Anastomosis Patterns between the Median and Ulnar Nerves in the Upper Limbs

There are four types of anastomoses between themedian and ulnar nerves in the upper limbs. It consists of crossings of axons that produce changes in the innervation of the upper limbs, mainly in the intrinsic muscles of the hand. The forearm has two anatomical changes ­ Martin-Gruber: branch originating close to the median nerve joining distally to the ulnar nerve; and Marinacci: branch originating close to the ulnar nerve and distally joining the median nerve. The hand also has two types of anastomoses, which are more common, and sometimes considered a normal anatomical pattern ­ Berrettini: Connection between the common digital nerves of the ulnar and median nerves; and Riche-Cannieu: anastomosis between the recurrent branch of the median nerve and the deep branch of the ulnar nerve. Due to these connection patterns, musculoskeletal disorders and neuropathies can be misinterpreted, and nerve injuries during surgery may occur, without the knowledge of these anastomoses. Therefore, knowledge of them is essential for the clinical practice. The purpose of the present review is to provide important information about each type of anastomosis of the median and ulnar nerves in the forearm and hand.

Nerve Conduction Study Findings in Ulnar-Median Nerve Intercommunications in the Upper Limb: A Short Review

Intercommunications between ulnar and median nerves in the forearm and hand are a commonly encountered phenomenon. Clinicians should be aware of these communications for better diagnosis and management of the patient, as the clinical presentation can often be misleading. Surgeons should be aware of these anastomoses so as to prevent any iatrogenic injury during the course of treatment. Furthermore, these intercommunications can distort the findings on nerve conduction studies, leading to misinterpretation and misdiagnosis. In the forearm region, there are two prominent median-ulnar anastomoses, namely, Martin–Gruber anastomosis (MGA) and reverse MGA (Marinacci anastomosis). Similarly, in the palm too, there are two major anastomoses, namely, Riche–Cannieu anastomosis and Berrittini anastomosis. Here, in this review, we would like to emphasize on electrophysiological findings that can be observed in the presence of such anastomoses.

Communicating branches between the median and ulnar nerves: proposal for inclusion in terminologia anatomica / Ramos comunicantes entre los nervios mediano y ulnar: propuesta de inclusión en terminologia anatomica

The ulnar and median nerves are widely distributed, innervating the muscles of the forearm and hand. In the latter, it also registers the sensitivity of a significant part of the skin. A series of communicating branches (CB) is described on the path of these nerves, including: 1) the Martin-Gruber communicating branch, 2) the Marinacci communicating branch, 3) the Riché-Cannieu communicating branch and 4) the Berrettini communicating branch. The aim of this study was to establish a correct denomination of these CB, using Latin and eliminating the use of eponyms. The exploratory study included books on anatomy and scientific articles that detailed the anatomical aspects of these CB. To these were added the terms that these branches presented in the various anatomical lists and terminologies. Each term proposal was done in Latin, using the corresponding gender, number and case. The CB between the median and ulnar nerves are described in anatomy texts as well as a plethora of publications. The prevalence rates of the CB range between 1.7 and 94 %; however, their inclusion in the anatomical terminologies has been limited. Based on the description of these branches and the presence of some of them in the existing terminologies, a proposal was prepared in line with the indications of the Federative International Programme on Anatomical Terminologies (FIPAT): 1) Ramus comunicans cum nervo ulnari, 2) Ramus comunicans cum nervo mediano, 3) Ramus communicans cum ramo profundo nervi ulnaris y 4) Ramus communicans cum nervo digitali palmari communi. Considering that terminologies are dynamic linguistic corpora, it is important to analyze constantly the incorporation of new terms that are in harmony with the scientific findings. The incorporation of new structures must follow FIPAT guidelines and include the grammatical aspects of Latin.

Los nervios ulnar y mediano presentan una amplia distribución que permite inervar músculos del antebrazo y mano, en esta última, también registran la sensibilidad de un importante territorio cutáneo. En el recorrido de estos nervios se describen una serie de ramos comunicantes (RC), entre los cuales destacan: 1) Ramo comunicante de Martin-Gruber 2) Ramo comunicante de Marinacci 3) Ramo comunicante de Riché-Cannieu y 4) Ramo comunicante de Berretini. El propósito de este trabajo fue establecer una correcta denominación de estos RC, usando para ello el latín y eliminando el uso de epónimos. El estudio exploratorio incluyó libros de anatomía y artículos científicos que detallaran los aspectos anatómicos de estos RC. A lo anterior se sumaron los términos que estos ramos presentaron en las diversas nóminas y terminologías anatómicas. Cada propuesta de denominación se realizó en latín, utilizando el género, número y caso correspondiente. Los RC entre los nervios mediano y ulnar se encuentran descritos tanto en textos de anatomía como en un sinnúmero de publicaciones. Las tasas de prevalencia de los RC fluctúan entre 1,7 y 94 %; a pesar de ello; su inclusión en las terminologías anatómicas ha sido limitado. En base a la descripción de éstos ramos y la presencia de algunos de ellos en las terminologías existentes, se elaboró una propuesta alineada con las indicaciones del Programa Federativo Internacional de Terminología Anatómica (FIPAT): 1) Ramus comunicans cum nervo ulnari, 2) Ramus comunicans cum nervo mediano, 3) Ramus communicans cum ramo profundo nervi ulnaris y 4) Ramus communicans cum nervo digitali palmari communi. Considerando que las terminologías son cuerpos lingüísticos dinámicos, resulta importante analizar constantemente la incorporación de nuevos términos que se encuentren en sintonía con los hallazgos científicos. La incorporación de nuevas estructuras debe seguir los lineamientos de FIPAT y considerar los aspectos gramaticales del latín.

