Human forearm position sense after fatigue of elbow flexor muscles

After a period of eccentric exercise of elbow flexor muscles of one arm in young, adult human subjects, muscles became fatigued and damaged. Damage indicators were a fall in force, change in resting elbow angle and delayed onset of soreness. After the exercise, subjects were asked to match the forearm angle of one arm, whose position was set by the experimenter, with their other arm. Subjects matched the position of the unsupported reference arm, when this was unexercised, with a significantly more flexed position in their exercised indicator arm. Errors were in the opposite direction when the reference arm was exercised. The size of the errors correlated with the drop in force. Less consistent errors were observed when the reference arm was supported. A similar pattern of errors was seen after concentric exercise, which does not produce muscle damage. The data suggested that subjects were using as a position cue the perceived effort required to maintain a given forearm angle against the force of gravity. The fall in force from fatigue after exercise meant more effort was required to maintain a given position. That led to matching errors between the exercised and unexercised arms. It was concluded that while a role for muscle spindles in kinaesthesia cannot be excluded, detailed information about static limb position can be derived from the effort required to support the limb against the force of gravity.     

Abnormal disposition of a branch of the ulnar nerve in the flexor retinaculum

The most frequent disposition of the structures within the ulnar tunnel is for the ulnar nerve to be located medial or posteromedial to the ulnar artery. The structures within the ulnar tunnel are closely related to the medial part of the flexor retinaculum. Lesions of the ulnar nerve and artery during endoscopic decompression of the carpal tunnel have been reported (Agee et al. 1992; Lee et al. 1992; Nath et al. 1993; De Smets & Fabry, 1995). An adequate anatomical knowledge of such structures and their variations is therefore important. During a study of the palmar region, we found that a special branch originated from the ulnar nerve in relation to the flexor retinaculum. Documentation of this variation will contribute to the knowledge of the anatomy of the ulnar nerve and its distal branches.     

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.     

Changes induced by eccentric training on force-velocity relationships of the elbow flexor muscles

The aim of this study was to examine the effects of a short term eccentric training period on force-velocity relationships of the elbow flexor muscles. From a muscle model, the maximal shortening velocity V_O(x) and the af parameter which varies according to the curvature of the force-velocity relationship of the muscle were determined. Sixteen volunteer subjects divided into 2 groups participated in this study (Group Eccentric GE, n=8 . Group Control GC, n=8). The subjects performed, on an isokinetic ergometer, 2 maximal concentric elbow flexions at different angular velocities (60, 120, 180; 240, 300, 360 °s^–1) and held maximal and submaximal isometric actions at an elbow flexion angle of 90°. Under isometric conditions, myoelectrical activity (EMG) of the biceps was recorded and quantified as a RMS value. All tests were performed before and after training sessions. Training was conducted 3 times a week for 4 weeks by the GE, and included 6×5 eccentric actions with a load of 100% of 1 RM. After training and for the GE, the af parameter and V_o(x) increased significantly (p<0.05). These changes were accompanied by a significant increase (p<0.05) of the RMS value of the maximal isometric action. This evolution towards faster characteristics for the elbow flexor muscles after training could be partly due to nervous adaptation.     

Functional relationships between the respiratory muscles and muscles performing dynamic work

Summary During training on the bicycle-ergometer a study was made of the electric activity of respiratory muscles and muscles participating in the work while on the bicycle-ergometer (gastrocnemius and femoral). The study was done on healthy individuals. A close two-way connection is established between the electric activity of respiratory muscles and muscles participating in dynamic work. Stabilization of electric activity occurs earlier in the working muscles than in the respiratory muscles. This fact points to the leading role played by afferent impulsation from the muscles participating in the dynamic work for the elaboration of respiration adequate for this work. On the other hand, a drop of the electric activity of working muscles was seen when conditions disturbing the established adequate respiration character were created in the individuals under study.(Presented by Active Member AMN SSSR V. V. Parin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 54, No. 11, pp. 17–21, November, 1962     

Functional relationships between the muscles of mastication and the muscles of the leg

Summary The authors have shown, with the help of electromyography, the functional relationship which exists between the muscles of mastication and certain muscles of the leg after artificially creating interdental occlusal dysfonction. While the activity of the tibialis anterior was not affected by the alteration in occlusion, that of the peroneus longus and gastrocnemius was markedly changed. This is due to the activation of long muscle chains as a consequence of the activation of complex nervous reflexes.

