Unusual vascularization and nerve supply of the fifth finger.

During a dissection course, an unusual variation in vascularization and nerve supply of the fifth finger of the right hand was found in a 73-year-old human male cadaver. The proper digital palmar artery arose from the superficial branch of the ulnar artery distel to the Guyon's canal. The proper digital palmar artery coursed first palmar to the ulnar nerve then between the abductor minimi and flexor digiti minimi muscles to reach the ulnar side of the fifth finger. Besides this, the ulnar border of the fifth finger was supplied on its palmar side by the dorsal branch of the ulnar nerve, which gave off two tiny twigs for the sensory innervation on the dorsal side of the same finger.     

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.     

Bilateral case of superficial ulnar artery originating from axillary artery

During the dissection of an 86-year-old male human cadaver, superficial ulnar arteries were found in both upper limbs. These arteries branched from the axillary arteries. In the left arm, the artery crossed ventral to the medial root of the median nerve before running towards the medial part of the arm. The persistence of the median artery was noted. In the right arm, the ulnar artery had a common origin with the subscapular artery. It crossed anterior to the lateral root of the median nerve and then, in the arm, ran alongside the anterolateral aspect of the median nerve, near the biceps brachii muscle, which was supplied by this superficial ulnar artery. Then the artery crossed the median nerve and the brachial artery. The embryology, incidence and clinical relevance of this anatomical variation are discussed. So this was a rare case where the ulnar arteries originated from the axillary artery on both sides, but then followed different courses in the arm and, on the right side, the superficial ulnar artery partly supplied the biceps brachii muscle.     

39例分娩性臂丛神经损伤新生儿的神经电生理评价

目的:探讨新生儿期电生理检测在评价分娩性臂丛神经损伤中的价值。方法:应用肌电一诱发电位仪对39例分娩性臂丛神经损伤新生儿进行检测。测试项目包括:①患侧臂丛神经五大分支腋神经、肌皮神经、正中神经、尺神经及桡神经运动神经传导速度测定;患侧正中神经、尺神经及桡神经感觉神经传导速度测定;②采用同芯针电极检测臂丛神经支配远端肌肉(三角肌、肱二头肌、4伸指总肌、外展拇短肌、外展小指肌或骨问肌)肌电图。结果:39例新生儿中全臂丛神经损伤11例(28％);上干损伤18例(46％);下干损伤3例(8％);后束损伤7例(18％)。节前损伤11例(28％)。结论:新生儿期神经电生理检测对早期评价分娩性臂丛神经损伤的范围、性质、部位及程度具有重要的临床价值。     

The actualization of heteronomous monosynaptic connections of IA afferents in the muscle motor centers of the human hand

Reflex excitability of spinal centers of hand muscles was examined in normal subjects and patients with traumatic lesion of forearm nerves. Central and peripheral muscle responses were evoked by stimulation of homonymous and heteronymous nerves. Patients with median and/or ulnar nerve lesion showed the heteronymous abductor pollicis brevis and abductor digit minimi H-responses. The cause of appearance of heteronymous responses is supposed to be actualization of latent heteronymous monosynaptic connections following traumatic lesion and afferent deprivation. It seems obvious that activation of heteronymous pathways corresponds to the process in afferent system known as "revitalization" of median-to-ulnar anastomoses after damage.     

正中和尺掌-腕混合神经潜伏期差在腕管综合征诊断中的应用

目的:评估正中和尺掌-腕混合神经潜伏期差在腕管综合征(CTS)诊断中的应用价值。方法:选取2019年1月至2019年12月在常熟市中医院门诊诊断为CTS的患者47例(77只手掌)作为研究组,同时收集同时段在体检中心健康检查的志愿者46名(69只手掌)作为对照组,分别记录正中神经腕-拇短展肌的远端运动潜伏期(DML)、腕-中指的感觉神经传导速度(SCV)、感觉神经动作电位(SNAP)波幅及正中和尺掌-腕混合神经潜伏期差(ΔDSL)。结果:研究组与对照组比较,腕-拇短展肌DML延长[(4.49±0.97)ms比(3.16±0.42)ms],腕-中指SCV减慢[(42.62±7.35)m/s比(60.65±6.70)m/s],SNAP波幅下降[(11.89±8.05)μV比(22.07±7.22)μV],正中和尺掌-腕混合神经ΔDSL延长[(0.84±0.34)ms比(0.23±0.10)ms],差异均具有统计学意义(P<0.05)。腕-拇短展肌DML、腕-中指SCV、正中和尺掌-腕混合神经ΔDSL诊断特异度分别为97.1%、100%、98.6%(P>0.05),诊断敏感度分别为66.2%、59.2%、90.1%(P<0.05)。结论:正中和尺掌-腕混合神经ΔDSL用于诊断CTS是比较敏感的,尤其可以提高早期CTS的阳性检出率。     