A preliminary study on the reinnervation effect of the Riche-Cannieu anastomosis / 中华显微外科杂志

ObjectiveTo study whether the abductor pollicis brevis been effected by the reinnervation of the Riche-Cannieu anastomosis in the median nerve injury cases.MethodsCollect 43 cases (29male,14 female,mean age 32.6)corresponds with the study needs: (1)The traumatic median nerve injury (proved by the results of electrophysiological examine and the clinic diagnose)on or below the forearm.(2)The existence of RCA was verified by the electrophysiological examine results,and the amplitude of electric potential was under 1mv.(3) Rule out the cases with the other injure of nerve or nervous system disease and cervical vertebra disease,diabetes patient.The analysis base on the results of 43 case's periodical examine,the periodical criteria as following: within 2-4th week,within the 2-4thmonth and 1 year after the injury.Results Forty-three cases had not obvious recovery indication of the median nerve under the clinical and electrophysiological aspect,eight cases of abductor pollicis brevis function improved quickly in 3 months,the relevant CMAP amplitude of Riche-Cannieu anastomosis increased apparently,the EMG (Electromyography)results of abductor pollicis brevis ameliorated accordingly.ConclusionIn the case of RCA combined with the median nerve injury,the abductor pollicis brevis fibra might be dominated by RCA reinnervation when losing domination of median nerve,the reinnervation process will much faster than the regeneration process of the broken nerve.

An electrophysiological study of Riche-Cannieu anastomosis / 中华物理医学与康复杂志

Objective To explore the optimal electrophysiologieal approach for detecting Riehe-Cannieu anastomosis(RCA),an anomalous anastomosis between the deep branch of ulnar nerve and the recurrent branch of the medial nerve in the palm of the hand,and to estimate its incidence. Methods One hundred subjects(56 male,44 female,mean age 37.8 years)without any hand motor or sensory dysfunction were selected randomly.The ulnar nerve was stimulated at both the elbow and wrist,and recordings were made from the abductor pollicis brevis,which is normally innervated by the medial nerve,to document any compound muscle action potentials(CMAP).CMAP recorded from both points during stimulation is an accepted indicator of RCA.Group A comprised 40 hands of 20 subjects,while group B included 160 hands of 80 subjects.Surface electrode stimulation was used in both groups.Surface and needle electrode recording was used in group A,while only needle electrode recording was used in group B.Results In group A,31 hands of 16 subjects were found to have RCA by means of surface electrode recording,but only 6 hands of 3 subjects were found to have RCA by means of concentric needle electrode recording.There was a difference of up t0 80.6% between results obtained by the 2 recording methods.In group B,35 hands of 20 subjects were found to have RCA.A total of 41 hands of 23 subjects among the 100 were found to have RCA when concentric needle electrode recording was used(20.5%incidence). Conclusion The type of recording electrode influences the accuracy of RCA examination.An accurate and reliable result can be obtained by using a concentric needle electrode.The abductor pollicis brevis can be anomalously innervated by the ulnar nerve because of RCA.When both the medial and ulnar nerve have been injured.RCA might result in anomalous clinical symptoms and electrophysiological findings.Thoroughly understanding this anomaly is of crucial importance in the clinical evaluation and diagnosis of medial or ulnar nerve injury,as well as to avoid mistakenly interpreting the electrophysiological data when Riche-Cannieu anastomosis is present.

The effect of Riche-Cannieu anastomosis on the diagnosis of patients with carpal tunnel syndrome / 中华物理医学与康复杂志

Objective To study the effect of the Riche-Cannieu anastomosis, an anomalous anastomosis between the deep branch of ulnar nerve and the recurrent branch of median nerve in the palm of the hand, on the diagnosis of patients with carpal tunnel syndrome. Methods Twelve patients (2 male, 10 female, mean age 49.8 years) with carpal tunnel syndrome with the presence of Riche-Cannieu anastomosis were tested in this study. Their clinical data including the symptoms and signs, electrophysiological findings and diagnosis were collected and discussed in relation to an anatomical review of these nerves. Results Due to the existence of the Riche-Cannieu anastomosis, the patients with carpal tunnel syndrome spared part or all of the function of the abductor pollicis brevis (APB) muscle. It may result in an unconformity of the patients′lesion degree caused by carpal tunnel syndrome and its clinical symptoms and electrophysiological findings. Conclusion Knowledge of the Riche-Cannieu anastomosis is of crucial importance in the clinical evaluation, diagnosis and treatment of carpal tunnel syndrome, as well as in avoiding errors in interpreting the electrophysiological data of the patients.