuscular nerve distribution of the FDS in three genera of Platyrrhini: three common marmosets (Callithrix jacchus), two squirrel monkeys (Saimiri sciureus) and two spider monkeys (Ateles sp.). We observed that the FDS consisted of multiple muscle bellies. The origin of the muscle bellies to digits II and V varied, whereas muscle bellies to digits III and IV consistently originated from the medial epicondyle. The muscle–tendon arrangement of the FDS differed among the three genera owing to the different origins of muscle bellies to digits II and V. In all the examined specimens, the muscle bellies to digits II and/or III were innervated by the direct nerve branches from the median nerve. However, the muscle bellies to digits IV and V never received direct nerve branches from the median nerve. Nerve branches within the belly to digit III extended into the belly to digit IV, and one nerve branch within the belly to digit IV extended into the belly to digit V. These consistent nerve distribution patterns suggest that different patterns of FDS muscle–tendon arrangement have changed from that of a common ancestral condition. It is plausible that the diverse origins of muscle bellies in the FDS are attributable to the difference in the destination for the relocation of the muscle bellies during developmental processes.     

Mild Muscular Features in Tenascin-X Knockout Mice,A Model of Ehlers–Danlos Syndrome

Introduction: Tenascin-X (TNX) is an extracellular matrix (ECM) glycoprotein, the absence of which in humans leads to a recessive form of Ehlers–Danlos syndrome (EDS), a group of inherited connective tissue disorders characterized by joint hypermobility, skin hyperextensibility, and tissue fragility. A mouse model of TNX-deficient type EDS has been used to characterize the dermatological, orthopedic, and obstetrical features. The growing insight in the clinical overlap between myopathies and inherited connective tissue disorders asks for a study of the muscular characteristics of inherited connective tissue diseases. Therefore, this study aims to define the muscular phenotype of TNX knockout (KO) mice. Materials and methods: We performed a comprehensive study on the muscular phenotype of these TNX KO mice, consisting of standardized clinical assessment, muscle histology, and gene expression profiling of muscle tissue. Furthermore, peripheral nerve composition was studied by histology and electron microscopy. Results: The main findings are the presence of mild muscle weakness, mild myopathic features on histology, and functional upregulation of genes encoding proteins involved in ECM degradation and synthesis. Additionally, sciatic nerve samples showed mildly reduced collagen fibril density of endoneurium. Discussion: The muscular phenotype of TNX KO mice consists of mild muscle weakness with histological signs of myopathy and of increased turnover of the ECM in muscle. Furthermore, mildly reduced diameter of myelinated fibers and reduction of collagen fibril density of endoneurium may correspond with polyneuropathy in TNX-deficient EDS patients. This comprehensive assessment can serve as a starting point for further investigations on neuromuscular function in TNX KO mice.     

A split and conjoined median nerve in the forearm

We observed a variation of the median nerve that split into two divisions in the proximal forearm and conjoined into a single cord in the distal forearm before entering the carpal tunnel. The medial division was larger than the lateral division. An aberrant muscular slip from the flexor digitorum superficialis ran over the medial division of the split median nerve. The muscular slip over the medial division might have caused an entrapment syndrome of this nerve due to several muscular and cutaneous branches originating from the medial division. This variation of the median nerve has not been reported to our knowledge and may affect diagnosis and treatment of any neuropathy of the median nerve.     

腓总神经压迫综合征的解剖学研究

在62侧成人下肢标本上观察了腓总神经穿行的腘窝外侧沟和腓骨长肌纤维拱的形态。拱的入口在腓骨头尘下方1.8cm,拱长2.4cm,属全腱性的拱仅占8.1％。对腓总神经的主要分支部位作了测量,这些数据对腓总神经压迫综合征的诊断和治疗有参考意义。