Muscle variations and abnormal branching and course of the ulnar nerve in the forearm and hand

During dissection of the right forearm of a 27-year-old female cadaver, variations in the form and insertion of the palmaris longus muscle were observed. The tendon of the palmaris longus muscle, which demonstrated a centrally placed belly, split into two tendons: one inserted into the palmar aponeurosis and the other into the proximal part of the flexor retinaculum. Additionally, we found an accessory muscle extending between the flexor retinaculum and the tendon of the abductor digiti minimi muscle. This accessory muscle was located deep to the ulnar artery but superficial to the superficial and deep branches of the ulnar nerve at the wrist. Finally, an aberrant branch of the ulnar nerve was identified in the forearm; it traveled distally alongside the ulnar artery and in the palm demonstrated communications with common palmar digital nerves from the ulnar and the median nerves. No variations were observed in the contralateral upper limb.     

Ulnar-to-median nerve anastomosis in the forearm. Review and report of 2 new cases

The ulnar-to-median nerve anastomosis in the forearm is a very rare occurrence, not mentioned in many anatomical text books. We found only 4 cases cited in medical literature. Here we describe 2 new cases, for which diagnosis was suspected when the compound muscle action potential of the abductor pollicis brevis muscle (APB), obtained by maximal stimulation of the median nerve at the elbow, was lower than that obtained at the wrist. The diagnosis was confirmed by stimulation of the ulnar nerve at the elbow, which evoked a compound muscle action potential of the APB with a clear negative initial deflection without volume-conducted potential.     

A new method using F-waves to measure muscle fiber conduction velocity (MFCV)

OBJECTIVE: First, to propose a new technique for measuring muscle fiber conduction velocity (MFCV). Second, to ascertain the validation of the new method that uses F-waves (F-MFCV) in healthy volunteers. Third, to examine the relationship between F-MFCV and motor nerve conduction velocity (MCV) in the same subjects. SUBJECTS AND METHODS: F-waves reflecting single motor units were recorded with a multi-channel surface electrode array and weak electrical stimulation to the median or ulnar nerves in 21 healthy volunteers. F-MFCVs of the abductor pollicis brevis (APB) and abductor digiti minimi (ADM) were calculated from the F-wave peak latency in each channel. MFCV during minimal voluntary contraction (V-MFVC) was measured in the same muscles. RESULTS: There was no significant difference between F-MFCV and V-MFCV in the muscles tested The mean F-MFCV value was similar to recently reported MFCV values generated by minimal voluntary contraction. No significant differences were found between the APB and ADM F-MFCVs, whereas the MCV of the ulnar nerve was faster than that of the median nerve. CONCLUSION: The MFCV in a single motor unit could be measured with a multi-channel surface electrode array by recording F-waves induced by weak stimulation. Since V-MFCV generated by minimal voluntary contraction is explained by the size principle, V-MFCV reflects small and slow conducting motor unit. There was no significant difference between F-MFCV and V-MFCV. It seemed that F-MFCV also reflected small motor unit. The reason for the lack of difference in the F-MFCVs of the ADM and APB is considered to be a relatively slow F-MFCV. Moreover, MCV reflected the speed of the fastest nerve fiber, whereas F-MFCV did not.     