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Rapports fonctionnels entre muscles masticateurs et muscles de la jambe : une étude EMG

Résumé Les auteurs ont mis en évidence à l'aide d'électromyogrammes le rapport fonctionnel qui existe entre les muscles masticateurs et certains muscles de la jambe, après avoir créé artificiellement un dysfonctionnement occlusal interdental. Alors que l'activité du m. tibial antérieur n'a pas été affectée par l'altération du plan occlusal interdental, celle du m. long fibulaire et du m. gastrocnémien a été sensiblement touchée. Ceci est dû à l'activation de longues chaînes musculaires et, par conséquent, à la réalisation de réflexes nerveux complexes.

     

成人前臂前群肌的神经入肌点定位及意义

目的 准确定位成人前臂前群肌神经入肌点（NEP）的体表位置和深度。 方法 成人尸体12具,仰卧。紧贴皮肤连接肱骨外上髁和内上髁间的曲线为横向参考线(H),肱骨外上髁和桡骨茎突间的曲线为纵向参考线(L)。解剖暴露NEP,硫酸钡标记,螺旋CT扫描与三维重建。将NEP在体表上的投影点记为P点,P点通过NEP后投射至前臂后体表上的点为P'点。P点投射到H线与L线上的位置分别记为PH和PL。Syngo系统下确定PH和PL在H和L线上的位置及NEP的深度。 结果 旋前圆肌、桡侧腕屈肌、掌长肌、尺侧腕屈肌、指浅屈肌、拇长屈肌、指深屈肌（正中神经支）、指深屈肌（尺神经支）、旋前方肌NEP的PH分别位于H线上的58.08%、64.17%、75.14%、61.14%、62.26%、52.07%、50.81%、63.38%和51.37%处;PL分别位于L线上的9.79%、3.97%、16.37%、4.42%、17.88%、34.17%、30.27%、11.48%和75.32%处;穿刺深度分别位于PP'线的26.80%、25.06%、27.68%、28.13%、37.30%、39.85%、49.26%、70.86%和44.25% 处。以上数据均为平均值。 结论 这些NEP的体表穿刺位置与深度的界定可为提高前臂前群肌痉挛肌外神经溶解术靶点阻滞的效率、手术切断神经肌支治疗肌痉挛的微创切口设计、作为供肌的功能评估、以及肌移植术中对神经的保护等提供形态学指导。     

Coupling between "hand" primary sensorimotor cortex and lower limb muscles after ulnar nerve surgical transfer in paraplegia

Previous neuroimaging evidence revealed an "invasion" of "hand" over "lower limb" primary sensorimotor cortex in paraplegic subjects, with the exception of a rare patient who received a surgical motor reinnervation of hip-thigh muscles by the ulnar nerve. Here, the authors show that a functional reorganization of cortico-muscular and cortico-cortical oscillatory coupling was related to the recovery of the rare patient, as a paradigmatic case of long-term plasticity in human sensorimotor cortex after motor reinnervation of paraplegic muscles. This conclusion was based on electroencephalographic and electromyographic data collected while the patient and normal control subjects performed isometric muscle contraction of the left hand or lower limb. Cortico-muscular and cortico-cortical coupling was estimated by electroencephalographic-electromyographic coherence and directed transfer function of a multivariate autoregressive model.     

