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Compression Neuropathies
Published in J. Terrence Jose Jerome, Clinical Examination of the Hand, 2022
The median nerve gives a recurrent motor branch at the distal end of flexor retinaculum to innervate the abductor pollicis brevis muscle, first two lumbricals and opponens pollicis muscles. The median nerve then divides into the digital nerves that provide sensation to the thumb and index finger, middle finger and radial half of the ring finger.
The neurological examination
Published in Michael Y. Wang, Andrea L. Strayer, Odette A. Harris, Cathy M. Rosenberg, Praveen V. Mummaneni, Handbook of Neurosurgery, Neurology, and Spinal Medicine for Nurses and Advanced Practice Health Professionals, 2017
Abductor pollicis brevis muscle (Figure 11.1n) Innervation: Recurrent branch of median nerve (C8 and T1).Function: Abduction of the thumb at right angles to plane of palm.Physical examination: The patient abducts the thumb at the carpometacarpal joint (arrow), in a right angle plane to the palm.
Visual attention affects late somatosensory processing in autism spectrum disorder
Published in International Journal of Neuroscience, 2022
Haruka Noda, Akiko Tokunaga, Akira Imamura, Goro Tanaka, Ryoichiro Iwanaga
Electroencephalogram (EEG) data were obtained using Neuropack μ MEB-9100 (Nihon Kohden Corp., Tokyo, Japan) and analyzed with LabChart (Bio Research Center Co, Ltd., Nagoya, Japan). The EEG responses from C3′ and C4′ (2 cm posterior to C3 and C4) were obtained, according to the International 10–20 System, using Ag-AgCl scalp electrodes. Reference electrodes were attached to the earlobes. Electrode impedance was kept below 5 kΩ during the course of the experiment. Simultaneously, electromyograph (EMG) data were recorded in the right abductor pollicis brevis muscle. Electrical stimulation was delivered at a frequency of 1 Hz to the right median nerve at the wrist, using a square-wave pulse (0.2 ms duration). The motor threshold of the abductor pollicis brevis muscle was identified from the amplitude of m-wave, and the electrical stimulus intensity was set at 1.3 times the motor threshold [21].
Bilateral Martin-Gruber and Marinacci Anastomosis Associated with Carpal Tunnel and Guyon’s Canal Syndrome: Case Report
Published in The Neurodiagnostic Journal, 2022
María Alejandra Maya-González, David Ernesto Geney-Castro, Fabio Salinas-Durán
While recording in the right abductor pollicis brevis muscle (APB), the median nerve compound muscle action potential (CMAP) amplitude, with stimulation at the wrist, was found to be 1.7 mV larger than the response obtained with stimulation at the antecubital fossa (6.1 mV and 4.4 mV, respectively), with normal distal latency and conduction velocity in the forearm. This suggested an anatomical variant, as a differential diagnosis of a partial conduction block. Then, the ulnar nerve was stimulated below the elbow while still recording in the APB, and a response with an amplitude of 1.7 mV was obtained. The sum of the responses obtained by stimulating the median nerve in the antecubital fossa and the ulnar nerve below the elbow was 6.1 mV, which corresponds to the same amplitude value of the CMAP obtained by stimulating the median in the wrist. This suggested the presence of crossing fibers of the ulnar nerve to the median nerve in the forearm (MA anastomosis, Figure 1). A similar pattern was observed in the left upper limb when obtaining a response of the median nerve stimulating in the wrist, with an amplitude of 5.6 mV, 4.2 mV when stimulating in the antecubital fossa and 1.5 mV when stimulating the ulnar nerve below the elbow; the sum of the amplitudes of the responses obtained by stimulating the median nerve in the antecubital fossa and the ulnar nerve below the elbow was 5.74 mV, which approximated the amplitude value of the potential obtained when the median nerve was stimulated in the wrist.
Impact of occupational lead exposure on nerve conduction study data
Published in International Journal of Neuroscience, 2022
Tülin Aktürk, Gülay Çeliker, Hikmet Saçmacı
Motor nerve conduction studies included median, ulnar, peroneal and tibial nerve studies. The median motor nerve was stimulated from the distal (wrist) and proximal (elbow) areas and recording was obtained from the abductor pollicis brevis muscle. The ulnar motor nerve conduction study was stimulated in the distal (wrist) and proximal (under elbow) areas and recording was obtained from the abductor digiti minimi muscle. The peroneal motor nerve was stimulated in distal (ankle) or proximal (knee) areas, respectively, and recording was made from the extensor digitorium brevis muscle. The tibial motor nerve was stimulated in distal (ankle) or proximal (popliteal fossa) areas, respectively, and a record was obtained from the abductor hallucis muscle. The distal motor latency was calculated as the time from stimulus to the initial compound muscle action potential (CMAP) deflection from baseline, and the amplitude of CMAP was measured from baseline to the negative peak.