Lack of topographic specificity in nerve fiber regeneration of rat forelimb mixed nerves

Multiple nerve repair by means of a Y-shaped nerve guide represents a good model for studying the specificity of peripheral nerve fiber regeneration. Here we have used it for investigating the specificity of axonal regeneration in mixed nerves of the rat forelimb model. The left median and ulnar nerves, in adult female rats, were transected and repaired with a 14-mm Y-shaped conduit. The proximal end of the Y-shaped conduit was sutured to the proximal stump of either the median nerve or the ulnar nerve. Ten months after surgery, rats were tested for functional recovery of each median and ulnar nerve. Quantitative morphology of regenerated myelinated nerve fibers was then carried out by the two-dimensional disector technique. Results showed that partial recovery of both median and ulnar nerve motor function was regained in all experimental groups. Performance in the grasping test was significantly lower when the ulnar nerve was used as the proximal stump. Ulnar test assessment showed no significant difference between the two Y-shaped repair groups. The number of regenerated nerve fibers was significantly higher in the median nerve irrespectively of the donor nerve, maintaining the same proportion of myelinated fibers between the two nerves (about 60% median and 40% ulnar). On the other hand, nerve fiber size and myelin thickness were significantly larger in both distal nerves when the median nerve was used as the proximal donor nerve stump. G-ratio and myelin thickness/axon diameter ratio returned to normal values in all experimental groups. These results demonstrate that combined Y-shaped-tubulization repair of median and ulnar nerves permits the functional recovery of both nerves, independently from the proximal donor nerve employed, and that tissue, and not topographic, specificity guides nerve fiber regeneration in major forelimb mixed nerves of rats.     

Accessory muscle in the hypothenar region: a functional approach.

An accessory muscle was found in the hypothenar region on both hands during routine cadaver dissection. This muscle originated from the tendon of the flexor carpi radialis, crossed the palma manus region superficially and inserted together with the abductor digiti minimi muscle into the ulnar aspect of the basis of the fifth proximal phalanx. The muscle was supplied by one branch arising from the main trunk of the ulnar nerve. Abnormalities of the hypothenar muscles have been described by many authors with a focus on their structural aspects, but there is not enough data about the possible functions they could induce. In our study, we try to elucidate the functions of this accessory muscle. We did not name the variant muscle as it has various functions, each similar to that of individual hypothenar muscles.     

人鱼际肌的肌内神经分支分布和肌梭密度研究

目的探索鱼际肌肌肌内神经分支和肌梭密度的分布。方法采用改良Sihler’s肌内神经染色法和HE染色法进行解剖学研究。结果鱼际肌的神经常从肌起端深面入肌,神经入肌后在拇短展肌、拇对掌肌、拇收肌横头内与肌长轴垂直走向,拇收肌斜头和拇短屈肌内沿肌长轴平行走形。80%～82.5%的拇短屈肌和拇指对掌肌接受正中神经和尺神经的双重支配。拇短屈肌浅头和深头、拇收肌横头和斜头有独立的神经支配,可分出神经肌肉亚部。4块肌内神经分支分布密集区多在肌的中部与近端,可见"Y"、"O"、"H"或"U"型等不同的神经吻合形式。鱼际肌肌梭密度高达16.19～27.14个/g,高低顺序为拇指对掌肌拇短屈肌拇短展肌拇收肌。结论鱼际肌肌内神经吻合丰富,肌梭密度高,除拇对掌肌外,其余肌块可作整肌或半肌移植的供体。     

Electrophysiologic signs of sensory fiber lesion in spinal amyotrophies and the role of physiologic variations of sensory finger innervation pattern

In 33 patients, 30 to 64 years old, with spinal amyotrophy and brachial paresis, the sensory symptoms and electrophysiologic signs were analyzed. The paresthesias were felt most often in the ulnar nerve innervation region. The motor conduction velocities, terminal latency quotient, sensory conduction on direct nerve stimulation were within the limits of normal in both median and ulnar nerve. On percutaneous stimulation normal values were obtained for median nerve, and significantly slower for ulnar nerve innervation region. In four cases no nerve potential was obtained over the ulnar nerve with stimulation of the fifth finger. The nerve potential over the ulnar nerve was elicited mostly by stimulation of median nerve innervated fingers. Congenital variations of sensory innervation pattern were considered, which may increase the liability to destruction.     

Vibrations and sounds from evoked muscle twitches.

