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Table 2 Target muscles with related functions and clinical tests

From: Increased task-uncorrelated muscle activity in childhood dystonia

Target muscles Function Clinical test
Flexor Carpi Ulnaris FCU Flexes and adducts the wrist, and may assist in flexion of the elbow Flexion of the wrist toward the ulnar side, with the forearm in full supination and supported by the examiner
Extensor Carpi Radialis ECR Extends and abducts the wrist, and assists in flexion of the elbow Extension of the wrist toward the radial side, with the forearm in slightly less than full pronation and rest on the table for support
Biceps Brachii BIC Flexes the shoulder joint and assists with shoulder adduction. Flexes the elbow and, with the origin fixed, supinates the forearm Elbow flexion with the forearm in supination
Triceps Brachii TRIC Extends the elbow joint and assists in adduction and extension of the shoulder joint Extension of the elbow joint, with the shoulder at 90° abduction, and with the arm supported by the table
Anterior Deltoid AD Flexes and, in the supine position, medially rotates the shoulder joint. Stabilizes the abduction of the shoulder joint. Shoulder abduction in slight flexion, with the humerus in slight lateral rotation
Lateral Deltoid LD Abduction of shoulder joint Shoulder abduction without rotation and with the elbow should be flexed
Posterior Deltoid PD Extends and, in the prone position, laterally rotates the shoulder joint. Stabilizes the abduction of the shoulder joint Shoulder abduction in slight extension, with the humerus in slight medial rotation
Supraspinatus SS Abducts and laterally rotates the shoulder joint, and stabilizes the head of the humerus in the glenoid cavity during these movements With the elbow bent, the arm is placed in abduction to shoulder level. Have the subject hold the position of slight anterior abduction and slight external rotation against pressure