Positional relationships between the masticatory muscles and their innervating nerves with special reference to the masseter and zygomaticomandibularis in Suncus murinus

In the present study, we investigated the structure and nerve innervation of the masseter, temporalis and zygomaticomandibularis of Suncus murinus which has no zygomatic arch. Detailed dissection of eight head halves of four S. murinus was performed. In S. murinus, small muscle bundle was observed to be adjoined with the lateral surface of the temporalis. This muscle bundle was completely separated from the masseter. Based on the positional relationships between the muscle bundle and supplying nerves, we conducted that the bundle corresponded to the zygomaticomandibularis of human described in our previous study (Shimokawa et al., 1999). In addition, some differences in the nerve distribution to the masticatory muscles were observed in S. murinus as compared with humans with respect to the following points: 1) The additional supplying branch to the masseter originated from the auriculo-temporal nerve: 2) The common trunk of the masseteric nerve and the nerve to the posterior part of the temporalis penetrated the superior head of the lateral pterygoid. A possible model to account for these differences based on the positional relationships among the muscles and supplying nerves is presented.     

The motor branches of median and ulnar nerves that innervate superficial flexor muscles: a study in human fetuses

Purpose  

We aimed to describe the distribution of the motor branches of the median and ulnar nerves that innervate the superficial flexor muscles in detail, as well as to determine any communication between these two nerves in a series of 100 human fetuses.     

肌皮神经并正中神经及尺神经变异1例

在解剖一具老年男性标本时，见左侧肌皮神经并正中神经及尺神经形态变异(附图)。经查有关文献，此类变异较为少见，现报道如下：     

尺神经沟肘管尺神经的观测及临床意义

目的 为探讨肘管综合症的发病机制。方法 测量肱骨尺神经沟的深度、肘管直径、尺神经肘管段直径。结果 肱骨尺神经沟深度为０．３６ｍｍ;上肢肘管平均直径为０．５５ｍｍ;尺神经肘管段平均直径为０．２４ｍｍ。结论 尺神经肘管段全部嵌入尺神经沟内,嵌合得越紧,发生肘管综合症的可能性越大。     

Complete ulnar innervation of the thenar muscles combined with normal sensory fibres in a subject with no peripheral nerve lesion.

A complete ulnar innervation of all thenar muscles, including the opponens, have to our knowledge been described only in patients with severe traumatic lesions of the median nerve. The present study reports a subject with exclusive ulnar innervation of the thenar muscles in the right hand. The patient had no anamnestic or objective signs of peripheral nerve lesions. While his sensory and motor ulnar nerve fibres were normal, electrophysiological examination of the right median nerve showed normal course of the sensory fibres but apparently no motor fibres to the thenar muscles.     

Connections between utricular nerve and neck flexor motoneurons of decerebrate cats

We studied the circuitry between the utricular (UT) nerve and ventral neck motoneurons innervating the longus capitis (LC), a neck flexor muscle, in decerebrate cats. We recorded intracellularly from 63 LC (ipsilateral 37, contralateral 26) motoneurons in C1 and C2 segments. UT nerve stimulation evoked disynaptic, excitatory postsynaptic potentials in all ipsilateral LC motoneurons, and inhibitory postsynaptic potentials that were at least trisynaptic in almost all contralateral LC motoneurons. UT effects on neck motoneurons innervating muscles involved in flexion and lateral turning are similar to the connections between the UT nerve and neck extensor motoneurons. These neuron circuits may play a role in fixing the head and the neck to the body during horizontal linear acceleration.     

Wide-range visualization of compound nerve action magnetic fields in the human median and ulnar nerves from the forearm to Erb's point

We successfully visualized the compound nerve action magnetic fields (CAFs) in the human median and ulnar nerves from the forearm to Erb's point. To observe the CAFs, we used a superconducting quantum interference device gradiometer system that was developed for human peripheral nerves. The CAFs were visualized as a quadrupole pattern consisting of leading and trailing dipoles. The CAFs propagated along the anatomical pathway and extended longitudinally in the proximal segment. The most reasonable explanation is that the peak separation in the trailing dipole appeared when the leading dipole reached the proximal segment after stimulation of the median nerve at the wrist. A temporal dispersion of the CAFs was suggested to be visualized.