Muscle sounds are related to force production, fatigue, and pathology of muscle. However, sound data are frequently contaminated by tremor and motivational artifacts. Also, sound data are frequently reported in transducer-dependent units such as millivolts. To eliminate tremor and motivational artifacts and to obtain data in fundamental, nontransducer-dependent units, an accelerometer was used to record vibrations from human hand muscle twitches evoked by percutaneous stimulation. Reliable and reproducible waveforms were obtained from normal adult volunteers by recording from abductor pollicis brevis (APB) or abductor digiti quinti hand (ADQH) muscle after median or ulnar nerve stimulation, respectively. Latencies from the stimulus to the onset of the acceleration waveform were 5.7 +/- 0.6 and 5.1 +/- 0.6 ms, peak-to-peak amplitudes were 6.5 +/- 2.4 and 7.2 +/- 2.0 m/s2 for the APB and ADQH muscles, respectively.     

儿童肘部尺神经前置术的应用解剖

目的为临床儿童尺神经前置术提供解剖学基础。方法 10具(共20肘)福尔马林固定的6~8岁儿童尸体上肢标本,解剖尺神经沟、尺神经行径伴行血管以及尺神经前置后解剖关系。结果尺神经主要接受尺侧上副动脉血供,前臂尺神经的血供则主要由尺动脉提供,尺侧上副动脉、尺侧下副动脉及尺侧返动脉后支血管的大部分行程与尺神经紧贴伴行,在尺神经前置越过肱骨内上髁时,不会造成伴行血管过度牵拉而对尺神经血供造成影响。尺神经前置后滑动性好,有良好的组织床,同时又能解除屈肘对尺神经牵拉。结论研究结果显示:尺神经前置术不会影响神经血供,具有可行性,前置时需切断上臂内侧肌间隔,皮下前置滑动性好。     

Changes in muscle responses to stimulation of the motor cortex induced by peripheral nerve stimulation in human subjects

The aim of this study was to determine whether prolonged, repetitive mixed nerve stimulation (duty cycle 1 s, 500 ms on-500 ms off, 10 Hz) of the ulnar nerve leads to a change in excitability of primary motor cortex in normal human subjects. Motor-evoked potentials (MEPs) generated in three intrinsic hand muscles [abductor digiti minimi (ADM), first dorsal interosseous (FDI) and abductor pollicis brevis (APB)] by focal transcranial magnetic stimulation were recorded during complete relaxation before and after a period of prolonged repetitive ulnar nerve stimulation at the wrist. Transcranial magnetic stimuli were applied at seven scalp sites separated by 1 cm: the optimal scalp site for eliciting MEPs in the target muscle (FDI), three sites medial to the optimal site and three sites lateral to the optimal stimulation site. The area of the MEPs evoked in the ulnar-(FDI, ADM) but not the median-innervated (APB) muscles was increased after prolonged ulnar nerve stimulation. Centre of gravity measures demonstrated that there was no significant difference in the distribution of cortical excitability after the peripheral stimulation. F-wave responses in the intrinsic hand muscles were not altered after prolonged ulnar nerve stimulation, suggesting that the changes in MEP areas were not the result of stimulus-induced increases in the excitability of spinal motoneurones. Control experiments employing transcranial electric stimulation provided no evidence for a spinal origin for the excitability changes. These results demonstrate that in normal human subjects the excitability of the cortical projection to hand muscles can be altered in a manner determined by the peripheral stimulus applied.     

早期腕管综合征的电生理指标比较

目的:分析诊断早期腕管综合征的电生理指标,比较其敏感性。方法:对临床诊断为早期腕管综合征、正中神经远端运动电位潜伏期(distal motor latency,DML)<4.5ms的患者50例60侧,测定正中神经、尺神经环指-腕的感觉神经动作电位(SNAP)潜伏期差值,正中神经、桡神经拇指-腕的SNAP潜伏期差值,以及正中神经节段检查两点间潜伏期差值,并对其结果进行比较分析。结果:正中神经、尺神经环指-腕的SNAP潜伏期差值异常(≥0.4ms)者58侧,达96.6%;正中神经、桡神经拇指-腕的SNAP潜伏期差值异常(≥0.4ms)者40侧,达80%;正中神经节段检查两点间潜伏期差值异常(≥0.4ms)者25侧,达41.6%。结论:正中神经、尺神经环指-腕的SNAP潜伏期差值异常是早期腕管综合征最敏感的指标。     

