Actions of the Biceps Brachii at the Shoulder: A Review

Abstract

Bi-articular muscles cross more than one joint and contribute to motion at both joints, and the extremities of the human body contain several such muscles. Actions produced by all muscles are determined, to a large extent, by joint moment arms and muscle length. These are transient factors which change as joint angles are altered. Measuring muscle moments while manipulating both joints will produce a better understanding of the actions of bi-articular muscles. This review summarizes investigations which have explored the actions of the biceps brachii as shoulder and elbow joints are moved into various angle combinations. Clinical implications of the findings are discussed.

Superficial Shoulder Muscle Synergy Analysis in Facioscapulohumeral Dystrophy During Humeral Elevation Tasks

“…This situation could produce unnecessary stress on the rotator cuff muscles, which provide a stabilizing function of the glenohumeral head and are preserved in FSHD individuals, based on MRI evidence [11], [12]. The increased synergist Biceps Brachii activity likely assisted in the stabilization of the humeral head and the elevation of the humerus within the decreased range of scapular motion [37]. However, a larger variability in muscle contributions did not reveal a clear relationship between the activity of lower scapular rotators or synergist muscles and the amount of humeral elevation.…”

Effect of preconditioning exercise on biceps brachii myotendinous junction displacement during elbow flexor eccentric exercise

“…The maximal eccentric exercise consisted of five sets of six maximal voluntary isokinetic eccentric contractions of the elbow flexors at an angular velocity of 30° s −1 from a flexed position (60°) to a fully extended position with the wrist being supinated 21 . This small range of motion was chosen, since biceps brachii distal myotendinous junction displacement was better traced for this range, 21 and biceps brachii is a prime mover of the elbow flexion in this range of motion 25 . Each contraction lasted for two seconds and was repeated every 10 seconds during which the isokinetic dynamometer passively returned the elbow joint to the flexed position at the velocity of 10° s −1 , with two minutes rest between sets.…”

Multisensory stimulation to promote upper extremity motor recovery in stroke: A pilot study

“…MMT was used for the evaluation of the motor recovery and strength of shoulder flexion after stroke. The biceps brachii, one of the stimulated target muscles, is one of the three muscles (with coracobrachialis and anterior deltoid) that flex the shoulder and plays an important role in stabilizing the upper limb for functional reaching tasks (Landin et al, 2017). MMT has been shown to be a clinically useful tool with excellent inter-rater reliability (ICC = 0.98) in trained examiners for the use in patients with stroke (Gregson et al., 2000).…”