Temporal discrimination of two passive movements in humans: a new psychophysical approach to assessing kinaesthesia

Percutaneous electrical stimulation of the motor point of the first dorsal interosseous muscle (FDI) was used to produce a non-painful contraction of the FDI muscle that caused index finger abduction movement but no radiating cutaneous paraesthesias or sharp sensations localized to joints. Pairs of stimuli separated by different time intervals were given and subjects were asked to report whether they perceived a single or a double index finger abduction movement. The threshold value was the shortest interval for which the subjects reported two separate index finger abduction movements. Temporal discrimination movement thresholds (TDMT) were measured for both right and left hand. To assess the possible role of muscle and cutaneous afferents in temporal discrimination, we investigated the effects of high-frequency (20 Hz) electrical stimulation of the right ulnar and radial nerves on TDMT. In humans, muscle afferents from FDI are supplied by the ulnar nerve whereas the cutaneous territory overlying the muscle and joint is supplied by the radial and median nerves. Threshold values were not significantly different for right (75.1 ms) and left (75.6 ms) hands. During ulnar and to a lesser extent during radial nerve stimulation, TDMT values were significantly increased (119.2 and 93.5 ms, respectively) compared with baseline conditions (78.0 ms) whereas no changes were observed during median nerve stimulation (80.5 ms). These results suggest that muscle, and in part cutaneous, afferents contribute to temporal discrimination of a dual movement. The technique may provide a useful way of measuring temporal discrimination of kinaesthetic inputs in humans.     

Definition of a safe-zone in open carpal tunnel surgery: a cadaver study

Carpal tunnel decompression is one of the most common surgical procedures in hand surgery. Cutaneous innervation of the palm by median and ulnar nerves was evaluated to find a suitable incision preserving cutaneous nerves. A morphometric study was designed to define the safe-zone for mini-open carpal tunnel release. Sixteen fresh-frozen (8 right, 8 left) and 14 formalin-fixed (8 right, 6 left) cadaveric hands were dissected. Anatomy of the palmar cutaneous branch of the median and the ulnar nerve, motor branch of the median nerve, superficial palmar arch were evaluated relative to the surgical incision. We also identified the motor branch of the median nerve. Detailed measurements of the whole palmar region are reported in this study. The motor branch of the median nerve was extraligamentous as 60%, subligamentous as 34%, transligamentous as 6%. The palmar cutaneous branches of the median and the ulnar nerves in the palmar region were classified as Type A (34%), Type B (13%), Type C (13%), Type D (none), Type E (40%) according to forms of palmar cutaneous innervation originating from the ulnar and median nerves. Injury to the palmar cutaneous branch of the median nerve (PCBMN) is the most common complication of the carpal tunnel surgery. Various techniques were described to decrease post-operative morbidity. Based on these anatomic findings mini incision between the superficial palmar arch and the most distal part of the PCBMN in the palmar region is the safe-zone for carpal tunnel surgery.     

47例腕管综合征患者的临床及神经电生理改变特征

目的：分析腕管综合征（CTS）患者临床及神经电生理改变特征,以提高临床诊断准确性。方法：对47例临床症状、体征均符合CTS患者的正中神经和尺神经各55条分别进行运动神经传导速度（MCV）和感觉神经传导速度（SCV）测定,其结果与正常参考值作比较;对拇短展肌和某些病例的掌长肌作针极肌电图（EMG）,观察失神经电位以作鉴别诊断。结果：本组正中神经肘-腕MCV有6条未引出动作电位,41条正常,8条减慢,平均MCV较正常参考值减慢,差异有显著意义（P％0．05）;正中神经远端潜伏期（DML）异常率为96％,平均DML较正常参考值延长,经比较差异有显著意义（P〈0．05）;尺神经肘-腕MCV均在正常范围,其DML异常率为2％,与正常参考值比较差异无统计学意义;正中神经SCV异常率为98％;尺神经SCV异常率为2％;47例共55块拇短展肌EMG有49％见失神经电位。结论：结合临床及神经电生理改变特点,可对CTS作出明确诊断,为治疗提供依据。